AREA FORECAST DISCUSSION
NWS MARQUETTE MI
AFDMQT 430 PM EST FRI JAN 19 2007
.SYNOPSIS AND SHORT TERM (TONIGHT)...
UPPER LEVEL TROUGH WITH COLD AIRMASS SETTLING ACROSS UPR GREAT
LAKES. H85 TEMPS AROUND -20C HAVE ARRIVED. THE COLD AIR ALONG WITH
SHORTWAVES ROTATING ON WEST PERIPHERY OF TROUGH INTENSIFIED LK
EFFECT SNOW BANDS BOTH LAST NIGHT AND AGAIN LATE THIS MORNING
THROUGH THIS AFTN. IR SATELLITE LOOP SHOWS BACK EDGE OF DEEPER
MOISTURE AND WEAK LIFT PRESSING INTO WESTERN LK SUPERIOR. 12Z RAOB
FM KAPX AND 16Z TAMDAR SOUNDING FM KSAW IN MODIFIED AIR DOWNSTREAM
OF LK SUPERIOR SHOWED INVERSION HEIGHTS AROUND 750MB WITH TEMPS AT
TOP OF INVERSION AROUND -18C (KAPX) AND -24C (KSAW). UPSTREAM IN
WAKE OF MOISTURE/SHORTWAVE...A 17Z TAMDAR FM KINL SHOWED INVERSION
LOWERING TO LESS THAN H9. LOW LEVEL WINDS TO H85 ARE MOSTLY FM 310
DIRECTION IN BTWN LOW PRES EXITING OFF COAST OF ME AND HIGH PRES
BUILDING ACROSS CNTRL CANADA INTO THE PLAINS. MUCH FARTHER UPSTREAM
A SHORTWAVE TROUGH IS PRESENT OVR FAR SW CONUS WITH PCPN ADVANCING
INTO WESTERN TX ATTM...WHILE ANOTHER SHORTWAVE COMPLEX IS DRIVING
INTO BRITISH COLUMBIA.
FOR THE VERY SHORT TERM...SNOW AMOUNTS AND STATUS OF HEADLINES ARE
MAIN CONCERNS. LK EFFECT SNOW SHOULD CONTINUE DESPITE INVERSION
LOWERING TO BLO 5 KFT AFTER MIDNIGHT AS TEMPS AT INVERSION TOP STAY
-15C TO -18C. HOWEVER...DUE TO THE DRIER AIR ADVECTING IN BENEATH
INVERSION (SUB ZERO SFC DEWPOINTS UPSTREAM) AND STRONG SUBSIDENCE
...EXPECT HEAVIER SNOW BANDS WILL BECOME FEWER IN NUMBER. WINDS VEER
A BIT LATE EVENING-EARLY OVERNIGHT IN WAKE OF SHORTWAVE PASSING BY
BUT OVERALL THE GREATEST CONVERGENCE AND BETTER CHANCE FOR DOMINANT
BANDING REMAINS EAST OF MARQUETTE FM SHOT POINT TO MUNISING AND
EAST TO KERY. SOME CONVERGENCE ALSO WILL SET UP OVR HIGHER TERRAIN
OVR ONTONAGON THROUGH BARAGA COUNTIES. SINCE STRONGER LK EFFECT IN
WEST IS EXPECTED TO DIMINISH WILL KEEP WARNINGS UNTIL ORIGINAL LATE
EVENING EXPIRATION. 3-6" OF ACCUMS SEEM LIKELY EAST OF MARQUETTE TO
NEWBERRY...ESPECIALLY IF ANOTHER ENHANCED DOMINANT BAND CAN DEVELOP
AS OCCURRED LATE LAST NIGHT NEAR MUNISING. IN THE WEST...ACCUMS
SHOULD TOP OUT AT 4" AND THAT WOULD BE MAINLY THIS EVENING BEFORE
SNOW SHOWERS DIMINISH IN INTENSITY. TEMPS...SW INTERIOR WILL HAVE
BEST CHANCE OF FALLING BLO ZERO AS WINDS IN FAR WEST ARE ALREADY
DECREASING AND SFC TD NEAR ZERO ARE MOVING IN. SOME CLEARING
OVERNIGHT AS WELL WILL ALSO AID TEMP DROP. SOME FALL IN TEMPS
FARTHER N AND E BUT SOME WIND OFF LK SUPERIOR WILL KEEP TEMPS MOSTLY
FM 5 TO 15 ABOVE ZERO.
&&
.LONG TERM...(SAT THROUGH FRI)
MAIN FCST CONCERNS ARE LES TRENDS SAT AND AGAIN NEXT WEEK.
SAT...12Z NAM/GFS FCST SOUNDINGS SHOW INVERSION HEIGHTS IN THE 4K-5K
FT RANGE OVER THE EAST WILL DROP TO NEAR 3K FT AS THE RDG BUILDS
INTO THE AREA. SO...LES...MAINLY BTWN KP53-KERY WITH BEST 950 MB
CONVERGENCE...WILL CONTINUE DURING THE MORNING BUT QUICKLY WIND DOWN
IN THE AFTERNOON TO MAINLY LIGHT SNOW SHOWERS OR FLURRIES AND END
LATE AS WINDS BECOME VARIABLE AND BACK SW. OVER THE NW CWA...ONLY
SCT LIGHT SNOW SHOWERS OR FLURRIES ARE EXPECTED AS THE ACYC FLOW AND
DRY AIR BUILD IN DURING THE MORNING. OTHERWISE...MDLS RH SUGGEST
SOME MID/HIGH CLOUDS MAY MOVE THROUGH BUT SHOULD BE THIN ENOUGH FOR
AT LEAST PARTLY SUNNY SKIES.
SAT NIGHT AND SUN...THE DEVELOPING WAA PATTERN INTO THE WESTERN
GREAT LAKES AS THE PLAINS SHRTWV LIFTS TO THE NE WILL BRING
THICKENING MID/HIGH CLOUDS OVER THE AREA LATE SAT AND SAT
NIGHT...PER NAM/GFS 290K-295K PROGS. LINGERING SFC RIDGING WITH LOW
LVL ACYC FLOW AS THE SHRTWV MOVES TO THE SRN LAKES WILL LIMIT LIGHT
SNOW CHANCES INTO UPPER MI. THE 18Z NAM HAS ALSO FINALLY COME INTO
BETTER AGREEMENT WITH THE MORE SRLY TRACK OF THE MORE CONSISTENT GFS
BUT STILL REMAINED SLOWER AND A BIT FARTHER N WITH ITS INCREASINGLY
SHEARED 500 MB LOW. SO...POPS WERE REDUCED TO SLIGHT CHANCE EXCEPT
OVER THE SOUTH.
SUN NIGHT INTO MON...LIGHT SNOW CHANCES STILL REMAIN WITH AS A SFC
TROF AND WEAK NRN STREAM SHRTWV MOVE THROUGH THE UPPER GREAT LAKES.
850 MB TEMPS FALLING ONLY TO AROUND -12C WILL BE MARGINAL FOR LES
BUT COULD SUPPORT SOME LAKE ENHANCEMENT INTO NRN UPPER MI AS WINDS
VEER NW. WITH THE LACK OF SIGNIFICANTLY COLDER AIR...OVERALL ONLY
LIGHT SNOW AMOUNTS IF ANY EXPECTED.
TUE-FRI...GENERAL MODEL TREND IS TOWARD A MORE AMPLIFIED POSITIVE
PNA PATTERN(WRN NOAM RDG AND TROF IN THE EAST).
HOWEVER...DIFFERENCES REMAIN IN TIMING OF THE ARRIVAL OF THE COLD
AIR AND ITS POSSIBLE DEPARTURE LATE IN THE WEEK. ANY LINGERING SNOW
SHOWERS WOULD LIKELY END EARLY TUE WITH WAA AND BACKING WINDS AHEAD
OF A CLIPPER SHRTWV. BY TUE NIGHT INTO WED...ADDITIONAL CLIPPER
SHRTWVS FROM CNTRL CANADA SHOULD HELP USHER IN MUCH COLDER AIR WITH
850 TEMPS DROPPING AOB -20C. THE GFS AND ITS ENSEMBLES ALONG WITH THE
UKMET SHOW MORE AMPLIFIED SOLUTIONS THAT PERSIST LATER INTO THE WEEK
COMPARED TO THE ECMWF/CANADIAN WHICH ALLOW A GLF AK TO HELP PUSH OUT
THE ERN TROF. FOLLOWING THE HPC PREFERENCE FOR THE GFS WOULD LEAD TO
MODERATE OR EVEN HEAVY LES AT TIMES FOR N TO NW FLOW FAVORED AREAS
WED INTO THU. SOME MODERATING MAY BE POSSIBLE BY FRI WITH LES
DIMINISHING AS THE GFS AND ENSEMBLES HINT AT DECENT WAA AHEAD OF A
CLIPPER LOW PASSING THROUGH NRN ONTARIO.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW WARNING THROUGH 11 AM EST SAT MIZ006-007-085.
LAKE EFFECT SNOW WARNING UNTIL 11 PM EST FRI MIZ002-004-084.
LAKE EFFECT SNOW WARNING UNTIL 11 PM EST FRI MIZ003.
LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST SAT MIZ001.
LAKE EFFECT SNOW ADVISORY UNTIL 9 AM EST SAT MIZ014.
LAKE EFFECT SNOW ADVISORY UNTIL 10 PM CST FRI MIZ009.
&&
$$
JLA(SHORT TERM)
JLB(LONG TERM)
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
AFDDTX 356 PM EST FRI JAN 19 2007
.SHORT TERM...TONIGHT AND SATURDAY
SCATTERED TO NUMEROUS SNOW SHOWER ACTIVITY TO CONTINUE AT LEAST INTO
THE EVENING HOURS AS UPPER LEVEL TROUGH AXIS PUSHES INTO THE
CENTRAL GREAT LAKES REGION. WITH THE LACK OF ORGANIZED BANDING
(ALTHOUGH THERE IS A HINT OF AN I-94 BAND) AND INVERSION HEIGHTS
AROUND 6000 FEET AT THE PRESENT TIME (PER DTW
TAMDAR)...ACCUMULATIONS SHOULD BE LESS THAN AN INCH FOR THE MOST
PART. WITH SOME SEMBLANCE OF AN I-94 BAND...WASHTENAW COUNTY STANDS
TO SEE THE MOST...PROBABLY AN INCH OR SLIGHTLY BETTER.
BOTH 12Z GFS/NAM INDICATING SATURATION AT 850 MB WITH TEMPS FALLING
TO -18C BY 6Z SATURDAY. INVERSION HEIGHTS THEN FALL BELOW 5000 FEET
LATE TONIGHT. HOWEVER...WITH THE AIRMASS AS COLD AS IT IS...MOISTURE
AT 925 MB COULD BE ENOUGH TO PRODUCE A FEW FLURRIES ON SATURDAY.
