FORECAST DISCUSSION
AFDPSR .SYNOPSIS...
A LOW PRESSURE SYSTEM WILL CONTINUE MOVING THROUGH ARIZONA TONIGHT
AND INTO NORTHWEST MEXICO TUESDAY. THIS SYSTEM IS QUITE DRY...
ESPECIALLY WEST OF THE PHOENIX METRO AREA. THE WINDS AROUND THIS
SYSTEM SHOULD KEEP MOST AREAS DRY...WHILE CLOUDS AND A VERY SLIGHT
CHANCE OF SHOWERS WILL REMAIN FOR AREAS NEAR GLOBE AFTER MIDNIGHT.
HIGH PRESSURE ALOFT WILL BUILD BACK INTO ARIZONA BY TUESDAY
AFTERNOON FOR A SLOW WARMING TREND. ANOTHER SYSTEM WILL MOVE ACROSS
CALIFORNIA INTO ARIZONA BY THE WEEKEND FOR ANOTHER SLIGHT CHANCE OF
SHOWERS...MAINLY OVER THE HIGHER TERRAIN.
&&
.SHORT TERM...
TONIGHT THROUGH THURSDAY...
UPPER LEVEL CLOSED LOW CENTERED OVER WCNTRL ARIZONA CONTINUED TO
SLIDE TO THE SOUTH THIS EVENING...AND THIS MOTION IS SUPPORTED BY
THE ORIENTATION OF THE HEIGHT RISE/FALL COUPLET SEEN ON THE 00Z H5
CHART...WITH MAX 100M FALLS AT TUS AND MAX 80M RISES OVER NRN
NEVADA. STRONG 110KT H3 JET ON BACK SIDE OF LOW IS HELPING DIG LOW
SOUTHWARD...AND MOST OF OUR CWA IS ON THE UNFAVORABLE LEFT REAR QUAD
OF THE JET...WHERE DVV CONTINUES TO BE PROGGED BY LATEST MODEL RUNS.
AS FORECAST BY PREVIOUS MODEL RUNS...THIS CONTINUES TO BE A VERY DRY
SYSTEM FOR ARIZONA AND IR IMAGERY AT 8 PM SHOWED MOSTLY CLEAR SKIES
OVER MUCH OF ARIZONA AS WELL AS OUR ENTIRE CWA. THERE HAVE BEEN SOME
MID CLOUD ELEMENTS AT TIMES OVER THE CENTRAL DESERTS...WRAPPING
AROUND THE BACK SIDE OF THE LOW BUT THEY HAVE NOT BEEN VERY
SIFNIFICANT. GOES PWAT IMAGERY THIS EVENING SHOWED A DRY STATE WITH
LESS THAN ONE HALF INCH VALUES EVERYWHERE...AND SURFACE DEWPOINTS
OVER OUR CENTRAL DESERTS WERE MOSTLY IN THE 30S...AND INTO THE TEENS
OUT WEST ALONG THE LOWER CO RIVER. FOR THE REST OF TONIGHT...PROGS
TAKE THE UPPER LOW SOUTH WITH THE CENTER MOVING INTO NRN GULF OF
CA/FAR NWRN MEXICO BY 12Z...WITH SOME MID LEVEL MOISTURE FORECAST TO
REMAIN OVER OUR ERN CWA. HOWEVER...UVVS ARE MOSTLY DOWNWARD ACROSS
THE AREA OVERNIGHT AND WITH AIRMASS DRY AT LOW LEVELS THERE WILL BE
LITTLE IF ANY CHANCE FOR SHOWERS EVEN OVER THE HIGHER TERRAIN TO OUR
EAST. WILL KEEP A SLIGHT CHANCE FOR SHOWERS GOING MAINLY EAST OF
GLOBE AFTER MIDNIGHT PRIMARILY TO BLEND IN WITH SURROUNDING OFFICES.
HAVE UPDATED GRIDS/FORECASTS TO REFLECT CURRENT SKY/WEATHER TRENDS
AND NO MORE UPDATES ARE PLANNED AT THIS TIME. THE REST OF THE
FORECAST WAS FROM THE PREVIOUS DAY SHIFT.
.PREVIOUS DISCUSSION...
IR AND WATER VAPOR IMAGERY CONTINUED SHOWING AN IMPRESSIVE CYCLONIC
CIRCULATION JUST NORTH OF PHOENIX THIS AFTERNOON. BUT THE ASSOCIATED
MOISTURE WAS NOT IMPRESSIVE...WITH SOME OF THE WRAP-AROUND
CLOUDINESS BREAKING UP AS THE LOW SAGS SLOWLY SOUTH. AIRCRAFT WINDS
FROM 41 THSD FT WERE REPORTED TO BE MUCH MORE NORTHERLY COMPARED
TO MODEL WINDS TODAY. ALTHOUGH THE MID LEVEL MOISTURE TENDS TO
INCREASE WITH TIME EARLY THIS WEEK ACROSS THE CENTRAL PORTIONS OF
OUR AREA...THE HIGH LEVEL MOISTURE DECREASES...ACCORDING TO LATEST
NAM CROSS SECTIONS. OVERALL PRECIP WATER AT PHOENIX APPEARS A BIT
OVERDONE...WITH ABOUT .50 INCH PROGGED FOR BOTH TUES AND WED. AS THE
CLOSED LOW CUTS ACROSS OUR CWA TONIGHT...HEIGHT FALLS AND A LITTLE
MORE INSTABILITY COULD GENERATE SOME LIGHT SHOWERS OR SPRINKLES
ACROSS ZONE 24. SOME WARMER AIR ALOFT AND LESS MOISTURE SHOULD ALLOW
FOR A DOWNWARD TREND IN POPS FOR THAT AREA INTO TUESDAY NIGHT.
CLOUDS WILL STILL HANG AROUND...BUT CHANCES OF ANY PRECIP MAKING
IT`S WAY TO THE GROUND APPEAR SLIM.
FLAT UPPER RIDGE AND MUCH WEAKER SURFACE GRADIENTS ARE STILL
EXPECTED ON WEDNESDAY. WILL ADJUST TEMPERATURES UPWARD A LITTLE AND
CALL FOR IMPERIAL/EL CENTRO TO WARM INTO THE MID 70S BY THURSDAY.
OTHERWISE...NO LARGE DAY-TO-DAY TEMPERATURE CHANGES EXPECTED.
&&
.LONG TERM...
THURSDAY NIGHT THROUGH MONDAY...
FLAT RIDGE IN PLACE OVER SOUTHEAST CA AND ARIZONA THU NIGHT BEFORE
ANOTHER DISTURBANCE SWINGS THROUGH THE WRN CONUS FRI/SAT. GFS AND
ECMWF SEEM TO BE IN FAIRLY GOOD AGREEMENT WITH THIS SYSTEM SLIDING
INLAND...THROUGH THE GREAT BASIN...AND OVER THE FOUR CORNERS REGION.
