Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 201816 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 216 PM EDT SUN APR 20 2014 .SYNOPSIS...
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HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH EARLY TUESDAY. WARMER WEATHER TUE...UNTIL A COLD FRONT MOVES ACROSS THE AREA TUE NIGHT AND EARLY WED. LOW PRESSURE WILL INTENSIFY SOUTH OF NOVA SCOTIA WED INTO THU...WHILE HIGH PRESSURE BUILDS IN FROM THE WEST... CAUSING STRONG NORTHWEST WINDS ACROSS SOUTHERN NEW ENGLAND. MAINLY DRY FRI...THEN UNSETTLED WEATHER INTO NEXT WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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215 PM UPDATE...NO MAJOR CHANGES TO THE FORECAST. TWEAKED NEAR TERM FORECAST TO REFLECT LATEST OBSERVED TRENDS. TONIGHT... A HIGH PRESSURE WILL SHIFT FARTHER EAST OF OUR REGION...BUT ITS RIDGE WILL ELONGATE W-E ACROSS OUR REGION. THIS WILL KEEP DRY CONDITIONS IN PLACE. MAY SEE SOME CLOUDS HERE AND THERE OVERNIGHT. THE LIGHT WIND FLOW IN PLACE WILL START OFF FROM THE EAST...THEN WILL VEER TO THE SOUTHEAST AND SOUTH OVERNIGHT. WIND SPEEDS WILL REMAIN LESS THAN 10 KT...WITH CALM CONDITIONS AT MANY LOCALES AFTER MIDNIGHT. WITH THE LIGHT SOUTHERLY FLOW ALOFT...AND 925 MB AND 850 MB TEMPERATURES STARTING TO RISE...NOT EXPECTING LOWS TO BE QUITE AS COLD AS SUNDAY MORNING WITH READINGS MAINLY IN THE 30S.
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&& .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
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A HIGH PRESSURE RIDGE GRADUALLY SHIFTS SOUTHEAST THROUGH THIS PERIOD...BUT WILL STILL BE CLOSE ENOUGH TO KEEP OUR WEATHER DRY. WINDS WILL CONTINUE TO SHIFT SOUTH...AND INCREASE FOR MONDAY AFTERNOON. CURRENTLY THINKING THE PRESSURE GRADIENT WILL BE WEAK ENOUGH FOR WEAK SEA BREEZES TO DEVELOP ALONG THE EAST COAST OF MA. TEMPERATURES WILL RISE TO ABOVE NORMAL LEVELS...EXCEPT ALONG THE IMMEDIATE COASTLINE. THE PROXIMITY TO THE COLDER OCEAN WILL KEEP TEMPERATURES IN THE 50S THERE...ESPECIALLY ALONG SOUTH-FACING COASTS. ONCE THE SEA BREEZES DIE OFF TOMORROW AFTERNOON ALONG THE EAST COAST OF MA...TEMPERATURES WILL RISE QUICKLY. LATEST GUIDANCE TEMPERATURES LOOKED VERY REASONABLE. HIGHER CLOUDS INCREASE MONDAY NIGHT AHEAD OF A COLD FRONT APPROACHING SOUTHERN NEW ENGLAND.
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&& .LONG TERM /TUESDAY THROUGH SATURDAY/...
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MODEL OVERVIEW...A STRONG UPPER LEVEL TROUGH OVER THE GREAT LAKES MON NIGHT AND TUE IS FORECAST TO AMPLIFY OVER NEW ENGLAND WED AND DEVELOP INTO A DEEP CUTOFF LOW SOUTH OF NOVA SCOTIA WED NIGHT AND THU. AT THE SURFACE...A COLD FRONT SWEEPS ACROSS SOUTHERN NEW ENGLAND TUE NIGHT INTO EARLY WED. LOW PRESSURE WILL INTENSIFY ALONG THE FRONT SOUTH OF NOVA SCOTIA WED INTO THU WHILE HIGH PRESSURE BUILDS IN FROM THE WEST. THE CIRCULATION AROUND THESE TWO SYSTEMS WILL CAUSE STRONG NORTHWEST WINDS ACROSS SOUTHERN NEW ENGLAND LATE WED AND ON THU. MODELS ARE IN GOOD AGREEMENT ON THIS SCENARIO. A WEAK HIGH PRESSURE RIDGE ALOFT MOVES THROUGH ON FRIDAY. MODELS INDICATE ANOTHER UPPER LOW HEADING SOUTHEAST FROM THE GREAT LAKES NEXT WEEKEND...RATHER