SURFACE RIDGE WILL SLOWLY BUILD INTO SOUTHEAST MICHIGAN DURING
SATURDAY AND ARRIVE BY EVENING...WITH CLEARING TAKING PLACE OVER THE
CWA. JUST NOT SURE HOW QUICK THE CLEARING WILL OCCUR...AS WE COULD
EASILY START THE DAY OUT MOSTLY CLOUDY WITH MOISTURE TRAPPED
UNDERNEATH THE INVERSION. OR...WE COULD START OUT WITH A FAIR AMOUNT
OF SUN...CU UP LATE MORNING...BEFORE MIXING OUT THE REMAINING LOW
LEVEL MOISTURE DURING THE AFTERNOON. EITHER WAY...THE DAY SHOULD
AVERAGE OUT TO AT LEAST PARTLY SUNNY. BLENDED THE NEW MAV GUIDANCE
AND PREVIOUSLY FORECASTED TEMPS FOR TONIGHT AND TOMORROW.
&&
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
SATURDAY NIGHT THROUGH MONDAY...
MODELS QUITE SIMILAR. SURFACE RIDGE ON TAP TO PASS THROUGH SATURDAY
NIGHT...BEFORE MOVING OFF TO THE EAST SUNDAY. ON ITS HEELS...A BROAD
DIFFUSE INVERTED TROUGH TO PROGRESS EAST ACROSS THE AREA SUNDAY
THROUGH SUNDAY NIGHT. AT 500 MB...SHORTWAVE RIDGE BUILDING IN
SATURDAY NIGHT...BEFORE IT GETS DISPLACED EAST SUNDAY AS A SHORTWAVE
TROUGH FROM THE SOUTHWEST SHEARS NORTHEAST INTO THE SOUTHERN LAKES
REGION AND CONTINUES EAST SUNDAY NIGHT. MORE MID LEVEL TROUGHINESS
APPROACHING MONDAY FROM THE WEST.
850 TO 500 MB MOISTURE RAPIDLY INCREASES SUNDAY AS PER GOOD MODEL
CONSENSUS...THEN TREND TOWARD SLIGHT LESSENING SUNDAY NIGHT AND
MONDAY. AT 925 MB...DRIER SATURDAY NIGHT IN PRESENCE OF LOW LEVEL
RIDGE...MOISTENING BY SUNDAY AFTERNOON AND CONTINUING MOIST THROUGH
MONDAY. GFS...NAM...AND LOCAL WRFHEMI ALL SHOW 700 MB THETA E RIDGE
NUDGING SOUTHERN LOWER MI SUNDAY.
A FEW UBAR/SEC OF OMEGA ASCENT SEEN SUNDAY AFTERNOON AS PER MODEL
CONSENSUS...THOUGH STRONGER GFS CLOSER TO 10 UBAR/SEC ASCENT DESPITE
LOWER MOS POPS. 850 TO 500 MB QVECTOR CONVERGENCE QUITE ROBUST
SUNDAY AFTERNOON...OTHERWISE LITTLE TO NONE FOR THIS PERIOD. DURING
SUNDAY...TOO...MAINLY IN THE AFTERNOON...MODELS ADVERTISE SLIGHT
SURFACE WIND CONVERGENCE...MODEST 850 TO 700 MB FRONTOGENESIS AND
DEFORMATION...AND PRETTY GOOD 250 MB DIVERGENCE/850 MB CONVERGENCE
COUPLING. FINALLY...A FEW UBAR/SEC ASCENT SEEN BY SUNDAY AFTERNOON
ON 280K SURFACE...AS CONDENSATION PRESSURE DEFICITS LOWER TO AROUND
10 MB IN MOST AREAS.
AFTER A DRY SATURDAY NIGHT...DYNAMICS AND MOISTURE JUSTIFY LIKELY POPS
SUNDAY...WHEN SNOWFALL AMOUNTS FROM AROUND AN INCH TO 2 INCHES ARE
ANTICIPATED...WITH HEAVIEST AMOUNTS EXPECTED NEAR THE SOUTHERN
BORDER.
AFTER MONDAY...
SURFACE LOW LEVEL CYCLONIC FLOW EXPECTED TO PREVAIL EARLY IN
WEEK...AHEAD OF A CLIPPER LIKE SYSTEM ARRIVING MID WEEK.
CONSIDERABLE MODEL TIMING VARIATION SEEN WITH THIS MID WEEK SYSTEM
AMONG MODELS AND GFS ENSEMBLE MEMBERS. AT ANY RATE...MODELS ARE IN
OVERALL AGREEMENT...WITH THE MID WEEK SYSTEM INTRODUCING A FRESH
REINFORCEMENT OF ARCTIC AIR BEHIND IT. 12Z MEX TEMPERATURES FOR
THURSDAY ARE ABOUT 10 DEGREES F COLDER THAN THE 00Z GUIDANCE...
REFLECTING A FASTER PROGRESSION AS PER THE 12Z GFS. HAVE LOWERED
TEMPERATURES A FEW DEGREES FOR THURSDAY...BUT THEY MAY NEED EVEN MORE
LOWERING IF LATER RUNS CONTINUE THIS TREND.
AT 500 MB...A LOOSELY PHASED HIGH AMPLITUDE SHORTWAVE TROUGH
EXPECTED TO SLOWLY ADVANCE EAST ACROSS THE AREA EARLY IN WEEK...WITH
COLD NORTHWEST FLOW IN ITS WAKE PERTURBED BY STRONG MID WEEK IMPULSE.
AS IN PREVIOUS FORECAST...CHANCE OF SNOW OR SNOW SHOWERS EACH DAY IS
HARD TO DISPUTE IN THIS TYPE OF PATTERN...GIVEN LAKE EFFECT COMBINED
WITH SYNOPTIC SCALE BOOST FROM TIME TO TIME.
&&
.PREV DISCUSSION...ISSUED 1205 PM EST FRI JAN 19 2007
AVIATION...
VFR CONDITIONS WITH PERIODS OF MVFR SNOW SHOWERS WILL CONTINUE TO
IMPACT SOUTHEAST MICHIGAN THROUGH TONIGHT. IN FACT...WITH THE UPPER
LEVEL TROUGH AXIS AND SURFACE TROUGH SWINGING INTO SOUTHEAST
MICHIGAN LATE TODAY/THIS EVENING...THERE WILL LIKELY BE SOME
ENHANCEMENT TO THE ACTIVITY...WITH POCKETS OF IFR SNOW SHOWERS
EXPECTED. HOWEVER...UNCERTAINTY WITH THE EXACT
TIMING...LOCATION...AND DURATION PRECLUDES THE MENTION AT TAF SITES
DURING THIS ISSUANCE. TAFS WILL BE AMENDED AS SHORT TERM TRENDS
DICTATE. TOMORROW MORNING WE ARE EITHER GOING TO CLEAR OUT OR
MOISTURE TRAPPED UNDERNEATH LOWERING SUBSIDENCE INVERSION WILL KEEP
MVFR CEILINGS LOCKED IN. FAVOR THE LATTER AT THIS POINT BASED ON THE
12Z NAM.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...GALE WARNING...NORTH HALFGALE WARNING...SOUTH HALF UNTIL 11 AM SATURDAY.
SMALL CRAFT ADVISORY...LHZ422 UNTIL 7 AM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON UNTIL 7 PM SATURDAY.
SMALL CRAFT ADVISORY...LHZ421 UNTIL 11 AM SATURDAY.
LAKE ST CLAIR...SMALL CRAFT ADVISORY...LCZ460 UNTIL 7 AM SATURDAY.
MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...UNTIL 7 AM SATURDAY.
&&
$$
SHORT TERM...SF
LONG TERM....DG
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
AFDCLE 1125 PM EST SAT JAN 20 2007
.AVIATION(06Z-06Z)...
LAKE EFFECT SNOW SHOWERS DRYING UP ALTHOUGH BORDERLINE VFR/MVFR
CEILINGS REMAIN AT KERI. EXPECT THESE CLOUDS TO REMAIN FOR A FEW
MORE HOURS BEFORE LIFTING TO VFR CEILINGS AND EVENTUALLY BREAKING TO
SCATTERED. ELSEWHERE FOR THE REMAINDER OF THE NIGHT THROUGH 12Z XPC
VFR CONDITIONS AS SURFACE HIGH DRIFTS EAST OF THE AREA. MID AND
HIGH LEVEL MOISTURE WILL CONTINUE TO INCREASE HOWEVER AHEAD OF NEXT
SURFACE WAVE MOVING OUT OF THE SOUTHERN PLAINS. AFTER 12Z DEEP
MOISTURE WILL BEGIN MOVING IN FROM THE SOUTHWEST. WILL ALLOW SNOW
TO DEVELOP AROUND SUNRISE TOL AND FDY...PROGRESSING EAST ALONG WITH
MVFR AND IFR CONDITIONS. EXPECT SNOW INTO KCLE BETWEEN 14 AND 16Z
WITH MAINLY IFR CONDITIONS IN SNOW CONTINUING THROUGH THE
AFTERNOON. THERE IS A SMALL POSSIBILITY THAT CONDITIONS COULD
DEVELOP THAT WOULD ALLOW FREEZING DRIZZLE TO OCCUR ESPECIALLY ACROSS
THE SOUTHERN TIER OF TERMINALS BUT FOR NOW WILL LEAVE OUT. NEW
GUIDANCE SUGGESTS WIND SHEAR STILL WILL OCCUR BUT AT MAGNITUDES THAT
WOULD BE LESS OF A CONCERN.
&&
.SHORT TERM UPDATE...
LAKE EFFECT IS SLOWLY WANING SO I CLEANED UP ZONE FORECASTS TO
REFLECT THIS TREND.
MID AND HIGH LEVEL CLOUDS ALREADY SPREADING INTO THE WESTERN
PORTIONS OF THE FORECAST AREA SO WENT WITH EITHER MOSTLY CLOUDY OR
INCREASING CLOUDINESS OVERNIGHT.
TEMPERATURES ARE DROPPING INTO THE LOWER 20S AND TEENS THIS EVENING
AND CURRENT FORECAST TEMPERATURES LOOK LIKE THEY ARE ON TARGET.
ZONES ALREADY SENT.
&&
.SHORT TERM(TONIGHT-TUE)...