THE AFOREMENTIONED TRAJECTORY WOULD BE DRY FOR MUCH OF OUR
CWA...ESPECIALLY THE WRN PORTION OVER SE CA AND ALONG THE CO RIVER
VALLEY. THE MAIN CONCERN OUT WEST WILL BE WINDS...AS THE PRESSURE
GRADIENT TIGHTENS AND FAVORS A MODERATE TO STRONG NORTHERLY WIND.
BREEZY TO LOCALLY WINDY CONDITIONS WILL START FRI AND CONTINUE
THROUGH SAT. AS FOR THE ERN CWA...MODELS ARE BREAKING OUT SOME
PRECIP OVER MAINLY THE HIGHER TERRAIN OF SOUTHERN GILA COUNTY (AZ
ZONE 24)...WHILE THE MEXMOS HAS A 12 POP FOR PHX FRI INTO SAT.
CURRENT FORECAST HAS A SLIGHT CHANCE CWA WIDE FRI NIGHT/SAT...AND
FOR NOW...THIS LOOKS OKAY. AGAIN...WITH THE INLAND TRAJECTORY OF
THIS SYSTEM...AND WITH THE PATTERN BEING SO PROGRESSIVE VIA BOTH THE
GFS AND ECMWF...WE`LL BE HARD PRESS TO GET ANY PRECIP ANYWHERE BUT
THE HIGHER TERRAIN. HOWEVER...AT THIS TIME...I FEEL COMPLETELY
PULLING POPS OVER THE GREATER PHX AREA IS A BIT HASTY AND TOO
OPTIMISTIC (IF YOU WILL). LATEST GUIDANCE SUGGESTS SEVERAL DEG OF
COOLING THU THROUGH SAT...AND HAVE MADE MINOR TWEAKS TO THE TEMP
GRIDS DURING THIS PERIOD TO REFLECT THIS THINKING. HEIGHTS WILL BE
QUICK TO REBUILD SAT INTO SUN...FOR WARMER TEMPS AND MOSTLY CLEAR
SKIES SUN AND MON.
&&
.AVIATION...
06Z TAFS AND TWEBS ADEQUATELY DEPICT EXPECTED WEATHER. SEE TAFS
PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE
DETAILED INFORMATION.
AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX
11/10/22
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
AFDLOT 1100 PM CST SUN DEC 31 2006
.DISCUSSION FOR AFTERNOON GRIDS/ZONES...
248 PM CST
UPR LOW CENTERED OVR NRN MO THIS AFTN...WITH STRONG S/WV ASSOCIATED
WITH 130KT JET STRK LIFTING NORTHEAST ACROSS MID MS/LWR OH VLYS. DRY
SLOT OVR MUCH OF FCST AREA SINCE THIS MORNING STARTING TO SHOW SIGNS
OF CONVECTIVE DVLPMNT...WITH SCT RW/TRW BEGINNING TO DVLP BENEATH
DIVERGENT LEFT EXIT REGION OF UPPER JET STRK ALONG LOW LEVEL
OCCLUDED FRONT AS UPPER LVL FORCING INCRSG WITH APPRCH OF S/WV.
RECENT ACARS AND FCST SOUNDINGS AS WELL AS SPC/RUC MESOANALYSIS
GRAPHICS INDICATE CAPE VALUES MARGINAL...THOUGH GIVEN STRENGTH OF
UPPER FORCING AND LOW LEVEL CONVERGENCE VCNTY OCCLUSION EXPECT
SCT RW/TRW TO CONTINUE NEXT FEW HOURS AS S/WV CONTINUES TO APPRCH.
MAIN UPPER LOW CENTER LIFTS NORTHEAST ACROSS FCST AREA THIS
EVENING...THOUGH SECONDARY VORT MAXIMA WRAPPING AROUND BACK SIDE
RESULTS IN LINGERING UPPER TROUGHINESS AND EXTENDED PERIOD OF WEAK
MID/UPR LVL FORCING INDICATED BY Q CONVERGENCE FIELDS. THIS S/WV
TROUGH AXIS FINALLY MOVES ACROSS FCST AREA MONDAY MORNING...THUS
EXPECT SOME LINGERING CHC FOR LIGHT SHOWERS OVRNGT HOURS INTO MONDAY
MORNING.
LOW LEVEL COLD ADVCTN TNGT RESULTS IN THICKNESS VALUES FALLING
ESPECIALLY AFTR MDNGT...WITH 1000-850 HPA BELOW 1300 METERS AND
850-700 HPA DOWN TO 1520-1530 METERS BY 12Z MON. FCST SOUNDINGS AND
TSECTS INDICATE MOIST LAYER FAIRLY SHALLOW BY THAT TIME
HOWEVER...WITH CLOUD TOP TEMPS GENERALLY WARMER THAN -10C THAT WOULD
NOT SUPPORT SIG ICE CRYSTAL NUCLEATION. HOWEVER...GIVEN PROLONGED
FORCING WITH SECOND VORT/TROUGH AND POTENTIAL FOR DEEPER CLOUD LAYER
OR SEEDING FROM COLDER HIGHER CLOUD LAYER...WILL MENTION LIGHT RA/SN
AFTER MDNT INTO MON MRNG. UPPER TROUGH AXIS THEN SHIFTS EAST OF FCST
AREA BY AFTN...WITH MODEL TSECTS AND DIV-Q/OMEGA FIELDS SUGGESTING
FAIRLY STRONG DEEP LAYER SUBSIDENCE DVLPG. THUS WILL GO DRY FOR MON
AFTN WITH CLRG SKIES BY EVENING AS SFC HIGH PRESSURE BUILDS ACROSS
MID MS/OH VLYS.
MID WEEK APPEARS DRY AND CONTINUED MILD AS ANOTHER UPPER TROUGH CUTS
OFF/CLOSES OFF OVER THE SOUTHWEST...AND NORTHERN BRANCH OF JET
BECOMES MORE ZONAL. GFS/NAM SIMILAR WITH NRN STRM S/WV MOVG THROUGH
THE UPPER MIDWEST TUES/TUES NGT...THOUGH WITH DRY LOW LEVELS AND SFC
RIDGE AXIS BLOCKING OFF MOISTURE RETURN FROM THE GULF EXPECT NO MORE
THAN SOME MID/HIGH CLOUDS WITH THIS FEATURE. SOUTHWESTERN UPPER
TROUGH KICKS OUT LATER IN THE WEEK...WITH GLOBAL MODELS DVLPG BROAD
TROUGH IN SOMEWHAT PHASED NRN/SRN STREAMS BY FRI/SAT. BEST PCPN
CHANCES INITIALLY TO OUR SOUTH AND OFF TO OUR NORTH...UNTIL MAIN
UPPER TROUGH APPRCHS FRI NGT AND SATURDAY. WILL CARRY CHC POPS FOR
INITIALLY RA FRI NGT AND THEN RA/SN SAT AS COLDER AIR MOVES IN
BEHIND SFC COLD FRONT.
TEMPS THROUGH THE PERIOD AGAIN TO REMAIN FAIRLY MILD. MAV GUIDANCE
NUMBERS GENERALLY PREFERRED EARLY ON...THEN GENERALLY AT OR A LITTLE
ABOVE THE HPC/MEX NUMBERS MID WEEK AS LLVL SW FLOW DVLPS.
