785
FXUS61 KBOX 252102
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
402 PM EST SAT JAN 25 2020
SYNOPSIS
LOW PRESSURE AND A RELATED FRONTAL SYSTEM APPROACHING FROM THE
MID ATLANTIC STATES WILL BRING A PERIOD OF HEAVY RAIN AND STRONG
COASTAL WINDS THIS EVENING. ANOTHER GENERALLY DRY WORK WEEK IS
ON TAP WITH SLIGHTLY ABOVE NORMAL TEMPERATURES. THERE IS THE
POTENTIAL FOR A STORM TO IMPACT THE REGION SOMETIME NEXT
WEEKEND, BUT THAT IS FAR FROM A CERTAINTY AT THIS POINT.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
CLOUDY CONDITIONS WITH EAST WINDS HAVING INCREASED OVER THE LAST
COUPLE HRS, DUE TO GRADIENT BETWEEN HIGH PRESSURE WEDGE OVER
COASTAL/DOWNEAST ME AND AN APPROACHING FRONTAL OCCLUSION TRAILING
FROM WESTERN NY THROUGH COASTAL NJ INTO THE NYC METRO AREA. REGIONAL
RADAR MOSAIC REVEALS A SWATH OF MODERATE TO AT TIMES HEAVY RAINS
ALONG THE EXTENT OF THE OCCLUDED FRONT, WITH 3 HOURLY RAIN TOTALS
PER METARS IN THE 0.7-1" RANGE, GIVEN AN ANOMALOUS PLUME OF
DEEP MOISTURE (PWATS 0.8-1" PER SPC MESOANALYSIS).
HIGH-RESOLUTION GUIDANCE REMAINS IN GOOD AGREEMENT IN PROGRESSING
THESE FRONTAL RAINS FROM SW TO NE ACROSS SOUTHERN NEW ENGLAND FROM 3-
5 PM TO 10-11 PM. A PERIOD OF MODERATE TO HEAVY RAINS IS LIKELY TO
ACCOMPANY THIS BAND AS IT PIVOTS NE, WITH STORM TOTAL QPF STILL ON
THE ORDER OF 0.8-1.5", THOUGH MUCH OF THAT WILL FALL OVER A 3-6 HR
PERIOD. MAY BE SOME PONDING AND URBAN/POOR DRAINAGE FLOODING, BUT
MAY PROVE MORE ISOLATED IF AT ALL, WITH STORM DRAINS NOT BEING
CLOGGED FROM EXISTING SNOWPACK.
NAM-BASED ELEVATED INSTABILITY PARAMETERS SUPPORT A POTENTIAL WINDOW
OF SOME RUMBLES OF THUNDER TOWARDS COASTAL RI, SE MA INTO THE CAPE
AND ADJACENT COASTAL WATERS. DID NOTE SOME COOLING CLOUD TOPS AND
GOES SATELLITE GLM LIGHTNING FLASH EXTENT DENSITY PRODUCT
INDICATES SOME CONVECTION TOWARDS THE WATERS SE OF MD/NJ.
APPEARS GREATEST POTENTIAL IS BETWEEN 8-10 PM. A STRONG ESE LOW-
LEVEL JET (925 MB WINDS AROUND 60 KT PER THE NAM AND THE GFS)
WILL BE ADVANCING NE ALONG AND JUST AHEAD OF THESE FRONTAL
SHOWERS. IT ISN'T LIKELY THAT THESE WINDS WILL BE ABLE TO MIX
THROUGH THE INVERSION WITHOUT THUNDER AIDING IN THAT PROCESS.
THEREFORE MAINTAINED GUSTY WINDS IN ISOLATED THUNDER TO AT LEAST
RAISE AWARENESS OF POTENTIAL FOR THUNDER TO ENHANCE GUSTS;
OVERALL IS LOW-PROBABILITY BUT THE THREAT ISN'T ZERO. SO COULD
SEE SOME NEED FOR SOME SHORT-FUSED STATEMENTS IF SUCH A THREAT
WERE TO MATERIALIZE.
FROM LATE EVENING INTO THE OVERNIGHT, EXPECT A SHARP WIND SHIFT FROM
E/SE TO W WITH FROPA, WITH A MARKED DECREASE IN WIND SPEEDS AND POPS
TOWARD DRY CONDITIONS. GUIDANCE INDICATES A GOOD AMOUNT OF MOISTURE
TRAPPED UNDER SUBSIDENCE INVERSION/DRYING ALOFT FOR LATER TONIGHT,
THOUGH. FOLLOWING THE HREF, SKIES MAY NOT FULLY CLEAR OUT AND THERE
MAY BE A FAIR AMOUNT OF LOW CLOUD COVER OR EVEN SOME MIST OR FOG
AROUND IN THE INTERIOR AND POTENTIALLY INTO THE COASTAL PLAIN. LOWS
MID/UPPER 30S TO LOWER 40S, THOUGH CLOSER TO FREEZING IN NW MA.
SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/
SUNDAY:
UPPER LEVEL LOW NEAR WESTERN NY WILL LIFT NE THROUGH THE ST.
LAWRENCE RIVER VALLEY AND NORTHERN ADIRONDACKS THROUGH SUNDAY, WITH
W GRADIENT FLOW CONTINUING ACROSS SOUTHERN NEW ENGLAND. MAY BE A
GENEROUS AMOUNT OF EARLY-DAY CLOUD COVER ACROSS THE INTERIOR INTO
THE COASTAL PLAIN AS MOST MODELS SHOW SHALLOW MOISTURE INITIALLY
BELOW SUBSIDENCE INVERSION. COOL ADVECTION SHOULD HELP TO
SCATTER/DISPERSE CLOUDINESS BY MID-MORNING. STILL, LOOKING AT PARTLY
TO MOSTLY CLOUDY SKIES (GREATEST FURTHEST NW CLOSER TO UPPER LOW)
AND W WINDS AROUND 10-15 MPH. THOUGH WE WILL HAVE COOL
ADVECTION, IT'S NOT A HUGE AIR MASS CHANGE WITH 925 MB TEMPS
RUNNING FROM -2 TO 0C THRU 00Z MONDAY. LESS CLOUD COVER IN THE
COASTAL PLAIN SUPPORTS HIGHS IN THE MID/UPPER 40S, LOWER-MID 40S
FOR THE HARTFORD- WORCESTER- SPRINGFIELD AREAS AND UPPER 30S-
LOW 40S NW MA INTO THE TERRAIN IN NORTHERN WORCESTER COUNTY
WHERE CLOUDS WILL BE HARDER TO FULLY SHAKE FREE FROM.
SUNDAY NIGHT:
MAINLY DRY WEATHER FOR THE FIRST PART OF SUNDAY NIGHT, WITH A
CONTINUATION OF W GRADIENT FLOW. LATE SUNDAY NIGHT INTO THE
OVERNIGHT HOURS, A 500 MB VORT LOBE AROUND THE UPPER LEVEL LOW THEN
PIVOTS SE FROM NORTHERN NY INTO INTERIOR NEW ENGLAND. THIS SHOULD
LEAD TO AN INCREASE IN CLOUDS INTO A LARGER PART OF CENTRAL MA AND
NORTHERN CT. MUCH OF EASTERN MA SHOULD BE DRY, THOUGH ENOUGH
MOISTURE IN THE SNOW GROWTH LAYER PER BUFKIT SOUNDINGS FROM
WORCESTER TO TOLLAND N/W COULD SUPPORT A FEW SNOW SHOWERS. HIGHER-
RESOLUTION GUIDANCE HINTS AT THIS PRECIP EXTENDING A BIT FURTHER
EAST. SOMETHING TO WATCH GIVEN THE FORCING, BUT FEEL DOWNSLOPING
WOULD LIMIT THE EASTWARD EXTENT. BEST CHANCE AT ANY REALLY LIGHT
ACCUMULATIONS IS IN THE BERKSHIRES WHERE SFC TEMPS ARE THE COLDEST.
SIDED ON THE WARMER END OF GUIDANCE AGAIN WITH THE CLOUD COVER AND
THE WINDS LEADING TO A SOMEWHAT BETTER MIXED ATMOSPHERE; IN TURN,
THIS RESULTS IN LOWS 30-32F ACROSS MOST OF THE INTERIOR, WITH
MID/UPPER 30S TOWARDS EASTERN MA AND THE SOUTH COAST INTO RI.
LONG TERM /MONDAY THROUGH SATURDAY/
HIGHLIGHTS...
* ANOTHER GENERALLY DRY WORK WEEK WITH SLIGHTLY ABOVE NORMAL TEMPS
* POTENTIAL STORM NEXT WEEKEND, BUT FAR FROM A CERTAINTY
DETAILS...
UPCOMING WORK WEEK...
THE UPCOMING WORK WEEK WILL FEATURE GENERALLY DRY AND TRANQUIL
WEATHER FOR THE END OF JANUARY. THE MILDEST DAY OF THE WEEK WILL BE
ON MONDAY, WHEN MANY LOCATIONS HAVE HIGHS WELL UP INTO THE 40S. A
COUPLE OF DRY COLD FRONTAL PASSAGES WILL RESULT IN HIGHS MAINLY IN
THE UPPER 30S TO THE LOWER 40S THE REST OF THE WORK WEEK. PERHAPS A
FEW DEGREES COLDER THAN THAT ON THU, WHEN HIGH PRESSURE IN QUEBEC
MAY ALLOW FOR A BIT OF COLDER AIR TO BRIEFLY WORK INTO THE REGION.