THE LAKE EFFECT SNOWS HAVE NEARLY DIMINISHED PER RADAR AND SATELLITE
PICTURES. ACARS/TAMDAR SOUNDINGS SHOW THAT THE INVERSION IS UNDER
4000 FT AND THE ANTICYCLONE TO THE WEST IS WINNING OUT. STILL SOME
LOWER VSBYS IN THE SNOWBELT PER OBSERVATIONS...BUT AM THINKING THAT
CONDITIONS SHOULD RAPIDLY IMPROVE AS THE INVERSION CRASHES AND THE
RIDGE CONTINUES TO BUILD EAST. WILL THEREFORE EXPIRE ALL
WARNINGS...BUT GO OUT WITH SNOW ENDING WORDING WITH LOCALLY AN
ADDITIONAL INCH OR TWO IN THE SNOWBELT. OTHERWISE...THE NEXT WEATHER
MAKER WILL BE THE QUICK MOVING SOUTHERN STREAM SYSTEM FORECAST TO
MOVE INTO THE AREA SUNDAY. THIS WILL BE A QUICK HITTER...BUT MAY
CAUSE A BRIEF PERIOD OF MODERATE SNOW ESPECIALLY ACROSS THE WESTERN
AND SOUTHERN 2/3 PART OF THE FORECAST AREA SUNDAY AFTN. LATEST MODEL
RUNS ARE IN GOOD AGREEMENT IN THE EVOLUTION OF THE SYSTEM...WITH THE
NAM COMING AROUND TO A FASTER SOLN LIKE THE GFS SUGGESTED YESTERDAY.
AS THE SYSTEM MOVES OUT OF THE SRN PLAINS TONIGHT...EXPECT THE UPPER
LOW TO OPEN UP AND QUICKLY SHEAR OFF TO THE NORTHEAST. THIS WILL
CAUSE A WEAK OPEN SFC LOW TO MOVE THRU THE OH VLY LATE SUNDAY INTO
SUNDAY NIGHT. CURRENT THINKING IS THAT A SNOW WILL START QUICKLY
LATE SUNDAY MORNING OVER THE FINDLAY AREA AND QUICKLY SPREAD EAST TO
NE OH/NW PA BY LATE AFTN/EARLY EVENING. ALTHOUGH THE PERIOD OF SNOW
WILL BE RELATIVELY SHORT /ON THE ORDER OF 6 HOURS/...THE INTENSITY
OF THE SNOW MAY BE MODERATE AT TIMES SUNDAY AFTERNOON AS THERE IS AN
INDICATION OF A MODERATE TO STRONG FRONTOGENESIS/FRONTOLYSIS COUPLET
WHICH RESEARCH SUGGESTS MAY BE A FAIRLY ACTIVE PART OF THE FRONTAL
ZONE. THIS ACTIVE FRONTAL ZONE COMBINED WITH SOME NEGATIVE EPV ABOVE
THE AREA OF F-GEN INDICATIVE OF WEAK STATIC STABILITY MAY ALLOW FOR
A PERIOD OF LOCALLY 1 INCH PER HOUR SYNOPTIC TYPE SNOW. MODELS SHOW
THAT THIS AREA WILL MOVE EAST QUICKLY...BUT NOT BEFORE THE NAM FCSTS
A QUICK 1-3 INCHES OF SYNOPTIC SNOW ACROSS MUCH OF THE AREA
ESPECIALLY SOUTH AND WEST OF CLE TO CAK LINE SUN AFTN. WITH THIS
ACTIVE FRONTAL ZONE...LATER SHIFTS WILL HAVE TO MONITOR FOR SLIGHTLY
HIGHER SNOW AMOUNTS...BUT FORTUNATELY THE SPEED OF THE SYSTEM MAY
LIMIT AMOUNTS. THE FRONTOGENESIS WEAKENS LATE SUN AFTN INTO SUN
NIGHT AS IT MOVES EAST AS THE UPPER JET QUICKLY MOVES EAST. WILL
CONTINUE WITH LIKELY POPS ACROSS THE EAST IN THE EVENING.
OTHERWISE...A DRY SLOT QUICKLY MOVES INTO THE AREA. MOISTURE IS
DEEPER WITH THIS RUN COMPARED TO PREVIOUS RUNS...SO ALHTOUGH THERE
IS VERY LITTLE UPWARD MOTION THERE WILL LIKELY BE SOME FLURRIES OR A
CHANCE OF LIGHT SNOW ACROSS THE ENTIRE AREA SUN NIGHT. THE CLOUD
TOPS ARE ALSO A LITTLE COLDER ESPECIALLY ACROSS THE NORTH...SO
FREEZING DRIZZLE SUN NIGHT NOT AS MUCH OF A THREAT. HOWEVER...CLOUD
TOPS A LITTLE WARMER ACROSS THE FAR SOUTH SO ICE CRYSTAL FORMATION
NOT AS LIKELY. WILL THEREFORE INTRODUCE FREEZING DRIZZLE ACROSS THE
FAR SOUTH SUNDAY NIGHT. WILL CONTINUE WITH CHC OF SNOW ON MONDAY
ALTHOUGH IT LOOKS LIKE ANY SNOW WILL BE MINIMAL. MAY BE A LITTLE
ENHANCEMENT IN THE SNOWBELT BUT 850MB TEMPS ONLY AROUND -10C SO
MARGINAL FOR LES. WEAK WARM ADVECTION TUE AHEAD OF THE WED SYSTEM
WILL ALLOW FOR A SMALL CHANCE OF SNOW...BUT AGAIN IT DOES NOT LOOK
SIGNIFICANT.
WILL GO ON THE COLDER END OF GUIDANCE FOR THE NEXT COUPLE OF
DAYS...ESPECIALLY NE DUE TO SNOW COVER.
&&
.LONG TERM(WED-SAT)...
THE EXTENDED MODELS CONTINUE TO SHOW A -NAO PATTERN...WHICH USUALLY
MEANS COLDER THAN NORMAL TEMPS FOR THE LOWER LAKES AND EASTERN U.S.
IN GENERAL. THE 00Z AND 06Z RUNS OF THE GFS SHOWS THIS TO BE TRUE
WITH AN ARCTIC EXPRESS TYPE SCENARIO AT 500MB WITH LONGITUDINAL FLOW
FROM THE ARCTIC CIRCLE BY THE END OF THE WORK WEEK. THE GFS SHOWS
THE COLDEST AIR OF THE YEAR THU INTO FRI WITH LESS THAN -20C AT
850MB. CANADIAN MODEL IN GENERAL AGREEMENT ALTHOUGH NOT AS COLD.
ECMWF IS THE OUTLIER SOLN WITH LESS AMPLIFICATION OF THE FLOW ACROSS
NOAM. HPC LIKES A 06Z ENSEMBLE MEAN SOLN WHICH TRENDS TOWARD THE
OPNL GFS ALTHOUGH NOT AS COLD. WITH THAT IN MIND...THE CLIPPER
SYSTEM ON WED WILL SPREAD LIGHT SNOW ACROSS THE ENTIRE REGION. WILL
CONTINUE CHANCE POPS FOR LIGHT SNOW WED. THIS WILL OPEN THE DOOR FOR
THE DEEP TROUGH TO DIG ACROSS THE LAKES WITH THU AND FRI SEEING
PLENTY OF SNOW SHOWERS WITH LAKE EFFECT SNOW CERTAINLY A CONCERN.
WILL CONTINUE WITH CHANCE POPS FOR THE ENTIRE AREA WITH SNOW LIKELY
IN THE NORTHEAST. IF THE GFS IS TRUE...THE STRONGLY CYCLONIC FLOW
WITH A SERIES OF UPPER DISTURBANCES MOVING ACROSS LAKE ERIE MAY
ALLOW FOR A SIGNIFICANT LAKE EFFECT EVENT FOR NORTHEAST OHIO THU AND
FRI BUT THIS IS CERTAINLY TOO FAR IN ADVANCE TO BE TALKING ABOUT ANY
ACCUMULATIONS. OTHERWISE...BY SATURDAY HIGH PRES BUILDS INTO THE
AREA. WILL GO WITH A DRY FCST ON SATURDAY. TEMPS WILL REMAIN BELOW
NORMAL THRU THE PERIOD. MAY SEE TEMPS STRUGGLE TO GET OUT OF THE
TEENS THU AND FRI IF THE GFS IS TRUE. FOR NOW...WILL LOWER TEMPS
INTO THE LOWER 20S THU AND FRI.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
&&
$$
SHORT TERM UPDATE...LOMBARDY
SHORT TERM...MRD
LONG TERM...MRD
AVIATION...TK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
AFDCLE 826 PM EST SAT JAN 20 2007
.SHORT TERM UPDATE...
LAKE EFFECT IS SLOWLY WANING SO I CLEANED UP ZONE FORECASTS TO
REFLECT THIS TREND.
MID AND HIGH LEVEL CLOUDS ALREADY SPREADING INTO THE WESTERN
PORTIONS OF THE FORECAST AREA SO WENT WITH EITHER MOSTLY CLOUDY OR
INCREASING CLOUDINESS OVERNIGHT.
TEMPERATURES ARE DROPPING INTO THE LOWER 20S AND TEENS THIS EVENING
AND CURRENT FORECAST TEMPERATURES LOOK LIKE THEY ARE ON TARGET.
ZONES ALREADY SENT.
&&
.AVIATION(00Z-24Z)...
LAKE EFFECT SNOW SHOWERS WILL BE THINNING THROUGH THE EVENING AS
WINDS DIE OFF AND THE SFC HIGH CONTINUES TO BUILD. ELSEWHERE
LEFTOVER MVFR CIGS SHOULD BEGIN TO BREAK INTO A SCT DECK. AFTER 06Z
ADVANCING MID AND HIGH LEVEL MOISTURE WILL BEGIN TO THICKEN ACROSS
THE AREA AS MOISTURE STREAMS AHEAD OF THE DEVELOPING SFC LOW IN THE
SOUTHERN PLAINS. EXPECT LIGHT SNOW TO BEGIN AROUND SUNRISE IN THE
WEST...AROUND NOON NEAR KCLE AND EARLY AFTERNOON KERI. AT THIS TIME
EXPECT CONDS TO DROP THROUGH MVFR TO OCNL IFR CIGS AND VSBYS IN
SNOW. WINDS ALOFT NOT STRONG ENOUGH FOR WIND SHEAR MOST PLACES
SUNDAY EVEN GIVEN A 30 TO 50 DEGREE DIRECTION CHANGE BUT IT GETS
CLOSE IN THE WEST SO BROUGHT IT IN FOR PORTIONS OF THE DAY WEST.
&&
.SHORT TERM(TONIGHT-TUE)...