RATZER
&&
.AVIATION DISCUSSION FOR 06Z TAFS...
MAIN PROBLEM OVERNIGHT WILL CONTINUE TO BE RAGGED CIGS AS COLD AIR
WRAPS INTO DEPARTING LOW PRESSURE CENTER OVR NRN LK MI. CIGS HAVE
BEEN GENLY VFR THRU MUCH OF THIS EVENING...BUT ARE IN THE PROCESS
OF LWRG INTO A MORE SLD LOW RANGE MVFR DECK WHICH WILL OVERSPREAD
TERMINAL AREA FROM SW BY 07Z. LEADING EDGE OF THESE LWR CIGS NOW
ADVANCING ACRS NWRN AND CNTRL IL AND ARE MOVG ENEWD NR 30 KTS.
COLD/DRY ADVECTION IN LLVLS SHOULD KEEP VIS UNRESTRICTED THRU MOST
OF PERIOD XCP INVOF LGT SHWRS WHICH WILL ALSO MOVE INTO RGN WITH
COLD AIR INFLUX. BY LATE TNGT...LGT SHWRS WILL LIKELY CHG OVER TO
FLURRIES AS SFC TEMPS COOL INTO MID 30S. DO NOT EXPECT PCPN TO BE
HEAVY ENUF TO ACCUMULATE ANY ICE OR SNOW ON RUNWAYS. WRAP ARND
STRATO CU DECK TO RMN IN PLACE THRU MIDDAY MON BEFORE WX SYS MOVES
FAR ENUF E OF AREA TO ALLOW FOR CLRG TO TAKE PLACE BY END OF FCST
PERIOD.
OTHER PROBLEM WILL BE WINDS. SWLY WINDS GUSTING TO NR 30 KTS OVR
WRN/NWRN IL WILL BE OVERSPREADING TERMINALS BY 07Z AS COLD AIR
ARRIVES BTWN 05 AND 07Z. ELEVATED WIND SPEEDS TO CONT THRU MON MRNG
WITH GRDL WDSHFT TO WNW AFT 12Z. WINDS TO DMNSH MID-LATE AFTN MON
AS COLD ADVECTION RELAXES.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
.IL...NONE.
.IN...NONE.
.LM...SCA IL WATERS TO GYY THRU 00Z TUESDAY.
SCA GYY TO MICHIGAN CITY THRU 06Z TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 705 PM EST TUE JAN 2 2007
.AVIATION...
S-SW LOW LEVEL FLOW WILL CONTINUE THROUGH THE TAF PERIOD AS SFC HIGH
OVER THE UPR OH VALLEY MOVES AWAY FROM THE AREA. AIRMASS OVER THE
REGION IS QUITE DRY, HWVR, RECENT UPSTREAM TAMDAR FROM CMI AND NAM12
BUFKIT FCST SOUNDINGS AT THE TERMINALS INDICATE A SHALLOW LAYER OF
RATHER MOIST AIR EXISTS FROM THE SFC UP TO ABOUT 1KFT. NAM12 BUFKIT
SOUNDINGS SUGGESTS THIS MOIST LAYER WILL BECOME SATURATED OVERNIGHT,
PSBLY RESULTING IN SOME STRATUS IN THE AREA. FOR THE 00Z TAF
ISSUANCE OPTED TO CONTINUE TO LEAVE MENTION OF LOW CLOUDS OUT OF
TAFS, SINCE MOIST LAYER APPEARED QUITE SHALLOW, HWVR, SUBSEQUENT
ASOS OBS FROM VPZ OF MVFR CLOUD DECK CONFIRMED BY LATEST 11U-3.9U
SATELLITE IMAGE SUGGESTS AMMENDMENTS MAY BE NEEDED. IF STRATUS DOES
FORM OVER THE AREA OVERNIGHT IT WOULD PRBLY LINGER INTO THE MORNING
BEFORE MIXING OUT WITH VFR CONDITIONS EXPECTED AGAIN WED AFTN.
&&
.PREV DISCUSSION...
SHORT TERM...
TONIGHT AND WEDNESDAY. QUIET WX CONTINUES THROUGH SHORT TERM. SOME
PATCHES OF DENSE FOG THIS AM IN RIVER VALLEYS...HOWEVER WITH
INCREASINGLY STRONG/CONFLUENT LOW LEVEL FLOW THROUGH THE PERIOD...BL
SHOULD REMAIN SUFFICIENTLY MIXED TO PRECLUDE BR/FG FORMATION AND
CONTINUE NIL WX. GAVE MORE SW-NE GRADIENT PER 925MB THERMAL PLAN
VIEW/AND SLIGHT BOOST TO TEMPS WITH NEAR FULL SUN/DRY AFTN
1000-850MB LAYER WITH DD 20-25C...AND SIMILAR TO TIGHT MOS SCATTER.
SHOULD AT LEAST REALIZE NEAR DRY AD TO NEAR 925MB TMWR AFT WITH SOME
STRONGER WIND GUSTS. INCREASED SWRLY FLOW FOR SCA CONDITIONS BEYOND
09Z.
LONG TERM...
WEDNESDAY NIGHT THROUGH TUESDAY.
MAIN FOCUS WILL BE ON PRECIP CHANCES POTENTIALLY ARRIVING AS EARLY
AS THURS NGT AND CONTINUING INTO SATURDAY. HIGH PRESSURE WILL MOVE
WELL EAST OF THE AREA WITH GULF BEGINNING TO OPEN UP IN RESPONSE TO
TROUGH STARTING TO DIG IN CENTRAL US. MODELS HAVE VARIED GREATLY IN
TERMS OF EFFECTS OF UPPER LEVEL ENERGY AND DEVELOPMENT OF SFC
REFLECTION AS WELL AS TIMING OF THESE FEATURES. WHILE THE 500 MB
CLOSED LOW LOOKS TO REMAIN ALONG THE GULF STATES INCREASING SW FLOW
WILL DRAW IN MSTR RATHER RAPIDLY BEGINNING ON THURSDAY. MODELS VARY
ON DEGREE OF MSTR AND OVERALL TRACK OF SYSTEMS BUT DO AGREE ON
INCREASING ISENTROPIC LIFT BY THURS NGT ACROSS MAINLY SE AREAS.
