Area Forecast Discussion
Issued by NWS Boston, MA

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548 FXUS61 KBOX 141511 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1011 AM EST SUN FEB 14 2016 .SYNOPSIS...
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HISTORIC ARCTIC OUTBREAK FOR THE MODERN ERA CONTINUES WITH DANGEROUSLY COLD WIND CHILLS OF 25 TO 35 BELOW. WINDS DIMINISH LATER TODAY AND ESPECIALLY TONIGHT...BUT IT WILL REMAIN BITTERLY COLD. A PERIOD OF ACCUMULATING SNOW IS THEN LIKELY FOR MUCH OF REGION ESPECIALLY AWAY FROM THE COAST LATE MONDAY AFTERNOON AND EVENING...CHANGING TO RAIN BY TUESDAY MORNING. A POWERFUL STORM SYSTEM WILL LIKELY TRACK WEST OF NEW ENGLAND TUESDAY INTO TUESDAY NIGHT BRINGING HEAVY RAIN...STRONG WINDS AND WARM TEMPERATURES TO THE REGION. A TREND TOWARD DRIER AND COLDER WEATHER FOLLOWS ON WEDNESDAY AND THURSDAY. ANOTHER WEATHER SYSTEM WILL BRING SNOW AND RAIN TOWARD THE END OF THE WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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*/ HIGHLIGHTS... * DANGEROUS WIND CHILLS OF 25 TO 40 BELOW ZERO TOWARDS NOON * HISTORIC ARCTIC OUTBREAK FOR THE MODERN ERA BRINGS THE COLDEST TEMPERATURES TO BOSTON AND WORCESTER SINCE 1957 WIND CHILLS 25 TO 35 BELOW-ZERO PERSIST TOWARDS NOON. BUT THE THREAT WILL DIMINISH AS WINDS RELAX THROUGH THE DAY WITH HIGH PRESSURE BUILDING INTO THE AREA. STILL FROSTBITE WILL REMAIN A THREAT WHICH CAN OCCUR ON EXPOSED FLESH IN JUST 10 MINUTES. ABUNDANT SUNSHINE BUT BENEATH A CONTINUED ARCTIC AIRMASS ALOFT. A DRY SUBSIDENCE INVERSION BUILDING ACROSS THE REGION IN TANDEM WITH HIGH PRESSURE WILL LIMIT MIXING THROUGH THE DAY PER SINKING AIR. HIGHS AROUND THE SINGLE DIGITS TO TEENS. RECORD MINIMUM HIGH TEMPERATURES LIKELY TO BE SET. OCEAN-EFFECT SNOW SHOWERS OVER THE OUTER-CAPE WILL DIMINISH WITH THE WINDS TO FLURRIES LATE. JUST TRACE ACCUMULATIONS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... ***BITTERLY COLD TONIGHT BUT WITHOUT THE WIND*** HIGH PRESSURE BUILDING ACROSS SOUTHERN NEW ENGLAND WILL RESULT IN LIGHT WINDS AND AN IDEAL NIGHT OF RADIATIONAL COOLING. GIVEN THE ARCTIC AIR FIRMLY IN PLACE ACROSS THE REGION...IT WILL BE ANOTHER BITTERLY COLD NIGHT BUT WITH OUT THE WIND. GUIDANCE TEMPS MAY BE 10+ DEGREES TOO WARM IN THE TYPICALLY PRONE OUTLYING LOCATIONS. WOULD THINK WE SEE LOW TEMPS NEAR 20 BELOW ZERO IN THE TYPICALLY COLDEST OUTLYING LOCATIONS OF WESTERN MA. MOST OTHER AREAS WILL LIKELY SEE LOW TEMPS BETWEEN -5 AND -15...BUT SOME URBAN HEAT ISLANDS WILL NOT GET QUITE THAT COLD. ONE EXAMPLE IS BOSTON...WHICH SHOULD SEE LOW TEMPS REMAIN ABOVE ZERO GIVEN LACK OF COLD ADVECTION WITH THAT LOCATION NEEDS TO GET BELOW ZERO. && .LONG TERM /MONDAY THROUGH SATURDAY/...