THE LAKE EFFECT SNOWS HAVE NEARLY DIMINISHED PER RADAR AND SATELLITE
PICTURES. ACARS/TAMDAR SOUNDINGS SHOW THAT THE INVERSION IS UNDER
4000 FT AND THE ANTICYCLONE TO THE WEST IS WINNING OUT. STILL SOME
LOWER VSBYS IN THE SNOWBELT PER OBSERVATIONS...BUT AM THINKING THAT
CONDITIONS SHOULD RAPIDLY IMPROVE AS THE INVERSION CRASHES AND THE
RIDGE CONTINUES TO BUILD EAST. WILL THEREFORE EXPIRE ALL
WARNINGS...BUT GO OUT WITH SNOW ENDING WORDING WITH LOCALLY AN
ADDITIONAL INCH OR TWO IN THE SNOWBELT. OTHERWISE...THE NEXT WEATHER
MAKER WILL BE THE QUICK MOVING SOUTHERN STREAM SYSTEM FORECAST TO
MOVE INTO THE AREA SUNDAY. THIS WILL BE A QUICK HITTER...BUT MAY
CAUSE A BRIEF PERIOD OF MODERATE SNOW ESPECIALLY ACROSS THE WESTERN
AND SOUTHERN 2/3 PART OF THE FORECAST AREA SUNDAY AFTN. LATEST MODEL
RUNS ARE IN GOOD AGREEMENT IN THE EVOLUTION OF THE SYSTEM...WITH THE
NAM COMING AROUND TO A FASTER SOLN LIKE THE GFS SUGGESTED YESTERDAY.
AS THE SYSTEM MOVES OUT OF THE SRN PLAINS TONIGHT...EXPECT THE UPPER
LOW TO OPEN UP AND QUICKLY SHEAR OFF TO THE NORTHEAST. THIS WILL
CAUSE A WEAK OPEN SFC LOW TO MOVE THRU THE OH VLY LATE SUNDAY INTO
SUNDAY NIGHT. CURRENT THINKING IS THAT A SNOW WILL START QUICKLY
LATE SUNDAY MORNING OVER THE FINDLAY AREA AND QUICKLY SPREAD EAST TO
NE OH/NW PA BY LATE AFTN/EARLY EVENING. ALTHOUGH THE PERIOD OF SNOW
WILL BE RELATIVELY SHORT /ON THE ORDER OF 6 HOURS/...THE INTENSITY
OF THE SNOW MAY BE MODERATE AT TIMES SUNDAY AFTERNOON AS THERE IS AN
INDICATION OF A MODERATE TO STRONG FRONTOGENESIS/FRONTOLYSIS COUPLET
WHICH RESEARCH SUGGESTS MAY BE A FAIRLY ACTIVE PART OF THE FRONTAL
ZONE. THIS ACTIVE FRONTAL ZONE COMBINED WITH SOME NEGATIVE EPV ABOVE
THE AREA OF F-GEN INDICATIVE OF WEAK STATIC STABILITY MAY ALLOW FOR
A PERIOD OF LOCALLY 1 INCH PER HOUR SYNOPTIC TYPE SNOW. MODELS SHOW
THAT THIS AREA WILL MOVE EAST QUICKLY...BUT NOT BEFORE THE NAM FCSTS
A QUICK 1-3 INCHES OF SYNOPTIC SNOW ACROSS MUCH OF THE AREA
ESPECIALLY SOUTH AND WEST OF CLE TO CAK LINE SUN AFTN. WITH THIS
ACTIVE FRONTAL ZONE...LATER SHIFTS WILL HAVE TO MONITOR FOR SLIGHTLY
HIGHER SNOW AMOUNTS...BUT FORTUNATELY THE SPEED OF THE SYSTEM MAY
LIMIT AMOUNTS. THE FRONTOGENESIS WEAKENS LATE SUN AFTN INTO SUN
NIGHT AS IT MOVES EAST AS THE UPPER JET QUICKLY MOVES EAST. WILL
CONTINUE WITH LIKELY POPS ACROSS THE EAST IN THE EVENING.
OTHERWISE...A DRY SLOT QUICKLY MOVES INTO THE AREA. MOISTURE IS
DEEPER WITH THIS RUN COMPARED TO PREVIOUS RUNS...SO ALHTOUGH THERE
IS VERY LITTLE UPWARD MOTION THERE WILL LIKELY BE SOME FLURRIES OR A
CHANCE OF LIGHT SNOW ACROSS THE ENTIRE AREA SUN NIGHT. THE CLOUD
TOPS ARE ALSO A LITTLE COLDER ESPECIALLY ACROSS THE NORTH...SO
FREEZING DRIZZLE SUN NIGHT NOT AS MUCH OF A THREAT. HOWEVER...CLOUD
TOPS A LITTLE WARMER ACROSS THE FAR SOUTH SO ICE CRYSTAL FORMATION
NOT AS LIKELY. WILL THEREFORE INTRODUCE FREEZING DRIZZLE ACROSS THE
FAR SOUTH SUNDAY NIGHT. WILL CONTINUE WITH CHC OF SNOW ON MONDAY
ALTHOUGH IT LOOKS LIKE ANY SNOW WILL BE MINIMAL. MAY BE A LITTLE
ENHANCEMENT IN THE SNOWBELT BUT 850MB TEMPS ONLY AROUND -10C SO
MARGINAL FOR LES. WEAK WARM ADVECTION TUE AHEAD OF THE WED SYSTEM
WILL ALLOW FOR A SMALL CHANCE OF SNOW...BUT AGAIN IT DOES NOT LOOK
SIGNIFICANT.
WILL GO ON THE COLDER END OF GUIDANCE FOR THE NEXT COUPLE OF
DAYS...ESPECIALLY NE DUE TO SNOW COVER.
&&
.LONG TERM(WED-SAT)...
THE EXTENDED MODELS CONTINUE TO SHOW A -NAO PATTERN...WHICH USUALLY
MEANS COLDER THAN NORMAL TEMPS FOR THE LOWER LAKES AND EASTERN U.S.
IN GENERAL. THE 00Z AND 06Z RUNS OF THE GFS SHOWS THIS TO BE TRUE
WITH AN ARCTIC EXPRESS TYPE SCENARIO AT 500MB WITH LONGITUDINAL FLOW
FROM THE ARCTIC CIRCLE BY THE END OF THE WORK WEEK. THE GFS SHOWS
THE COLDEST AIR OF THE YEAR THU INTO FRI WITH LESS THAN -20C AT
850MB. CANADIAN MODEL IN GENERAL AGREEMENT ALTHOUGH NOT AS COLD.
ECMWF IS THE OUTLIER SOLN WITH LESS AMPLIFICATION OF THE FLOW ACROSS
NOAM. HPC LIKES A 06Z ENSEMBLE MEAN SOLN WHICH TRENDS TOWARD THE
OPNL GFS ALTHOUGH NOT AS COLD. WITH THAT IN MIND...THE CLIPPER
SYSTEM ON WED WILL SPREAD LIGHT SNOW ACROSS THE ENTIRE REGION. WILL
CONTINUE CHANCE POPS FOR LIGHT SNOW WED. THIS WILL OPEN THE DOOR FOR
THE DEEP TROUGH TO DIG ACROSS THE LAKES WITH THU AND FRI SEEING
PLENTY OF SNOW SHOWERS WITH LAKE EFFECT SNOW CERTAINLY A CONCERN.
WILL CONTINUE WITH CHANCE POPS FOR THE ENTIRE AREA WITH SNOW LIKELY
IN THE NORTHEAST. IF THE GFS IS TRUE...THE STRONGLY CYCLONIC FLOW
WITH A SERIES OF UPPER DISTURBANCES MOVING ACROSS LAKE ERIE MAY
ALLOW FOR A SIGNIFICANT LAKE EFFECT EVENT FOR NORTHEAST OHIO THU AND
FRI BUT THIS IS CERTAINLY TOO FAR IN ADVANCE TO BE TALKING ABOUT ANY
ACCUMULATIONS. OTHERWISE...BY SATURDAY HIGH PRES BUILDS INTO THE
AREA. WILL GO WITH A DRY FCST ON SATURDAY. TEMPS WILL REMAIN BELOW
NORMAL THRU THE PERIOD. MAY SEE TEMPS STRUGGLE TO GET OUT OF THE
TEENS THU AND FRI IF THE GFS IS TRUE. FOR NOW...WILL LOWER TEMPS
INTO THE LOWER 20S THU AND FRI.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
&&
$$
SHORT TERM UPDATE...LOMBARDY
SHORT TERM...MRD
LONG TERM...MRD
AVIATION...TK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
AFDCLE 600 PM EST SAT JAN 20 2007
.AVIATION(00Z-24Z)...
LAKE EFFECT SNOW SHOWERS WILL BE THINNING THROUGH THE EVENING AS
WINDS DIE OFF AND THE SFC HIGH CONTINUES TO BUILD. ELSEWHERE
LEFTOVER MVFR CIGS SHOULD BEGIN TO BREAK INTO A SCT DECK. AFTER 06Z
ADVANCING MID AND HIGH LEVEL MOISTURE WILL BEGIN TO THICKEN ACROSS
THE AREA AS MOISTURE STREAMS AHEAD OF THE DEVELOPING SFC LOW IN THE
SOUTHERN PLAINS. EXPECT LIGHT SNOW TO BEGIN AROUND SUNRISE IN THE
WEST...AROUND NOON NEAR KCLE AND EARLY AFTERNOON KERI. AT THIS TIME
EXPECT CONDS TO DROP THROUGH MVFR TO OCNL IFR CIGS AND VSBYS IN
SNOW. WINDS ALOFT NOT STRONG ENOUGH FOR WIND SHEAR MOST PLACES
SUNDAY EVEN GIVEN A 30 TO 50 DEGREE DIRECTION CHANGE BUT IT GETS
CLOSE IN THE WEST SO BROUGHT IT IN FOR PORTIONS OF THE DAY WEST.
&&
.SHORT TERM(TONIGHT-TUE)...
THE LAKE EFFECT SNOWS HAVE NEARLY DIMINISHED PER RADAR AND SATELLITE
PICTURES. ACARS/TAMDAR SOUNDINGS SHOW THAT THE INVERSION IS UNDER
4000 FT AND THE ANTICYCLONE TO THE WEST IS WINNING OUT. STILL SOME
LOWER VSBYS IN THE SNOWBELT PER OBSERVATIONS...BUT AM THINKING THAT
CONDITIONS SHOULD RAPIDLY IMPROVE AS THE INVERSION CRASHES AND THE
RIDGE CONTINUES TO BUILD EAST. WILL THEREFORE EXPIRE ALL
WARNINGS...BUT GO OUT WITH SNOW ENDING WORDING WITH LOCALLY AN
ADDITIONAL INCH OR TWO IN THE SNOWBELT. OTHERWISE...THE NEXT WEATHER
MAKER WILL BE THE QUICK MOVING SOUTHERN STREAM SYSTEM FORECAST TO
MOVE INTO THE AREA SUNDAY. THIS WILL BE A QUICK HITTER...BUT MAY
CAUSE A BRIEF PERIOD OF MODERATE SNOW ESPECIALLY ACROSS THE WESTERN
AND SOUTHERN 2/3 PART OF THE FORECAST AREA SUNDAY AFTN. LATEST MODEL
RUNS ARE IN GOOD AGREEMENT IN THE EVOLUTION OF THE SYSTEM...WITH THE
NAM COMING AROUND TO A FASTER SOLN LIKE THE GFS SUGGESTED YESTERDAY.
