Area Forecast Discussion
Issued by NWS Boston, MA

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225 FXUS61 KBOX 052103 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 403 PM EST FRI FEB 5 2016 .SYNOPSIS...
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STRONG LOW PRESSURE CENTER OFFSHORE MOVES EAST OF THE REGION ALLOWING WINDS AND SNOWS TO END THIS EVENING EVERYWHERE. COLDER WEATHER FOLLOWS TONIGHT INTO TOMORROW. HIGH PRESSURE BRINGS DRY WEATHER THIS WEEKEND WITH ABOVE NORMAL TEMPERATURES BY SUNDAY. A PERIOD OR TWO OF ACCUMULATING SNOW IS LIKELY MONDAY INTO WEDNESDAY ESPECIALLY ACROSS EASTERN MA...BUT ITS UNCERTAIN IF THIS WILL MAINLY BE A NUISANCE EVENT OR A SIGNIFICANT WINTER STORM.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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*** WARNINGS AND ADVISORIES DROP THIS EVENING *** *** COLD AIR WILL ALLOW UNTREATED SURFACES TO FREEZE OVERNIGHT *** BEST F-GEN BAND AROUND H6 COINCIDENT WITH HEAVY BANDED SNOW NOW ORIENTED OVER CAPE/ISLANDS. ACK WAS THE FINAL PIN TO FALL INTO ALL SNOW OVER THE LAST HOUR. THIS FEATURE CONTINUES TO DROP ABOUT 2-3 INCH/HOUR SNOWFALL RATES ALONG WITH AREAS TO THE W STILL RECEIVING AROUND AN INCH/HOUR. NOTING A STRONGER WESTERLY COMPONENT TO THE FLOW THANKS TO STRONGER ISALLOBARIC WINDS WITH THE LOW PRES MAKING ITS CLOSEST PASS TO THE E. THIS IS ALLOWING FOR MORE DRY AIR TO WEDGE INTO THE LOWER LVLS. ITS ALL ENDED FOR AREAS WEST OF WORCESTER AND TOLLAND COUNTIES. THE SNOWS WILL CONTINUE TO PUSH OFFSHORE AND END FROM W-E OVER THE NEXT 3-4 HOURS...POSSIBLY ABOUT 6 HOURS FOR ACK. THIS SUGGESTS AN ADDITIONAL 1-4 INCHES OF LOCALIZED SNOWFALL LEFT FOR THOSE STILL RECEIVING SNOW. THE DRY AIR IS ASSOCIATED WITH VERY LOW SFC DWPTS IN THE TEENS...WHICH WILL HELP ALLOWING TEMPS TO COOL WITH RAPIDLY CLEARING SKIES ACROSS THE REGION THROUGH THE EVENING. WILL ALLOW THE CURRENT WARNINGS/ADVISORIES TO CONTINUE. INCLUDING THE WIND ADVISORY FOR THE CAPE AND ISLANDS WITH VERY STRONG PRES CHANGE COUPLET NOTED ON MSAS/LAPS THROUGH THE EVENING JUST OFFSHORE. THIS WILL GRADUALLY END THIS EVENING THOUGH...WITH WINDS DYING OFF AT THE SFC. SO...COMBINING THE CLEARING SKIES...ENDING SNOWS AND WEAKENING PRES GRADIENT...GOOD SETUP FOR RAPID COOLING OVERNIGHT THANKS TO DWPTS FALLING INTO THE LOW TEENS. SO A VERY COLD NIGHT AHEAD BEHIND THIS STORM. GIVEN THE VERY WET NATURE OF THE SNOWFALL AND CLEANUP EFFORTS TODAY...UNTREATED SFCS WILL LIKELY BECOME VERY SLIPPERY OVERNIGHT WHERE THE LEFTOVER BREEZES ARE UNABLE TO DRY. PATCHY BLACK ICE POSSIBLE. WILL BE ISSUING AN SPS FOR THIS RISK FOR THE OVERNIGHT HOURS. EXPECT MINS MAINLY IN THE TEENS AND LOW 20S.