PREVIOUS SHIFT ADDED POPS IN FOR THIS TIME FRAME AND WILL MAINTAIN
AND ACTUALLY EXPAND NW BUT KEEP IN CHC POP RANGE AS BEST MSTR RETURN
WILL HOLD OFF UNTIL FRIDAY/FRIDAY EVENING AS JET DYNAMICS BECOME
INVOLVED AND INCREASE CHANCE FOR PRECIP. 12Z NAM-WRF SUGGESTS SOME
CONVECTIVE CONCERNS WITH K INDICES INCREASING IN TO THE LOW 30S BY
LATE FRI AFTN AND SFC DEWPTS INTO THE LOW-MID 50S. NORMALLY WOULD BE
RATHER SKEPTICAL OF THIS BUT CONSIDERING WHAT THE LAST SYSTEM
BROUGHT IN TERMS ON CONVECTION AND THIS SYSTEM HAVING SOME
SIMILARITIES...CAN`T BE ENTIRELY DISCOUNTED. DO THINK THAT QPF SHOWN
BY NAM ON FRI IS RATHER OVERDONE WITH BULLSEYE OF NEARLY 1.5 INCHES
OVER 12 HOURS. GFS KEEPS MSTR FURTHER SOUTH AS WELL AS CONVECTIVE
POTENTIAL. HAVE OPTED TO INCREASE POPS SOME AS WELL ON FRIDAY BUT
KEEP IN CHC CATEGORY AS WELL DESPITE SOME GUIDANCE SHOWING
LIKELY/CAT POPS. WOULD LIKE TO SEE MORE TREND CONTINUE FOR A FEW
MORE RUNS BEFORE JUMPING ON THINGS. TEMPS THROUGH SATURDAY WILL
REMAIN WELL ABOVE NORMAL THROUGH FRIDAY AND THEN DROP BUT REMAIN A
GOOD 5 TO 10 DEGREES ABOVE NORMAL. IF HIGHER DEWPTS CAN MATERIALIZE
AS NAM-WRF SHOWS THEN INCREASE IN TEMPS WILL BE NEEDED FOR THEN.
BEYOND SATURDAY GULF MSTR WILL BE REMOVED FROM THE REGION AND LIKELY
REMAIN THAT WAY THROUGH THE REMAINDER OF THE PERIOD. SEVERAL SYSTEMS
ARE EXPECTED TO TRACK ACROSS THE AREA AS GENERAL TROUGH REMAINS IN
PLACE. WITH AMOUNTS OF MSTR AND EXACT TRACKS QUESTIONABLE AT THIS
POINT WITH ANY ONE WAVE...WILL MAINTAIN DRY FORECAST. SOME
INDICATIONS REMAIN OF COLDER AIR ARRIVING FOR THIS PERIOD...BUT
ANY ARCTIC INTRUSION WILL BE WELL AFTER THIS TIME FRAME.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 4 AM WEDNESDAY TO 7 PM EST THURSDAY
FOR LMZ043-LMZ046.
&&
$$
SHORT TERM...MURPHY
LONG TERM....FISHER
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 945 PM EST TUE JAN 2 2007
.UPDATE...
REVIEW OF OBS ACROSS THE AREA SHOWS CENTER OF SFC HI PRESSURE
STARTING TO WORK EAST OF THE BLUEGRASS STATE...CREATING VERY
LITTLE GRADIENT WIND...ALSO IT APPEARS FROM CURRENT ACARS
SOUNDINGS THAT THE ATMOSPHERE HAS DECOUPLED. WINDS HAVE BECOME
CALM AT NEARLY EVERY OBS SITE ACROSS THE REGION...WITH DEWPOINTS
IN THE LOWER 30S TO UPPER 20S. THIN CIRRUS HAS BECOME QUITE SCARCE
THE LAST FEW HOURS AS IT HAS SHRUNKEN AND MOVED THRU THE OHIO
VALLEY...UPSTREAM LITTLE CLOUD COVER AT ALL IS FOUND...WILL GO WITH
CLEAR SKY CONDITION THROUGH THE REST OF THE OVERNIGHT AS NO OPAQUE
CLOUDS ARE PROGGED ACROSS THE FORECAST AREA.
TEMPS AND ANY FOG FORMATION OVERNIGHT WILL BE THE MAIN FORECAST
PROBLEM...GROUND HAS PLENTY OF MOISTURE FROM PREVIOUS RECENT
RAINS...AND NEAR PERFECT RAD COOLING CONDITIONS ARE
PREVALENT...WILL CONTINUE WITH THE PATCHY FOG MENTION AS EVEN
THOUGH DECOUPLING LOOKS LIKELY THRU THE EARLY MORNING HOURS AS WE
APPROACH DAYBREAK THE ATMOSPHERE APPEARS TO GET SOMEWHAT MORE MIXY
WITH A DECENT 25-30 KT LOW LEVEL JET SHOWING UP AROUND 1.5 TO 2.0K
FT. HAVE MENTIONED LOW LEVEL WIND SHEAR IN TAFS DUE TO THIS
FEATURE. THEREFORE FOG SHOULD BE REGULATED TO THE MORE PRIME AREAS
NEAR SHELTERED AREAS...AND LOW LYING AREAS.
TEMPS ARE THE OTHER ISSUE...AS THE CURRENT GRIDS WERE 3 TO 4
DEGREES TOO WARM AS OF 9 PM...HAVE LOWERED ALL THE FORECAST LOWS
AT LEAST INTO THE UPPER 20S (AND EVEN SOME MID 20S IN SHELTERED
AND LOW LYING AREAS ACROSS THE REGION WILL BE POSSIBLE)...OUTSIDE
OF THE SDF METRO AREA (HEAT ISLAND EFFECT).
SCHOTT
&&
.PREV DISCUSSION... /ISSUED 247 PM EST TUE JAN 2 2007/
SHORT TERM (TONIGHT AND WEDNESDAY)...
HIGH PRESSURE FROM OKLAHOMA TO OHIO AND WEST VIRGINIA HAS PROVIDED
MOSTLY SUNNY SKIES FOR THE CWA TODAY...AFTER MORNING STRATO-CU
CLOUDS OVER THE EAST FINALLY DISSIPATED. TEMPS HAVE RECOVERED FROM
THE CHILLY MORNING START...AND UNDER A LIGHT EAST WIND...CURRENT
READINGS RANGE FROM THE MID TO UPPER 40S.
HIGH PRESSURE WILL SLIDE TO THE EAST TONIGHT...BUT STILL SHOULD KEEP
MOSTLY CLEAR AND CALM CONDITIONS IN PLACE THROUGH MUCH OF THE
OVERNIGHT HOURS. DIFFICULT FORECAST FOR EITHER FOG OR LOW STRATUS
POTENTIAL TOWARD MORNING. NAM BUFKIT SOUNDINGS MUCH MORE PESSIMISTIC
THAN GFS/NGM MOISTURE PROFILES AFTER MIDNIGHT. NAM INDICATING IFR
STRATUS DECK CAUSED BY LL MOISTURE AND STRONGER BL WINDS ACROSS
THE NRN CWA. HOWEVER IT IS SHOWING FOG POTENTIAL FURTHER SOUTH
WHERE WINDS ARE NOT AS STRONG. IF WE CAN DECOUPLE...DEFINITELY
THINK FOG IS POSSIBLE AS DEWPOINTS HAVE NOT REALLY DROPPED OFF
TODAY AND TEMPS SHOULD BOTTOM OUT OVERNIGHT NEAR THOSE VALUES. GFS
TIME- HEIGHT CROSS-SECTIONS SHOW A BIT OF LL MOISTURE...WITH THE
NAM SHOWING MORE. HOWEVER BOTH MODELS INDICATE WEAK LIFT FROM
06-12Z...AND NAM EVEN GENERATES SOME DRIZZLE WITH THIS TOWARD
MORNING. WILL TREND TOWARD A FEW-SCT LL STRATUS AT SDF AND
LEX...AND TOWARD A LOWER VIS/CLR SKY SCENARIO AT BWG. IN
ADDITION...WINDS MAY PUSH LLWS CRITERIA AT SDF IN THE
MORNING...AND PERHAPS AT LEX.