AS THE SYSTEM MOVES OUT OF THE SRN PLAINS TONIGHT...EXPECT THE UPPER
LOW TO OPEN UP AND QUICKLY SHEAR OFF TO THE NORTHEAST. THIS WILL
CAUSE A WEAK OPEN SFC LOW TO MOVE THRU THE OH VLY LATE SUNDAY INTO
SUNDAY NIGHT. CURRENT THINKING IS THAT A SNOW WILL START QUICKLY
LATE SUNDAY MORNING OVER THE FINDLAY AREA AND QUICKLY SPREAD EAST TO
NE OH/NW PA BY LATE AFTN/EARLY EVENING. ALTHOUGH THE PERIOD OF SNOW
WILL BE RELATIVELY SHORT /ON THE ORDER OF 6 HOURS/...THE INTENSITY
OF THE SNOW MAY BE MODERATE AT TIMES SUNDAY AFTERNOON AS THERE IS AN
INDICATION OF A MODERATE TO STRONG FRONTOGENESIS/FRONTOLYSIS COUPLET
WHICH RESEARCH SUGGESTS MAY BE A FAIRLY ACTIVE PART OF THE FRONTAL
ZONE. THIS ACTIVE FRONTAL ZONE COMBINED WITH SOME NEGATIVE EPV ABOVE
THE AREA OF F-GEN INDICATIVE OF WEAK STATIC STABILITY MAY ALLOW FOR
A PERIOD OF LOCALLY 1 INCH PER HOUR SYNOPTIC TYPE SNOW. MODELS SHOW
THAT THIS AREA WILL MOVE EAST QUICKLY...BUT NOT BEFORE THE NAM FCSTS
A QUICK 1-3 INCHES OF SYNOPTIC SNOW ACROSS MUCH OF THE AREA
ESPECIALLY SOUTH AND WEST OF CLE TO CAK LINE SUN AFTN. WITH THIS
ACTIVE FRONTAL ZONE...LATER SHIFTS WILL HAVE TO MONITOR FOR SLIGHTLY
HIGHER SNOW AMOUNTS...BUT FORTUNATELY THE SPEED OF THE SYSTEM MAY
LIMIT AMOUNTS. THE FRONTOGENESIS WEAKENS LATE SUN AFTN INTO SUN
NIGHT AS IT MOVES EAST AS THE UPPER JET QUICKLY MOVES EAST. WILL
CONTINUE WITH LIKELY POPS ACROSS THE EAST IN THE EVENING.
OTHERWISE...A DRY SLOT QUICKLY MOVES INTO THE AREA. MOISTURE IS
DEEPER WITH THIS RUN COMPARED TO PREVIOUS RUNS...SO ALHTOUGH THERE
IS VERY LITTLE UPWARD MOTION THERE WILL LIKELY BE SOME FLURRIES OR A
CHANCE OF LIGHT SNOW ACROSS THE ENTIRE AREA SUN NIGHT. THE CLOUD
TOPS ARE ALSO A LITTLE COLDER ESPECIALLY ACROSS THE NORTH...SO
FREEZING DRIZZLE SUN NIGHT NOT AS MUCH OF A THREAT. HOWEVER...CLOUD
TOPS A LITTLE WARMER ACROSS THE FAR SOUTH SO ICE CRYSTAL FORMATION
NOT AS LIKELY. WILL THEREFORE INTRODUCE FREEZING DRIZZLE ACROSS THE
FAR SOUTH SUNDAY NIGHT. WILL CONTINUE WITH CHC OF SNOW ON MONDAY
ALTHOUGH IT LOOKS LIKE ANY SNOW WILL BE MINIMAL. MAY BE A LITTLE
ENHANCEMENT IN THE SNOWBELT BUT 850MB TEMPS ONLY AROUND -10C SO
MARGINAL FOR LES. WEAK WARM ADVECTION TUE AHEAD OF THE WED SYSTEM
WILL ALLOW FOR A SMALL CHANCE OF SNOW...BUT AGAIN IT DOES NOT LOOK
SIGNIFICANT.
WILL GO ON THE COLDER END OF GUIDANCE FOR THE NEXT COUPLE OF
DAYS...ESPECIALLY NE DUE TO SNOW COVER.
&&
.LONG TERM(WED-SAT)...
THE EXTENDED MODELS CONTINUE TO SHOW A -NAO PATTERN...WHICH USUALLY
MEANS COLDER THAN NORMAL TEMPS FOR THE LOWER LAKES AND EASTERN U.S.
IN GENERAL. THE 00Z AND 06Z RUNS OF THE GFS SHOWS THIS TO BE TRUE
WITH AN ARCTIC EXPRESS TYPE SCENARIO AT 500MB WITH LONGITUDINAL FLOW
FROM THE ARCTIC CIRCLE BY THE END OF THE WORK WEEK. THE GFS SHOWS
THE COLDEST AIR OF THE YEAR THU INTO FRI WITH LESS THAN -20C AT
850MB. CANADIAN MODEL IN GENERAL AGREEMENT ALTHOUGH NOT AS COLD.
ECMWF IS THE OUTLIER SOLN WITH LESS AMPLIFICATION OF THE FLOW ACROSS
NOAM. HPC LIKES A 06Z ENSEMBLE MEAN SOLN WHICH TRENDS TOWARD THE
OPNL GFS ALTHOUGH NOT AS COLD. WITH THAT IN MIND...THE CLIPPER
SYSTEM ON WED WILL SPREAD LIGHT SNOW ACROSS THE ENTIRE REGION. WILL
CONTINUE CHANCE POPS FOR LIGHT SNOW WED. THIS WILL OPEN THE DOOR FOR
THE DEEP TROUGH TO DIG ACROSS THE LAKES WITH THU AND FRI SEEING
PLENTY OF SNOW SHOWERS WITH LAKE EFFECT SNOW CERTAINLY A CONCERN.
WILL CONTINUE WITH CHANCE POPS FOR THE ENTIRE AREA WITH SNOW LIKELY
IN THE NORTHEAST. IF THE GFS IS TRUE...THE STRONGLY CYCLONIC FLOW
WITH A SERIES OF UPPER DISTURBANCES MOVING ACROSS LAKE ERIE MAY
ALLOW FOR A SIGNIFICANT LAKE EFFECT EVENT FOR NORTHEAST OHIO THU AND
FRI BUT THIS IS CERTAINLY TOO FAR IN ADVANCE TO BE TALKING ABOUT ANY
ACCUMULATIONS. OTHERWISE...BY SATURDAY HIGH PRES BUILDS INTO THE
AREA. WILL GO WITH A DRY FCST ON SATURDAY. TEMPS WILL REMAIN BELOW
NORMAL THRU THE PERIOD. MAY SEE TEMPS STRUGGLE TO GET OUT OF THE
TEENS THU AND FRI IF THE GFS IS TRUE. FOR NOW...WILL LOWER TEMPS
INTO THE LOWER 20S THU AND FRI.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
&&
$$
SHORT TERM...MRD
LONG TERM...MRD
AVIATION...TK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
AFDCLE 325 PM EST FRI JAN 19 2007
.SHORT TERM(TONIGHT-MONDAY)...
NO CHANGES ARE PLANNED TO CURRENT HEADLINES. A LITTLE LULL IN LAKE
EFFECT JUST IN TIME FOR THE EVENING RUSH HOUR AS THE SHORT WAVE
RESPONSIBLE FOR ENHANCING THE LAKE EFFECTS BANDS LATE THIS MORNING
INTO THIS AFTERNOON HAS EXITED EAST CAUSING SOME DRYING AND WK
SYNOPTIC DOWNWARD MOTION. HOWEVER...WATER VAPOR AND RUC ANALYSIS
INDICATE A SHEARED SHORT WAVE FROM WI TO LOWER MI WHICH IS FCST TO
MOVE ACROSS THE AREA AROUND OR AFTER 00Z THIS EVENING. THIS SHORT
WAVE WILL SERVE TWO PURPOSES. IT WILL FIRST ALLOW FOR THE LAKE
EFFECT SNOW TO BE ENHANCED AGAIN THIS EVENING WITH WK MID LVL
Q-VECTOR CONVERGENCE...AND SECONDLY THIS SHORT WAVE WILL ALLOW FOR
THE WINDS TO VEER TO A MORE NWLY DIRECTION WHICH SHOULD ALLOW THE
SNOW BANDS TO MOVE FURTHER INLAND. SEE NO REASON TO MAKE MAJOR
CHANGES TO THE FCST SNOW AMOUNTS TONIGHT...WITH 4 TO 8 INCHES
POSSIBLE IN THE SNOWBELT...AND 2-5 INCHES NEAR THE LAKESHORE AND
INTO EASTERN CUYAHOGA COUNTY. I AM NOT SURE IF ANYWHERE CAN SEE A
FOOT TONIGHT GIVEN THE SLOWLY VEERING WINDS AND THE SHORT NW FETCH
THAT WILL DEVELOP OVERNIGHT WITHOUT ANY LAKE HURON SUPPORT UNTIL
LATE. WITH NW FLOW DEVELOPING...THERE IS A CONCERN THAT THE
SECONDARY BELTS IN NRN SUMMIT AND PORTAGE COUNTIES MAY BE ABLE TO
SEE ADVY CRITERIA. THIS WILL NEED TO BE WATCHED...BUT IT SEEMS LIKE
WHEN THE WINDS TURN ENOUGH TO ALLOW FOR STRONG BANDS INTO THE
SECONDARY BELT...THE INVERSION WILL ALSO START TO LOWER SO IT SEEMS
REASONABLE TO CONTINUE WITH A 1 TO 3 INCH FORECAST FOR THE SECONDARY
BELTS. SHOULD ALSO SEE SOME BLOWING AND DRIFTING THIS EVENING WITH
GUSTS TO 30 MPH ESPECIALLY IN THE WARNING AREA.
STRONG RIDGING AND DRYING BUILDS INTO THE AREA FOR THE DAY SATURDAY.