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
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NOSE OF HIGH PRES BUILDS OVER FROM THE W. THE COMBINATION OF COLD ADVECTION ALOFT AND SLIGHT INCREASE IN LOW-MID LVL MOISTURE SUGGESTS SOME AFTERNOON CLOUD DEVELOPMENT...BUT LITTLE ELSE. DROPPED HIGHS A LITTLE BIT FROM CURRENT FORECASTS AS THE ADDED SNOWPACK WILL LIKELY KEEP 2M TEMPS A BIT LOWER THAN SOME OF THE GUIDANCE IS CURRENTLY SUGGESTING. EXPECT HIGHS MAINLY IN THE 30S.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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HIGHLIGHTS... * DRY WITH RELATIVELY MILD TEMPS SUN * PERIOD OR TWO OF ACCUMULATING SNOW LIKELY MON-WED ESPECIALLY COAST * UNCERTAIN IF MON-WED IS NUISANCE SNOW OR SIGNIFICANT WINTER STORM DETAILS... SATURDAY NIGHT AND SUNDAY... WEAK RIDGE OF HIGH PRESSURE WILL RESULT IN DRY WEATHER. LOW TEMPS SAT NIGHT MAINLY IN THE 20S...BUT SOME UPPER TEENS POSSIBLE ACROSS THE NORMALLY COLDER OUTLYING LOCATIONS. PLENTY OF SUNSHINE ON SUNDAY AND WESTERLY FLOW SHOULD ALLOW MUCH OF THE REGION TO SEE HIGHS WELL INTO THE 40S. LATE SUNDAY NIGHT THROUGH WEDNESDAY... EXTREMELY COMPLEX AND DIFFICULT FORECAST OVER THIS TIME PERIOD. A COUPLE OF POTENT SHORTWAVES WILL CARVE OUT A DEEP EAST COAST TROUGH. THERE IS SO MUCH ENERGY IN THE FLOW THAT THE MODELS ARE GOING TO HAVE A TOUGH TIME ON RESOLVING WHAT EXACTLY UNFOLDS. FIRST THING IS FIRST...AN INITIAL SHORTWAVE WILL EMERGE OFF THE SOUTHEAST COAST AND RAPIDLY INTENSIFY AS IT MOVES NORTHEAST. CURRENT INDICATIONS TAKE THE STORM SOUTHEAST OF THE BENCHMARK. NOW OF COURSE THAT IS 72+ HOURS OUT...SO A TRACK CLOSER TO THE COAST IS CERTAINLY POSSIBLE AND WILL NEED TO BE WATCHED. HOWEVER...EVEN IF THE STORM PASSES WELL SOUTHEAST OF THE BENCHMARK...MAY STILL END UP WITH A LIGHT TO MODERATE SNOW EVENT ESPECIALLY ON THE COAST. THIS STORM LOOKS TO HAVE A FAIRLY BROAD CIRCULATION WITH 35 TO 50 KNOTS OF ENE FLOW AT 850 MB...SO ACCUMULATING SNOW IS LIKELY FOR AT LEAST THE COASTAL PLAIN. ALSO...SOME