Area Forecast Discussion
Issued by NWS Boston, MA

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330 FXUS61 KBOX 121035 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 535 AM EST FRI FEB 12 2016 .SYNOPSIS...
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DRY BUT VERY COLD WEATHER IS ON TAP FOR TODAY. AN OCEAN STORM WILL TRACK WELL OFFSHORE TONIGHT BUT WILL BRING A PERIOD OF ACCUMULATING SNOW TO THE CAPE AND ISLANDS. AN ARCTIC FRONT WILL DELIVER DANGEROUSLY COLD WIND CHILLS OF 20 TO 35 BELOW ZERO LATE SATURDAY INTO SUNDAY MORNING! FOR TUESDAY AND TUESDAY NIGHT...A STORM WILL LIKELY BRING SNOW QUICKLY CHANGING TO RAIN ALONG THE COAST AND TO FREEZING RAIN AND THEN RAIN INLAND AS MUCH MILDER AIR MOVES INTO NEW ENGLAND.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/... A BITTERLY COLD START TO THE MORNING WITH TEMPERATURES WELL DOWN INTO THE SINGLE DIGITS FOR MOST LOCALES AND EVEN A FEW BELOW ZERO READINGS IN WESTERN MA. STRONG COLD ADVECTION WILL COME TO AN END LATER THIS MORNING/AFTERNOON AS FLOW TURNS SOUTHWESTERLY AHEAD OF ANOTHER AND EVEN MORE INTENSE ARCTIC COLD FRONT. NOT TOO MUCH MODERATION OCCURS THIS AFTERNOON AS 850 MB TEMPS REMAIN BELOW -15C. THEREFORE...EXPECT HIGH TEMPS TO ONLY RECOVER INTO THE 20 TO 25 DEGREE RANGE THIS AFTERNOON BUT WINDS WILL BECOME RELATIVELY LIGHT. SUNNY SKIES THIS MORNING SHOULD GIVE WAY TO AN INCREASE IN MID LEVEL CLOUDINESS FROM WEST TO EAST DURING THE LATE AFTERNOON. OCEAN EFFECT CLOUDS WILL ALSO DEVELOP ALONG THE SOUTH COAST WITH COLD SOUTHWEST FLOW ACROSS OUR SOUTHERN WATERS. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
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*** ACCUMULATING SNOW TONIGHT ACROSS CAPE COD AND THE ISLANDS *** *** BITTERLY COLD AIR INVADES THE REGION SATURDAY AFTERNOON WITH STRONG WIND GUSTS AND RAPIDLY FALLING TEMPERATURES *** TONIGHT... AN INTERESTING SETUP FOR TONIGHT AS AN OCEAN STORM WILL INTENSIFY AS IT PASSES WELL SOUTHEAST OF THE BENCHMARK. AT THE SAME TIME...POTENT SHORTWAVE ENERGY WILL BE APPROACHING FROM THE WEST WITH AN ARCTIC COLD FRONT. THIS WILL SETUP AN INVERTED TROUGH EXTENDING BACK INTO FAR SOUTHEAST NEW ENGLAND. THE RESULT WILL BE A PERIOD OF LOW LEVEL CONVERGENCE FOCUSED ACROSS THE CAPE/ISLANDS. MODEL SOUNDINGS SHOW MODEST OMEGA ON THE ORDER OF 10 TO 20 MICROBARS PER SECOND. WILL ALSO LIKELY HAVE SOME OCEAN ENHANCEMENT WITH LOW LEVEL SOUTHWEST FLOW RESULTING IN OCEAN INDUCED CAPES BETWEEN 400 AND 500 J/KG. OVERALL THINK 1 TO 3 INCHES OF SNOW IS A GOOD BET FOR MOST OF THE CAPE/VINEYARD WITH A LOW RISK OF 4 INCHES. WILL ISSUE A SPECIAL WEATHER STATEMENT FOR THESE LOCATIONS...BUT LATER SHIFTS