FXUS61 KBOX 050850
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
350 AM EST SUN FEB 5 2012

.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND TODAY SHIFTS SOUTH TONIGHT. A WARM
FRONT CROSSES THE REGION TONIGHT BRINGING MILDER AND CONTINUED
DRIER WEATHER MONDAY. A COLD FRONT DIPS THROUGH NEW ENGLAND
TUESDAY...FOLLOWED BY A RETURN TO HIGH PRESSURE WEDNESDAY. LOW
PRESSURE MOVING OUT OF THE SOUTHERN PLAINS MAY BRING PRECIPITATION
OUR WAY WEDNESDAY NIGHT AND THURSDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
HIGH PRESSURE OVER NEW YORK IS BUILDING ACROSS NEW ENGLAND WITH
MOSTLY CLEAR SKIES. THREE CLOUD AREAS OF CONCERN FOR TODAY.

FIRST...AN AREA OF OCEAN CLOUDS OVER THE GULF OF MAINE HAS
CLIPPED THE OUTER CAPE AND MAY CONTINUE TO AFFECT THE OUTER CAPE
THIS MORNING. WINDS ARE MARGINAL WITH PROVINCETOWN AT 10 KNOTS AND
WINDS FARTHER WEST AND SOUTHWEST AROUND 5 KNOTS. AIR-OCEAN
TEMPERATURE DIFFERENCE IS FAVORABLE AT AROUND 16C NEAR
PROVINCETOWN. INVERSION DEPTH IS RATHER SHALLOW AT 3000 FEET. SO
NOT A GREAT SETUP FOR OCEAN EFFECT...BUT IT MAY BE ENOUGH TO
SUPPORT SOME CLOUDS THIS MORNING BEFORE THE SURFACE HIGH MOVES
OVERHEAD KILLING THE WIND AND SHIFTING THE DIRECTION OUT TO SEA.

SECOND...A SHIELD OF CIRRUS AND ALTOCUMULUS MOVED ACROSS
PENNSYLVANIA OVERNIGHT AND INTO SOUTHERN NEW ENGLAND. THIS IS THE
NORTHERN EDGE OF CLOUDS ASSOCIATED WITH LOW PRESSURE THAT HAS
MOVED FROM COLORADO TO THE MID ATLANTIC COAST. THESE CLOUDS ARE
MOVING WEST TO EAST AND WILL CROSS OUR AREA THIS
MORNING...ESPECIALLY CT-RI-SOUTHEAST MASS. IT SHOULD BE OFFSHORE
BY AFTERNOON.

THIRD...AREA OF LOW CLOUDS OVER THE GREAT LAKES EXTENDING INTO
WESTERN NY. THIS HAS MOSTLY BEEN MOVING SOUTH BUT WITH A SLOW
DRIFT TO THE EAST. THIS SEEMS TO BE ASSOCIATED WITH A SHARP
SHORTWAVE DIVING SOUTHEAST FROM ONTARIO. THE NAM-GFS-GGEM-ECMWF ALL
LOSE THE MOISTURE AS IT APPROACHES NEW ENGLAND THIS
AFTERNOON/EVENING. STRAIGHT EXTRAPOLATION WOULD BRING THESE CLOUDS
TO THE CT VALLEY AROUND 16Z-17Z AND TO EASTERN MASS AROUND 19Z-
20Z. WE WILL SHOW SOME AFTERNOON SKY COVER...BUT LESS THAN 50
PERCENT. THIS CLOUD AREA WILL NEED TO BE MONITORED IN CASE IT DOES
NOT DIMINISH AS EXPECTED.

MIXING REACHES TO NEAR 900 MB TODAY. AFTERNOON TEMPS AT THAT LEVEL
WILL BE AROUND -6C TO -7C...SUPPORTING MAX TEMPS IN THE 30S.
WARMEST TEMPS WILL BE IN CT AND MAY BE NEAR 40 IN SOME SPOTS.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
TONIGHT...
WARM FRONT MOVES ACROSS NEW ENGLAND TONIGHT. BEST ISENTROPIC LIFT
AND AVAILABLE MOISTURE AS SHOW ON THE 285K AND 290K SURFACES WILL
BE IN NORTHERN NEW ENGLAND...SO THE GREATEST SKY COVER OVERNIGHT
WILL BE TO OUR NORTH BUT WITH A PERIOD OF CLOUDS MOVING THROUGH OUR
AREA OVERNIGHT. TEMPS COME FROM A BLEND OF MOS.