DRY WEATHER WILL GENERALLY PREVAIL FOR THE UPCOMING WORK WEEK WITH
TROUGH AXIS SETTING UP TO OUR EAST. PERHAPS A FEW BRIEF SPOT
RAIN/SNOW SHOWERS ON MONDAY WITH THE COLD FRONT AND MOST OF THOSE
WILL BE FOUND ALONG THE EAST SLOPES OF THE BERKS. MAY ALSO SEE A
FEW OCEAN EFFECT LIGHT SNOW SHOWERS/FLURRIES ON THE CAPE SOMETIME
TUE/TUE NIGHT. REGARDLESS, DRY/TRANQUIL WEATHER WILL BE THE MAIN
STORY FOR THE UPCOMING WORK WEEK.
NEXT WEEKEND...
THE LONG RANGE GUIDANCE CONTINUES TO INDICATE THE POTENTIAL FOR A
STORM TO IMPACT THE REGION SOMETIME NEXT WEEKEND. HIGH UNCERTAINTY
THOUGH GIVEN THIS POTENTIAL STORM IS 7-8 DAYS OUT, WHICH IS
BASICALLY AN ETERNITY IN THE MODEL WORLD. WHAT EVENTUALLY HAPPENS
WILL DEPEND ON THE STRENGTH/TIMING OF SOUTHERN AND NORTHERN STREAM
ENERGY AND IF THERE IS PHASING, WHICH IS UNKNOWN AT THIS POINT. THE
GEFS/EPS ENSEMBLES BOTH SHOW AN EXTREME AMOUNT OF SPREAD BETWEEN A
VERY STRONG STORM TO NOTHING MORE THAN A WEAK FRONTAL WAVE, AS THERE
ARE SO MANY MOVING PARTS INVOLVED.
SO IN A NUTSHELL, WHILE THERE IS THE POTENTIAL FOR A STORM SOMETIME
NEXT WEEKEND THAT IS ABOUT ALL WE CAN SAY AT THIS POINT. IF IT DOES
COME TO FRUITION, PTYPE WOULD ALSO BE UNCERTAIN AS ANTECEDENT
AIRMASS IS NOT THAT COLD.
AVIATION /21Z SATURDAY THROUGH THURSDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
21Z TAF UPDATE:
SHORT TERM /THROUGH SUNDAY NIGHT/...
REST OF TODAY INTO TONIGHT: MODERATE CONFIDENCE.
DETERIORATION TO WIDESPREAD IFR EXPECTED AS FRONTAL RAINS
CONTINUE TO OVERSPREAD THE TAFS THRU 03Z. MAY BE PERIODS LIFR
AT TIMES. VISBYS MAINLY MVFR-IFR WITH POSSIBLE RUMBLE OF THUNDER
TOWARDS SE MA AND THE CAPE (S/E OF BOS/PVD). LOW
CLOUDS/POSSIBLE FOG AFTER 04Z IN THE INTERIOR AND POTENTIALLY TO
THE COASTAL PLAIN WITH IFR- MVFR CONDITIONS THRU 10Z.
IMPROVEMENT TOWARDS MVFR-VFR EXPECTED AFTER 10Z.
NE WINDS INCREASING AROUND 10-15 KT THIS AFTERNOON, WITH GUSTS
TO 25-30 KT EASTERN TAFS BY TONIGHT. POCKETS OF LOW-LEVEL WIND
SHEAR POSSIBLE GIVEN STRONG LOW-LEVEL ESE WINDS OF 50-55 KT
ABOVE INVERSION. ESE TO W WIND SHIFT ~01-03Z FROM SW TO NE,
WITH SPEEDS THEN LIGHTENING TO 6-10 KT, WITH GUSTS TO 20-25 KT
ON THE CAPE/ISLANDS.
SUNDAY: HIGH CONFIDENCE.
LEFTOVER SUB-VFR CONDITIONS IMPROVE TO VFR BY MID-MORNING. MAY
SEE SPOTTY MVFR CIGS LATE FOR THE BERKSHIRES/TERRAIN, POSSIBLY
AT BAF. W WINDS 8-12 KTS, WITH GUSTS 20-25 KT AS CLOUDS START
TO SCATTER.
SUNDAY NIGHT: HIGH CONFIDENCE.