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HIGHLIGHTS... * WINTRY MIX POSSIBLE MONDAY NIGHT * HEAVY RAIN EXPECTED ON TUESDAY * BRIEF COOL DOWN WEDNESDAY NIGHT INTO THURSDAY OVERVIEW AND MODEL PREFERENCES... ALTHOUGH CURRENT WESTERN HEMISPHERIC SETUP SHOWS NEGATIVE NAO/AO AND POSITIVE PNA...WHICH HAS ALLOWED ARCTIC AIR TO SPILL SOMEWHAT MODIFIED ARCTIC AIR ACROSS THE REGION...THIS WILL BE CHANGING. IN FACT...THE MORE AMPLIFIED FLOW PATTERN BECOMES MUCH MORE ZONAL ACROSS THE CENTRAL CONUS MUCH OF THE COMING WEEK AND THESE SAME TELECONNECTIONS TREND IN THE OPPOSITE DIRECTION. THIS SUGGESTS A FAIRLY ACTIVE PATTERN BUT WITH LESS COLD AIR THAN THE LAST WEEK OR SO. INDEED THE TWO MOST IMPACTFUL FEATURES CURRENTLY PROGGED LOOK TO BE INSIDE RUNNERS THANKS TO EARLIER SHARPENING OF THE ASSOCIATED TROF ALONG WITH SOME INFLUENCE OF THE SRN STREAM. A BLEND OF OPERATIONAL GUIDANCE WILL BE USED AS A BASELINE AS THE TRACK DISCREPANCIES ARE BEGINNING TO CONVERGE FOR THE TUE LOW PRES PASSAGE. DETAILS... MON... HIGH PRES WILL BE MOVING OVER THE REGION THROUGH THE DAY ON MON. ALTHOUGH TEMPS WILL START COLD THANKS TO GOOD RADIATIONAL COOLING SUN NIGHT...MODEST LATE DAY RETURN FLOW WILL ALLOW FOR SOME WARMING AS H92 TEMPS INCREASE BACK TO NEAR -8C. THIS WILL ALLOW A BIT OF A REPRIEVE AS HIGHS GO BACK INTO THE 20S TO MID 30S. HOWEVER...DIURNAL COOLING...ALONG WITH EVAPORATIONAL COOLING IS EXPECTED AS ISENTROPIC LIFT BEGINS BY LATE AFTERNOON/EVENING. MON NIGHT INTO TUE NIGHT... STRENGTHENING BUT NON-OCCLUDING LOW PRES APPROACHES FROM THE MISSISSIPPI VALLEY...CARRYING WITH IT GULF MOISTURE AND PWATS OF 2 STD DEVIATIONS ABOVE NORMAL...OR GENERALLY ABOVE 1.00 INCHES. ISENTROPIC LIFT ON THE FRONT END MON NIGHT WILL YIELD EVAPORATIVE COOLING AND DIURNAL COOLING SUCH THAT PRECIP WILL START IN THE EVENING AS LIGHT-MOD SN. QPF VALUES DURING THIS PERIOD RANGE FROM ABOUT 0.1 TO 0.25 INCHES...SO WHERE IT STAYS DEEPLY COLDEST THE LONGEST /NW MA/...AS MUCH AS 2-3 INCHES OF SNOW /LESS AND LESS TOWARD THE COAST/ IS POSSIBLE BEFORE WARMER AIR ABOVE 0F MOVES IN AT H92-H85. THIS WILL BEGIN A TRANSITION TO RAIN FROM S-N AFTER MIDNIGHT THROUGH ABOUT 7AM. NOT A TRADITIONAL COLD AIR DAMMING SITUATION HERE AS HIGH PRES IS ORIENTED WELL TO THE ENE...ALTHOUGH DO NOTE SOME RESPONSE IN THE MASS FIELDS IN THE FORM OF AN INVERTED RIDGE. THEREFORE...CAN/T RULE OUT SOME ICE ACCRETION ON THE NEW FRESH SNOWPACK...ESPECIALLY IN THE CT VALLEY AND COLDER VALLEYS OF THE WORCESTER HILLS AND NRN CT HIGH TERRAIN. POSSIBLE T-0.2 INCHES OF ICE IS POSSIBLE...SUGGESTING AT LEAST WINTER WX ADVISORIES ARE LIKELY GOING TO BE NEEDED. BY TUE...WARM ADVECTION WILL HAVE INCREASED ENOUGH TO BRING SFC TEMPS ABOVE NORMAL IN SPITE OF THE MODEST SNOWPACK ACROSS THE REGION. THIS WILL LEAD TO A CHANGEOVER TO ALL RAIN. HEAVY RAIN LOOKS LIKELY AT TIMES GIVEN THE HIGH PWATS AND INCREASING LLJ WITH 60-70 KT POSSIBLE AS LOW AS H92. QPF VALUES COULD BE GREATER THAN AN INCH AFTER THE CHANGEOVER GIVEN THE DYNAMICS AND MOISTURE AVAILABLE...SO WILL NEED TO WATCH FOR MINOR/NUISANCE FLOODING ESPECIALLY AS SNOWS COULD CLOG