MODEL GUIDANCE SHOWS A LAKE HURON FETCH...BUT A WEAKER ONE WITH THE
INVERSION AROUND 5000 FT AND DRY AIR MOVING IN. WILL CONTINUE WITH
CATEGORICAL WORDING IN THE SNOWBELT...WITH 3-6 INCHES ADDITIONAL
ACCUMULATION. MAY BE A LITTLE HIGHER IF A STRONGER LAKE HURON BAND
SETS UP BUT MOST 3-6 SHOULD COVER THE MAJORITY OF THE SNOWBELT.
SOME MODEL DIFFS STARTING SAT NIGHT AND CONTINUING INTO SUNDAY WITH
THE SRN STREAM SYSTEM. GFS IS FASTER BY ABOUT 6 HOURS AND FURTHER
EAST WITH THE SHORT WAVE ENERGY ON SUNDAY. PREFER THE GFS PRIMARILY
DUE TO THE FAST AND CONFLUENT FLOW ACROSS THE EASTERN PART OF THE
COUNTRY. THE GFS SHOWS A FAIRLY POTENT SHORT WAVE AND ASSOCIATED
INVERTED TROUGH MOVING THRU THE AREA SUNDAY AFTERNOON INTO THE
EVENING. THIS SYSTEM HAS SOME FAVORABLE DYNAMICS FOR A PERIOD OF
SNOW...STRONG DUAL UPPER JETS...AN AREA OF STRONG ISENTROPIC
UPGLIDE...AND AN AREA OF FRONTOGENESIS MOVING THRU THE AREA. WILL GO
WITH SNOW LIKELY OVER THE WEST SUN AFTN WITH HIGH CHANCE POPS SUN
EVENING FOR THE ENTIRE REGION. WILL NEED TO MONITOR THIS SYSTEM AS
INVERTED TROUGHS ARE NOTORIOUS FOR CREATING MORE PCPN THAN THE
MODELS PREDICT. DRYING BEHIND THE SYSTEM SUN NIGHT INTO MON MAY
ALLOW FOR FREEZING DRIZZLE...BUT FOR NOW HAVE OPTED TO KEEP JUST LOW
CHC POPS FOR SNOW INTO MONDAY.
TEMPS WILL CONTINUE BELOW NORMAL THRU SUNDAY. WILL GENERALLY GO WITH
A BLEND OF GUIDANCE THRU THE PERIOD.
.LONG TERM(TUE-FRI)...
NO SIGNIFICANT CHANGES TO GOING FORECAST... WITH NORTHWEST FLOW ALOFT
STILL THE RULE THROUGH THE PERIOD. LOW LEVEL FLOW OFF THE LAKES
CONTINUES TO HANG ON THROUGH TUESDAY AS RIDGING PUSHES INTO THE AREA
FROM THE SOUTH. EXPECT CLOUDS AND SOME SNOW TO CONTINUE IN THE
SNOWBELT AREAS AT LEAST THROUGH TUESDAY NIGHT BEFORE WEAK RETURN
FLOW BEGINS WEDNESDAY MORNING AHEAD OF A FAST MOVING CLIPPER SYSTEM.
NOT MUCH MOISTURE AVAILABLE FOR THIS SYSTEM... BUT PLENTY OF COLD
AIR BEHIND IT. THE GFS IS CONSIDERABLY COLDER THAN YESTERDAYS RUN...
WITH 850 TEMPS FROM THIS MORNINGS RUN HITTING -20 OVER THE AREA BY
FRIDAY MORNING. BUT THIS COLDER SOLUTION IS IN BETTER AGREEMENT
WITH THE ECMWF... AND I TRENDED THE TEMPS COLDER ON DAYS 6-7 TO
REFLECT THIS. COLDEST TEMPS OF THE SEASON ARE NOT OUT OF THE
QUESTION TOWARDS NEXT WEEKEND... AND A SOLID SHOT OF LAKE EFFECT
SNOW IS LOOKING PRETTY GOOD FOR THE END OF THE WEEK AS THIS AIR
MOVES OVER THE STILL WARM LAKES.
.AVIATION (18Z-18Z)...
SCATTERED RATHER INTENSE SNOW SHOWERS HAVE PREVAILED ACROSS NORTHERN
OHIO AT MIDDAY WITH THE HEAVIEST ACTIVITY FROM THE LAKE ERIE ISLANDS
EAST TO CAK AND YNG. VSBYS FREQUENTLY DROP TO BELOW 1 MILE WITH CIGS
BELOW 1000 FEET IN THE MORE INTENSE SHOWERS NEAR THE LAKE. EXPECT
THE SNOW SHOWER ACTIVITY TO PERSIST INTO THE EVENING HOURS AND THEN
DIMINISH SLOWLY AFTER MIDNIGHT. CURRENT ACARS SOUNDINGS SHOW THE
INVERSION HEIGHT NEAR CLE AROUND 7900 FEET AT 16Z WITH MOIST
CONDITIONS BELOW THE INVERSION. THIS IS A RATHER DEEP MIXED BOUNDARY
LAYER WHICH SHOULD CONTINUE TO SUPPORT INTENSE SCATTERED SNOW
SHOWERS. THE INVERSION BASE IS EXPECTED TO LOWER AFTER MIDNIGHT AND
THIS SHOULD HELP TO SUPPRESS SNOW SHOWERS.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...LAKE EFFECT SNOW WARNING FROM FRIDAY AFTERNOON THROUGH SATURDAY
AFTERNOON FOR OHZ011>014-023-089.
PA...LAKE EFFECT SNOW WARNING FROM FRIDAY AFTERNOON THROUGH SATURDAY
AFTERNOON FOR PAZ001>003.
&&
$$
SHORT TERM...MRD
LONG TERM...ASTIFAN
AVIATION...REL
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
AFDCLE 1242 PM EST FRI JAN 19 2007
.AVIATION (18Z-18Z)...
SCATTERED RATHER INTENSE SNOW SHOWERS HAVE PREVAILED ACROSS NORTHERN
OHIO AT MIDDAY WITH THE HEAVIEST ACTIVITY FROM THE LAKE ERIE ISLANDS
EAST TO CAK AND YNG. VSBYS FREQUENTLY DROP TO BELOW 1 MILE WITH CIGS
BELOW 1000 FEET IN THE MORE INTENSE SHOWERS NEAR THE LAKE. EXPECT
THE SNOW SHOWER ACTIVITY TO PERSIST INTO THE EVENING HOURS AND THEN
DIMINISH SLOWLY AFTER MIDNIGHT. CURRENT ACARS SOUNDINGS SHOW THE
INVERSION HEIGHT NEAR CLE AROUND 7900 FEET AT 16Z WITH MOIST
CONDITIONS BELOW THE INVERSION. THIS IS A RATHER DEEP MIXED BOUNDARY
LAYER WHICH SHOULD CONTINUE TO SUPPORT INTENSE SCATTERED SNOW
SHOWERS. THE INVERSION BASE IS EXPECTED TO LOWER AFTER MIDNIGHT AND
THIS SHOULD HELP TO SUPPRESS SNOW SHOWERS.
&&
.SHORT TERM (TODAY THROUGH SUNDAY)...
COLD FRONT MOVED THROUGH OVERNIGHT. LACK OF ICE CRYSTALS CAUSED SOME
FREEZING DRIZZLE FOR SHORT TIME. MOST AREAS HAVE SWITCHED OVER TO
LIGHT SNOW...OR SHOULD DO SO SHORTLY. OTHERWISE COLD ARCTIC AIR
MOVING IN BEHIND FRONT. WILL TRANSITIONING FROM LIGHT SYNOPTIC SNOW
TO PRIMAIRLY LAKE EFFECT SNOW LATER TODAY AND CONTINUING INTO PART
OF SATURDAY. WILL ISSUE LAKE EFFECT SNOW WARNING FROM NOON TODAY
UNTIL 4 PM SATURDAY. MAY BE SOMEWHAT OF A BREAK THIS MORNING BEFORE
THE LAKE EFFECT GETS GOING BUT WITH THE WESTERLY FLOW AND 8H TEMPS
DROPPING TO ARND -13C BY EVENING FELT THE LAKE EFFECT SNOW WARNING
SHOULD START AT NOON THOUGH THE THE HEAVIEST MAY NOT GET GOING UNTIL
THIS EVENING. PREVIOUS FORECAST OF 6 TO 12 FOR THE SNOW BELT LOOKS
OK. WESTERLY FLOW THIS AFTERNOON AND EARLY TONIGHT GRADUALLY BECOMES
WELL AROUND TO NW AND MAY ADD LAKE HURON FETCH AFFECTING NW INLAND
PA WHICH COULD RAISE SNOW AMOUNTS. HIGH PRESSURE BUILDING IN ON
SATURDAY WILL CUT OFF LAKE EFFECT IN MORNING ARND CLEVELAND BUT
SHOULD LINGER IN THE EAST UNTIL AFTERNOON. THEN FLURRIES FAR EAST
SATURDAY EVENING THEN HIGH MOVES QUICKLY ACROSS SATURDAY NIGHT. THEN
LOW MOVES INTO MID MISSISSIPPI VALLEY SUNDAY BRINGING ANOTHER CHANCE
FOR SOME SNOW.
&&
.LONG TERM (SUNDAY NIGHT THROUGH THURSDAY)...
NW FLOW GENERALLY CONTINUES THROUGH THE PERIOD. FLOW IS FAIRLY
FAST SO PINNING DOWN INDIVIDUAL DETAILS TRICKY. NO BIG
STORMS...MOSTLY JUST CLIPPER TYPE SYSTEMS BUT EACH ONE OPENS THE
DOOR TO AT LEAST SOME SNOW SHOWERS AS WELL AS LAKE EFFECT SNOWS.
TROUGH ALOFT AND SECONDARY COLD FRONT AT SURFACE DROP SOUTH ACROSS
THE LOWER LAKES BY LATE MONDAY. I THINK THE MAJORITY OF THE COLDER
AIR WILL SLIDE OFF TO THE NORTH BUT SOME COLDER AIR WILL TRICKLE
SOUTHWARD AND WITH NNW FLOW SOME LAKE EFFECT POSSIBLE BY TUESDAY.
