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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