LAND/SEA INTERFACE AND OCEAN ENHANCEMENT MAY OCCUR IN EASTERN MA. A SECOND POTENT SHORTWAVE WILL DROP DOWN FROM THE GREAT LAKES. THIS WILL ALLOW LOW PRESSURE TO DEVELOP OFF THE MID ATLANTIC COAST AND TRACK NORTHEAST TUE INTO EARLY WED. A LOT OF WHAT HAPPENS WITH THIS SYSTEM WILL BE AFFECTED BY THE STRENGTH/TRACK OF THE FIRST SYSTEM ON MONDAY. THERE ARE A WIDE RANGE OF POSSIBILITIES...FROM A GLANCING BLOW...TO A STRONG NOREASTER AND EVEN AN INVERTED TROUGH SETUP. TO SUM UP...THE MAIN IDEA IS THAT WE ARE LIKELY TO RECEIVE AT LEAST SOME SNOW AT TIMES MONDAY INTO WED. WHETHER OR NOT WE SEE A SIGNIFICANT WINTER STORM REMAINS TO BE SEEN...BUT AS MENTIONED IN THE PREVIOUS PARAGRAPHS ALL OPTIONS ARE ON THE TABLE. WE ARE LIKELY TO SEE AT LEAST SOME ACCUMULATING SNOW ESPECIALLY ALONG THE COAST. THURSDAY AND FRIDAY... LOTS OF UNCERTAINTY OVER THIS TIME FRAME. WILL HAVE TO WATCH A WAVE OR TWO OF LOW PRESSURE THAT MAY END UP BRINGING A BIT MORE SNOW...BUT MUCH OF THIS PERIOD MAY END UP DRY. GIVEN LOW CONFIDENCE...WILL KEEP POPS AT SLIGHT CHANCE FOR NOW.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
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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 SATURDAY/... THROUGH 00Z...HIGH CONFIDENCE IN TRENDS...TIMING MAY BE OFF A BIT. AREAS OF LIFR/IFR IN HEAVY SNOW AND LOW CIGS CONTINUE THROUGH ABOUT 20Z EVERYWHERE...THEN GIVE WAY TO VFR FROM W-E THROUGH 00Z. STRONG N WINDS WITH GUSTS 20-30 KT OVER THE INTERIOR AND 30-40 KT ALONG THE CAPE/ISLAND. TONIGHT...HIGH CONFIDENCE. MAINLY VFR. ANY UNTREATED AND WET RUNWAYS WILL FREEZE AS TEMPERATURES DROP RAPIDLY. WIND GUSTS REMAIN N-NW BUT DIMINISH THROUGH THE OVERNIGHT HOURS. TOMORROW...HIGH CONFIDENCE. MAINLY VFR. WINDS SHIFT TO THE SW...BUT SHOULD REMAIN AROUND 10 KT OR LESS. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS...TIMING MAY BE OFF A BIT. KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS....TIMING MAY BE OFF A BIT. OUTLOOK /SATURDAY NIGHT THROUGH WEDNESDAY/... SATURDAY NIGHT AND SUNDAY...HIGH CONFIDENCE IN VFR CONDITIONS. MONDAY THROUGH WEDNESDAY...LOW CONFIDENCE ESPECIALLY ON TIMING. PERIOD OR TWO OF SNOW LIKELY IN THIS TIME FRAME...SO WILL PROBABLY SEE SOME IFR CONDITIONS ESPECIALLY ALONG THE COAST ON MON. NORTHEAST WIND GUSTS OF 30 TO 40 KNOTS LIKELY ON MONDAY ALONG THE COAST.