MONDAY...
HIGH PRESSURE TO OUR SOUTH WITH WEST TO SOUTHWEST WINDS BEARING
MILDER TEMPS ALOFT. WITH THE WARM FRONT MOVING OFF TO THE
EAST...ANY MORNING CLOUDS SHOULD DIMINISH. THE REST OF THE DAY
SHOULD BE SUNNY AND MILD. WARM ADVECTION ALOFT WILL KEEP THE
MIXING DEPTH MORE SHALLOW. BUT TEMPS AT 925 MB WILL BE 0-3C AND AT
950 MB 2-4C. THIS SHOULD SUPPORT MAX TEMPS AT LEAST TO THE 40S AND
POSSIBLY TO THE LOWER 50S. WITH THE EXPECTED SUNSHINE WE ARE GOING
WITH THE MILDER VALUES IN THE SOUTHERN 2/3 OUR OUR AREA.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
HIGHLIGHTS...
* QUIET WEATHER EXPECTED THROUGH MID-WEEK
* LOW PROBABILITY OF A STORM LATE NEXT WEEK

OVERVIEW AND MODEL PREFERENCES...
05/00Z MODEL SUITE CONTINUES TO HAVE GOOD AGREEMENT THROUGH MID
WEEK...WITH TYPICAL BIASES/DISCREPANCIES APPARENT THEREAFTER. THE
PERIOD IS MARKED BY VERY AMPLIFIED FLOW PATTERN OVER MUCH OF
CANADA WITH STRONG RIDGING OVER WRN PORTIONS AND A GRADUALLY
DEEPENING HUDSON BAY VORTEX. THE FORMER WILL CONTINUE TO SUPPLY
BOTH SUBSIDENCE AND NW TO W FLOW THROUGH MID WEEK...ALLOWING G THE
DRY WX TO CONTINUE. GIVEN THAT THIS IS WELL AGREED UPON BY
AVAILABLE GUIDANCE...WILL CONTINUE WITH THE GFS/ECMWF BLEND WHICH
HAS BEEN USED IN PREVIOUS FORECASTS. ONCE AGAIN...THERMAL
STRUCTURES APPEAR TO BE FAIRLY CLOSE...SO NO MODEL IS FAVORED FOR
THAT EITHER. IT IS THE STRENGTH OF THE DEEPENING AS WELL AS THE
FINAL LOCATION OF THE TROF ASSOCIATED WITH THE HUDSON BAY VORTEX
THAT IS CAUSING A DIVERGENCE IN POTENTIAL SOLNS LATE IN THE WEEK.
ECMWF IS SHOWING ITS TYPICAL STRONG AMPLIFICATION BIAS...SUGGESTING
THAT THE TROF IS VERY DEEP AND WELL ENTRENCHED OVER ERN PORTIONS
OF THE CONUS BY THE WEEKEND. THE OPERATIONAL GFS IS LESS DEEP WITH
THE BASE CENTERED CLOSER TO THE GREAT LAKES AND NORTHERN
PLAINS...ALTHOUGH IT TOO DEEPENS AND SHIFTS E LATER IN THE
WEEKEND. GEFS AND ECENS MEMBERS ARE DECIDEDLY MIXED ON THIS
ALTHOUGH THE MEANS OF EACH SEEM TO BE SLIGHTLY CLOSER TO THE ECMWF
SPATIALLY. GIVEN THIS WILL TREND LATTER PORTION OF THE FORECAST
/THURSDAY INTO THE WEEKEND/ TOWARD THE ECMWF TIMING. HOWEVER IN
EITHER CASE...UNDER SW FLOW WITH INCREASING MOISTURE A PERIOD OF
UNSETTLED WX IS LIKELY. THE DETAILS OF ANY PARTICULAR STORM WILL
HAVE TO BE IRONED OUT IN UPCOMING FORECASTS DUE LOW CONFIDENCE IN
THE PROGRESSION OF ANY SHORTWAVES AND ASSOCIATED SFC LOW PRES.

DETAILS...

