AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
230 PM PST SUN FEB 18 2007
.SYNOPSIS...
AN APPROACHING PACIFIC STORM WILL BRING A CHANCE OF SHOWERS LATE
TONIGHT...BECOMING LIKELY MONDAY AND TAPERING OFF MONDAY NIGHT.
THERE WILL ALSO BE A SLIGHT CHANCE OF THUNDERSTORMS MONDAY. DRY AND
A LITTLE WARMER TUESDAY AND WEDNESDAY UNDER WEAK HIGH PRESSURE.
ANOTHER PACIFIC STORM WILL CAUSE A CHANCE OF SHOWERS THURSDAY INTO
FRIDAY FOLLOWED BY DRY NORTHWEST FLOW ALOFT NEXT WEEKEND.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES.
.SHORT TERM (TONIGHT-WED)...
THERE WAS VARIABLE HIGH CLOUDINESS TODAY. STRATUS IN THE COASTAL
WATERS WAS STARTING TO MOVE ONSHORE THIS AFTERNOON. EARLY AFTERNOON
ACARS SOUNDINGS SHOWED S TO SW WINDS THROUGH THE COLUMN. INCREASING
ONSHORE GRADIENTS WITH 4-5 MB SAN-IPL.
NAM HAS BEEN INCONSISTENT WITH THE TROUGH APPROACHING FROM THE
NW...ALTHOUGH IT IS CURRENTLY BACK IN BETTER AGREEMENT WITH OTHER
MODEL SOLUTIONS. PRIMARILY WENT WITH THE GFS. THE ACROSS TROUGH WILL
MOVE THROUGH MON WITH A COUPLE OF VORT MAXS ROTATING TROUGH. THE
CHANCE OF SHOWERS WILL GRADUALLY INCREASE TONIGHT...BECOMING LIKELY
OVER AND W OF THE MOUNTAINS MON. SHOWERS WILL TAPER OFF MONDAY
NIGHT. RAINFALL TOTALS SHOULD RANGE FROM ABOUT A QUARTER TO HALF AN
INCH W OF THE MOUNTAINS EXCEPT LOCAL AMOUNTS TO NEAR AN INCH ON SW
FACING MOUNTAIN SLOPES. THERE COULD ALSO BE LOCAL BRIEF HEAVY
SHOWERS IN CONVECTION WITH POSSIBLE THUNDERSTORMS...WATERSPOUT AND
FUNNEL CLOUDS MON AS COLDER UNSTABLE AIR MOVES IN ALOFT. THE SW
FACING SLOPES OF THE SAN BERNARDINO COUNTY MOUNTAINS WILL BE A
FAVORED AREA FOR GETTING THE MOST PRECIP. THE SNOW LEVEL WILL LOWER
TO ABOUT 5500 FT BY LATE MON AND COULD BE LOCALLY LOWER IN
CONVECTION. SNOWFALL AMOUNTS SHOULD MOSTLY BE LESS THAN 4 INCHES BUT
THERE COULD BE ISOLATED TOTALS TO SEVERAL INCHES AT THE HIGHER
ELEVATIONS. GUSTY WINDS WILL ACCOMPANY THIS SYSTEM...MAINLY IN THE
MOUNTAINS AND DESERTS. THERE HAS ALREADY BEEN A LOT OF COOLING NEAR
THE COAST AND MORE COOLING WILL SPREAD INLAND MON. DRY WITH
DECREASING CLOUDINESS AND WARMING TUE UNDER A SHORT WAVE RIDGE. THE
RIDGE SHIFTS E WED WITH FLAT W TO SW FLOW ALOFT FOR GRADUALLY
INCREASING CLOUDINESS AND A LITTLE COOLING.
.LONG TERM (THU-SUN)...
ANOTHER PAC TROUGH WILL BRING A CHANCE OF SHOWERS THU INTO FRI WITH
ASSOCIATED CLOUDS...COOLING AND LOCAL GUSTY WINDS. DRY NW FLOW ALOFT
AND WEAK OFFSHORE GRADIENTS NEXT WEEKEND FOR GENERALLY FAIR AND
WARMER WEATHER.
&&
.AVIATION...
LARGE STRONG EDDY CENTERED OVER SAN NICOLAS ISLAND CAUSING
10-15 KT SOUTH WINDS ALONG THE COAST AND COASTAL WATERS THIS
AFTERNOON. THIS ALSO CAUSING LARGE PATCHES OF 1000 FT BASE STRATUS
TO DEVELOP NEAR AND ON SHORE. EXPECT THE STRATUS TO BECOME QUITE
EXTENSIVE AND MOVE INLAND LATE THIS AFTERNOON THROUGH EVENING.