CONCERNING OVERNIGHT LOW TEMPS...THE POTENTIAL FOG/STRATUS COULD
HAVE A LARGE AFFECT ON THAT. FOR NOW ASSUMING A BIT OF STRATUS FORMS
OVER THE NORTH OVERNIGHT...WILL HAVE THE LOWEST TEMPS ACROSS THE
SWRN CWA. TEMPS WILL ROUGHLY RANGE FROM THE UPPER 20S TO LOW 30S.
AS THE HIGH PRESSURE SLIDES EAST...WINDS WILL INCREASE AND VEER
AROUND TO THE SOUTH ON WEDNESDAY...HELPING TO INCREASE TEMPS A FEW
DEGREES FROM TODAY`S READINGS. HIGHS SHOULD RANGE IN THE MID TO
UPPER 50S. MID-TO-HIGH LEVEL CLOUDS WILL BE ON THE INCREASE FROM THE
WEST TOMORROW AFTERNOON AHEAD OF THE NEXT STORM SYSTEM.
AL
LONG TERM (WEDNESDAY NIGHT - TUESDAY)...
WED NIGHT-THURS NIGHT...
PRIMARY FOCUS IN THE LONG TERM IS ON EVOLUTION OF UPPER TROF NOW
OVER NW MEXICO. THIS FEATURE HAS TAKEN A NEARLY DUE SOUTH TRACK IN
PAST FEW FRAMES OF WATER VAPOR IMAGERY...WHICH BOTH NAM/GFS PICK UP
ON...BEFORE TURNING IT EASTBOUND BY 0Z/THURS. SREF ALONG WITH
OPERATIONAL MODELS SHOW TWO AREAS OF PRECIP DEVELOPING IN THE
VICINITY THURS AFTN...ONE OVER SRN IND ASSOC WITH SMALL SCALE JET
STREAK AND ANOTHER LARGER AREA TO THE SOUTH OVER TENN/LOWER MISS
RIVER VALLEYS ASSOC WITH LOWER LEVEL FORCING/STRONG POSITIVE THETA-E
ADVECTION. HAVE ARRANGED POPS THIS WAY FOR THURSDAY...WITH A
RELATIVE MIN OVER THE BLUEGRASS IN BETWEEN FEATURES.
AS UPPER TROF LIFTS NE INTO SE TX BY 12Z/FRI...FORCING FOR ASCENT
WILL BE MAXIMIZED OVER THE CWA THURSDAY NIGHT INTO EARLY FRI
MORNING. FCST MOISTURE TRANSPORT INTO THE REGION IS IMPRESSIVE...
WITH LATEST SREF SHOWING PW ANOMALIES OF 3-4 STD DEV ABOVE NORMAL
BETWEEN 3-15Z/FRI. THIS COUPLED WITH ELEVATED INSTABILITY AND DECENT
ALIGNMENT BETWEEN LLJ AND 0-6KM MEAN WIND SUGGEST A GOOD POTENTIAL
FOR TRAINING/LOCALLY HVY RAINFALL DURING THE 3-15Z/FRI PERIOD. HAVE
OPTED TO MENTION THIS IN THE FCST THURS NIGHT...AND KEEP THUNDER IN
FROM LATE THURSDAY ACROSS SRN KY AND THE WHOLE CWA THURS NIGHT INTO
FRI MORNING.
FRIDAY-SUNDAY NIGHT...
FEEL THAT CHANCES FOR PRECIP WILL DIMINISH SOME ON FRIDAY AS PRIMARY
FORCING FOR ASCENT MOVES OFF TO THE EAST...HOWEVER WITH UPPER TROF
IN VICINITY AND SOME UNCERTAINTY ABOUT IT`S SPEED...WILL CONTINUE
WITH CHC POPS (HIGHEST IN THE ERN ZONES). A BREAK IN THE PRECIP IS
POSSIBLE FRI NIGHT INTO EARLY SAT...BUT A SECOND UPPER WAVE OVER THE
GREAT LAKES IS FCST TO HELP DROP A FRONT INTO THE CWA SOMETIME
SATURDAY. FEEL THERE IS A DECENT CHANCE FOR SOME -RA WITH THIS
FROPA.
INTO SUNDAY...ECMWF/GFS/NCEP ENS MEAN SHOW ANOTHER UPPER WAVE COMING
OUT OF THE SRN STREAM PRODUCING A WEAK SFC LOW OVER THE GULF STATES.
AT THIS TIME...LMK CWA WILL BE ON THE NORTH EDGE OF ANY PRECIP THAT
FALLS. WILL CONTINUE CHC POPS SUN-SUN NIGHT. ALL PTYPE DIAGNOSTICS
FROM GFS SUGGEST RAIN BEING THE DOMINANT PTYPE WITH THIS SYSTEM...
BUT IT CERTAINLY BEARS WATCHING IN FUTURE MODEL RUNS.
MONDAY-TUESDAY...
WE WILL CONTINUE THE DRY FORECAST AS NCEP ENS MEAN SHOWS LARGE TROF
DEVELOPING OVER THE CNTRL/ERN CONUS... GENERALLY A COOL BUT DRY
PATTERN FOR US. ONE CAVEAT WOULD BE ANY CLIPPER WAVES THAT DROP INTO
THE REGION WITHIN NW FLOW ALOFT. THESE HARD-TO-PREDICT SYSTEMS (AT
THIS TIME RANGE) CAN ALWAYS PRODUCE SOME LIGHT QPF (SNOW?). GFS AND
ECMWF INDICATE ONE SUCH FEATURE PASSING THROUGH THE GREAT LAKES LATE
MONDAY OR TUESDAY. IF ONE EXTRAPOLATES THE ECMWF...SOME ENHANCED
850MB RH WILL MAKE IT INTO OUR CWA TUESDAY...SOMETHING TO WATCH FOR
POTENTIAL PRECIP DEVELOPMENT.
CS
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
AFDLWX 947 PM EST TUE JAN 2 2007
.SHORT TERM /REST OF TONIGHT/...
HIGH PRESSURE WILL DRIFT EAST ACROSS THE FORECAST AREA OVERNIGHT.
AN APPROACHING SHORT WAVE FROM THE UPPER MID WEST WILL BRING A FEW
HIGH CLOUDS ACROSS THE REGION OVERNIGHT. HAVE DECREASED OVERNIGHT
CLOUD COVER TO MOSTLY CLEAR FROM PARTLY CLOUDY. THEREFORE...HAVE
ALSO LOWERED TEMPERATURES FOR OVERNIGHT BY A COUPLE DEGREES.
OTHERWISE FORECAST LOOKS TO BE ON TRACK AND UPDATE WILL BE OUT
SHORTLY.
&&
.AVIATION /03Z-24Z/...
VFR CONDITIONS EXPECTED TO PREVAIL FOR THE NEXT 24 HOURS. A FEW HIGH
CLOUDS WILL SPREAD FROM WEST TO EAST OVERNIGHT BEFORE CLEARING OUT
TOMORROW AFTERNOON. LIGHT WINDS WILL GRADUALLY INCREASE FROM THE
SOUTH TOMORROW.