ELSEWHERE THERE SHOULD BE SOME CLEARING. LOOKS LIKE A BIT OF A BREAK
LATER TUE NGT INTO WEDNESDAY. STILL NOT SURE WITH A FAST FLOW THAT
THERE MIGHT BE A SMALL CHANCE OF SNOW SHOWERS BUT IT LOOKS UNTIL
LATER WED/WED NGT THAT NEXT SHORT WAVE DROPS ACROSS FCST AREA WITH
SOME LAKE EFFECT BY THURSDAY AS SOME COLDER AIR RETURNS. LAKE EFFECT
WILL CONTINUE INTO FRIDAY WITH DRIER AND COLDER CONDITIONS
ELSEWHERE. ECMWF COLDER BY THE END OF THE WEEK AS GFS SHOWS A BIT OF
A CHINOOK FLOW DEVELOPING BY FRIDAY WHERE AS ECMWF BRINGS A MORE
SIGNIFICANT CHUNK OF COLDER AIR SOUTHWARD. CONSENSUS THINKING IS
THAT COLDER SOLUTION MIGHT BE BETTER.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...LAKE EFFECT SNOW WARNING FROM FRIDAY AFTERNOON THROUGH SATURDAY
AFTERNOON FOR OHZ011>014-023-089.
PA...LAKE EFFECT SNOW WARNING FROM FRIDAY AFTERNOON THROUGH SATURDAY
AFTERNOON FOR PAZ001>003.
&&
$$
SHORT TERM...WCR
LONG TERM...KOSARIK/ASTIFAN
AVIATION...REL
AREA FORECAST DISCUSSION
NWS NORMAN OK
AFDOUN 317 PM CST FRI JAN 19 2007
.DISCUSSION...A WINTER STORM OF MAINLY SNOW AND SLEET CONTINUES TO
COME TOGETHER. THE UPPER LEVEL CYCLONE HAS BEEN STALLED OVER THE
BAJA PENINSULA BENEATH SHORTWAVE RIDGING FARTHER NORTH. THIS RIDGING
SHOULD CONTINUE TO MOVE EAST...OWING TO ITS SHORT WAVELENGTH...AND
SATELLITE SHOWED A KICKER TROUGH APPROACHING THE WEST COAST.
THEREFORE...HAVE GOOD CONFIDENCE IN THE UNANIMOUS COMPUTER MODEL
FORECASTS THAT SHOW THE LOW KICKING OUT INTO THE PLAINS VERY QUICKLY
FROM SATURDAY INTO SATURDAY NIGHT.
MOISTURE ADVECTION AND ISENTROPIC UPGLIDE ALREADY EVIDENT AHEAD OF
THE LOW...WITH A LOT OF VIRGA AND LIGHT PRECIPITATION FROM WEST
TEXAS TOWARD THE RED RIVER. MORNING SOUNDINGS INDICATED A LOT OF DRY
AIR THAT WILL NEED TO BE COOLED BY EVAPORATION BEFORE PRECIPITATION
REACHES THE GROUND...BUT ONCE PRECIPITATION BEGINS IT SHOULD BE
STEADY AND WIDESPREAD. ALL ALONG...THERE HAS BEEN SUBSTANTIAL
UNCERTAINTY AS TO THE TYPE OF PRECIP THAT WILL BE OBSERVED FROM
CENTRAL OKLAHOMA SOUTHWARD...AS TEMPERATURE PROFILES HOVER CLOSE TO
FREEZING THROUGH A GREAT VERTICAL DEPTH. THE LATEST THINKING IS THAT
THE EVENT APPEARS SLIGHTLY COLDER...AND MORE LIKELY TO SUPPORT SNOW
FOR A LONGER TIME BEFORE BECOMING MIXED WITH SLEET OR RAIN. THE
EVIDENCE LIES MAINLY IN THE WET BULB PROFILE IN THE NORMAN
SOUNDING...COLDER NAM AND GFS FORECAST SOUNDINGS...AND A FEW
TEMPERATURE PROFILES OBTAINED FROM THE TAMDAR AIRCRAFT ASCENT DATA.
BECAUSE OF THE COLDER PROFILES AND AN EARLIER ONSET NOW AGREED UPON
BY THE MODELS...WENT AHEAD AND PULLED THE WINTER STORM WARNING
FARTHER SOUTH. ALSO WILL HAVE A WINTER WEATHER ADVISORY IN THE FAR
SOUTHEAST. THE MAIN CONCERN IS FOR TONIGHT INTO SATURDAY MORNING FOR
SOUTHERN OKLAHOMA...WITH A FEW INCHES OF ACCUMULATION BEFORE
CHANGING TO RAIN TOMORROW AFTERNOON.
MEANWHILE...THE MODELS HAVE ALSO CONTINUE TO TREND TOWARD A DEEPER
LOW TRACKING SLIGHTLY FARTHER SOUTH THAN IN PREVIOUS FORECAST
CYCLES. THE LOW IS QUITE IMPRESSIVE ON SATELLITE...AND WILL HAVE A
FAIRLY SHORT WAVELENGTH AND FAST MOTION AS IT COMES OUT...TO
GENERATE VERY DEEP AND STRONG LIFT OVER THE REGION. THIS ALSO FAVORS
MORE SNOW...ESPECIALLY NEAR AND NORTH OF THE UPPER LOW TRACK. MOST
OF THE PRECIPITATION IS EXPECTED TO BE SNOW TO THE NORTH OF A LINE
FROM VERNON TEXAS TO LAWTON...NORMAN...AND SHAWNEE.
SOME OF THE SNOW IS EXPECTED TO BE QUITE HEAVY AROUND MIDDAY
SATURDAY INTO THE AFTERNOON. CROSS SECTIONS INDICATE STRONG LIFT
THROUGH THE DENDRITIC ICE CRYSTAL LAYER OVER A FAIRLY BROAD REGION
OF WEST CENTRAL...CENTRAL...AND NORTH CENTRAL OKLAHOMA. THIS COUPLED
WITH TEMPERATURES PROFILES JUST A FEW DEGREES BELOW FREEZING THROUGH
A GREAT DEPTH...MAY RESULT IN SOME HEAVY FALLS OF LARGE WET
SNOWFLAKES. THIS MAXIMUM IN SNOWFALL RATES MAY NOT LAST LONG...BUT
COULD PUSH STORM TOTAL ACCUMULATIONS TOWARD 10 INCHES IN SOME AREAS.
ELSEWHERE...A RANGE OF 4 TO 8 INCHES SEEMS LIKELY...AND SOME OF THAT
WILL BE SLEET TO THE SOUTH OF THE UPPER STORM TRACK.
AS A FURTHER COMPLICATION...FAR SOUTHEAST OKLAHOMA MAY SEE SOME
FAIRLY HEAVY RAIN SATURDAY AFTERNOON AND EVENING...WHERE LOW LEVEL
FRONTOGENESIS IS MAXIMIZED...AND THERE IS SOME INDICATION OF MID
LEVEL INSTABILITY. THIS WOULD BE MAINLY THE COUNTIES THAT ARE IN THE
WINTER WEATHER ADVISORY. WILL LET THE ADVISORY RUN THROUGH SATURDAY
NIGHT...HOWEVER...AS THERE IS POTENTIAL FOR TEMPERATURES TO FALL
AGAIN OVERNIGHT AND RESULT IN FREEZING DRIZZLE. THE SAME COULD BE
SAID FOR OTHER PARTS OF OKLAHOMA...WHERE FREEZING DRIZZLE MAY BECOME
A CONCERN BEHIND THE UPPER LOW...WHERE MOISTURE DEPTH BECOMES
SHALLOW.
IN THE EXTENDED...WILL MAINTAIN A CHANCE FOR LIGHT SNOW IN NORTH
TEXAS AND SOUTHERN OKLAHOMA MONDAY. OTHERWISE...CONTINUED IN A COLD
BUT DRY NORTHERLY FLOW ALOFT...WITH COOL BUT NOT BITTERLY COLD
SURFACE HIGH PRESSURE ENTRENCHED OVER THE PLAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 26 32 29 33 / 70 100 60 10
HOBART OK 24 31 27 32 / 90 100 40 10
WICHITA FALLS TX 29 33 31 37 / 100 100 40 10
GAGE OK 23 30 25 31 / 70 90 50 10
PONCA CITY OK 23 32 28 32 / 30 100 80 20
DURANT OK 31 37 33 40 / 90 100 70 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...WINTER STORM WARNING UNTIL 6 AM CST SUNDAY FOR OKZ004>020-
022>032-039>042-045-046.
WINTER STORM WARNING UNTIL 6 AM CST SUNDAY FOR OKZ021-033>038-
044.
WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR
OKZ043-047-048- 050>052.
TX...WINTER STORM WARNING UNTIL 6 AM CST SUNDAY FOR TXZ086-088>090.
WINTER STORM WARNING UNTIL 6 AM CST SUNDAY FOR TXZ083>085-087.
&&
$$
BURKE/07
AREA FORECAST DISCUSSION
NWS PORTLAND OR
AFDPQR 830 AM PST FRI JAN 19 2007
.SYNOPSIS...A WEAKENING COLD FRONT IS SPREADING RAIN ACROSS THE
FORECAST AREA THIS MORNING WITH RAIN IN THE VALLEYS AND SNOW IN THE
CASCADES. THERE MAY BE ISOLATED POCKETS OF FREEZING RAIN IN THE
COLDER VALLEYS OF THE COAST RANGE AND ALONG THE LOWER COLUMBIA RIVER
AND NEAR HILLSBORO THIS MORNING TILL AROUND 930 AM BUT EXPECT THAT
SHALLOW COLD AIR TO MIX OUT QUICKLY. SHOWERS WILL CONTINUE BEHIND THE
FRONT TONIGHT AND SATURDAY AS WEAK PACIFIC WEATHER SYSTEMS BRUSH OUR
FAR NORTHERN ZONES. HIGH PRESSURE BUILDS OVER THE PAC NW EARLY NEXT
WEEK...WITH DRY WEATHER FOR MONDAY THROUGH AT LEAST WEDNESDAY.
&&
.SHORT TERM...A SHEARED PACIFIC COLD FRONT NEAR THE COAST WILL MOVE
INLAND SHORTLY. THE FRONT HAS A WIDE MOISTURE SHIELD AND IT APPEARS
ON SATELLITE THAT THE MID AND UPPER PORTIONS SHEARED EASTWARD AHEAD
OF THE SURFACE FEATURE UNDER THE INFLUENCE OF A STRONG WESTERLY JET
APPROACHING THE PACNW. ALTHOUGH THAT WEAKENS THE FRONT IT ALSO SPED
UP THE ONSET OF PRECIPITATION A FEW HOURS AHEAD OF THE MODELS. SINCE
THE PRECIPITATION ARRIVED IN THE MORNING WITH WEAKER DYNAMICS IT
PRECEDED THE MIX OUT OF ALL THE COLDER AIR AND LEFT SOME SHALLOW
POOLS OF COLD AIR WITH SOME FREEZING PRECIPITATION AND FOG DURING
THE MORNING HOURS OVER THE COAST RANGE...LOWER COLUMBIA RIVER WEST
OF PORTLAND...AND POSSIBLY TO WESTERN WASHINGTON COUNTY WHERE
POCKETS OF FREEZING TEMPERATURES EXIST. OBSERVATIONS AT SCAPPOOSE
AND HILLSBORO SHOWED SOME FREEZING RAIN THIS MORNING...THAT WILL BE
BRIEF WITHOUT ANY SIGNIFICANT ACCUMULATION AND EXPECT IT WILL NOT BE
INCLUDED IN THE FORECAST PACKAGE ISSUED AT 940 AM. THE AIRCRAFT
SOUNDINGS OVER THE PORTLAND AIRPORT ARE ALL ABOVE FREEZING AND THE
SURFACE TEMPERATURE THERE THIS MORNING AT 8 AM IS 35 DEGREES. WITH A
SHEARED FRONT EXPECT PRECIPITATION AMOUNTS IN GENERAL TO BE LOW.