MARINE LAYER WILL DEEPEN OVERNIGHT...SO BASES MAY LIFT TO 1500 FT
MSL. 550 UPPER LOW AND ASSOCIATED COLD FRONT WILL BRING LIKELY
SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS STARTING AT ABOUT 4 TO
6 AM...AND CONTINUE INTO MONDAY EVENING. MID AND HIGH CLOUDS ABOVE
THE STRATUS WILL INCREASE AROUND MIDNIGHT AS THE FRONT APPROACHES
FROM THE WEST. CLOUD BASE DURING FRONTAL PASSAGE AND MOST OF THE DAY
MONDAY WILL BE AROUND 2500 FT MSL EXCEPT LOWER WITH HEAVIER SHOWERS.
S-SW 10-15 KT SURFACE WINDS WILL CONTINUE THIS AFTERNOON THROUGH
MONDAY. SURGE IN SW WINDS AND MOISTURE AT 700 MB WILL CONTINUE TO
CAUSE WAVE CLOUDS AND TURBULENCE OVER THE MOUNTAINS TODAY AND
TONIGHT.
&&
.MARINE...
INCREASING WEST SWELL WILL REACH PEAK HEIGHT OF 8 FEET EARLY MONDAY
MORNING...WITH THE LARGE SWELL CONTINUING THROUGH MONDAY NIGHT AND
SUBSIDING TO 6 FEET ON TUESDAY. THIS WILL CAUSE HIGH SURF MAINLY ON
THE SAN DIEGO COUNTY COAST.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
SPECIAL WEATHER STATEMENT. SEE LAXSPSSGX.
HIGH RIP CURRENT RISK AT THE BEACHES THROUGH MON. SEE LAXSRFSGX
HIGH SURF ADVISORY IN EFFECT FOR SAN DIEGO BEACHES UNTIL 2 PM TUE.
SEE LAXCFWSGX.
&&
$$
PUBLIC...DVA
AVIATION/MARINE...MACKECHNIE
AREA FORECAST DISCUSSION
NWS JACKSON KY
935 PM EST MON FEB 19 2007
.SHORT TERM.../THE REST OF TONIGHT THROUGH WEDNESDAY NIGHT/...UPDATED
CONSIDERABLE MID AND HIGH LEVEL CLOUDINESS CONTINUES TO WAFT
OVERHEAD AS ISENTROPIC UPGLIDE STRENGTHENS ALOFT. THERE MAY BE A FEW
BREAKS FROM TIME TO TIME... HOWEVER LATEST SATELLITE IMAGERY SHOWS
MID LEVEL STUFF REDEVELOPING UPSTREAM OVER WESTERN KENTUCKY AND
TENNESSEE SO BELIEVE A MOSTLY CLOUDY REST OF TONIGHT IS ON TAP.
DESPITE THE CLOUDS... RIDGE/VALLEY TEMP DIFFERENCES ARE BEING
ESTABLISHED OVER THE EASTERN HALF OF THE FORECAST AREA AS VALLEY
WINDS HAVE GONE NEARLY CALM. PRESTONSBURG AND PIKEVILLE REPORTED 39
AND 40 DEGREES RESPECTIVELY AT 9 PM WHILE THE RIDGES REMAIN IN THE
MID 40S. WILL THUS NEED TO ADJUST OVERNIGHT WIND SPEEDS AND TEMPS
BASED ON CURRENT TRENDS. EXPECT MIXING TO INCREASE IN THE NEXT FEW
HOURS THEREFORE LOWS SHOULDN/T TUMBLE TOO FAR EVEN IN OUR VALLEYS.
IN ADDITION...WILL MAKE ONE ADJUSTMENT TO THE FORECAST SUITE BEYOND
TONIGHT. WITH GROUND TEMPS VERY COLD AND A MILD AND VERY MOIST
AIRMASS ADVECTING IN TOMORROW AND TOMORROW NIGHT... ALONG WITH
RAINFALL... BELIEVE THE STAGE IS SET FOR AT LEAST PATCHY FOG LATE
TUESDAY AFTERNOON INTO TUESDAY NIGHT AND THIS WILL BE ADDED TO THE
FORECAST.
PERTINENT PARTS OF THE PREVIOUS SHORT TERM DISCUSSION FOLLOW BELOW...