&&
.PREV DISCUSSION...
/ISSUED 238 PM EST TUE JAN 2 2007/
SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
WATER VAPOR LOOP SHOWS A WAVE MOVING OFF THE NEW ENGLAND SHORE. THE
NEXT NORTHERN STREAM WAVE IS TILTED POSITIVELY AS IT MOVES ACROSS
THE UPPER MIDWEST. A DEEP UPPER LOW IS SINKING SOUTH INTO NORTHERN
MEXICO. ACARS 400-250MB WIND OBSERVATIONS REVEAL A 100-120KT
WESTERLY JET FROM THE MIDWEST EAST ACROSS THE NORTHERN MID ATLANTIC.
12Z SURFACE ANALYSIS PLACED A SECONDARY COLD FRONT FROM THE NEW
ENGLAND SHORE SOUTHWEST THROUGH WESTERN MARYLAND. A TROUGH WAS IN
THE LEE OF THE APPALACHIANS...WITH A 1032MB ANTICYCLONE SPRAWLED
ACROSS THE CENTRAL CONUS.
THE SKY WILL START OUT CLEAR THIS EVENING WITH THE EROSION OF
MOUNTAIN STRATO-CU. HAVE RAISED CLOUD COVER (ESPECIALLY
ACROSS THE NORTHERN FORECAST AREA) LATE TONIGHT AND WEDNESDAY
MORNING IN ANTICIPATION OF INCREASING HIGH LEVEL MOISTURE
ASSOCIATED WITH THE PASSAGE OF THE NORTHERN STREAM WAVE FROM THE
LOWER GREAT LAKES REGION. THE SKY SHOULD CLEAR FOR THE AFTERNOON
HOURS BEHIND THE WAVE...AS A NORTHWESTERLY UPPER LEVEL JET
STRENGTHENS ACROSS THE TENNESSEE VALLEY...TRAPPING UPPER LEVEL
MOISTURE FROM THE SOUTHERN STREAM SYSTEM SOUTH OF THE REGION.
LOWS TONIGHT WILL RANGE FROM THE MID TO UPPER 30S DOWNTOWN...LOW 30S
ABOVE 2500FT AND ALONG THE BAY...TO THE MID 20S ACROSS RURAL LOW
LYING AREAS. THE ADVECTION SIGN WILL SHIFT FROM COLD TO WARM
OVERNIGHT...WITH SOUTHWEST WINDS USHERING IN +5C OF WARMING NEAR
850MB. 09Z SHORT RANGE ENSEMBLES SUGGEST 850MB TEMPERATURES TOMORROW
WILL BE +1-1.5 STANDARD DEVIATIONS ABOVE CLIMATOLOGY. THIS WILL
SUPPORT HIGH TEMPERATURES REACHING 60F WEDNESDAY.
AVIATION /20Z-18Z/...
P6SM SKC THROUGH MUCH OF THE NIGHT. WINDS GUSTS HAVE SLACKENED WITH
A SURFACE HIGH BUILDING IN. MAY SEE FEW-SCT250 AS UPPER LEVEL
MOISTURE ADVECTS IN AHEAD OF A WEAK SHORTWAVE LATE TONIGHT AND
TOMORROW MORNING.
MARINE...
12Z GFS/ETA MOS AT THOMAS POINT...15Z LWX WRF-NMM MARINE AND 12Z
NAM/GFS PROXIMITY LAND BUFKIT FORECAST SOUNDINGS ALL SUGGEST
SUSTAINED WINDS AND GUSTS WILL QUICKLY FALL BELOW SMALL CRAFT
CRITERIA THROUGH THE MID AFTERNOON. 18Z OBSERVATIONS ALREADY SHOW
THIS TREND...SO WILL CANCEL THE SMALL CRAFT ADVISORY WITH THE 330PM
COASTAL WATER FORECAST ISSUANCE.
WINDS WILL APPROACH SMALL CRAFT FRIDAY AFTERNOON AND EVENING BUT AT
THIS TIME ARE FORECAST TO STAY JUST BELOW 15 KT.
TIDES...
WATER LEVELS ARE CURRENTLY AT OR JUST BELOW ASTRONOMIC PREDICTIONS.
THE LUNAR CYCLE IS AT A FULL MOON (99% FULL). THE CHESAPEAKE AND
POTOMAC EXPERIENCED A BLOWOUT...WITH WATER LEVELS RETURNING NEAR
NORMAL.
LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
IT WILL TAKE SOME TIME FOR THE LARGE HIGH TO MOVE ACROSS THE AREA...
BUT BY THU NIGHT RETURN FLOW WILL BRING RAIN BACK INTO THE FORECAST.
ONCE IT IS HERE THAT UNSETTLED WEATHER WILL LAST UNTIL SATURDAY WHEN
A COLD FRONT WILL FINALLY CLEAR THE REGION WITH A RETURN TO TEMPS
THAT ARE CLOSER TO SEASONABLE BUT CERTAINLY NOT COLD FOR EARLY NEXT
WEEK. BEST CHANCE OF RAIN SEEMS TO BE LATE THU NIGHT INTO FRI MORN
AT THE MOMENT... AND THE TIMING SEEMS TO BE SETTLING IN AFTER SOME
ACCELERATION IN THE SYSTEM DURING PREVIOUS MODEL RUNS.
IN THE VERY LONG TERM. WINTER DOES SEEM TO BE MASSING ITS TROOPS ON
THE CANADIAN BORDER DURING MIDDLE JANUARY. THE PAST FEW RUNS ON THE
GFS INDICATE A PATTERN SHIFT UPCOMING LATER IN THE MONTH AS THE
POLAR VORTEX SWINGS AROUND TO OUR PART OF THE GLOBE. IT CERTAINLY
WOULD MAKE SENSE AS WE NOW HAVE HAD SEVERAL WEEKS OF ABNORMALLY WARM
TEMPERATURES AND IT IS DIFFICULT TO MAINTAIN A LARGE ANOMALY LIKE
THAT FOR MORE THAN A FEW WEEKS. OTHER THAN A FEW BRIEF SHOTS OF COOL
AIR... WE HAVE BEEN NEAR TO WELL ABOVE NORMAL SINCE EARLY NOVEMBER.
DECEMBER WAS THE TENTH WARMEST ON RECORD IN DC AND 13TH WARMEST FOR
BALTIMORE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
SHORT TERM/AVIATION...SAR
PREV. DISCUSSION...ROGOWSKI/STRONG
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
AFDGRR 352 AM EST MON JAN 1 2007
.SHORT TERM...
