Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 132026 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 326 PM EST SAT FEB 13 2016 .SYNOPSIS... * UPDATES TO NEAR AND SHORT TERM FORECAST PORTIONS ONLY DANGEROUSLY COLD WIND CHILLS OF 20 TO 35 BELOW ZERO INTO SUNDAY MORNING. A PERIOD OF ACCUMULATING SNOW AND ICE IS THEN LIKELY FOR MUCH OF REGION ESPECIALLY AWAY FROM THE COAST MONDAY AFTERNOON AND EVENING. 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 NEXT WEDNESDAY AND THURSDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... */ HIGHLIGHTS... * DANGEROUSLY COLD WIND CHILLS OF 20 TO 35 BELOW ZERO TONIGHT INTO SUNDAY MORNING * COLDEST LOW TEMPERATURES SINCE JANUARY 2004 APPEAR LIKELY IN BOSTON AND WORCESTER BY EARLY SUNDAY MORNING * SEVERAL RECORD LOW TEMPERATURES MAY BE RECORDED ACROSS SOUTHERN NEW ENGLAND ARCTIC BLAST! EVALUATING SOUNDING CLIMATOLOGIES ACROSS THE REGION FOR 12Z FEBRUARY 14TH...THE EXPECTED AIRMASS DROPPING S OVER THE REGION OVERNIGHT IS NEAR OR BELOW RECORD MINIMUMS AT H925-85 GOING AS FAR BACK AS 1948 WITH FORECAST VALUES OF 25 TO 30 DEGREES BELOW ZERO. UNDOUBTEDLY WE WILL SEE SOME OF THE COLDEST AIR IN THE PAST DECADE WITH SEVERAL RECORD LOW TEMPERATURES ACROSS S NEW ENGLAND LIKELY TO BE BROKEN COME SUNDAY MORNING. FORECAST LOWS 5 TO 15 DEGREES BELOW ZERO! COUPLED WITH A MID TO UPPER LEVEL VORTMAX WHICH WILL LEND TO AN ENHANCEMENT OF THE LOW-LEVEL WIND PROFILE /THE HEIGHT OF WHICH IS DURING THE EARLY EVENING/...LOOKING AT NW WIND GUSTS 30 TO 40 MPH AROUND 8 PM TAPERING OFF TOWARDS MORNING. STILL BRISK THOUGH...WILL SEE WIND CHILL VALUES AS LOW AS 25 TO 35 DEGREES BELOW ZERO. HEAD- LINES REMAIN THE SAME WITH WIND CHILL WARNINGS OVER MUCH OF S NEW ENGLAND...ADVISORIES OVER THE CAPE AND ISLANDS. OTHERWISE TWO OTHER CONCERNS: SNOW ACROSS THE OUTER-CAPE AND HEAVY FREEZING SPRAY / ARCTIC SMOKE OVER THE WATERS. QUITE AN UNSTABLE LOW LEVEL MOIST PROFILE WITH ARCTIC AIR SURGING OVER SEA SURFACE TEMPS IN THE LOW-40S. INSTABILITY CONFINED TO THE LOWEST 1-2 KFT BENEATH A DRY INVERSION PER LARGE TEMPERATURE DIFFERENCE ON THE ORDER OF 35C. DO NOT DISAGREE WITH THE PREVIOUS FORECASTER OF OCEAN-INDUCED CAPE VALUES OF 1500 J/KG AND NORMALIZED CAPE UP TO 0.4. BUT AS NOTED... TWO THINGS THAT DIMINISH THE THREAT IS THE 300-310 WIND DIRECTION AT THE SURFACE AND A VEERING WIND PROFILE ALOFT. SO NOT TOTALLY SOLD A 2-3 INCH SNOWFALL EVENT. MORE INCLINED TO THINK A 1-2 INCH EVENT WITH WINDS DIMINISHING TOWARDS MORNING. MAYBE