BIG QUESTION IS WHEN WILL THE PRECIPITATION BEGIN. THE GFS IS
QUICKER WITH THE FRONT...HOWEVER THE NAM MAY ACTUALLY BE THE BETTER
SOLUTION. THE NAM IS IN BETTER AGREEMENT WITH THE ECMWF AND THE GFS
ENSEMBLE. THE REASON FOR DELAYING THE FRONT IS THAT THERE WILL BE
SOME WAVES FORMING ON THE FRONT OUT TO THE SOUTHWEST OF KY. THIS
SHOULD HOLD UP THE FRONT SO THAT THE PRECIPITATION DOES NOT MOVE INTO
THE AREA UNTIL TUESDAY MORNING. THE MODELS ARE ALSO SHOWING THAT THE
STRONGEST PORTION OF THE FRONT WILL BE COMING THROUGH ON TUESDAY
EVENING AFTER ABOUT 7 PM. THERE IS SOME ELEVATED INSTABILITY
ASSOCIATED WITH THE SYSTEM AND THE MODEL TOTAL TOTALS WERE 54.
HOWEVER CONSIDERING THE TIME OF DAY THE FRONT IS COMING THROUGH AND
THE TIME OF THE YEAR...I HELD OFF PUTTING ANY THUNDERSTORMS IN THE
FORECAST FOR TUESDAY AFTERNOON AND EVENING. THE FRONT WILL STALL OVER
THE AREA ON WEDNESDAY AND WILL ALLOW THE TEMPERATURE TO MAKE IT INTO
THE 50S ON WEDNESDAY. FOR THE TEMPERATURE FORECAST...JUST MADE MINOR
ADJUSTMENTS TO THE MOS.
.LONG TERM.../THURSDAY THROUGH MONDAY/
THE LONG TERM PORTION OF THE FORECAST STARTS OUT WITH A WEAK COOL
FRONT MOVING THROUGH THE AREA DURING THE DAY ON THURSDAY. THE MODELS
DO NOT SHOW ENOUGH MOISTURE WITH THIS FEATURE TO PRODUCE ANY PRECIP.
LEFT THE FORECAST DRY...WITH PARTLY CLOUDY SKIES. FRIDAY SOME WEAK
CAA OCCURS WITH HIGH PRESSURE BUILDING BACK IN. THE MODEL SOLUTIONS
BEGIN TO DIVERGE BY FRIDAY NIGHT...WITH THE 00Z GFS AND ECMWF MORE
AGGRESSIVE WITH MOISTURE RETURN OVER THE AREA...AND PRECIP. A CLOSED
H5 LOW IS FORECAST TO MOVE NORTHEAST OUT OF TEXAS TO IOWA FROM LATE
SATURDAY INTO SUNDAY...WITH A RESULTANT SOUTHWESTERLY FLOW AT H5 OUT
AHEAD OF THE LOW. A SURFACE LOW IS PROGGED TO MOVE NORTHEAST OUT OF
THE SOUTHERN PLAINS DURING THIS SAME TIME PERIOD. A WARM FRONT
EXTENDING FROM THE LOW SHOULD MOVE NORTH THROUGH THE AREA ON
SATURDAY. THERE DOES NOT APPEAR TO BE A LOT OF DYNAMICS WITH THIS
FRONT...BUT DID MENTION A CHANCE OF SHOWERS FOR SATURDAY. I BELIEVE
THE 00Z ECMWF AND GFS MOVE THE COLD FRONT ASSOCIATED WITH THE
SURFACE LOW TOO FAST TO THE EAST. THE 00Z MODELS BRING THE FRONT
THROUGH EASTERN KENTUCKY LATE SATURDAY NIGHT INTO EARLY SUNDAY
MORNING. I PREFER THE 06Z GFS SOLUTION...WHICH IS SLOWER. THE 06Z
GFS BRINGS THE FRONT THROUGH LATE SUNDAY AFTERNOON. BROUGHT LIKELY
POPS FOR SHOWERS IN DURING THAT TIME PERIOD...AND KEPT A CHANCE OF
THUNDERSTORMS MENTIONED. THE LATEST MODELS DO NOT SHOW AS MUCH
INSTABILITY WITH THE FRONT AS YESTERDAYS RUNS...BUT I BELIEVE THERE
WILL STILL BE ENOUGH INSTABILITY FOR SOME THUNDER WITH THE FRONT. A
QUICK LOOK AT THE 12Z GFS HAS A SLIGHTLY FASTER MOVEMENT WITH THE
FRONT...BRINGING IT THROUGH EARLY SUNDAY AFTERNOON...HOWEVER I
PREFER THE SLOWER MOVEMENT WITH THE SOUTHWESTERLY H5 FLOW AND A
CLOSED LOW TO OUR NORTHWEST. THIS FLOW WOULD RESULT IN LESS OF AN
EASTWARD PUSH OF THE COLD FRONT. AFTER THE FRONT MOVES THROUGH LATE
SUNDAY AFTERNOON OR EARLY EVENING...DRIER AND COOLER AIR SHOULD
FILTER IN BEHIND THE FRONT. TEMPS WILL REMAIN WARM THROUGH MUCH OF
THE EXTENDED PERIOD. WENT HIGHER THAN HPC AND MOS TEMPS FOR THE
WEEKEND...WITH A DELAYED FROPA TIMING.