ANOTHER CONCERN IS IN THE COLUMBIA RIVER GORGE AROUND HOOD RIVER
WHERE AREAS OF FREEZING TEMPERATURES EXIST. ROOSTER ROCK SHOWED 35
DEGREES AND BONNEVILLE 33 AT 8 AM AND CASCADE LOCKS WAS ABOVE
FREEZING BUT HOOD RIVER AIRPORT WAS STILL 28 DEGREES AND HOOD RIVER
AGRIMET SHOWED 27 DEGREES THIS MORNING. MODELS ARE NOT HANDLING THIS
SHEARED SYSTEM WELL AT ALL AND i LIKE THE PREVIOUS FORECAST IDEA TO
MENTION POSSIBILITY OF FREEZING PRECIPITATION IN THE HOOD RIVER AND
PARKDALE AREA AS PRECIPITATION ARRIVES. A SPECIAL WEATHER STATEMENT
HIGHLIGHTS THE POSSIBILITY OF FREEZING PRECIPITATION IN THESE AREAS.
ONCE THE COLD FRONT IS THROUGH TONIGHT ONSHORE FLOW WILL FINALLY
PUSH THE SHALLOW COLD AIR ALL THE WAY OUT. WEAK WARM ADVECTION
OVERRUNNING MOISTURE WILL GIVE A CHANCE OF LIGHT PRECIPITATION TO
THE NORTHWEST PART OF THE FORECAST AREA SATURDAY NIGHT AND SUN AS
THE OFFSHORE UPPER LEVEL RIDGE BUILDS AND PUSHES PRECIPITATION AREAS
BACK NORTH OF THE AREA...MODELS VARY RUN TO RUN ON AREAL COVERAGE OF
THIS PRECIP EVENT WITH BEST PROSPECTS FOR RAIN OVER THE NORTHWEST
CORNER OF THE FORECAST AREA. WILLSON.
&&
.LONG TERM...A STRONG UPPER RIDGE WILL REMAIN OVER THE PACIFIC NW
THROUGH THE MIDDLE OF NEXT WEEK WITH DRY WEATHER. MODELS INDICATING
A WEAK FRONT WILL RUN INTO THE RIDGE AND WEAKEN LATE WEDNESDAY/
THURSDAY. MODELS IMPLY THAT MAY BE THE BEGINNING OF A CHANGE FROM
THE RIDGE/DRY PATTERN...BUT SOLUTIONS DIVERGE QUITE A BIT. WILL
CONTINUE CHANCE POPS FOR THE END OF THE EXTENDED PERIOD. BOHL
&&
&&
.AVIATION...THE BACK EDGE OF THE FRONT WILL MOVE INLAND OVER THE
COAST WITHIN THE NEXT HOUR OR TWO. TEMPERATURES THIS MORNING ARE
GENERALLY IN THE 30S. PRECIPITATION IS MAINLY STARTING AS RAIN WITH
A FEW PATCHES OF FREEZING RAIN IN AREAS SUCH AS HILLSBORO WHERE
SURFACE TEMPERATURES ARE STILL BELOW FREEZING. THIS COLD AIR WILL
MIX OUT QUICKLY AS THE FRONT MOVES INLAND. NON LIQUID PRECIPITATION
WILL REMAIN A PROBLEM LONGER IN THE COLUMBIA RIVER GORGE WHERE MORE
COLD AIR IS ENTRENCHED. A TRAILING UPPER LEVEL DISTURBANCE CURRENTLY
ALONG THE BRITISH COLUMBIA COAST WILL BRING ANOTHER SHOT OF RAIN AND
LOWER CEILINGS THIS EVENING AND TONIGHT. RUTHFORD.
&&
.MARINE...SOUTHERLY WINDS OFFSHORE ARE CURRENTLY GUSTING TO AROUND
25 KNOTS AT BUOYS 29 AND 50 WITH SEAS OF 10 FEET AND 8 FT
RESPECTIVELY. WINDS WILL TURN TO THE WEST AND DROP INTO THE TEENS
THIS AFTERNOON ONCE THE FRONT MOVES THROUGH. SEAS ARE EXPECTED TO
BUILD TO 11 FEET TODAY THEN CONTINUE AROUND 10 FEET THROUGH
SATURDAY. WINDS IN THE NORTHERN WATERS WILL INCREASE TO 20 OR 25
KNOTS AGAIN TONIGHT AS AN UPPER LEVEL DISTURBANCE MOVES THROUGH THE
AREA. RUTHFORD.
&&
.PQR WATCHES/WARNINGS/ADVISORIES
.OR/WA...SMALL CRAFT ADVISORY FOR WINDS THROUGH TONIGHT FOR THE
COASTAL WATERS FROM CAPE SHOALWATER TO CASCADE HEAD.
SMALL CRAFT ADVISORY FOR WINDS TODAY FOR THE COASTAL WATERS
FROM CASCADE HEAD TO FLORENCE.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR TODAY AND
TONIGHT FOR COASTAL WATERS FROM CAPE SHOALWATER TO CASCADE
HEAD.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR TODAY AND
TONIGHT.
&&
.PRELIMINARY POINT POPS...
AST 97355 PDX 87311 SLE 76311 EUG 66311
$$
MORE WEATHER INFORMATION ONLINE AT...
Http://weather.gov/portland
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
AFDGRB 515 AM CST FRI JAN 19 2007
.SHORT TERM...TODAY THROUGH SATURDAY...UPPER PATTERN OVER STATE WILL
SHIFT FROM NW FLOW TO A MORE WESTERLY PATTERN FOR SATURDAY AS RIDGE
BUILDS IN. ONE MORE DISTURBANCE DROPPING SOUTHEAST. SEEN ON IMAGERY OVER
EASTERN ND. BOTH MODELS BRING IT THROUGH STATE THIS AFTERNOON. FAVORABLE
QG FORCING BETWEEN 5K AND 3K WITH BEST OMEGA OVER NORTHEAST CWA.
FORECAST QUESTION IS PCPN CHANCE WITH FEATURE. FEATURE HAS MUCH LESS
MOISTURE TO WORK WITH THAN PREVIOUS WAVES. IMAGERY SHOWING LOW CLOUDS
OVER WI ERODING WITH CLEARING INTO WESTERN WI. SOME MID CLOUDS WITH WAVE
MOVING SOUTHEAST. MODELS BOTH DEPICT LOW CLOUDS CONTINUING TO SCOUR OUT
OVER THE WEST. HAVE TRIMMED BACK ON PCPN CHANCE TODAY...WITH FLURRIES
SOUTH AND WEST AS SHORT WAVE PASSES THROUGH...STAYING WITH CHANCE POPS
FURTHER NORTH WHERE MOISTURE BETTER. HAVE STAYED WITH MOSTLY CLOUDY
WORDING...THOUGH SOME SUNNY BREAKS MORE THAN LIKELY...ESPECIALLY OVER
CENTRAL WI.
LAKE EFFECT NOT OVERLY IMPRESSIVE AT THIS TIME WITH WINDS MORE WESTERLY
AS DEPICTED IN EARLIER RUNS. LATE EVENING TAMDAR SOUNDINGS INDICATED
INVERSIONS NR 6K FEET...THOUGH MODELS BOTH INDICATE THIS TO DROP TO NEAR
3K FEET LATE THIS AFTERNOON. WILL STAY WITH CURRENT TRENDS AND GO WITH
MORE SCATTERED WORDING AND LIMIT ADDITIONAL ACCUMULATIONS TO AROUND AN
INCH.
RIDGE TO BUILD IN TONIGHT AND SATURDAY WITH FURTHER CLEARING TREND.
GUSTY WINDS/CAA PATTERN HAVE KEPT TEMPS UP OVER PREVIOUS THINKING.
CONTINUED CAA TODAY WILL LIMIT DIURNAL RISE...WITH MANY MAXES LIKELY
SEEN EARLY THIS MORNING. LIGHT WINDS OVERNIGHT WITH SFC HIGHS SHOULD
ALLOW TEMPS TO FALL SIGNIFICANTLY...BELOW GUIDANCE TREND FROM PREVIOUS
SHIFT CONTINUED.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY.
SNOW ASSOCIATED WITH A SURFACE SYSTEM AND MID LEVEL SHORT WAVE LIFTING
NORTHEAST OUT OF THE PLAINS SHOULD REACH THE FORECAST AREA ON SUNDAY.
NAM/WRF AND GFS KEEP SATURDAY NIGHT DRY SINCE IT IS LIKELY TO TAKE THAT
LONG FOR SIGNIFICANT MOISTURE TO ARRIVE. HAVE LIKELY POPS GOING FOR MOST
OF THE AREA BY AFTERNOON...BUT DID LOWER POPS INTO THE CHANCE CATEGORY
OVER THE NORTH WHERE MOISTURE IS MORE LIMITED. LOOKS LIKE ABOUT 2 TO 3
INCHES ACROSS THE SOUTHERN HALF OF THE AREA WITH 1 TO 2 INCHES POSSIBLE
OVER THE NORTH. THIS FITS FAIRLY WELL WITH SURROUNDING SNOWFALL GRIDS
AND HPC GUIDANCE. A FRONTAL BOUNDARY MOVING SOUTH INTO THE STATE ON
MONDAY WILL KEEP CHANCE POPS IN THROUGH 00Z TUESDAY. LEFT CHANCE POPS
FOR SNOW SHOWERS IN THE NORTH MONDAY NIGHT...BUT WIND DIRECTION NOT
REALLY FAVORABLE FOR LES. JUST WENT WITH SCATTERED FLURRIES ACROSS THE
REST OF THE AREA. TUESDAY LOOKS LIKE A DRY DAY AS HIGH PRESSURE SLIDES
ACROSS THE REGION. BUT AN APPROACHING SYSTEM WILL BRING A CHANCE OF SNOW
BACK TO THE WESTERN HALF OF THE AREA TUESDAY NIGHT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
$$
TE/MG
WEATHER.GOV/GREENBAY