Area Forecast Discussion
Issued by NWS Boston, MA

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923 FXUS61 KBOX 041459 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 959 AM EST THU FEB 4 2016 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL MOVE ACROSS THE REGION TODAY BRINGING SOME LIGHT PRECIP TO THE REGION. THIS FRONT WILL STALL JUST OFF THE COAST THIS AFTERNOON...THEN LOW PRESSURE WILL DEVELOP ALONG THE MID ATLC COAST THU NIGHT AND TRACK ALONG THE FRONT PASSING SOUTH AND EAST OF NANTUCKET FRIDAY. THIS STORM WILL LIKELY BRING ACCUMULATING SNOW TO SOUTHEAST NEW ENG LATE THU NIGHT INTO FRIDAY. HIGH PRESSURE BRINGS DRY WEATHER OVER THE WEEKEND...ALTHOUGH A WEAK COLD FRONT SUNDAY MAY BRING A FEW CLOUD. A COMPLEX COASTAL STORM SHOULD AFFECT THE REGION LATER MONDAY INTO TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 10 AM UPDATE... WEAK BAND OF ECHOES BETWEEN 15-20DBZ JUST W OF PVD AND NOW THROUGH BOS MARKS THE COLD FRONT WHICH CONTINUES TO SWEEP THROUGH THE REGION THIS MORNING. THE PRECIP SHIELD ENDS WITHIN MINUTES OF THIS FROPA. CURRENT TIMING PUSHES IT OFFSHORE BY ABOUT NOON FOR THE CAPE/ISLANDS. TIMING OF POPS WERE UPDATED TO REFLECT THIS THINKING. ALSO AJDUSTED TEMPS/DWPTS AS THEY BEGIN TO DROP BEHIND THE EASTWARD MOVING FRONT. PREVIOUS DISCUSSION... WEAK 850 MB TROUGH WILL MOVE THE FRONT THROUGH THE AREA BETWEEN 12- 18Z. THIS WILL ALLOW FOR A FEW SCT SHOWERS TO DEVELOP. STRONG CAA WILL MOVE INTO THE REGION AS 850 MB TEMPS DROP SEVERAL DEGREES THROUGHOUT THE DAY. THEREFOR ANTICIPATE MAX TEMPS TO OCCUR THIS MORNING. THIS COLD FRONT WILL STALL JUST OFFSHORE LATE THIS AFTERNOON AS NORTHERN ATLANTIC RIDGE BUILDS. THIS FRONT WILL BE THE FOCUS FOR PRECIP DURING THE EVENING HOURS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... TONIGHT INTO TOMORROW... *** WINTER STORM WATCH ISSUED FOR FAR SE MASS...SOUTH AND EASTERN RHODE ISLAND...CAPE COD AND MARTHAS VINEYARD *** OVERVIEW... COLD FRONT STALLED OFF THE COAST WILL BE THE FOCUS FOR PRECIPITATION TONIGHT AND INTO TOMORROW. VERY SHARP MID LEVEL TROUGH WILL APPROACH FROM THE WEST TONIGHT...AND WITH POTENT SHORTWAVE ROUNDING THE TROUGH A SURFACE LOW WILL DEVELOP OFF THE MID-ATLANTIC COAST. THIS LOW WILL MOVE ALONG THE STALL COLD FRONT PUSHING THE PRECIP SHIELD BACK TOWARDS THE REGION TONIGHT AND INTO TOMORROW. UNCERTAINTY... STILL UNCERTAINTY WITH THIS SYSTEM AS MODELS CONTINUE TO PUSH THE PRECIP SHIELD FARTHER WEST WITH EACH RUN. HOWEVER SOME HI-RES GUIDANCE DOES SHOW A EXTREME CUT-OFF IN QPF KEEPING THE WESTERN HALF OF THE REGION PRECIP FREE. ASIDE FROM QPF...THERE IS SOME QUESTION ON WHEN RAIN WILL SWITCH OVER TO SNOW LATE THURSDAY NIGHT INTO EARLY FRIDAY MORNING. HOWEVER GUIDANCE DOES HINT THAT IT WILL BE BETWEEN 06-09Z. THIS IS IN LINE WHEN 925 MB TEMPS QUICKLY COOL BELOW 0C AS WINDS BECOME MORE IN A NORTHERLY DIRECTION. FINALLY SNOWFALL AMOUNTS ARE IN QUESTION