Area Forecast Discussion
Issued by NWS Boston, MA

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389 FXUS61 KBOX 101516 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1016 AM EST WED FEB 10 2016 .SYNOPSIS... FAST MOVING LOW PRESSURE WILL BRING SCATTERED BUT LOCALLY HEAVY SNOW SHOWERS TODAY. MAINLY DRY WEATHER IS EXPECTED BY TONIGHT...BUT A COLD FRONT WILL BRING THE RISK FOR MORE SCATTERED SNOW SHOWERS ON THURSDAY. BITTERLY COLD WEATHER IS EXPECTED THIS WEEKEND. THERE IS POTENTIAL FOR MORE PRECIP EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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*** SCATTERED BUT LOCALLY HEAVY SNOW SHOWERS THIS AFTERNOON MAY RESULT IN SOME UNTREATED ROADWAYS QUICKLY BECOMING SNOW COVERED *** 10 AM UPDATE... AREA OF SNOW ASSOCD WITH LEAD SHORTWAVE HAS PRODUCED 1-2 INCHES ACROSS PORTIONS OF W MA THIS MORNING. ACTIVITY WILL TEMPORARILY DIMINISH BUT ANOTHER ROUND OF SCT SNOW SHOWERS EXPECTED THIS AFTERNOON AS NEXT SHORTWAVE TROF MOVES INTO NEW ENG. WHILE BRUNT OF SHORTWAVE ENERGY PASSES TO THE SOUTH...MODEST LARGE SCALE FORCING AHEAD OF THE SHORTWAVE COMBINED WITH DEEP MOISTURE AND IMPRESSIVE INSTABILITY WILL LEAD TO MORE SCT SNOW SHOWERS AND POSSIBLE LOCALLY HEAVY SNOW SQUALLS. MID LEVEL LAPSE RATES EXCEED 8 C/KM WHICH IS PRETTY EXTREME AND TOTALS TOTALS NEAR 60 SO POTENTIAL EXISTS FOR HEAVY CONVECTIVE SNOW SQUALLS WITH POOR VSBYS AND A QUICK INCH OR 2 OF SNOW. ANY SQUALLS WILL BE ISOLATED BUT WOULD HAVE A SIGNIFICANT IMPACT WHERE THEY OCCUR. THE BULK OF THE SCATTERED SNOW SHOWERS SHOULD EXIT THE REGION BY 00Z THIS EVENING...BUT STILL MAY IMPACT THE EVENING RUSH HOUR.
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&& .SHORT TERM /THURSDAY/... TONIGHT... AS MENTIONED IN THE PREVIOUS SECTION...BULK OF THE SCATTERED SNOW SHOWERS SHOULD HAVE EXITED THE COAST BY 00Z. OTHERWISE...MUCH OF THE NIGHT WILL FEATURE DRY WEATHER OTHER THAN PERHAPS A SPOT FLURRY/SNOW SHOWER. LOW TEMPS WILL MAINLY BE IN THE UPPER TEENS TO LOWER 20S. THURSDAY... ANOTHER POTENT SHORTWAVE AND ASSOCIATED COLD FRONT WILL MOVE ACROSS THE REGION ON THURSDAY. IN RESPONSE...SCATTERED FLURRIES/SNOW SHOWERS MAY BE ON GOING BY EARLY THU MORNING ACROSS PORTIONS OF WESTERN MA/NORTHERN CT. THIS ACTIVITY MAY OVERSPREAD THE REST OF THE REGION LATER IN THE MORNING AND AFTERNOON. WHILE WE CAN/T RULE OUT SOME LOCALIZED HEAVIER SNOW SHOWERS...DRY AIR WORKING IN THE BOUNDARY LAYER MAY LIMIT THAT POTENTIAL COMPARED TO TODAY. IT WILL ALSO BE COLDER ON THURSDAY WITH HIGHS MAINLY IN THE UPPER 20S TO AROUND 30. WESTERLY WIND GUSTS WILL ALSO INCREASE TO BETWEEN 25 AND 35 MPH BY MID TO LATE AFTERNOON BEHIND THE COLD FRONT. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... HIGHLIGHTS... * SNOW SHOWERS POSSIBLE THROUGH SAT * MUCH COLDER AIR MOVES INTO SOUTHERN NEW ENGLAND FOR THE WEEKEND * MORE PRECIPITATION POSSIBLE EARLY NEXT WEEK OVERVIEW AND MODEL PREFERENCES... WITH A MODESTLY NEGATIVE NAO/AO REGIME...A LONGWAVE TROF REMAINS IN PLACE ACROSS ERN CANADA AND ACTS AS A CONDUIT FOR COLD AIR TO ENTER NEW ENGLAND INTO EARLY NEXT WEEK. THIS COLD AIR COMES AS A SERIES OF ARCTIC SHORTWAVES...THE DEEPEST AND STRONGEST OF WHICH WILL BRING ABOUT THE COLDEST AIRMASS OF THE SEASON THUS FAR THIS WEEKEND. IT ALSO SUGGESTS A RELATIVELY ACTIVE PATTERN WITH A NEARLY DAILY LOW RISK FOR SHSN ACROSS THE REGION UNTIL THE PROGGED SHIFT OCCURS EARLY NEXT WEEK. THERE IS ENOUGH AGREEMENT BETWEEN OPERATIONAL MODELS THAT A BLEND OF THESE MODELS WILL WORK AS A BASELINE FOR THIS FORECAST. DETAILS... THU NIGHT INTO FRI... THE FIRST SHORTWAVE WILL ALREADY BE SLIDING E OF THE REGION BY THU EVENING...ALLOWING ANY DIURNALLY DRIVEN SHSN TO DISSIPATE. MODEST RIDGING IN BETWEEN THIS WAVE AND THE STRONGER ARCTIC WAVE FOR THE WEEKEND...WILL BUILD ACROSS THE AREA YIELDING A MAINLY DRY 24 HR PERIOD. MODEST INCREASE IN H92 TEMPS FROM ABOUT -18C TO ABOUT -12C BY 00Z FRI WILL STILL KEEP TEMPS COLD...MINS IN THE SINGLE DIGITS WITH HIGHS ONLY IN THE 20S. FRI NIGHT INTO SAT... STRONG ARCTIC FRONT ASSOCIATED WITH LOW PRES DIVING SE OUT OF ONTARIO WILL BRING IN ONE OF THE COLDEST AIRMASSES WE HAVE SEEN IN SOME TIME. THERE IS EXPECTED TO BE SOME INTERACTION WITH THE SRN STREAM...BUT MAINLY OFFSHORE WITH STRONG BOMBING CYCLOGENESIS OCCURRING TOO FAR DOWNSTREAM. ENSEMBLES/OPERATIONAL MODELS CONTINUE TO AGREE HERE...SO SUSPECT DIRECT IMPACT FROM THIS BOMBING LOW TO MINIMAL AT THIS TIME. OTHERWISE...ISALLOBARIC PRES COUPLET MAINLY W-E ORIENTED SUGGESTS THAT STRONG FLOW WITH STRONG PRES GRADIENT MAY HAVE TOO MUCH OF A WESTERLY COMPONENT FOR OCEAN EFFECT. HOWEVER...ANY SHIFT TO THE N...WITH SST-H85 DELTA-T VALUES EXCEEDING 25C...COULD YIELD SOME ADVISORY LEVEL /IF NOT HIGHER/ SNOWFALL FOR CAPE COD. THE STRONG COLD ADVECTION BEGINNING LATE FRI NIGHT MEANS THERE WILL BE LITTLE INCREASE FROM THE MINS IN THE SINGLE DIGITS AND TEENS TO THE HIGHS ON SAT. SAT NIGHT INTO SUN... H92/H85 TEMPS DROP TO ALMOST 4 STD DEVIATIONS BELOW NORMAL /NEAR -30C AT H85/. THIS WILL COMBINE WITH A FAIRLY PERSISTENT N-S PRES GRADIENT TO