&&
.AVIATION.../00Z TO 24Z/
THICK ALTOSTRATUS LAYER HAS OVERSPREAD THE AREA... INDICATIVE OF
STRENGTHENING ISENTROPIC UPGLIDE TAKING PLACE ALOFT IN ADVANCE OF
APPROACHING COLD FRONT OVER THE UPPER MIDWEST. LOW LEVEL JET WILL
INCREASE THIS EVENING AND MODEL PROGS ARE PROBABLY HANDLING THIS
PRETTY WELL AS LATEST ACARS SOUNDINGS REVEAL A 50 KT 85H JET
PRESENTLY OVER SDF... IN GOOD AGREEMENT WITH LATEST MODEL SOUNDINGS.
WILL THEREFORE CONTINUE TO ADVERTISE LLWS OVERNIGHT INTO THE EARLY
MORNING HOURS. LOW LEVEL JET IS PROGGED TO WEAKEN SUFFICIENTLY
ENOUGH TO END LLWS HAZARD BY MID MORNING TOMORROW.
WAVE OF LOW PRESSURE WILL DEVELOP ON THE FRONT OVER OKLAHOMA LATE
TONIGHT AND PUSH EASTWARD TOMORROW. ATMOSPHERIC COLUMN WILL MOISTEN
FROM THE TOP DOWN LATE TONIGHT WITH MVFR CIGS EXPECTED BY 12Z OR
SHORTLY THEREAFTER. THE MOISTENING PROCESS WILL CONTINUE THROUGH THE
DAY WITH CIGS EXPECTED TO GRADUALLY LOWER INTO THE IFR RANGE AFTER
21Z. SHRA SHOULD REMAIN SPARSE UNTIL THE COLD FRONT NEARS VERY LATE
IN THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...JJ/ABE
LONG TERM....WJM
AVIATION...ABE
AREA FORECAST DISCUSSION
NWS JACKSON KY
640 PM EST MON FEB 19 2007
.SHORT TERM.../TONIGHT THROUGH WEDNESDAY NIGHT/
THE LEADING EDGE OF THE MIDDLE AND HIGH CLOUDS ASSOCIATED WITH THE
NEXT SYSTEM HAVE BEGUN TO MOVE INTO THE AREA. A WARM FRONT ALSO
PASSED THROUGH THE AREA AND BROUGHT IN SOME WELCOME WARM AIR. MOST
PLACES IN THE FORECAST REGION HAD HIGHS NEAR 50 DEGREES TODAY. THE
BIG QUESTION IS WHEN WILL THE PRECIPITATION BEGIN. THE GFS IS
QUICKER WITH THE FRONT...HOWEVER THE NAM MAY ACTUALLY BE THE BETTER
SOLUTION. THE NAM IS IN BETTER AGREEMENT WITH THE ECMWF AND THE GFS
ENSEMBLE. THE REASON FOR DELAYING THE FRONT IS THAT THERE WILL BE
SOME WAVES FORMING ON THE FRONT OUT TO THE SOUTHWEST OF KY. THIS
SHOULD HOLD UP THE FRONT SO THAT THE PRECIPITATION DOES NOT MOVE
INTO THE AREA UNTIL TUESDAY MORNING. THE MODELS ARE ALSO SHOWING
THAT THE STRONGEST PORTION OF THE FRONT WILL BE COMING THROUGH ON
TUESDAY EVENING AFTER ABOUT 7 PM. THERE IS SOME ELEVATED INSTABILITY
ASSOCIATED WITH THE SYSTEM AND THE MODEL TOTAL TOTALS WERE 54.
HOWEVER CONSIDERING THE TIME OF DAY THE FRONT IS COMING THROUGH AND
THE TIME OF THE YEAR...I HELD OFF PUTTING ANY THUNDERSTORMS IN THE
FORECAST FOR TUESDAY AFTERNOON AND EVENING. THE FRONT WILL STALL
OVER THE AREA ON WEDNESDAY AND WILL ALLOW THE TEMPERATURE TO MAKE IT
INTO THE 50S ON WEDNESDAY. FOR THE TEMPERATURE FORECAST...JUST MADE
MINOR ADJUSTMENTS TO THE MOS.