AS THE LATEST EC AND 18Z NAM ARE ON THE HIGH SIDE SHOWING LOCATIONS ACROSS RI AND SE MASS REACHING BETWEEN 7-10 INCHES. AT THIS TIME...HAVE A HIGHER CONFIDENCE FOR SIGNIFICANT SNOW ACCUMULATION FOR THE COASTAL PLAIN AND LOCATIONS NEAR THE CANAL. LESS CONFIDENCE ON THE NORTHWEST PORTION OF THE SNOW SHIELD AS WELL AS LONG THE OUTER CAPE AND NANTUCKET. QPF... THERE APPEARS TO BE 2 DIFFERENT CAMPS IN TERMS OF QPF. THE UKMET/EC/NAM IS ONE BRINGING SIGNIFICANT QPF AND THUS SNOW INTO SOUTHEAST COASTAL PLAIN AND ACROSS SOUTHERN RHODE ISLAND. WHILE THE NMM AND ARW ARE ON THE OPPOSITE...KEEPING THE HEAVIEST QPF OVER THE CAPE AND IMMEDIATE PORTION OF SE MASS WITH AN EXTREME CUTOFF NORTH OF THE I-95 CORRIDOR. THE GFS APPEARS TO BE IN THE MIDDLE OF THE ROAD ALONG WITH THE EPS. USED A BLEND OF THE GUIDANCE WITH AN EMPHASIS ON WPC QPF TO GET A TREND...WHICH SHOWS THAT THE 00Z GUIDANCE HAS SHIFTED WESTWARD. SNOWFALL... DECIDED TO EXPAND THE THE WATCH DUE TO THE WESTWARD SHIFT WITH THE GUIDANCE. HIGHEST CONFIDENCE OF 6 INCHES IS NEAR THE CAPE COD CANAL AS WELL AS INTERIOR BRISTOL...PLYMOUTH AND WASHINGTON COUNTY RHODE ISLAND. SNOW COULD BE HEAVY AT TIMES VERY LATE TONIGHT INTO FRI MORNING WHICH MAY AFFECT THE MORNING COMMUTE. THANKS TO STRONG OMEGA LIFT WITHIN THE SNOW GROWTH REGION AS WELL AS F-GEN AS NOTED AT THE 600MB LEVEL. BUFKIT SOUNDINGS ALSO SHOW SNOW ACCUMULATIONS YIELDING CLOSE TO 1 INCH PER HOUR...REDUCING VSBYS FOR THE MORNING COMMUTE. LOCATIONS ACROSS NANTUCKET AND THE OUTER CAPE WILL SEE LESS SNOWFALL DUE TO LATER TIMING OF CHANGEOVER AND MARGINAL BOUNDARY LAYER WHICH WILL LEAD TO SOME MELTING. AGAIN WITH THE SHARP QPF GRADIENT ON THE NW FRINGE OF THE PRECIP SHIELD THERE IS THE POTENTIAL FOR A BUST. AS THE PREV FORECASTER MENTIONED...IF THE SYSTEM TRACKS EASTWARD THEN ACCUMULATIONS WILL BE LESS. WHILE IF THE SYSTEM TRACKS FARTHER WEST...THEN HEAVY SNOW COULD EXTEND BACK WESTWARD...WHICH IS WHAT THE LATEST TRENDS HAVE SHOWN. RECOMMEND USERS TO LOOK AT THE PROBABILISTIC SNOWFALL MAPS AND BEST/WORST CASE SCENARIOS WHICH COMMUNICATE THE EXPECTED SNOWFALL RANGES. IMPACTS... THIS WILL BE A WET SNOW AND IF HEAVY SNOW MATERIALIZES THERE WILL BE POTENTIAL FOR POWER OUTAGES DUE TO ACCUMULATION ON TREES AND POWER LINES. SNOWFALL WILL BEGIN TO WANE BY THE AFTERNOON HOURS AS THE LOW PRESSURE SYSTEM MOVES TOWARDS THE MARITIMES. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... BIG PICTURE... LONGWAVE SCALE PATTERN SHOWS DIGGING TROUGH EAST AND BUILDING RIDGE WEST. THIS POINTS TO COLDER AND MORE UNSETTLED WEATHER OVER THE WEEKEND AND FIRST HALF OF NEXT WEEK. SEVERAL SHORTWAVES MOVE THROUGH THE EASTERN TROUGH WITH CONTINUED VARIATIONS BETWEEN MODELS ESPECIALLY ON POSITIONS AND EFFECTS. TWO KEY SHORTWAVES ARE EITHER OVER THE PACIFIC OR JUST MOVING ASHORE OVER THE WESTERN USA AND ITS DENSER OBSERVATION NETWORK. THEREFORE CHANGEABLE RUN-RUN DIFFERENCES IN