YIELD BLUSTERY CONDITIONS. AMBIENT TEMPERATURES ALONE WILL STRUGGLE TO REACH INTO THE POSITIVE SINGLE DIGITS. WITH WIND GUSTS 20-30 MPH...THIS WILL LIKELY LEAD TO NEGATIVE DOUBLE DIGIT WIND CHILLS SAT NIGHT INTO EARLY SUN. WIND CHILL ADVISORIES/WARNINGS ARE LOOKING QUITE LIKELY. OTHER THAN COLD...LOW RISK FOR OCEAN EFFECT CONTINUES DEPENDING ON EXACT FLOW PATTERN. MON... STRONG HIGH PRES CRESTS OVER THE REGION...AND ALTHOUGH MODEST RETURN FLOW WILL DEVELOP LATE MON...THE COLD AIRMASS REMAINS THE DOMINANT PLAYER. ALTHOUGH NOT AS COLD AS SAT NIGHT AND SUN...TEMPS ARE LIKELY TO STILL REMAIN WELL BELOW NORMAL...ESPECIALLY IF GOOD RADIATIONAL COOLING IS OBSERVED LATE SUN NIGHT. MID NEXT WEEK... LOTS OF UNCERTAINTY HERE AS STRONG SHORTWAVE MOVES MAINLY S OF THE REGION...WITH THE SRN STREAM BEING DOMINANT. EXACT PATH OF ATTENDANT LOW PRES REMAINS DIFFICULT TO RESOLVE AS ENSEMBLES RANGE FROM A WARM INSIDE RUNNER...TO A HARD HITTING BENCHMARK LOW...TO A WIDE RIGHT MISS. STILL SOME TIME...BUT THIS WILL BE ONE TO WATCH AS THE PATTERN LOOKS TO SHIFT BACK...AWAY FROM THE CURRENT COLD PATTERN TO A WARMER ONE BY THE END OF THE MONTH. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY/... TODAY...MODERATE CONFIDENCE. NOTE...NO MAJOR CHANGES WITH 12Z TAF UPDATE...FORECAST DESCRIPTION BELOW PROVIDES BEST DETAIL. CONDITIONS ARE QUITE VARIABLE RANGING FROM IFR IN SNOW SHOWERS TO VFR. TREND WILL BE FOR MAINLY MVFR CIGS THIS AFTERNOON WITH LOCALIZED BRIEF IFR/LIFR IN SCT HEAVY SNOW SHOWERS AND QUICKLY COVERING AIRPORT RUNWAYS. THE BULK OF THE ACTIVITY SHOULD EXIT THE COASTAL PLAIN BY AROUND 00Z. TONIGHT...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS...BUT WILL HAVE TO WATCH FOR SOME SCATTERED SNOW SHOWERS DEVELOPING ACROSS SOUTHWEST MA/NORTHERN CT TOWARDS 12Z THURSDAY. THURSDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS BUT SCATTERED FLURRIES/SNOW SHOWERS MAY RESULT IN BRIEFLY LOWER CONDITIONS. NORTHWEST WINDS WILL LIKELY GUST TO AROUND 30 KNOTS BY AFTERNOON BEHIND A STRONG COLD FRONT. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF TODAY. BIGGEST UNCERTAINTY IS THE TIMING OF ANY SCATTERED SNOW SHOWERS WHICH MIGHT BE BRIEFLY HEAVY...RESULTING IN POOR VISIBILITY. HIGHEST RISK FOR THAT IS BETWEEN 17Z AND 23Z. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF TODAY. SCATTERED SNOW SHOWERS SHOULD OVERSPREAD THE AREA BY 12Z AND MAY COAT RUNWAYS. THE RISK FOR SCATTERED SNOW SHOWERS...A FEW OF WHICH MAY BE BRIEFLY HEAVY WILL CONTINUE INTO THE AFTERNOON. OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/... THU NIGHT INTO FRI...HIGH CONFIDENCE. MAINLY VFR AFTER AN SHSN DISSIPATE THU EVENING. W WINDS GUST 25-30 KT POSSIBLE THU NIGHT...BUT LIGHTER FRI. FRI NIGHT INTO SUN... MAINLY VFR INLAND...BUT SOME OCCASIONAL MVFR/IFR POSSIBLE ESPECIALLY OVER CAPE COD DUE TO OCEAN EFFECT CLOUDS AND POSSIBLE SHSN. GUSTY WINDS EXPECTED AT TIMES...20-30 KT POSSIBLE ALONG WITH VERY COLD CONDITIONS.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY/... TODAY...HIGH CONFIDENCE. SOUTHWEST WINDS GUSTS WILL GENERALLY REMAIN LESS THAN 20 KNOTS TODAY. HOWEVER...SOUTH TO SOUTHEAST SWELL WILL KEEP SEAS BETWEEN 3 AND 6 FEET ACROSS OUR OUTER-WATERS AND WESTERN SOUNDS TODAY...SO SMALL CRAFT HEADLINES WILL CONTINUE. TONIGHT...HIGH CONFIDENCE. WESTERLY WIND GUSTS OF 20 TO 25 KNOTS EXPECTED ON THE OPEN WATERS ALONG WITH 3 TO 6 FOOT SEAS. SCA HEADLINES REMAIN IN EFFECT. THURSDAY...MODERATE TO HIGH CONFIDENCE. STRONG COLD FRONT WORKS ACROSS THE REGION AND WIND GUSTS WILL INCREASE TO NEAR 35 KNOTS DURING THE AFTERNOON AND EVENING. THIS IS SUPPORTED BY SOUNDINGS AND 850T DROPPING TO NEAR -20C. GALE WATCHES HAVE BEEN ISSUED THURSDAY AFTERNOON AND EVENING FOR OUR OPEN WATERS WITH SCA HEADLINES FOR BOSTON HARBOR/NARR BAY. OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/... THU NIGHT...HIGH CONFIDENCE. GALE FORCE WINDS WILL GRADUALLY DISSIPATE THROUGH THE EVENING HOURS...GIVING WAY TO SMALL CRAFT THRESHOLD WINDS AND SEAS BY EARLY MORNING. SOME LIGHT FREEZING SPRAY IS POSSIBLE. FRI AND FRI NIGHT...HIGH CONFIDENCE. BRIEF PERIOD OF HIGH PRES WILL LEAD TO CONDITIONS DROPPING BELOW SMALL CRAFT THRESHOLDS BRIEFLY. OTHERWISE COLD CONDITIONS. SAT AND SUN...MODERATE CONFIDENCE. NW WINDS MAY GUST TO GALE FORCE AT TIMES EACH DAY...BUT ESPECIALLY SAT. THIS WILL BE ACCOMPANIED BY COLD AIR AND THE POTENTIAL FOR FREEZING SPRAY...WHICH COULD BE MODERATE AT TIMES. EVEN IF WINDS DON/T FULLY REACH GALE FORCE...SMALL CRAFT CONDITIONS ARE EXPECTED AS SEAS BUILD AND APPROACH 6-9 FT. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...GALE WATCH FROM THURSDAY AFTERNOON THROUGH LATE THURSDAY NIGHT FOR ANZ231>235-237-250-251-254>256. SMALL CRAFT ADVISORY FROM 10 AM TO 10 PM EST THURSDAY FOR ANZ230-236. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ235- 237-250-254>256.
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&& $$ SYNOPSIS...FRANK/DOODY NEAR TERM...KJC/FRANK SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY MARINE...FRANK/DOODY

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