MON NIGHT INTO TUE...
ROBUST COLD FRONT WILL BE MOVING S FROM QC AND ON
PROVINCES...THEN MOVING THROUGH SOUTHERN NEW ENGLAND TUE MORNING
INTO THE EVENING. DESPITE THE FACT THAT CROSS SECTIONS SHOW A
TIGHT LLVL GRADIENT OF ISENTROPES WITH A BIT MORE MOISTURE THAN
PREVIOUS WAVES...THE SUBSIDENCE INVERSION DEPICTED ON SOUNDINGS
AND CONTINUATION OF W TO NW FLOW ALOFT SUGGEST THAT THIS FRONT
GOES THROUGH DRY. INDEED MODEL QPF OUTPUT IS DRIER THAN PREVIOUS
RUNS...SUGGESTING LITTLE PRECIP EVEN IN THE NW WHERE OROGRAPHIC
ENHANCEMENT IS POSSIBLE. HOWEVER WITH NEAR 90 PERCENT RH JUST
ABOVE THE BOUNDARY LAYER...FEEL THAT THERE WILL BE A FAIR AMOUNT
OF SC AND EVEN POSSIBLE FLURRIES TO CONTEND WITH ESPECIALLY DURING
THE DAY.

OVERNIGHT MINS MON NIGHT WILL BE WARM GIVEN A WARM START AND
LLVLS...AND INCREASING CLOUDINESS DURING THE PEAK OF POTENTIAL RAD
COOLING LATE. TUE...H92 TEMPS WILL GRADUALLY DROP THROUGH THE DAY
TO AN AVERAGE OF AROUND -5C. WITH A FAIR AMOUNT OF CLOUD COVER
EXPECTED FEEL THAT TEMPS WILL BE COOLER THAN MON BUT GENERALLY
STILL SLIGHTLY ABOVE NORMAL. CLOSER TO THE S COAST A WEAK
DOWNSLOPE COMPONENT MAY ALLOW FOR MORE CLEARING...WHICH WOULD
ALLOW TEMPS TO REACH INTO THE MID 40S AGAIN.

TUE NIGHT INTO WED...
IT IS DURING THIS PERIOD THAT THE PATTERN BEGINS TO SHIFT MOST.
THE HIGH PRES THAT BROUGHT THE LONG PERIOD OF DRY WX WILL BEGIN TO
MOVE E OF THE REGION INTO THE DAY WED AS LONGWAVE TROF BEGINS TO
DIG AND DEEPEN OVER N CENTRAL TO NERN PORTIONS OF THE CONUS.
PREVIOUS RUNS...SUGGESTED THIS HIGH PASSES S OF SOUTHERN NEW
ENGLAND WHILE NOW IT IS AGREED UPON THAT THE HIGH WILL PASS N.
THEREFORE...NOT EXPECTING MUCH IN THE WAY OF AN AIRMASS CHANGED
UNTIL SW FLOW AND WAA ESTABLISHES BEHIND THE HIGH LATE WED. SO
EXPECTING TEMPS TO BE CLOSE TO ALBEIT SLIGHTLY ABOVE NORMAL FOR
MAXES...WHILE OVERNIGHT MINS TUE NIGHT WILL BE ON THE COOL COOL
NLY FLOW AND CLEARING SKIES.

THE GFS TRIES TO PUSH A VERY WEAK WAVE THROUGH THE CONFLUENT FLOW
OVER THE NORTHEAST DURING THE DAY WED WITH SOME WETTING PRECIP
SUGGESTED. GEFS/ECENS MEAN AND ECMWF ARE BOTH DRY CONSIDERING HIGH
PRES OF NEAR 1030 HPA WILL BE CRESTING OVER THE AREA AT THIS TIME.
FOR NOW WILL CONTINUE WITH THE DRY FORECAST AS EVEN GFS SOUNDINGS
SEEM TO BE TOO DRY TO SUPPORT ANY WIDESPREAD PRECIPITATION.

THU INTO THE WEEKEND...
THE HIGH PRES WHICH SO DOMINATED THE FORECAST BEGINS TO SLIP INTO
THE MARITIMES. BROAD SCALE TROF STEMMING FROM HUDSON BAY VORTEX
WILL BE GRADUALLY DEEPENING AND DIGGING TOWARD THE NORTHEAST CONUS
DURING THIS PERIOD. GIVEN THE STRENGTH OF THE EXITING HIGH AND
SUGGESTION OF SOME LLVL INVERTED RIDGING...FEEL ALL MODELS MAY BE
A BIT TOO FAST IN TRYING TO BRING ANY STORMS AND PRECIP TO THE
AREA EVEN THOUGH FLOW IS MORE OUT OF THE SW. ECMWF...WHICH WILL BE
WEIGHTED MORE HEAVILY FOR THIS FORECAST...SUGGESTS ANY
STORMS/PRECIP HOLDS OFF UNTIL THE DAY THU. THE KEY WILL BE ANY
SHORTWAVES...WHICH WILL BE DIFFICULT TO RESOLVE UNTIL THEY CAN BE
SAMPLED VIA REMOTE SENSING AND OBSERVING STATIONS.
THEREFORE...CONFIDENCE REMAINS LOW DURING THIS PERIOD OF THE
FORECAST...WHICH WILL LIKELY CHANGE IN THE COMING DAYS.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT

TODAY... VFR. HIGH CONFIDENCE. AN AREA OF 3500 FOOT CEILINGS HAS
MOVED FROM THE GULF OF MAINE OVER PROVINCETOWN AND THE OUTER CAPE.
THIS SHOULD AFFECT AREAS FROM HYA AND TO THE EAST FOR A FEW HOURS
THIS MORNING...BUT THEN THE CLOUD AREA WILL SHIFT EAST BY LATE
MORNING.

TONIGHT...
VFR. HIGH CONFIDENCE. WARM FRONT MOVES THROUGH...BRINGING MID AND
HIGH CLOUDS.

MONDAY...
VFR. HIGH CONFIDENCE. WINDS INCREASE FROM THE WEST BRINGING MILDER
AIR. A COLD FRONT DROPS SOUTH TO THE CANADIAN BORDER.

KBOS TERMINAL...
VFR THROUGH THE PERIOD. HIGH CONFIDENCE. THERE WILL BE SOME CLOUDS
LATE TODAY AND TONIGHT AS A WARM FRONT MOVES THROUGH...BUT ALL
ABOVE 3000 FEET. WEST WINDS MONDAY 10 TO 15 KNOTS.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...

MON NIGHT INTO TUE...
MODERATE TO HIGH CONFIDENCE. VFR. THERE IS THE LOW PROBABILITY OF
SOME MVFR CIGS AND MVFR VSBYS IN -SHSN WITH A COLD FRONTAL PASSAGE
MONDAY NIGHT...PARTICULARLY IN THE NW.

WED...
LOW TO MODERATE CONFIDENCE. MAINLY VFR.

THU...
LOW TO MODERATE CONFIDENCE. LOW PRESSURE MAY BRING SOME MVFR CIGS
AND VSBYS IN SNOW/RAIN DURING THE DAY THURSDAY.

&&

.MARINE...
TODAY...
HIGH PRESSURE SETTLES OVER THE WATERS. WINDS AND SEAS SHOULD
REMAIN BELOW SMALL CRAFT ADVISORY LEVELS.

TONIGHT...
A WARM FRONT CROSSES NEW ENGLAND TONIGHT. WINDS THEN INCREASE FROM
THE WEST. SPEEDS WILL REACH 20-22 KNOTS OVERNIGHT. WINDS AND SEAS
SHOULD REMAIN BELOW SMALL CRAFT LEVELS.

MONDAY...
SEAS AND WEST WINDS WILL CONTINUE TO BUILD. FREQUENT WIND GUSTS
SHOULD REACH 25 KNOTS ON MOST WATERS...AND SEAS WILL BUILD TO 5-7
FEET ON THE OUTER WATERS. THIS MAY EVENTUALLY REQUIRE A SMALL
CRAFT ADVISORY TO BE ISSUED.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...

MON NIGHT INTO TUE...
A COLD FRONT WILL APPROACH THE WATERS OVERNIGHT MON NIGHT...AND
THEN CROSS THE WATERS TUE. WINDS AND SEAS ARE LIKELY TO ELEVATE
ABOVE SCA THRESHOLDS...ESPECIALLY OVER THE OUTER WATERS MON NIGHT
INTO THE EARLY PART OF THE DAY TUE. LATE IN THE DAY TUE...WINDS
AND SEAS SHOULD SUBSIDE.

TUE NIGHT INTO THU...
RELATIVELY TRANQUIL WINDS AND SEAS EXPECTED FOR MOST OF THIS
PERIOD AS HIGH PRESSURE MOVES OVER THE WATERS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...WTB/DOODY
NEAR TERM...WTB
SHORT TERM...WTB
LONG TERM...DOODY
AVIATION...WTB/DOODY
MARINE...WTB/DOODY




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