THE MODELS ARE TO BE EXPECTED. CONFIDENCE FOR THE EVOLVING WEATHER FOR EARLY NEXT WEEK REMAINS LOW. THE DAILIES... FRIDAY NIGHT-SATURDAY... HIGH PRESSURE BUILDS OVER THE REGION. EXPECT DRY WEATHER WITH CLEAR SKIES FRIDAY NIGHT AND INCREASING MID AND HIGH CLOUDS SATURDAY. OBSERVED TEMPS UPSTREAM UNDER THE RIDGE SUGGEST MIN TEMPS HERE IN THE 20S. MIXING SHOULD REACH A LITTLE ABOVE 900 MB...WITH TEMPS AT THE TOP OF THE LAYER SUPPORTING MAX SFC TEMPS IN THE LOWER 40S. SUNDAY... NORTHERN STREAM SHORTWAVE SWEEPS SOUTH AND EAST FROM CENTRAL CANADA TO QUEBEC AND NEW ENGLAND. THIS DRIVES A COLD FRONT THROUGH OUR AREA EARLY SUNDAY. MOISTURE FIELDS ARE MORE ROBUST IN NORTHERN NEW ENGLAND AS IS THE DYNAMICS. EXPECT SOME SKY COVER LATE SATURDAY NIGHT AND PART OF SUNDAY BUT AT BEST SOME WIDELY SCATTERED MORNING SNOW SHOWERS. MODEL GUIDANCE BRINGS MAX SFC TEMPS INTO THE 40S. BUT AFTERNOON MIXING SUGGESTS HIGHS IN THE MID AND UPPER 30S. WILL NUDGE MODEL FORECAST DOWN 1-2 DEGREES. MONDAY-TUESDAY... SOUTHERN STREAM SHORTWAVE STARTS TODAY OVER THE PACIFIC NORTHWEST AND CROSSES TO THE SOUTHEAST USA...FORMING A CLOSED UPPER LOW ALONG THE CAROLINA COAST SUNDAY. THE LOW THEN PASSES WELL OFFSHORE OF NANTUCKET ON MONDAY. MODEL SOLUTIONS FOR THE UPPER LOW DIVERGE BY SUNDAY WITH THE ECMWF FARTHEST WEST AND CLOSEST TO THE ATLANTIC COAST. IN MOST CASES THE CLOUDS AND PCPN STAY WELL OFFSHORE. BUT THE ECMWF IS CLOSE ENOUGH AND BRINGS ENOUGH OF AN EAST FLOW TO BRING MEASURABLE PCPN TO SOUTHERN NEW ENGLAND. AS IT IS THE OUTLIER SOLUTION WE WOULD TEND TO DISCOUNT IT. BUT WITH DIGGING TROUGH OVER THE MIDWEST/APPALACHIANS AND BENDING OF THE FLOW MORE UP THE COAST...A MORE WESTERN TRACK IS IN THE REALM OF POSSIBILITY. THIS WILL NEED TO BE MONITORED. WE WILL BRING SLIGHT CHANCE POPS TO SOUTHERN NEW ENGLAND MONDAY AND VERY-LOW-END CHANCE POPS TO CAPE COD AND ISLANDS. THE NEXT SHORTWAVE STARTS SOUTH OF THE ALEUTIANS THIS MORNING AND MOVES ACROSS THE PACIFIC NORTHWEST FRIDAY NIGHT TO THE WESTERN LAKES SUNDAY. IT THEN DIGS AND CARVES A DEEP TROUGH/CLOSED LOW OVER THE EASTERN USA WITH A SOUTH-TO-NORTH FLOW OVER THE EASTERN USA BY MONDAY EVENING. AT THIS TIME THE BEST CHANCE FOR PCPN LOOKS TO BE MONDAY NIGHT AND TUESDAY. TEMPERATURES BEHIND SUNDAY/S FRONT AND WITH THE DIGGING UPPER TROUGH SUGGEST MAINLY SNOW. UNCERTAINTIES IN THE EVOLUTION AND TRACK OF THE SURFACE SYSTEM LEAVE THE CHANCE OF A CHANGE TO RAIN IN THE COASTAL PLAIN TUESDAY. WEDNESDAY... YET ANOTHER SHORTWAVE MOVES THROUGH THE TROUGH AND KICKS IT NORTHEAST THROUGH NEW ENGLAND INTO THE MARITIMES. THIS SHOULD BRING DRYING AND IMPROVING SKIES BUT WITH LINGERING WIDELY SCATTERED SNOW SHOWERS AS THE COLD POOL SWINGS OVERHEAD. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH FRIDAY/...MODERATE CONFIDENCE. TODAY...HIGH CONFIDENCE. MVFR THIS MORNING WITH AREAS OF IFR CIGS/VSBYS. ONE PATCH OF SHOWERS MOVES THROUGH RI AND EASTERN MASS THROUGH 15Z. COULD BE OTHER PATCHES OF SHOWERS THIS MORNING. COLD FRONT ENTERING THE CT VALLEY AT 12Z WILL MOVE ACROSS THE REGION BY MIDDAY. IMPROVEMENT TO VFR EXPECTED WITH THE WIND SHIFT BEHIND THE FRONT. SKY COVER WILL LINGER THROUGH MUCH OF THE DAY. TONIGHT INTO FRIDAY...VFR FOR WESTERN MASS. HIGH CONFIDENCE IN IFR/LIFR DEVELOPING SE NEW ENG AND CAPE/ISLANDS WITH RAIN CHANGING TO ACCUMULATING SNOW LATE THU NIGHT INTO FRI MORNING...IMPROVING FRI AFTERNOON. LOW CONFIDENCE ON WHERE TRANSITION FROM IFR TO VFR OCCURS. ANTICIPATE ACCUMULATING SNOW FOR RUNWAYS. KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN TIMING OF PRECIP TONIGHT. KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS. OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/... FRIDAY NIGHT THROUGH SUNDAY...MODERATE CONFIDENCE. VFR. MONDAY...LOW CONFIDENCE. POTENTIAL FOR MVFR CIGS/VSBYS IN DEVELOPING LIGHT RAIN/SNOW LATE IN THE DAY. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE. HAVE DROPPED GALE WARNING FOR ALL THE WATERS AND CONVERTED THEM TO SCA. COLD FRONT WILL MOVE OVER THE WATERS TODAY AND STALL OUT. A LOW PRESSURE SYSTEM WILL DEVELOP ALONG THE FRONT THURSDAY NIGHT INTO FRIDAY BRINGING PRECIP AND PERHAPS SNOW OVER THE WATERS. VSBYS MAY BE REDUCED AS WELL. GUSTS WILL INCREASE CLOSE TO 25-30 KTS SO EXPECT SCA TO EXPAND THURSDAY NIGHT INTO FRIDAY. OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...MODERATE CONFIDENCE... FRIDAY NIGHT...LOW PRESSURE MOVES OFF ACROSS NOVA SCOTIA AND HIGH PRESSURE BUILDS IN. NORTHWEST WINDS GUSTING TO 25 KNOTS WILL DIMINISH OVERNIGHT. SEAS 5 TO 9 FEET WILL ALSO DIMINISH. SMALL CRAFT ADVISORY WILL BE NEEDED FOR AT LEAST THE OUTER WATERS. SATURDAY-SUNDAY...SOUTHWEST WINDS SATURDAY BECOME NORTHWEST SUNDAY AS A COLD FRONT SWINGS ACROSS THE WATERS. A FEW GUSTS TO 25 KNOTS ARE POSSIBLE ESPECIALLY EAST OF CAPE ANN. SEAS 5 TO 6 FEET MAINLY ON THE OUTER WATERS. A SMALL CRAFT ADVISORY MAY BE NEEDED ON THE OUTER WATERS. SUNDAY NIGHT-MONDAY...NORTH WINDS TURNING NORTHEAST AND INCREASING WITH GUSTS TO AT LEAST 30 KNOTS. SEAS WILL SUBSIDE BELOW 5 FEET INITIALLY...BUT THEN INCREASE FROM THE SOUTH AGAIN MONDAY NIGHT. && .CLIMATE... RECORD HIGHS FOR FEB 4TH... BOS...64/1991 BDL...64/1991 PVD...66/1991 ORH...61/1991 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY AFTERNOON FOR MAZ017>023. RI...WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY AFTERNOON FOR RIZ002-004>008. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ231>234-251. SMALL CRAFT ADVISORY UNTIL 7 AM EST FRIDAY FOR ANZ235-237. SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR ANZ250-254. SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR ANZ255-256. && $$ SYNOPSIS...WTB/DUNTEN NEAR TERM...WTB/DOODY SHORT TERM...DUNTEN LONG TERM...WTB AVIATION...WTB/DUNTEN MARINE...WTB/DUNTEN CLIMATE...

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