THE UPPER SYSTEM THAT HAS HAS BROUGHT A SNOW STORM TO THE WRN AND
CENTRAL PORTIONS OF THE COUNTRY...SEVERE WEATHER TO THE DEEP
SOUTH...AND EVEN A FEW THUNDERSTORMS TO LOWER MICHIGAN ON NEW YEARS
EVE IS CURRENTLY IN THE PROCESS OF EXITING THE COUNTRY. ONE MORE SET
OF SHORT WAVES RIDING ON THE BACKSIDE OF THE MAIN SYSTEM OVER WI/IL
IS ALL THAT REMAINS TO AFFECT LOWER MICHIGAN WITH THIS SYSTEM. THE
MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN CHCS AND PCPN
TYPE TODAY AS THE LAST UPPER WAVE PASSES THROUGH. THE ONLY OTHER
ISSUE IS TO DETERMINE THE TIMING OF THE CLEARING BEHIND THIS SYSTEM
LATER THIS AFTERNOON AND TONIGHT.
THE WAVE THAT HELPED TO PRODUCE THE SHOWERS AND STORMS LAST EVENING
ACROSS THE SE HALF OF THE CWFA HAS MOVED EAST...AND ONLY A COUPLE
LIGHT SHOWERS REMAIN AS OF 0830Z PER THE KGRR 88D. SFC ANALYSIS AT
08Z SHOWS A SFC TROUGH/SECONDARY FRONT EXTENDING FROM GREEN BAY DOWN
THROUGH THE QUAD CITIES. AS THE UPPER TROUGH AND THE ASSOCIATED SFC
TROUGH SWING ACROSS THE CWFA LATER THIS MORNING...A FEW MORE SHOWERS
ARE EXPECTED TO REDEVELOP. SHOWERS WILL LIKELY HAVE A LITTLE BETTER
COVERAGE UP NORTH AS THERE IS A LITTLE BIT BETTER DEEP MOISTURE TO
WORK WITH. EITHER WAY...THE SHOWERS ARE NOT EXPECTED TO AMOUNT TO
MUCH MORE THAN ANOTHER TENTH OF AN INCH OF PCPN. AS FAR AS PCPN TYPE
IS CONCERNED...TEMPS ARE STILL IN THE 40S ACROSS THE CWFA. A TAMDAR
FLIGHT OUT OF KORD AROUND 05Z SHOWED THE FREEZING LEVEL THERE WAS
STILL AROUND 4K FEET AND SLOWLY LOWERING. ANY SHOWERS INITIALLY
SHOULD START OUT AS RAIN THIS MORNING. PCPN WILL BEGIN TO CHANGE TO
A MIX LATER THIS MORNING ONCE THE SFC TROUGH MOVES THROUGH AND MORE
COOLER AIR ADVECTS IN. THE UPPER TROUGH IS EXPECTED TO PASS EAST OF
THE CWFA BY MID AFTERNOON...ALLOWING PCPN TO END. THERE MAY BE A FEW
PLACES THAT SEE PCPN GO OVER TO ALL SNOW BRIEFLY BEFORE ENDING...BUT
THIS WILL BE A VERY SHORT TIME IF AT ALL...AND WE JUST HAVE GONE
WITH A RA/SN MIX AFTER MID MORNING. TEMPS ARE EXPECTED TO FALL
SLOWLY THROUGH THE DAY FROM EARLY HIGHS THIS MORNING IN THE 40S WITH
THE COLD AIR ADVECTION AND LOW SUN ANGLE.
SOME CLEARING WILL BE POSSIBLE RIGHT AROUND SUNSET OVER THE NW
CORNER OF THE CWFA PER 925 MB RH PROGS OFF OF THE NAM AND GFS. THIS
CLEARING SHOULD PROGRESS ACROSS THE CWFA FROM WEST TO EAST THROUGH
THE EVENING. SKIES MAY GO CLEAR BRIEFLY AFTER THE CLEARING LINE
MOVES THROUGH. A SHORT WAVE TROUGH WILL THEN APPROACH THE AREA LATE
IN THE NIGHT...PROVIDING A CANOPY OF THIN HIGH CLOUDS LATE IN THE
NIGHT. ALSO...THE MODELS ARE HINTING ARE HINTING AT SOME LOW CLOUD
DEVELOPMENT UP NORTH OVER THE HIGHER ELEVATIONS OF CENTRAL LOWER
MICHIGAN. THIS LOOKS LIKE IT WOULD BE TEMPORARY WITH THE GOOD PUSH
OF DRIER AIR FROM THE NW OVERNIGHT. WE WILL GO WITH BECOMING PARTLY
CLOUDY/PARTLY CLOUDY OVER THE CWFA TONIGHT. LOWS SHOULD DIP INTO THE
MID 20S OVER THE NE CORNER OF THE CWFA TO THE LOWER 30S DOWN
SOUTH.
THE PERIOD OF TUE THROUGH WED AFTERNOON LOOKS LIKE A FAIRLY QUIET
AND TRANQUIL PERIOD...ESPECIALLY FOR THE BEGINNING OF JANUARY FOR
LOWER MICHIGAN. LOWER MICHIGAN IS EXPECTED TO BECOME UNDER THE
INFLUENCE OF BROAD LONG WAVE RIDGING ALOFT INBETWEEN LONG WAVE
TROUGHING OVER THE CANADIAN MARITIMES AND OVER THE NE PACIFIC.
THERE WILL BE TWO SHORT WAVE TROUGHS MOVING THROUGH THE LONG WAVE
RIDGE AND ACROSS THE GREAT LAKES. THE TROUGH ON TUE WILL HAVE SOME
HIGH CLOUDS OVERHEAD EARLY...BUT THESE SHOULD MOVE EAST OF THE CWFA
DURING THE AFTERNOON. THE TROUGH COMING IN ON WED IS EVEN MORE
MOISTURE STARVED AND ONLY A FEW THIN HIGH CLOUDS AT WORST WILL BE IN
PLACE. RETURN FLOW IN THE LOWER LEVELS WILL SET UP LATE TUE AND INTO
WED ON THE BACKSIDE OF THE SFC RIDGE THAT PASSES EAST DURING THE DAY
ON TUE. THIS WILL HELP TO MODIFY TEMPS AS H850 TEMPS INCREASE FROM
AROUND -1C TO -2C TUE MORNING TO AROUND +4C WED AFTERNOON. HIGHS ON
TUE SHOULD WARM INTO THE LOW TO MID 40S...AND TEMPS SHOULD WARM INTO
THE MID TO POSSIBLY UPPER 40S ON WED WITH PLENTY OF SUNSHINE.
.LONG TERM...
SPLIT FLOW WILL BE IN PLACE FOR THE BEGINNING OF THE LONG TERM
PERIOD...WEDNESDAY NIGHT. THE FLOW TRENDS WITH TIME TOWARD ZONAL BY
THE END OF THE LONG TERM PERIOD WHICH IS SUNDAY. WILL CONTINUE THE
DRY FORECAST FROM WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH A MILD
SOUTHWEST FLOW IN PLACE. FRIDAY AN UPPER TROUGH APPROACHES FROM THE
WEST IN THE INCREASINGLY ZONAL FLOW. THE TROUGH MOVES THROUGH IN THE
FRIDAY NIGHT AND SATURDAY TIME FRAME. ANY PRECIP FRIDAY INTO FRIDAY
EVENING SHOULD BE RAIN...BUT AS COLDER AIR ADVECTS IN BEHIND THE
UPPER TROUGH FRIDAY NIGHT AND SATURDAY...SOME SNOW MAY MIX IN. HAVE
LINGERED POPS INTO SATURDAY NIGHT...BUT THIS MAY END UP BEING A DRY
PERIOD AS IT LOOKS LIKE A SURFACE RIDGE MOVES THROUGH THE FORECAST
AREA. LEFT SUNDAY DRY. OVERALL...MID WEEK LOOKS DRY WITH BETTER
CHANCES FOR PRECIPITATION TOWARD THE END OF THE WEEK. IT SHOULD BE A
MILD PERIOD OVERALL...WITH A TREND TOWARD COLDER WEATHER INTO THE
WEEKEND AND ESPECIALLY INTO NEXT WEEK.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...SMALL CRAFT ADVISORY FOR THE
ENTIRE NEARSHORE THROUGH 11Z TUE.