.LONG TERM.../THURSDAY THROUGH MONDAY/
THE LONG TERM PORTION OF THE FORECAST STARTS OUT WITH A WEAK COOL
FRONT MOVING THROUGH THE AREA DURING THE DAY ON THURSDAY. THE MODELS
DO NOT SHOW ENOUGH MOISTURE WITH THIS FEATURE TO PRODUCE ANY PRECIP.
LEFT THE FORECAST DRY...WITH PARTLY CLOUDY SKIES. FRIDAY SOME WEAK
CAA OCCURS WITH HIGH PRESSURE BUILDING BACK IN. THE MODEL SOLUTIONS
BEGIN TO DIVERGE BY FRIDAY NIGHT...WITH THE 00Z GFS AND ECMWF MORE
AGGRESSIVE WITH MOISTURE RETURN OVER THE AREA...AND PRECIP. A CLOSED
H5 LOW IS FORECAST TO MOVE NORTHEAST OUT OF TEXAS TO IOWA FROM LATE
SATURDAY INTO SUNDAY...WITH A RESULTANT SOUTHWESTERLY FLOW AT H5 OUT
AHEAD OF THE LOW. A SURFACE LOW IS PROGGED TO MOVE NORTHEAST OUT OF
THE SOUTHERN PLAINS DURING THIS SAME TIME PERIOD. A WARM FRONT
EXTENDING FROM THE LOW SHOULD MOVE NORTH THROUGH THE AREA ON
SATURDAY. THERE DOES NOT APPEAR TO BE A LOT OF DYNAMICS WITH THIS
FRONT...BUT DID MENTION A CHANCE OF SHOWERS FOR SATURDAY. I BELIEVE
THE 00Z ECMWF AND GFS MOVE THE COLD FRONT ASSOCIATED WITH THE
SURFACE LOW TOO FAST TO THE EAST. THE 00Z MODELS BRING THE FRONT
THROUGH EASTERN KENTUCKY LATE SATURDAY NIGHT INTO EARLY SUNDAY
MORNING. I PREFER THE 06Z GFS SOLUTION...WHICH IS SLOWER. THE 06Z
GFS BRINGS THE FRONT THROUGH LATE SUNDAY AFTERNOON. BROUGHT LIKELY
POPS FOR SHOWERS IN DURING THAT TIME PERIOD...AND KEPT A CHANCE OF
THUNDERSTORMS MENTIONED. THE LATEST MODELS DO NOT SHOW AS MUCH
INSTABILITY WITH THE FRONT AS YESTERDAYS RUNS...BUT I BELIEVE THERE
WILL STILL BE ENOUGH INSTABILITY FOR SOME THUNDER WITH THE FRONT. A
QUICK LOOK AT THE 12Z GFS HAS A SLIGHTLY FASTER MOVEMENT WITH THE
FRONT...BRINGING IT THROUGH EARLY SUNDAY AFTERNOON...HOWEVER I
PREFER THE SLOWER MOVEMENT WITH THE SOUTHWESTERLY H5 FLOW AND A
CLOSED LOW TO OUR NORTHWEST. THIS FLOW WOULD RESULT IN LESS OF AN
EASTWARD PUSH OF THE COLD FRONT. AFTER THE FRONT MOVES THROUGH LATE
SUNDAY AFTERNOON OR EARLY EVENING...DRIER AND COOLER AIR SHOULD
FILTER IN BEHIND THE FRONT. TEMPS WILL REMAIN WARM THROUGH MUCH OF
THE EXTENDED PERIOD. WENT HIGHER THAN HPC AND MOS TEMPS FOR THE
WEEKEND...WITH A DELAYED FROPA TIMING.
&&
.AVIATION.../00Z TO 24Z/...UPDATED
THICK ALTOSTRATUS LAYER HAS OVERSPREAD THE AREA... INDICATIVE OF
STRENGTHENING ISENTROPIC UPGLIDE TAKING PLACE ALOFT IN ADVANCE OF
APPROACHING COLD FRONT OVER THE UPPER MIDWEST. LOW LEVEL JET WILL
INCREASE THIS EVENING AND MODEL PROGS ARE PROBABLY HANDLING THIS
PRETTY WELL AS LATEST ACARS SOUNDINGS REVEAL A 50 KT 85H JET
PRESENTLY OVER SDF... IN GOOD AGREEMENT WITH LATEST MODEL SOUNDINGS.