SOME ISOLATED HIGHER AMOUNTS FROM CHATHAM TO PROVINCETOWN. A VERY LIGHT SNOW...IT WILL BE TOUGH TO MEASURE AND LIKELY BLOWING AND DRIFTING. ASIDE FROM SOME VISIBILITY RESTRICTIONS THERE MAY NOT BE TOO MUCH OF AN IMPACT OTHER THAN DRIFTS COLLECTS ON THE EASTERN-SIDE OF ROADWAYS. AS TO HEAVY FREEZING SPRAY/ARCTIC SMOKE...BLUSTERY NW-WINDS RESULTING IN BUILDING SEAS. COMBINED WITH ARCTIC AIR AND A LARGE TEMPERATURE DIFFERENCE OVER THE OCEAN-WATERS...THERE IS THE LIKELIHOOD OF MODERATE TO HEAVY FREEZING SPRAY AS WELL AS ARCTIC SMOKE. WAVES BUILDING 8 TO 10 FEET. MORE DETAILS IN THE MARINE DISCUSSION BELOW. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... SUNDAY... WIND CHILLS 25 TO 35 BELOW-ZERO PERSIST TOWARDS MID-MORNING. BUT THE THREAT WILL DIMINISH AS WINDS RELAX THROUGH THE DAY AS HIGH PRESSURE BUILDS INTO THE AREA. 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. ANY OCEAN- EFFECT SNOW SHOWERS SHOULD HAVE DIMINISHED TO FLURRIES IF ANYTHING AT ALL. SUNDAY NIGHT... HIGH PRESSURE. LIGHT WINDS. MOSTLY CLEAR CONDITIONS PRIOR TO CLOUDS INCREASING MONDAY MORNING. A GOOD RADIATIONAL COOLING SETUP. WILL SEE LOWS DROP BELOW-ZERO ACROSS MUCH OF S NEW ENGLAND. COLDEST SPOTS WHEREVER DEEP SNOW PACK RESIDES...NAMELY N/W MASS WHERE LOWS ARE FORECAST TO BOTTOM OUT AROUND 10 BELOW-ZERO. && .LONG TERM /MONDAY THROUGH SATURDAY/... *** DANGEROUSLY COLD WIND CHILLS SUNDAY MORNING *** HIGHLIGHTS... * SOME ACCUMULATING SNOW AND ICE LIKELY MON AFTERNOON/EVENING * TEMPS IN THE 50S TUE-TUE NGT W/HEAVY RAIN AND STRONG WINDS OVERVIEW AND MODEL PREFERENCES... A CHANGEABLE PATTERN THROUGH THE WEEK IS EXPECTED AS THE INITIAL ARCTIC OUTBREAK FROM THE WEEKEND DISSIPATES AND GIVES WAY TO THE SRN STREAM BRIEFLY. HOWEVER...THIS IS NOT LONG LIVED AS A PERSISTENT VORTEX NEAR BAFFIN ISLAND WILL LEAD TO ANOTHER /ALTHOUGH NOT NEARLY AS ROBUST/ ARCTIC INFLUENCE AS STRONG RIDING AMPLIFIES OVER THE WRN HALF OF THE CONUS. THIS RIDGING WILL KEEP THE ARCTIC INFLUENCE SHORT LIVED AS IT ONCE AGAIN ALLOWS FOR SRN STREAM DOMINANCE BY THE END OF THE WEEK. SO...IN OTHER WORDS...A BIT OF A ROLLER COASTER WITH TEMPERATURES DURING THE WEEK. THERE IS REASONABLE AGREEMENT BETWEEN OPERATIONAL MODELS THROUGH THE PERIOD...SUCH THAT A BLEND OF THESE SOURCES SHOULD SUFFICE AS BASELINE FOR MOST OF THE PERIOD. HOWEVER...WILL CONTINUE WITH AN ENSEMBLE BLEND FOR THE LOW PRES PASSAGE LATE MON INTO TUE...THIS IS DUE TO ITS MORE PERSISTENT SUGGESTION OF A WESTERLY TRACK WHEN COMPARED