GENERALLY VFR, THOUGH MVFR CEILINGS/ISO -SHSN POSSIBLE MAINLY
FOR THE BERKSHIRES. W WINDS 7-10 KT.
KBOS TERMINAL...MODERATE CONFIDENCE. A PERIOD OF MODERATE TO
HEAVY RAINFALL ~00-02Z THIS EVENING WITH GOOD CONFIDENCE IFR,
LOWER- CONFIDENCE LIFR. E GUSTS PEAKING AROUND 30 KT THIS
EVENING. WIND SHIFT TO W AFTER 03Z.
KBDL TERMINAL...MODERATE CONFIDENCE. A PERIOD OF MODERATE TO
HEAVY RAINFALL EXPECTED NEXT COUPLE OF HOURS, WITH MAINLY IFR,
LOWER- CONFIDENCE LIFR. W/WNW WIND SHIFT AROUND 02Z.
OUTLOOK /SUNDAY NIGHT THROUGH MONDAY/ ...
MONDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. SLIGHT
CHANCE SHRA.
MONDAY NIGHT: VFR. BREEZY.
TUESDAY THROUGH WEDNESDAY: VFR.
WEDNESDAY NIGHT: VFR. BREEZY.
THURSDAY: VFR.
MARINE
SHORT TERM /THROUGH SUNDAY NIGHT/...HIGH CONFIDENCE.
DUE TO 5-6' SEAS SHOWING UP A BIT EARLY ACROSS EASTERN MA, HAVE
STARTED THE GALE WARNING A LITTLE EARLIER WITH THE IDEA THAT
E/ESE WINDS WILL BE ON THE INCREASE. WINDS MAY BE CLOSER TO SCA
CRITERIA THIS AFTERNOON, BUT ARE EXPECTED TO INCREASE TO GALE
FORCE EARLY TONIGHT BEFORE WSW WIND SHIFT AROUND MIDNIGHT - 2
AM. EVENTUAL CONVERSION TO SCAS NEEDED ONCE GALE CONDITIONS
EASE.
IN ADDITION, SMALL CRAFT ADVISORIES REMAIN IN EFFECT ON THE SOUTHERN
WATERS SW OF CAPE COD. SCA CONDITIONS LIKELY TO CONTINUE THROUGH
SUNDAY OWING TO SEAS OVER 5', ESPECIALLY SOUTHERN OFFSHORE WATERS.
TONIGHT: THRU MIDNIGHT, E/SE WINDS 15-25 KT GUSTS TO 30 KT ON THE
SOUTHERN WATERS, AND 20-25 KT GUSTS TO 35-40 KT ON THE EASTERN
WATERS. AFTER MIDNIGHT, WIND SHIFT TO WSW WITH SPEEDS AROUND 10-15
KT GUSTS TO 25 KT ON MOST WATERS. SEAS BUILD TO 5-9 FT SOUTHERN
WATERS, AND TO 8-12 FT ON EASTERN OFFSHORE WATERS EAST OF CAPE COD.
RAIN, HEAVY AT TIMES WITH POSSIBLE THUNDER SOUTHERN WATERS.
VISIBILITIES 1-3 MILES.
SUNDAY: W WINDS AROUND 10-15 KT, WITH GUSTS TO 23-28 KT BY
AFTERNOON, HIGHEST ON THE EASTERN WATERS. SEAS 7-9 FT, DECREASING
TO 5-8 FT LATE. GOOD VISIBILITY.
SUNDAY NIGHT: W/WSW WINDS AROUND 10-15 KT, GUSTS 20-23 KT. SEAS 5-7
FT OFFSHORE, 2-3 FT NEARSHORE. GOOD VISIBILITY.
OUTLOOK /MONDAY THROUGH THURSDAY/...
MONDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 25 KT. AREAS OF ROUGH SEAS.
MONDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT.
TUESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT CHANCE
OF SNOW SHOWERS. AREAS OF VISIBILITY 1 TO 3 NM.
TUESDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. LOCAL VISIBILITY 1 TO 3 NM.
WEDNESDAY THROUGH WEDNESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS
LOCALLY APPROACHING 5 FT.
THURSDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...GALE WARNING UNTIL 1 AM EST SUNDAY FOR ANZ231-232-251.
SMALL CRAFT ADVISORY UNTIL 1 AM EST SUNDAY FOR ANZ230-233-234-
236.
SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ235-237-255-
256.
GALE WARNING UNTIL 3 AM EST SUNDAY FOR ANZ250-254.
SYNOPSIS...FRANK/LOCONTO
NEAR TERM...LOCONTO
SHORT TERM...LOCONTO
LONG TERM...FRANK
AVIATION...FRANK/LOCONTO
MARINE...FRANK/LOCONTO
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