WILL THEREFORE CONTINUE TO ADVERTISE LLWS OVERNIGHT INTO THE EARLY
MORNING HOURS. LOW LEVEL JET IS PROGGED TO WEAKEN SUFFICIENTLY
ENOUGH TO END LLWS HAZARD BY MID MORNING TOMORROW.
WAVE OF LOW PRESSURE WILL DEVELOP ON THE FRONT OVER OKLAHOMA LATE
TONIGHT AND PUSH EASTWARD TOMORROW. ATMOSPHERIC COLUMN WILL MOISTEN
FROM THE TOP DOWN LATE TONIGHT WITH MVFR CIGS EXPECTED BY 12Z OR
SHORTLY THEREAFTER. THE MOISTENING PROCESS WILL CONTINUE THROUGH THE
DAY WITH CIGS EXPECTED TO GRADUALLY LOWER INTO THE IFR RANGE AFTER
21Z. SHRA SHOULD REMAIN SPARSE UNTIL THE COLD FRONT NEARS VERY LATE
IN THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...JJ
LONG TERM....WJM
AVIATION...ABE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
440 PM EST SUN FEB 18 2007
.SHORT TERM (TONIGHT AND MON)...
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A PATTERN CHANGE UNDERWAY
ACROSS NAMERICA AS FLOW IS BECOMING MORE PROGRESSIVE/ZONAL...
SIGNALING A RETURN TO NORMAL/ABOVE NORMAL TEMPS HERE THIS WEEK. A
TROF HAS MOVED ONSHORE OVER THE WRN CONUS...FORCING DOWNSTREAM RIDGE
E INTO THE PLAINS. COLD TROF OVER ERN NAMERICA IS ALSO BEING FORCED
EWD. SHORTWAVE ENERGY IN THE NRN END OF WRN TROF IS THE MAIN FEATURE
OF INTEREST IN THE SHORT TERM AS IT WILL SUPPORT A SFC LOW MOVING
ACROSS SRN CANADA TO VCNTY OF LAKE SUPERIOR BY MON EVENING. STRONG
WAA/ISENTROPIC ASCENT REGIME IS DEVELOPING ACROSS THE PLAINS. 12Z
RAOBS SHOWED 850MB TEMP OF +7C IN ERN MT WHILE IT WAS STILL -20C AT
KINL. THE WAA IS CREATING AN EXTENSIVE SHIELD OF MID/HIGH CLOUDS
ACROSS THE DAKOTAS/MN INTO SCNTRL CANADA. RIBBON OF STRATUS/STRATOCU
IS ALSO PRESENT FROM NE IA/SW WI TO SRN MANITOBA. CANADIAN RADARS
SHOW A BAND OF ECHOES IN SRN MANITOBA TOWARD LAKE OF THE WOODS...BUT
ONLY A COUPLE OF OBS HAVE INDICATED ANY -SN REACHING THE GROUND.
CLOSER TO HOME...DIMINISHING LES GENERALLY FROM MUNISING TO SENEY
AND EWD CONTINUES TO WIND DOWN. GOING HEADLINES ARE SCHEDULED TO
EXPIRE AT 00Z...BUT WILL CANCEL THEM WITH THIS FCST ISSUANCE AS
ADDITIONAL ACCUMULATIONS WILL BE LESS THAN 1 INCH.
THERE WILL BE A BRIEF WINDOW FOR TEMPS TO CRASH THIS EVENING WITH
SFC HIGH PRES RIDGE QUICKLY SLIDING ACROSS THE AREA. IT APPEARS THE
ERN FCST AREA WILL HAVE THE BEST OPPORTUNITY TO CHILL BEFORE
MID/HIGH CLOUDS INCREASE AND RETURN FLOW KICKS IN. FRESH SNOW COVER
WILL ALSO AID THE TEMP DROP. HAVE THUS GONE SLIGHTLY BLO GUIDANCE...
LOWERING MINS TO AROUND ZERO THERE. EXPECT WARMEST READINGS OUT W
WHERE TEMPS SHOULD ONLY DROP A FEW DEGREES THIS EVENING. OVERALL...
TEMPS SHOULD REACH THEIR LOW POINT IN THE MID/LATE EVENING AND THEN
RISE SLOWLY THRU THE NIGHT. AS FOR SNOW...EXPECT LES TO END OVER THE
NE FCST AREA BY MID EVENING. THEN ATTENTION IS ON ISENTROPIC ASCENT.