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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 SATURDAY/...HIGH CONFIDENCE. STRONG NORTHERLY WINDS WILL DISSIPATE THROUGH THE LATE EVENING HOURS SUCH THAT MOST GALE WARNINGS CAN BE DROPPED BY ABOUT MIDNIGHT. SMALL CRAFT ADVISORIES WILL HAVE TO FOLLOW...BECAUSE EVEN THOUGH WINDS WILL DROP BELOW THRESHOLDS...HIGH SEAS OF 10-12 FT HAVE DEVELOPED AND WILL LINGER WELL INTO THE DAY TOMORROW. SO...EXPECT SMALL CRAFT ADVISORY...MAINLY FOR HAZARDOUS SEAS TO FOLLOW. AREAS OF SNOW/RAIN/FOG REDUCING VSBYS WILL COME TO AN END BETWEEN 6PM AND 10PM LOCAL. OUTLOOK /SATURDAY NIGHT THROUGH WEDNESDAY/... SATURDAY NIGHT AND SUNDAY...HIGH CONFIDENCE. LEFT OVER 5 FOOT SWELL MAY LINGER INTO EARLY SUNDAY MORNING ACROSS OUR EASTERN OUTER- WATERS. OTHERWISE...WINDS/SEAS WILL BE BELOW SMALL CRAFT ADVISORY THRESHOLDS WITH A WEAK RIDGE OF HIGH PRESSURE IN CONTROL. MONDAY...MODERATE CONFIDENCE. GALE FORCE NORTHEAST WIND GUSTS LIKELY AS A RAPIDLY DEEPENING LOW PRESSURE SYSTEM LIKELY TRACKS SOUTHEAST OF THE BENCHMARK. THERE IS A LOW PROBABILITY FOR A PERIOD OF STORM FORCE WIND GUSTS IF THAT SYSTEM TRACKS CLOSER TO THE COAST THAN CURRENTLY EXPECTED. SEAS LIKELY BUILD TO AT LEAST 15 FEET ACROSS OUR EASTERN OUTER-WATERS WITH LONG NORTHEAST FETCH AND GOOD MIXING. TUESDAY AND WEDNESDAY...LOW CONFIDENCE. AT THE VERY LEAST NORTHEAST SMALL CRAFT WIND GUSTS AND HIGH SEAS WILL CONTINUE INTO TUE EVENING. HOWEVER...POTENTIAL FOR STRONGER WIND GUSTS DEPENDING ON STRENGTH AND LOCATION OF ANOTHER LOW PRESSURE SYSTEM. BY WEDNESDAY WIND GUSTS AND SEAS ARE QUITE UNCERTAIN...DEPENDING ON WHAT HAPPENS WITH THAT SECOND LOW PRESSURE SYSTEM.
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&& .TIDES/COASTAL FLOODING...
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MONDAY... THERE IS A FAIRLY HIGH ASTRO TIDE OF 11.2 IN BOSTON LATE MONDAY MORNING. NORTHEAST WIND GUSTS OF 30 TO 40 KNOTS FROM LARGE CIRCULATION OF THE INTENSIFYING OCEAN STORM WILL LIKELY RESULT IN A 1 TO 1.5 SURGE. SEAS SHOULD BE BUILT UP TO BETWEEN 10 AND 15 FEET BY THEN...SO FEEL THERE IS A DECENT SHOT FOR POCKETS OF MINOR COASTAL FLOODING ALONG EASTERN MA COAST. THERE IS A LOW RISK FOR POCKETS OF MODERATE COASTAL FLOODING...IF THE STORMS ENDS UP A BIT FASTER AND TRACKING FURTHER WEST THAN CURRENT GUIDANCE INDICATES. MONDAY NIGHT AND TUESDAY... MAIN CONCERN IS IF WE END UP WITH A SECOND AREA OF STRONG LOW PRESSURE TRACKING UP THE COAST...WHICH COULD IMPACT ADDITIONAL HIGH TIDE CYCLES. LARGE SPREAD IN THE GUIDANCE ON WHETHER OR NOT THIS HAPPENS. IF SO...WILL HAVE TO WATCH THE TUESDAY NOON HIGH TIDE CYCLE ACROSS EASTERN MA AS BOSTON HAS AN 11.5 ASTRO TIDE.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR CTZ003- 004. MA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MAZ022- 023. WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR MAZ019>021. WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR MAZ004>007-012>018-026. WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ022>024. RI...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR RIZ008. WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR RIZ007. WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR RIZ001>006. MARINE...GALE WARNING UNTIL 10 PM EST THIS EVENING FOR ANZ231>234-250- 254>256. SMALL CRAFT ADVISORY UNTIL 4 AM EST SATURDAY FOR ANZ230. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ236. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ235-237. SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR ANZ251.
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&& $$ SYNOPSIS...FRANK/DOODY NEAR TERM...DOODY SHORT TERM...DOODY LONG TERM...FRANK AVIATION...FRANK/DOODY MARINE...FRANK/DOODY

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