AREA DRAINS. OTHER ISSUES IS THE LLJ ITSELF...WHICH COULD YIELD DANGEROUS STRONG WINDS. HOWEVER...THE EARLY SNOW AND INCREASE IN TEMPS ALOFT COULD YIELD ENOUGH OF AN INVERSION TO LIMIT POTENTIAL WIND GUSTS. BUFKIT CURRENTLY SUPPORTS THIS HYPOTHESIS...KEEPING ANY MOMENTUM TRANSFER NUMBERS BELOW EVEN ADVISORY CRITERIA. WILL STILL NEED TO WATCH THIS HOWEVER...GIVEN HOW STRONG THE LLJ IS EXPECTED TO BE /AS MUCH AS 3 STD DEVIATIONS ABOVE H92 NORMAL/. OVERNIGHT LOWS IN THE 20S WILL GIVE WAY TO HIGHS MAINLY IN THE UPPER 30S AND 40S...ALTHOUGH AN ISOLATED 50F CANNOT BE RULED OUT. WED INTO THU... SECONDARY ARCTIC FRONT WILL BE SLIDING THROUGH THE REGION FOLLOWING THE EXITING LOW PRES. WED HIGHS STILL MILD...MAINLY IN THE UPPER 30S TO UPPER 40S AS THE COLD AIR WILL NOT ARRIVE UNTIL OVERNIGHT. AN ISOLATED OVERNIGHT SHSN IS POSSIBLE AS THE WAVE MOVES THROUGH...BUT OVERALL THIS FEATURE IS MOISTURE STARVED SO ANY ACCUMS WOULD BE LIGHT. HOWEVER THE INCREASED CLOUD COVER WILL KEEP MINS MAINLY IN THE 20S. BY THU...H92 TEMPS ARE BACK TO NEAR -10C...SO HIGHS WILL ONLY BE IN THE 20S TO MID 30S AT THE WARMEST IN SPITE OF THE CLEARING SKIES. THU NIGHT INTO FRI... HIGH PRES CRESTS OVER THE REGION...WITH ANOTHER GRADUAL WARMING TREND AS THE HIGH MOVES E AND H92 TEMPS RETURN TO NEAR -4C. THIS SUGGESTS HIGHS FRI BACK IN THE 40S ONCE AGAIN. SAT INTO SUN... ALTHOUGH FAR FROM A WASHOUT...ALBERTA CLIPPER ASSOCIATED WITH SHORTWAVE ENERGY CURRENTLY WRAPPED UP IN THE ALLEUTIAN VORTEX WILL BE CROSSING THE REGION. CURRENT STEERING FLOW SUGGESTS A NORTHWARD PASSAGE WHICH KEEPS SRN NEW ENGLAND ON THE CLIMATOLOGICALLY DRIER SIDE OF A CLIPPER. THEREFORE...EXPECT THE MILDER WX TO CONTINUE...WITH A RISK FOR SHRA FOR A PERIOD ONCE THE TIMING IS BETTER LOCKED IN. THIS WILL BE LIKELY ONCE THE AFOREMENTIONED SHORTWAVE MOVES ONSHORE FROM THE PACIFIC.
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&& .AVIATION /15Z SUNDAY THROUGH THURSDAY/...
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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 TONIGHT/... NO MAJOR CHANGES WITH 12Z UPDATE... TODAY AND TONIGHT...HIGH CONFIDENCE. VFR. NW-GUSTS 20-30 KTS DIMINISHING THROUGH THE DAY AS WELL AS MVFR THREATS WITH -SHSN PERSIST FOR THE OUTER CAPE. WITH -SHSN ONLY EXPECT LIGHT SNOW ACCUMS. KBOS TERMINAL... NW-GUSTS UP TO 30 KTS EXPECTED FOR THE EARLY-HALF OF THE DAY. WILL TAPER THEREAFTER. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK /MONDAY THROUGH THURSDAY/... MONDAY...HIGH CONFIDENCE. VFR. WINDS SHIFT OUT OF THE SE. MON NIGHT INTO TUE NIGHT...MODERATE CONFIDENCE. PERIODS OF IFR/MVFR DUE TO A COMBINATION OF LOW CIGS AND VSBYS. PRECIP STARTS AS SNOW MON EVENING...THEN TRANSITIONS TO A BRIEF PERIOD OF FZRA/SLEET BRIEFLY BEFORE TURNING TO ALL RAIN DURING THE DAY ON TUE. SE WINDS MAY GUST 20-30 KT AT TIMES DURING THE DAY ON TUE...BUT VERY STRONG WINDS JUST OFF THE DECK COULD MIX DOWN AT TIMES. EXPECT LLWS...WITH AS MUCH AS 60-70 KT AT 2KFT. WED INTO THU...MODERATE CONFIDENCE. MAINLY VFR BUT WITH COOLING CONDITIONS LATE WED INTO THU. LOW RISK FOR AN ISOLATED SHSN WED NIGHT.