BAND OF RADAR RETURNS ACROSS SE MANITOBA MATCHES WELL WITH
ISENTROPIC ASCENT ON GFS 290K SFC. THE STRONG ASCENT/RIBBON OF LOW
CONDENSATION PRES DEFICITS EXPANDS SE INTO UPPER MI TONIGHT. THERE
IS ALWAYS THE QUESTION OF HOW MUCH LIFT WILL BE SUFFICIENT TO
OVERCOME THE INITIAL DRY LOW-LEVEL AIRMASS (NOTE VERY DRY PROFILE ON
12Z KINL SOUNDING). EARLY AFTN TAMDAR SOUNDING FROM KINL HAS NOT
SHOWN MUCH MOISTENING YET. IN ANYCASE...THINK INDICATED ASCENT IS
SUFFICIENT TO WARRANT A LOW CHC POP MENTION ACROSS LAKE
SUPERIOR/KEWEENAW AND EVENTUALLY TO THE NE FCST AREA LATE TONIGHT.
THERE MAYBE A FEW FLURRIES S OF THAT AREA. INITIAL COLD AIRMASS MAY
YIELD SOME LES OFF LAKE MICHIGAN INTO SCHOOLCRAFT COUNTY LATE
TONIGHT AS WINDS BACK SRLY OVER THE LAKE. HAVE INCLUDED LOW CHC POPS
FOR THIS POSSIBILITY.
LOW-LEVEL JET OF 40-50KT WILL SHIFT ACROSS FCST AREA LATE TONIGHT
THRU EARLY MON AFTN. AIRMASS IS STABLE...SO THOSE SPEEDS WILL NOT BE
MIXING TO THE SFC. HOWEVER...HAVE INCLUDED 25-35MPH GUSTS MON
MORNING/EARLY AFTN FOR PORTIONS OF NCNTRL AND ERN FCST AREA THAT
TYPICALLY SEE STRONG WINDS IN SRLY FLOW. SRLY GALES ARE A GOOD BET
ON ERN LAKE SUPERIOR. AS FOR PCPN...UNDER PERSISTENT ISENTROPIC
ASCENT...HAVE MAINTAINED LOW RANGE POPS FOR -SN MON PER INHERITED
FCST. WITH THE POSSIBILITY OF SOME ENHANCMENT OFF LAKE MICHIGAN IN
SRLY FLOW...KEPT POPS IN THE HIGH CHC RANGE FOR THE FAR ERN FCST
AREA. THERE STILL APPEARS TO BE SUFFICIENT MIDLEVEL DRYING TO
MENTION PATCHY -FZDZ OVER THE SW HALF OF FCST AREA MON AFTN AS TEMP
IN THE LOW-LEVEL MOIST LAYER RISES TO -10C OR HIGHER.
.LONG TERM (MONDAY NIGHT THROUGH SUNDAY)...
THE SHORTWAVE WILL SWEEP THROUGH THE FORECAST AREA MONDAY NIGHT
WHILE THE SURFACE LOW MOVES INTO EAST CENTRAL ONTARIO. THE WINDS WILL
BECOME ORGANIZED WITH A NORTHWEST FLOW OVER THE LAKE LATE. DELTA-T`S
WILL AROUND 14C OVER EASTERN PART OF THE LAKE. THE AIR MASS
CONTINUES TO BE FAIRLY DRY OVER CENTRAL CANADA...SO THE LES WILL BE
VERY LIMITED. WILL KEEP JUST A CHANCE OF FLURRIES LATE MONDAY INTO
TUESDAY AS A SURFACE RIDGE WILL SHIFT OVER THE U.P. ON TUESDAY. THIS
WILL BACK THE WINDS TO THE SOUTHWEST LATE TUESDAY WHICH SHOULD END
THE LES OVER LAKE SUPERIOR. WARM AIR ADVECTION WITH THE SOUTHWEST
FLOW OVER THE AREA WILL FURTHER REDUCE CHANCES OF LES. A WEAK
SHORTWAVE WILL MOVE QUICKLY ACROSS SOUTHERN CANADA TO WESTERN
ONTARIO ON WEDNESDAY. AS THE SURFACE RIDGE MOVES EAST ANOTHER
SURFACE LOW WILL MOVE INTO NORTHWEST ONTARIO. ISENTROPIC ASCENT
AHEAD OF THE SURFACE LOW COULD SQUEEZE SOME MOISTURE OUT OF THE AIR
MASS OVER THE FORECAST AREA SO WILL KEEP A SLIGHT CHANCE GOING
THROUGH THE DAY ON WEDNESDAY.
