Area Forecast Discussion
Issued by NWS Boston, MA

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643 FXUS61 KBOX 101200 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 700 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 MAY RESULT IN SOME UNTREATED ROADWAYS QUICKLY BECOMING SNOW COVERED TODAY... 7 AM UPDATE... YET ANOTHER SHORTWAVE IS MOVING INTO SRN NEW ENGLAND WITH ATTENDANT MESO-LOW PRES UPSTREAM. THIS IS ALREADY BEGINNING TO LEAD TO LIGHT SN ACROSS CT AND WRN MA THIS MORNING WITH LIGHT ACCUMS ALREADY BEING REPORTED. IT WILL TAKE SOME TIME TO SPREAD E...GIVEN FAIRLY DRY DWPTS REPORTED ACROSS THE REGION. HOWEVER...MOST OF THE REGION WILL AT LEAST SEE A RISK FOR SHSN...EVEN AS THIS FIRST MECHANISM DIMINISHES...THE LOW-LVL INSTABILITY WILL BEGIN TO MAKE UP THE DIFFERENCE THANKS TO STRONG COLD ADVECTION ALOFT AND MODEST MOISTURE AVAILABLE ABOVE THE SFC. MAINTAINED SOME POPS THROUGH THE DAY FOLLOWING PREVIOUS FORECASTER/S LEAD. PREVIOUS DISCUSSION... POTENT SHORTWAVE TROUGH WILL BE LIFTING NORTHEAST ACROSS THE REGION TODAY. IN RESPONSE...SCATTERED SNOW SHOWERS WILL LIKELY OVERSPREAD WESTERN MA/NORTHERN CT BY 12Z AND WORK INTO THE REST OF THE REGION LATER THIS MORNING/EARLY AFTERNOON. THE MODELS CONTINUE TO SHOW VERY FAVORABLE INGREDIENTS FOR BRIEF LOCALLY HEAVIER SNOW SHOWERS. LOW LEVEL MOISTURE WILL COMBINED WITH STEEP MID LEVEL LAPSE RATES ON THE ORDER OF 7C TO 8C/KM AND TOTAL TOTALS BETWEEN 55 AND 60! THEREFORE...WILL HAVE TO BE ON THE LOOK OUT FOR BRIEF HEAVY SNOW SHOWERS THAT CAN QUICKLY COVER ROADWAYS AND RESULT IN POOR VISIBILITY. GIVEN THE POTENTIAL IMPACT TO MOTORISTS WILL CONTINUE THE SPECIAL WEATHER STATEMENT. WHILE THESE LOCALIZED HEAVIER SNOW SHOWERS WILL BE POSSIBLE LATER THIS MORNING...A BETTER CHANCE MIGHT BE THIS AFTERNOON WHEN DIURNAL HEATING INCREASES INSTABILITY. THE BULK OF THE SCATTERED SNOW SHOWERS SHOULD EXIT THE REGION BY 00Z THIS EVENING...BUT STILL MAY IMPACT THE EVENING RUSH HOUR. SNOW ACCUMULATIONS GENERALLY WILL RANGE FROM A COATING TO 2 INCHES IN MOST LOCATIONS. ONE ADDITIONAL THING WE ARE WATCHING IS A MESO LOW THAT WAS SPINNING OFF THE NEW JERSEY COAST. SOME GUIDANCE YESTERDAY INDICATED IT MAY AFFECT PORTIONS OF OUR SOUTHERN ZONES. THE LATEST DATA HAS TRENDED FURTHER SOUTH AND WE SHOULD NOT EXPERIENCE A DIRECT IMPACT FROM IT. HOWEVER...ITS POSSIBLE THAT A MINI INVERTED TROUGH DEVELOPS AND EXTENDS BACK TOWARDS EASTERN NEW ENGLAND THIS AFTERNOON/EARLY EVENING INCREASING THE AREAL COVERAGE/INTENSITY OF SNOW SHOWERS.
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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 /11Z 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. A MIXTURE OF VFR TO MVFR CIGS EARLY THIS MORNING SHOULD BECOME MAINLY MVFR AFTER 12Z AND CONTINUE THROUGH THE AFTERNOON. OTHERWISE...WE WILL BE WATCHING AN AREA OF SCATTERED SNOW SHOWERS WHICH SHOULD WORK INTO WESTERN MA/NORTHERN CT THROUGH 12Z. THIS SCATTERED ACTIVITY SHOULD SPREAD ACROSS THE REST OF THE REGION THROUGH EARLY AFTERNOON. A FEW OF THE SNOW SHOWERS WILL BE BRIEFLY HEAVY...POSSIBLY RESULTING IN BRIEF IFR TO LIFR CONDITIONS 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...
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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...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.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... 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. SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR ANZ251. && $$ SYNOPSIS...FRANK/DOODY NEAR TERM...FRANK/DOODY SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY MARINE...FRANK/DOODY

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