WITH PARTICULARLY THE GFS OPERATIONAL SOLUTION. DETAILS... SUN NIGHT INTO MON... GOOD SETUP FOR RADIATIONAL COOLING SUN NIGHT...SO THANKFULLY NOT AS MUCH WIND TO YIELD THE BITTER WIND CHILLS OF SAT NIGHT. HOWEVER...WITH A SNOWPACK AND COLD H92 TEMPS...INVERSIONS WILL STILL ALLOW SEVERAL LOCATIONS ACROSS THE INTERIOR TO DROP BELOW 0F... WITH ONLY SINGLE DIGITS NEAR THE COAST MON MORNING. THE COLD START...AND CRESTING HIGH PRES WILL MEAN TEMPS ARE NOT GOING TO REBOUND AS WELL AS THEY COULD GIVEN THE H92 TEMPS APPROACH -8C BY AFTERNOON. INCREASING CLOUDS MON WITH HIGHS IN THE 20S AND LOW 30S. MON EVENING INTO TUE NIGHT... SRN STREAM LOW PRES IS CURRENTLY PROGGED TO PASS W OF NEW ENGLAND DURING THE DAY ON TUE. GIVEN THIS HAS SRN STREAM INFLUENCE AND GULF OF MEXICO MOISTURE...PRECIP PRODUCTION WILL BE RELATIVELY EFFICIENT WITH PWATS 2 STD DEVIATIONS ABOVE NORMAL AND A 40-50 KT LLJ. THE INITIAL ISENTROPIC LIFT IS LIKELY TO BE SNOW THANKS TO A LEFTOVER DOME OF COLD AIR IN ADVANCE OF THE WARM ADVECTION. QPF PRIOR TO THE CHANGEOVER SUPPORTS ANYWHERE FROM 1-4 IN OF SNOWFALL..BUT AS MENTIONED BE THE PREVIOUS FORECASTER...THIS IS ONLY AN INITIAL LOOK UNTIL TRACK/THERMAL PROFILES ARE BETTER RESOLVED. THE SNOWFALL COULD ACTUALLY INCREASE THE RISK FOR SOME FZRA/ICE DEVELOPMENT INITIALLY AS THE CHANGEOVER TO RAIN OCCURS AND SFC TEMPS REMAIN NEAR FREEZING. HOWEVER...EXPECT ALL RAIN BY ABOUT SUNRISE ON TUE DUE TO INFLUENCE OF THE LLJ. PERIODS OF HEAVY RAIN POSSIBLE AT TIMES TUE...WITH FINAL LIQUID TOTALS OF AN INCH OR MORE POSSIBLE. MODERATING TEMPS SUGGEST LOWS NEAR NORMAL BUT HIGHS ABOVE NORMAL AND IN THE 40S TO EVEN NEAR 50 BY TUE AFTERNOON. WED AND WED NIGHT... ARCTIC SHORTWAVE WILL ROTATE THROUGH THE MUCH SUPPRESSED LONGWAVE TROF ASSOCIATED WITH BAFFIN LOW CUTOFF. AT THIS POINT...IT/S LIKELY THIS WILL PASS WITH LITTLE FANFARE EXCEPT MAYBE A FEW -SHSN THANKS TO COLD ADVECTIVE DRIVEN INSTABILITY. WILL NEED TO WATCH SOME OFFSHORE WAVE DEVELOPMENT...BUT THIS APPEARS TO BE TOO PROGRESSIVE FOR A NORMAL HIT...HENCE THE LOWER END POPS. HIGHS IN THE 30S AND 40S DUE TO THE LATE PASSAGE WED EVENING...OVERNIGHT LOWS IN THE TEENS AND 20S. THU AND FRI... HIGH PRES ASSOCIATED WITH COLD AIRMASS EXPECTED THU. H85 TEMPS ONLY DROP TO AROUND -18C AS COMPARED TO THE -30C EXPECTED THIS WEEKEND. BUT THIS IS STILL ENOUGH TO KEEP HIGHS THU IN THE 20S AND LOW 30S AND OVERNIGHT MINS IN THE LOW TEENS WITH A FEW SINGLE DIGITS. SOME WARMING EXPECTED FRI AS THE HIGH SHIFTS E AND