THE SHORTWAVE TRAPPED IN THE ZONAL FLOW ACROSS NORTHERN CONUS WILL
SWEEP ACROSS THE FORECAST AREA WEDNESDAY NIGHT AND REACH NEW ENGLAND
ON THURSDAY. THE STRONGEST 850-500MB Q-VECTOR CONVERGENCE WILL BE
NORTH OF LAKE SUPERIOR. A RIDGE WILL BEGIN TO BUILD OVER THE
NORTHERN PLAINS. THE SURFACE LOW OVER WESTERN ONTARIO WILL REACH
EASTERN CENTRAL ONTARIO BY THURSDAY MORNING DRAGGING A COLD FRONT
THROUGH THE FORECAST AREA. THE LOW WILL REACH THE EAST COAST BY
THURSDAY EVENING ALLOWING A SURFACE RIDGE TO BUILD OVER THE UPPER
MISSISSIPPI RIVER VALLEY. DRY AIR ADVECTING INTO THE AREA WILL END
THE CHANCE OF SNOW. THE DELTA-T`S OVER EASTERN LAKE SUPERIOR WILL BE
AROUND 13C AND THE WINDS WILL SHIFT TO THE WEST NORTHWEST JUST
ENOUGH TO GENERATE SOME LES OVER PART OF THE FORECAST AREA WEDNESDAY
NIGHT. THE SURFACE RIDGE WILL RELOCATE OVER THE FORECAST THURSDAY
NIGHT. AS THE MID LEVEL RIDGE MOVES OVER THE UPPER GREAT LAKES
REGION...THE SURFACE RIDGE WILL SHIFT INTO EASTERN ONTARIO ON
FRIDAY. WEAK SHORTWAVE WILL ATTEMPT TO NAVIGATE THROUGH THE RIDGE. A
SURFACE LOW WILL DEEPEN OVER COLORADO. DEEP MOISTURE WILL SPREAD
INTO NORTHERN MINNESOTA AND WISCONSIN AND INTO THE WESTERN U.P.
BRINGING SOME SNOWS OVER THAT AREA.
THE MID LEVEL RIDGE WILL BUILD OVER THE UPPER GREAT LAKES...WHILE
THE TROUGH DEEPENS OVER THE SOUTHERN ROCKIES FRIDAY NIGHT. SEVERAL
WEAK SHORTWAVE WILL WORK ITS WAY THROUGH THE RIDGE OVER THE UPPER
GREAT LAKES. 850MB TEMPERATURE WILL BE AROUND -5C. WARM AIR
ADVECTION WILL BE PUSHING THE 850MB TEMPERATURES WELL ABOVE
FREEZING. HOWEVER...BELOW 875MB TEMPERATURES WILL BE WELL BELOW
FREEZING. THUS GRAPPLE OR SNOW WILL STILL BE EXPECTED. THIS IS
AROUND A CRITICAL POINT...THERE IS EVEN A POSSIBILITY OF SOME
FREEZING RAIN. THUS THIS SHOULD BE MONITORED CLOSELY.
THE MID LEVEL LOW WILL SHIFT FROM NEW MEXICO ON SATURDAY MORNING TO
EASTERN KANSAS BY MIDNIGHT TO WESTERN IOWA BY NOON ON SUNDAY AND
INTO MINNESOTA BY MIDNIGHT SUNDAY NIGHT. MEANWHILE...AT THE
SURFACE...THE LOW WILL MOVE INTO WESTERN KANSAS BY NOON
SATURDAY...INTO NORTHWEST MISSOURI BY MIDNIGHT SUNDAY NIGHT AND INTO
NORTHERN WISCONSIN BY MIDNIGHT SUNDAY NIGHT. THE LOW WILL DRAG A
COLD FRONT THROUGH THE SOUTHERN PLAINS INTO THE MISSISSIPPI RIVER
VALLEY. THE COLD FRONT WILL DIRECT DEEP GULF MOISTURE NORTHWARD INTO
THE FORECAST AREA. FOLLOWING THE 06Z GFS IT LOOKS AS IF THERE WILL BE
A MIX OF SNOW CHANGING TO RAIN. BECAUSE OF THE UNCERTAINTY OF THE
TEMPERATURES 7 DAYS OUT WILL STAY WITH A MIX. IT MAY BE POSSIBLE
TO BE ALL RAIN BY MIDNIGHT SUNDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
GALE WARNING E HALF OF LAKE SUPERIOR.
HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR.
&&
$$
ROLFSON (SHORT TERM)
DLG (LONG TERM)
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