MAY HAVE TO CONSIDER A WINTER WEATHER ADVISORY. LIFT/FORCING PERSISTS A BIT LONGER ACROSS NANTUCKET AND WITH A PERIOD OF MODEST SNOWGROWTH...FEEL 2 TO 4 INCHES IS REASONABLE AND WILL HOIST A WINTER WEATHER ADVISORY FOR THEM. BULK OF THE SNOW LOOKS TO FALL BETWEEN 9 PM AND 5 AM...BUT SOME SNOW SHOWERS MAY PERSIST INTO MID MORNING SAT. ACROSS THE REST OF THE REGION...DRY WEATHER WILL DOMINATE TONIGHT. SOME SNOW SHOWERS MAY BRIEFLY EXTEND BACK INTO RHODE ISLAND/EASTERN MA WITH MINOR ACCUMS POSSIBLE CLOSER TO THE SOUTH COAST. A FEW SNOW SHOWERS/FLURRIES ALSO POSSIBLE ACROSS THE INTERIOR MAINLY TOWARD DAYBREAK AS THE ARCTIC COLD FRONT APPROACHES. LOW TEMPS WILL MAINLY BE IN THE 10 TO 15 DEGREE RANGE WITH UPPER TEENS AND LOWER 20S ACROSS CAPE/NANTUCKET. SATURDAY... ARCTIC COLD FRONT SWEEPS ACROSS THE REGION SATURDAY MORNING. IT MAY BE ACCOMPANIED BY A FEW SNOW SHOWERS/FLURRIES...BUT THE MAIN STORY WILL BE THE DANGEROUSLY COLD AIRMASS THAT WILL INVADE THE REGION. MIDDAY HIGH TEMPS IN THE MIDDLE TEENS TO LOWER 20S WILL RAPIDLY FALL BY LATE AFTERNOON/EARLY EVENING. IN FACT...BY 00Z SUNDAY 850MB TEMPS WILL BE DOWN TO RARE VALUES OF -26 TO -30C FOR SOUTHERN NEW ENGLAND STANDARDS. THE RESULT WILL BE EARLY SAT EVENING TEMPS ALREADY BELOW ZERO ACROSS THE INTERIOR AND SINGLE DIGITS ACROSS THE COASTAL PLAIN. GIVEN THE EXTREMELY COLD AIR WORKING INTO THE REGION EXPECT EXCELLENT MIXING. NORTHWEST WIND GUSTS OF 35 TO 45 MPH WITH A FEW GUSTS NEAR 50 MPH ARE EXPECTED TO DEVELOP SATURDAY AFTERNOON AND CONTINUE INTO SAT NIGHT. WE ALREADY ISSUED A WIND ADVISORY FOR CAPE COD/NANTUCKET GIVEN VERY STEEP LAPSE RATES AS ARCTIC AIR STREAMS IN OVER THE RELATIVELY MILD OCEAN. WIND ADVISORY MAY BE NEEDED FOR A TIME ACROSS THE REST OF THE REGION...BUT APPEARED TO MARGINAL TO ISSUE THIS FAR OUT.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... *** DANGEROUSLY COLD WIND CHILLS SATURDAY NIGHT *** HIGHLIGHTS... * BITTER COLD ARCTIC AIR MOVES INTO SOUTHERN NEW ENGLAND FOR THE WEEKEND * SNOW CHANGING TO RAIN LIKELY TUE AND TUE NIGHT OVERVIEW AND MODEL PREFERENCES... MODELS CONTINUE AGREE WELL INTO EARLY NEXT WEEK. THE DEEP AMPLIFIED FLOW WHICH WILL ALLOW FOR THE COLDEST AIRMASS OF THE SEASON TO ARRIVE BY LATE SAT...WILL THEN TRANSITION TO MORE ZONAL FLOW AS THE SOUTHERN STREAM LOOKS TO REGAIN CONTROL. HOWEVER...WITH SOME LINK TO A VORTEX HOVERING AROUND THE QUEEN ELIZABETH ISLANDS...THE WARMING TREND WILL NOT LAST...AND GIVE WAY TO ANOTHER ROUND OF COOLER CONDITIONS TOWARD THE END OF THE WEEK. GIVEN THERE IS GOOD AGREEMENT...A GENERAL BLEND OF OPERATIONAL GUIDANCE WILL BE USED AS A BASELINE FOR ALL BUT THE SRN STREAM DOMINANT SYSTEM MON-TUE. A