ALLOWS MODEST RETURN FLOW. EXPECT HIGHS BACK IN THE 30S TO AROUND 40 BUT MAINLY DRY WX TO PREVAIL. NEXT WEEKEND... ALTHOUGH THERE IS SOME UNCERTAINTY FOLLOWING THE RIDGING...W-E TRAVERSING WAVE WILL APPROACH AND CURRENTLY LOOKS TO BE YET ANOTHER INSIDE RUNNER BASED ON THE SHARPENING TROF. STILL LOT/S OF TIME HERE...BUT CONDITIONS LOOK TO BE MORE ACTIVE FOLLOWING THE LATE WEEK HIGH PRES. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SUNDAY NIGHT/... 21Z UPDATE... TONIGHT...HIGH CONFIDENCE. OVERALL VFR. BKN-OVC MVFR ACROSS MAINLY THE OUTER-CAPE WITH -SHSN. LIGHT ACCUM OF 1-2 INCHES POSSIBLE. NW-GUSTS 30-40 KTS AROUND 0Z...DIMINISHING TOWARDS MORNING. LOW CONFIDENCE CONCERNING THE NEED FOR AIRPORT WEATHER WARNINGS. SUNDAY...HIGH CONFIDENCE. VFR. NW-GUSTS 20-30 KTS STRONGEST ALONG THE SHORES INITIALLY... GRADUALLY TAPERING OFF THROUGH THE DAY. SCT-BKN MVFR DISSIPATING WITH WINDS ALONG WITH -SHSN FOR OUTER CAPE AND NANTUCKET. SUNDAY NIGHT...HIGH CONFIDENCE. VFR. LIGHT WINDS. KBOS TERMINAL... STRONGEST WINDS AROUND 0-1Z WITH NW-GUSTS AROUND 30 TO 35 KTS. LOWER CONFIDENCE OF 40 KT GUSTS AND THE NECESSITY OF AIRPORT WEATHER WARNINGS. WINDS TAPERING THROUGH LATE EVENING TOWARDS SUNDAY MORN. KBDL TERMINAL... NW-GUSTS 30 TO 35 KTS PERSISTING TO AROUND 23-0Z...WILL TAPER THROUGH THE LATE EVENING HOURS AND TOWARDS SUNDAY MORNING. OUTLOOK /MONDAY THROUGH THURSDAY/... MONDAY...HIGH CONFIDENCE. HIGH PRES YIELDS A PERIOD OF MAINLY VFR CONDITIONS. MON EVENING INTO TUE NIGHT...MODERATE CONFIDENCE. MIX OF IFR/MVFR...FIRST AS SNOWFALL OVERSPREADS THE REGION MONDAY NIGHT...CHANGING TO A MIX OF RAIN AND POSSIBLE BRIEF PERIOD OF FREEZING RAIN. ALL RAIN EXPECTED ON TUESDAY. WINDS WILL BE SHIFTING BUT GUSTS TO 20-30 KT POSSIBLE MAINLY DURING THE DAY TUE. LLWS POSSIBLE TUE AS WELL. WED...MODERATE CONFIDENCE. MAINLY VFR...BUT BRIEF SHRA/SHSN POSSIBLE. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SUNDAY NIGHT/...HIGH CONFIDENCE. */ HIGHLIGHTS... * GALE FORCE WIND GUSTS AND HEAVY FREEZING SPRAY EXPECTED THIS AFTERNOON INTO SUNDAY MORNING THROUGH TONIGHT...HIGH CONFIDENCE. ARCTIC AIRMASS BUILDING S. INCREASING TEMPERATURE DIFFERENTIAL BETWEEN SEA-SURFACE TEMPERATURES IN THE LOW-40S AND AIR TEMPERATURES DROPPING TO LOWS IN THE SINGLE DIGITS TO BELOW-ZERO ALONG THE SHORES. MIX DOWN OF 40 KT GUSTS THIS EVENING RESULTING IN WAVES BUILDING 8-10 FEET. LIKELY THREATS OF MODERATE TO HEAVY FREEZING SPRAY AS WELL AS ARCTIC SEA SMOKE. HAVE INCLUDED BOTH BOSTON HARBOR