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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 TONIGHT/...HIGH CONFIDENCE. */ HIGHLIGHTS... * HEAVY FREEZING SPRAY/ARCTIC SEA SMOKE AND GALE FORCE WIND GUSTS PERSISTS INTO MID/LATE MORNING BEFORE DIMINISHING NW-GUSTS TO DIMINISH ALONG WITH THE THREATS OF GALE FORCE WINDS AND HEAVY FREEZING SPRAY. HEADLINES TO ALTER OVER ALL WATERS BY MIDDAY TO A FREEZING SPRAY ADVISORY ALONG WITH SMALL CRAFT ADVISORIES. ANTICIPATING ALL HEADLINES TO DROP OFF INTO THIS EVENING. ARCTIC SEA SMOKE LINGERS WITH THE RECORD BREAKING ARCTIC AIR ACROSS THE WATERS WITH SEA SURFACE TEMPERATURES IN THE LOW 40S. OUTLOOK /MONDAY THROUGH THURSDAY/... MON...HIGH CONFIDENCE. QUIET BOATING WEATHER WITH HIGH PRES OVER THE WATERS. MON NIGHT INTO TUE NIGHT...MODERATE CONFIDENCE. LOW PRES WILL APPROACH FROM THE SW...THEN MOVE INLAND DURING THE DAY TUE. INCREASE SE WINDS WILL LEAD TO GUSTS 25-30 KT MON NIGHT...THEN SHIFTING LATE TUE NIGHT. SEAS BUILD DURING THIS TIME AS WELL...AND COULD REACH 10-13 FT BY TUE EVENING. SMALL CRAFT ADVISORIES WILL BE NEEDED. THERE IS A LOW RISK FOR GALES...BUT IT IS UNCERTAIN AT THIS TIME. WED AND WED NIGHT...HIGH CONFIDENCE. WINDS SHIFT TO THE W...BUT DROP BELOW 25 KT. SEAS WILL BEGIN TO SUBSIDE...BUT WILL TAKE SOME TIME. SO SMALL CRAFT ADVISORIES ARE LIKELY TO CONTINUE THROUGH MUCH OF THE DAY FOR SEAS ALONE. THU...HIGH CONFIDENCE. ALTHOUGH WIND GUSTS SHOULD REMAIN BELOW THRESHOLD AS WINDS SHIFT TO THE NW AND PERSIST...THERE COULD BE 5-7 FT SEAS PERSISTING ON THE OCEAN WATERS.
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&& .CLIMATE...
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***COLDEST TEMPERATURES RECORDED IN BOSTON/WORCESTER SINCE 1957*** RECORD LOW TEMPERATURES FOR FEBRUARY 14TH BOSTON -9 /PREV -3 IN 1937/. COLDEST SINCE 1957. HARTFORD -12 /PREV -9 IN 1979/. PROVIDENCE -9 /PREV -7 IN 1979/. WORCESTER -16 /PREV -11 IN 1979/. COLDEST SINCE 1957. RECORD MINIMUM HIGHS FOR FEB 14TH... BOSTON.......14/1916 HARTFORD.....11/1979 PROVIDENCE...10/1979 WORCESTER.... 7/1979 BLUE HILL....10/1979 RECORD COLD LOWS FOR 15TH... BOSTON...... -14/1943 HARTFORD.... -18/1943 PROVIDENCE.. -14/1943 WORCESTER... -19/1943 BLUE HILL... -18/1943
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...WIND CHILL WARNING UNTIL NOON EST TODAY FOR CTZ002>004. MA...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR MAZ022>024. WIND CHILL WARNING UNTIL NOON EST TODAY FOR MAZ002>021-026. RI...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR RIZ008. WIND CHILL WARNING UNTIL NOON EST TODAY FOR RIZ001>007. MARINE...HEAVY FREEZING SPRAY WARNING UNTIL 11 AM EST THIS MORNING FOR ANZ231>235-237-250-251-254>256. SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ230- 232>237. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ231- 251-255-256. GALE WARNING UNTIL 2 PM EST THIS AFTERNOON FOR ANZ250-254.
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&& $$ SYNOPSIS...FRANK/DOODY NEAR TERM...FRANK/DOODY/SIPPRELL SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY/SIPPRELL MARINE...FRANK/DOODY/SIPPRELL CLIMATE...WFO BOX STAFF

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