BLEND OF ENSEMBLES WILL BE USED FOR THIS FEATURE DUE TO TRACK DISCREPANCIES. DETAILS... SAT NIGHT INTO SUN... REINFORCING ARCTIC SHORTWAVE WILL BE MOVING THROUGH THE LONGWAVE TROF ACROSS THE REGION. THIS SHORTWAVE WILL HAVE SEVERAL CONSEQUENCES. IT WILL ALLOW THE DEEPEST OF THE COLD AIR TO SPILL ACROSS THE REGION...NEARING -30C AT H85. AT THE SAME TIME THE STRONG MID LVL COLD ADVECTION AND INCREASED ISALLOBARIC RESPONSE WILL LEAD TO INCREASED WIND ACROSS THE REGION...EXACERBATING AN ALREADY VERY COLD SITUATION. TEMPS ARE LIKELY TO ALREADY BE NEAR OR BELOW 0F IN THE INTERIOR BY EVENING AND ONLY DROPPING INTO THE SINGLE DIGITS TO TEENS BELOW 0F THROUGH THE OVERNIGHT HOURS. THE INCREASED NW FLOW AT THE SFC...WITH GUSTS 20-30 MPH AT TIMES...WILL LEAD TO DANGEROUSLY COLD WIND CHILLS BETWEEN -20F AND -30F OR EVEN -35F IN SPOTS. WILL BE UPGRADING INTERIOR MA/CT AND RI TO WIND CHILL WARNINGS WITH THIS UPDATE...BUT LEAVE WATCHES NEAR THE SOUTH COAST WHERE MORE UNCERTAINTY LIE. WILL EXPAND THE WATCH TO INCLUDE CAPE COD...AS CURRENT NUMBERS SUGGEST IT COULD BE CLOSE THERE AS WELL. THE HIGHS WILL ONLY REACH INTO THE SINGLE DIGITS AND TEENS ABOVE 0F ON SUN...SO THE COLD WIND CHILLS ARE LIKELY TO LINGER WELL INTO THE DAY IN SPITE OF MAINLY SUNNY CONDITIONS. THE FINAL ISSUE OF NOTE...IS THAT IT WILL TURN MID LVL WINDS TOWARD THE N. IN SPITE OF THE FLOW REMAINING MORE NW AT THE SFC. THIS MAY ALLOW A LONG ENOUGH FETCH ACROSS ANOMALOUSLY WARM GULF OF MAINE WATERS TO YIELD A HIGHER RISK FOR OCEAN EFFECT SNOWS ESPECIALLY ACROSS CAPE COD. WITH SST-H85 DELTA-T VALUES NEARING 30C AND NORMALIZED CAPE VALUES AROUND 0.3 WILL NEED TO WATCH IF ANY BANDS SETUP...ESPECIALLY AS AN INVERTED TROF FROM THE MAINE COAST SHIFTS N. ACCUMULATING SNOW IS CERTAINLY POSSIBLE GIVEN THE VERY DESTABILIZED LOW LVLS. SUN NIGHT INTO MON... HIGH PRES WILL BE MOVING IN AND CROSSING THE REGION...YIELDING MAINLY DRY CONDITIONS AND SOME WARMING. H92 TEMPS REBOUND BACK CLOSER TO -10C...OR AT LEAST CLOSER TO SEASONAL NORMALS. AFTER A COLD START WITH SEVERAL SITES STILL BELOW 0F /THANKS TO SOME RADIATIONAL COOLING/ HIGHS REACH INTO THE MID 20S TO LOW 30S. MON NIGHT INTO TUE NIGHT... ENSEMBLE MEANS ARE STARTING TO LEAN CLOSER TO AN INSIDE RUNNER LOW PRES SYSTEM WITH TIES TO GULF OF MEXICO MOISTURE THANKS TO ITS STRONGER SRN STREAM INFLUENCE. THEREFORE...WILL CONTINUE THE TREND SET FORTH BY THE PREVIOUS FORECASTER...AND LEAN THE FORECAST IN THIS DIRECTION. THIS IS BETTER NEWS AS IT DOES NOT PROMOTE GOOD COLD AIR DAMMING. THEREFORE...THERMAL PROFILES ON BUFKIT SUGGESTS AN INITIAL SNOWY START LATE MON NIGHT...TRANSITIONING TO AN ALL RAIN EVENT BY TUE. 40-50 KT