AND NARRAGANSETT BAY IN THE FREEZING SPRAY WARNING. GALE WARNINGS CONTINUE. OTHER CONCERN IS PERIODS OF OCEAN EFFECT SNOW ACROSS THE E-WATERS AND OUTER. EXPECT POOR VISIBILITY WITH ANY SNOW. SUNDAY INTO SUNDAY NIGHT...HIGH CONFIDENCE. NW-WINDS TAPERING ALONG WITH SEAS. GALES CONCLUDING...SMALL CRAFT HEADLINES WILL LIKELY HOLD FOR A MAJORITY OF THE FORECAST PERIOD. HIGH PRESSURE BUILDING ACROSS THE WATERS. OUTLOOK /MONDAY THROUGH THURSDAY/... MONDAY...HIGH CONFIDENCE. WINDS AND SEAS WILL DISSIPATE AS HIGH PRES MOVES OVER THE REGION. A PERIOD OF MAINLY QUIET BOATING WEATHER IS EXPECTED AFTER THE WINDS SUBSIDE AND FREEZING SPRAY SUBSIDES. TUE NIGHT INTO WED...MODERATE CONFIDENCE. A PERIOD OF AT LEAST SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED AS LOW PRES MOVES INLAND. GUSTS COULD REACH GALE FORCE DURING THE DAY ON TUE...BUT STRONG SMALL CRAFTS ARE EXPECTED AT LEAST. WAVES REACH 8-10FT BUT THEN DISSIPATE. && .CLIMATE... BITTERLY COLD TEMPERATURES ARE EXPECTED THIS WEEKEND. RECORD COLD HIGH AND LOW TEMPERATURES MAY BE TIED OR BROKEN. HERE ARE THE CURRENT RECORDS FOR THE WEEKEND. RECORD COLD HIGHS FOR FEB 13TH - 14TH... BOSTON.......15/1979 - 14/1916 HARTFORD.....11/1979 - 11/1979 PROVIDENCE...10/1979 - 10/1979 WORCESTER.... 8/1899 - 7/1979 BLUE HILL.... 9/1899 - 10/1979 RECORD COLD LOWS FOR FEB 13TH - 14TH - 15TH... BOSTON...... -3/1967 - -3/1934 - -14/1943 HARTFORD.... -7/1967 - -9/1979 - -18/1943 PROVIDENCE.. -5/1967 - -7/1979 - -14/1943 WORCESTER...-12/1967 - -11/1979 - -19/1943 BLUE HILL...-10/1967 - -9/1979 - -18/1943 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...WIND CHILL WARNING UNTIL NOON EST SUNDAY FOR CTZ002>004. MA...WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR MAZ022>024. WIND CHILL WARNING UNTIL NOON EST SUNDAY FOR MAZ002>019-026. WIND CHILL WARNING UNTIL NOON EST SUNDAY FOR MAZ020-021. RI...WIND CHILL ADVISORY UNTIL NOON EST SUNDAY FOR RIZ008. WIND CHILL WARNING UNTIL NOON EST SUNDAY FOR RIZ001>004. WIND CHILL WARNING UNTIL NOON EST SUNDAY FOR RIZ005>007. MARINE...HEAVY FREEZING SPRAY WARNING UNTIL 10 AM EST SUNDAY FOR ANZ231>235-237-250-251-254>256. GALE WARNING UNTIL 10 AM EST SUNDAY FOR ANZ231>235-237-250-251- 254>256. GALE WARNING UNTIL 7 AM EST SUNDAY FOR ANZ230-236. && $$ SYNOPSIS...DOODY/SIPPRELL NEAR TERM...SIPPRELL SHORT TERM...SIPPRELL LONG TERM...DOODY AVIATION...DOODY/SIPPRELL MARINE...DOODY/SIPPRELL CLIMATE...WFO BOX STAFF

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