&&
$$
NJJ DUKE
AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 915 AM PST MON JAN 1 2007
.SYNOPSIS...PRECIPITATION WILL CONTINUE TO MOVE INLAND THROUGH
MIDDAY AND THEN CONTINUE OFF AND ON THROUGH TUE. THE PRECIPITATION
MAY BECOME BECOME HEAVY AT TIMES TUESDAY AHEAD OF A COLD FRONT THAT
WILL MOVE SOUTHEAST ACROSS THE AREA LATE IN THE AFTERNOON. ANOTHER
LOW WILL MOVE EAST ALONG THE WASHINGTON-OREGON BORDER WEDNESDAY. AN
UPPER LEVEL TROUGH WILL MAINTAIN A COOL AND SHOWERY PATTERN
THURSDAY.
&&
.SHORT TERM...RAIN SPREADING INLAND RATHER QUICKLY THIS MORNING
ALONG WITH THE WARM AIR. FREEZING LEVEL OVER SEATTLE PUSHING 5000 FT
ACCORDING TO ACARS DATA AND ALREADY OVER 6000 FT ALONG THE COAST.
THE PRECIPITATION WILL CONTINUE TO WORK INLAND THIS MORNING...PRETTY
MUCH COVERING ALL AREAS BY NOON.
WHICH BRINGS US TO AN ISSUE...AND AN UPDATE. CURRENTLY HAVE A WINTER
STORM WATCH FOR THE CASCADES FOR TONIGHT. WITH A LOOK AT THE
SITUATION AND THE PROGRESS OF THE PRECIP...WILL CHANGE THIS TO A
WINTER WEATHER ADVISORY FOR A PERIOD OF SNOW AND THEN SOME FREEZING
RAIN. THIS WILL BE FOR THE TODAY THROUGH TONIGHT TIME FRAME WITH AN
EMPHASIS ON THIS AFTERNOON AND EVENING. AFTER THIS EVENING THE
PRECIP SHOULD LIGHTENUP AS THE FOCUS OF THE FORCING SHIFTS NORTH AS
WE END UP IN THE WARM SECTOR. THE ADVISORY WILL FOCUS ON THE PASSES
AS THAT IS WHERE THE FREEZING RAIN WILL BE. ELSEWHERE IN THE
MOUNTAINS THE SNOW WILL TURN TO RAIN BELOW ABOUT 5000 FT...WHICH
WILL BRING US TO THE NEXT ISSUE.
POTENTIAL FLOOD CONCERNS. WITH THE QPF (RAINFALL ESTIMATE) FOR THE
NEXT FEW DAYS PROVIDED TO THE RIVER FORECAST CENTER THIS
MORNING...SEVERAL RIVERS IN WESTERN WASHINGTON BECOME A CONCERN FOR
FLOODING. LOOKING AT THE SAT PIX...THERE IS PLENTY OF MOISTURE THIS
SYSTEM IS TAPING INTO...IT WILL JUST DEPEND WHETHER IT IS FOCUSED
HERE OR IN BRITISH COLUMBIA. THE RIVER GUYS ARE STILL WORKING ON
MANY OF THE RIVERS BUT A COUPLE HAVE SURFACED THAT MAY NEED TO BE
DEALT WITH. OF COURSE THE SKOKOMISH IS ONE...BUT THE SNOHOMISH
WATERSHED...CHEHALIS AND THE SATSOP COME CLOSE TO FLOOD IN THIS
SCENARIO. RIVERS WON`T BE CRESTING UNTIL TUE NIGHT THRU WED...SO
WILL WAIT FOR THE FINAL NUMBERS TO COME THROUGH TO DECIDE WHERE TO
POST A WATCH. A WATCH FOR THE SKOKOMISH IS A SURE BET.
WILL BE ISSUING AN UPDATE SHORTLY...MAINLY TO CHANGE THE CASCADE
HEADLINE BUT WILL LIKELY TWEAK AND TWIDDLE WITH THE REST OF THE AREA
AS WELL. CERNIGLIA
.LONG TERM...FROM PREVIOUS DISCUSSION...MODELS APPEAR CONSISTENT IN
SHOWING ANOTHER WARM FRONT MOVING INTO THE AREA FRI WITH A STREAM OF
MOIST AIR AIMED INTO OUR AREA NEXT WEEKEND AND A SERIES OF DIFFICULT
TO TIME SYSTEMS MOVING THRU. WILL NOT MAKE CHANGES TO THE ONGOING
BROAD BRUSH FORECAST AT THIS TIME. ALBRECHT
&&
.AVIATION...CEILINGS NEARLY UNIFORM 5K-6K FT AROUND PUGET SOUND THIS
MORNING. WARM FRONT MOVING IN WILL LOWER THEM TO 2K-3K FT IN RAIN BY
NOON. SOME VISIBILITY RESTRICTIONS ON THE ORDER OF 4-5SM IN MODERATE
RAIN AT TIMES. POSSIBLY A LULL IN RAIN AND BRIEF LIFTING OF CEILINGS
TONIGHT...BUT THEN COLD FRONT WILL BRING MORE RAIN AND LOWER
CEILINGS BY TUE MORNING. CHB
.MARINE...SYSTEM LOOKING STRONGER THAN PREVIOUS FORECASTS AND HAVE
HOISTED GALES MOST WATERS. WIND WILL BE STRONG TODAY...WITH POSSIBLY
A LULL TONIGHT...BUT THEN STRONG AGAIN TUESDAY. GALE WARNINGS IN
FORCE THROUGH TUESDAY 4 PM BUT COULD LAST A BIT LONGER. COULD GET
GALE FORCE SW WINDS IN PUGET SOUND TUE AFTERNOON WITH FRONTAL
PASSAGE AND ALSO GALE WESTERLIES DOWN THE STRAIT. BURKE
.SEW WATCHES/WARNINGS/ADVISORIES...
.WINTER WEATHER ADVISORY FOR THE CASCADE PASSES THROUGH TONIGHT.
.GALE WARNING THROUGH TUESDAY AFTERNOON COAST...STRAIT ENTRANCES...
ADMIRALTY INLET...AND CAMANO ISLAND TO POINT ROBERTS.
.SMALL CRAFT ADVISORY THROUGH TUESDAY AFTERNOON PUGET SOUND AND HOOD
CANAL.
$$
WEATHER.GOV/SEATTLE