LLJ AND PWATS NEARLY 2 STD DEVIATIONS ABOVE NORMAL SUPPORT THE HIGH QPF MODELS CURRENTLY PROJECT...SO IT COULD BE THAT LIQUID TOTALS OF AN INCH OR EVEN MORE ARE POSSIBLE BY THE TIME THIS SYSTEM MOVES OUT TUE NIGHT. CERTAINLY SOMETHING TO WATCH GIVEN IT WILL BE A MIXED PRECIP EVENT WITH THE POTENTIAL FOR HEAVY RAIN. WED INTO FRI... SECOND ROUND OF ARCTIC AIR MOVES IN ASSOCIATED WITH A COLD FRONTAL PASSAGE ON WED. THIS AIRMASS IS NOT NEARLY AS DEEPLY COLD AS THIS WEEKEND/S AIRMASS. H85 TEMPS DROP TO AROUND -22C ON AVERAGE...SUPPORTED BY ENSEMBLE MEANS. THIS MEANS TEMPS WILL CERTAINLY REMAIN BELOW NORMAL...BUT NOT AS DANGEROUS AS THIS WEEKEND/S. WILL STILL NEED TO WATCH FOR WIND CHILL VALUES REACHING ADVISORY LEVELS FOR SOME MAINLY WED NIGHT INTO THU...WHEN WINDS ARE AT THEIR STRONGEST. SLIGHT MODERATION EXPECTED BY FRI. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY THROUGH SATURDAY/... TODAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR BUT SOME MARGINAL MVFR CIGS MAY DEVELOP IN SOME LOCALES THIS AFTERNOON. TONIGHT...MODERATE TO HIGH CONFIDENCE. SNOW DEVELOPS THIS EVENING ACROSS THE CAPE/ISLANDS AND CONTINUE INTO THE OVERNIGHT HOURS...BRINGING IFR CONDITIONS. ACROSS THE REST OF THE REGION A BROKEN DECK OF LOW END VFR TO MVFR CIGS. MAINLY DRY WEATHER OTHER THAN PERHAPS A PASSING SNOW SHOWER OR TWO. SATURDAY...MODERATE TO HIGH CONFIDENCE. LOW END VFR TO MARGINAL MVFR CIGS WILL DOMINATE. MUCH OF THE DAY WILL BE DRY BUT A FEW SNOW SHOWERS WILL BE POSSIBLE AS ARCTIC FRONT CROSSES THE REGION SAT AM. NORTHWEST WIND GUSTS PICKUP TO BETWEEN 35 AND 40 KNOTS SATURDAY AFTERNOON. KBOS TERMINAL...MODERATE TO HIGH CONFIDENCE IN TAF. KBDL TERMINAL...MODERATE TO HIGH CONFIDENCE IN TAF. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/... SAT NIGHT THROUGH SUN...HIGH CONFIDENCE. MAINLY VFR INLAND...WITH SOME MVFR CONDITIONS IN OCEAN EFFECT CIGS/SNOWS SAT NIGHT INTO EARLY SUN. BITTERLY COLD CONDITIONS WITH WIND GUSTS 20-30 KT POSSIBLE UNTIL MID DAY SUN. MON...HIGH CONFIDENCE. VFR. MON NIGHT THROUGH TUE...LOW TO MODERATE CONFIDENCE. BECOMING IFR WITH SNOW CHANGING TO RAIN WITH AREAS OF FOG LATE MON NIGHT INTO TUE. STRONG SOUTHERLY WINDS ALOFT MAY RESULT IN SIGNIFICANT LOW LEVEL WIND SHEAR TUE AFTERNOON. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY THROUGH SATURDAY/...HIGH CONFIDENCE. TODAY...NORTHWEST WIND GUSTS STILL GUSTING OVER 30 KNOTS EARLY THIS MORNING AS BITTERLY COLD AIR MOVES OVER THE RELATIVELY MILD OCEAN. WINDS SHOULD CONTINUE TO DIMINISH THIS MORNING AND DROP BELOW SMALL CRAFT ADVISORY THRESHOLDS BY NOON...AS COLD ADVECTION COMES TO AN END AND WINDS BECOME SOUTHWEST. FREEZING SPRAY ADVISORIES CONTINUE THROUGH 8 AM...BUT SHOULD BE ALLOWED TO EXPIRE ON TIME AS WINDS DIMINISH. TONIGHT...WINDS/SEAS REMAIN BELOW SMALL CRAFT THRESHOLDS FOR MOST OF THE NIGHT...BUT NORTHWEST WINDS WIND GUSTS OF 25 KNOTS WILL DEVELOP BY DAYBREAK. SATURDAY...ARCTIC FRONT BLASTS THROUGH WITH EXTREME COLD ADVECTION OVER THE WATERS. PRETTY MUCH A SLAM DUNK ON NORTHWEST WIND GUSTS OF 35 TO 40 KNOTS ACROSS ALL WATERS. HAVE HOISTED GALE HEADLINES SATURDAY AFTERNOON THROUGH SATURDAY NIGHT. THE AIRMASS IS SO COLD THAT MODERATE FREEZING SPRAY WILL HAVE ALREADY DEVELOPED BY EARLY SAT EVENING. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/... *** GALE FORCE WINDS AND HEAVY FREEZING SPRAY EXPECTED SAT EVENING INTO EARLY SUN *** SATURDAY NIGHT INTO SUNDAY...HIGH CONFIDENCE. STRONG AND BITTERLY COLD NORTHWEST WINDS WILL GUST TO GALE FORCE THROUGHOUT THE NIGHT AND INTO EARLY SUNDAY. THIS WILL BE ACCOMPANIED BY A RISK FOR HEAVY FREEZING SPRAY. GALE WARNINGS AND FREEZING SPRAY WATCHES HAVE BEEN ISSUED FOR THIS RISK. CONDITIONS DROP TO SMALL CRAFT THRESHOLDS BY LATE SUN. OCEAN EFFECT SNOWFALL IS LIKELY ACROSS SOME OF THE OTHER EASTERN WATERS. SUN NIGHT INTO MON...HIGH CONFIDENCE. BRIEF RIDGE OF HIGH PRES MOVES ACROSS THE WATERS. THIS WILL ALLOW ANY SMALL CRAFT ADVISORIES TO DROP BY EARLY MON MORNING WITH MAINLY QUIET BOATING WEATHER TO FOLLOW FOR THE REST OF MON. MON NIGHT INTO TUE...MODERATE CONFIDENCE. WINDS SHIFT TO THE SW AS LOW PRES APPROACHES FROM THE SW. WINDS AND SEAS MAY REACH SMALL CRAFT THRESHOLDS AS EARLY AS TUE MORNING AND THEN CONTINUE THROUGH THE DAY. SOME RAIN/FOG MAY LEAD TO LOWER VISIBILITIES. && .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 FROM 4 PM SATURDAY TO NOON EST SUNDAY FOR CTZ002>004. MA...WIND CHILL WARNING FROM 4 PM SATURDAY TO NOON EST SUNDAY FOR MAZ002>019-026. WIND CHILL WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON FOR MAZ020>022. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 9 AM EST SATURDAY FOR MAZ024. WIND ADVISORY FROM 11 AM SATURDAY TO 4 AM EST SUNDAY FOR MAZ022-024. RI...WIND CHILL WARNING FROM 4 PM SATURDAY TO NOON EST SUNDAY FOR RIZ001>004. WIND CHILL WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON FOR RIZ005>007. MARINE...HEAVY FREEZING SPRAY WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR ANZ231>235-250-251. GALE WARNING FROM 11 AM SATURDAY TO 7 AM EST SUNDAY FOR ANZ230>237-250-251-254>256. FREEZING SPRAY ADVISORY UNTIL 8 AM EST THIS MORNING FOR ANZ231- 233>235-250-251. && $$ SYNOPSIS...FRANK/DOODY NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY MARINE...FRANK/DOODY CLIMATE...STAFF

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