SIMILAR TO THE ONE DURING MIDWEEK. THERE IS CONSIDERABLE MODEL DIVERGENCE ON THE EXACT PLACEMENT OF THIS HOWEVER...WHETHER IT IS OVER SOUTHERN NEW ENGLAND OR PASSING TO OUR NORTHEAST REMAINS IN QUESTION AT THIS TIME. HIGHLIGHTS... * WARM TUESDAY. SHOWERS LIKELY LATE TUESDAY AFTERNOON AND NIGHT. * STRONG NORTHWEST WIND GUSTS AND POSSIBLE GALES LATE WEDNESDAY AND THURSDAY. * UNSETTLED WEATHER NEXT WEEKEND DAILIES... TUESDAY/TUESDAY NIGHT...HIGH PRESSURE SLIPS FARTHER OFF THE COAST. RETURN FLOW ON THE BACK OF THE HIGH WILL ALLOW 925 MB TEMPS TO WARM TO +11C EASTERN AREAS TO +15C WESTERN AREAS. THE MORNING WILL FEATURE SUNSHINE WHICH SHOULD ALLOW TEMPERATURES TO SOAR THROUGH THE 60S AND INTO THE LOWER 70S OVER THE INTERIOR...EXCEPT MUCH COOLER ON THE CAPE AND ISLANDS. WEAK SEA BREEZES COULD ALSO DEVELOP ELSEWHERE ALONG THE COAST. A COLD FRONT WILL MOVE THROUGH THE REGION TUE NIGHT AND EXIT THE COAST EARLY WED. SHOWERS ARE LIKELY ALONG AND AHEAD OF THIS FRONT...BEGINNING IN WESTERN SECTIONS LATE TUE AFTERNOON. PRECIPITABLE WATERS ARE ABOVE NORMAL WITH THIS FRONT. TOTAL TOTALS INDICES APPROACH 50...TQ INDICES ARE 17 TO 18...AND K INDICES OF 31. THESE MIGHT INDICATE THAT A RUMBLE OF ELEVATED THUNDER IS NOT OUT OF THE QUESTION...BUT OTHER STABILITY INDICES SUCH AS THE SHOWALTER AND LIFTED INDICES ARE IN POSITIVE TERRITORY...SO THIS IS NOT A BIG RISK. COULD SEE UP TO 0.60 INCHES OF RAIN IN SOME AREAS. WEDNESDAY AND THURSDAY...LOW PRESSURE WILL INTENSIFY ALONG THE FRONT SOUTH OF NOVA SCOTIA WHILE HIGH PRESSURE BUILDS IN FROM THE WEST. THE CIRCULATION AROUND THESE TWO SYSTEMS WILL CAUSE STRONG NORTHWEST WINDS ACROSS SOUTHERN NEW ENGLAND. MODELS DIFFER A LITTLE IN MAGNITUDE AND TIMING BUT THE CONSENSUS IS THAT 40-45 KT WINDS AT BOTH 925 AND 850 MB PERSIST ACROSS THE REGION WED NIGHT AND THU. THE BEST MIXING IS FORECAST TO OCCUR ON THU. WE COULD SEE WIND GUSTS APPROACHING 30-35 MPH OVER THE LAND AND GALE FORCE GUST OVER THE OUTER WATERS. THERE WILL BE A BATTLE BETWEEN COLD ADVECTION AND WARM APRIL SUNSHINE. THE NET RESULT WILL BE COOLER WEATHER WITH HIGHS ONLY IN THE 50S TO PERHAPS NEAR 60 BOTH DAYS. FRIDAY...WEAK HIGH PRESSURE MOVES ACROSS THE REGION BUT CLOUDS INCREASE LATE IN THE DAY AS WEAK LOW PRESSURE MOVES TO OUR SOUTHWEST. THERE IS A SLIGHT CHANCE OF A SHOWER LATE IN THE DAY. HIGHS RETURNING TO THE 60S. SATURDAY...AS DESCRIBED IN THE MODEL SECTION ABOVE...THERE IS CONSIDERABLE DISCREPANCY AS TO THE EXACT PLACEMENT OF UPPER AND SURFACE LOW PRESSURE MAKING ITS WAY SOUTHEASTWARD FROM THE GREAT LAKES. THIS SYSTEM IS SIMILAR TO THE SYSTEM DURING MIDWEEK. IT IS TOO EARLY TO TELL WHETHER WE WILL BE QUITE WET...OR WHETHER IT WILL PASS TO OUR NORTHEAST...KEEPING US DRY AND WINDY. FOR NOW...HAVE INDICATED CHANCE PROBABILITIES OF SHOWERS.
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&& .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH MONDAY NIGHT...HIGH CONFIDENCE. VFR CONDITIONS CONTINUE. WINDS CONTINUE TO SHIFT SOUTHEAST...THEN SOUTH LATE TONIGHT INTO MONDAY. SOUTH WINDS INCREASE MONDAY AFTERNOON...THEN DIMINISH MONDAY NIGHT. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. EXPECTING A WEAK SEA BREEZE TO DEVELOP FROM MID MORNING INTO EARLY AFTERNOON...MAINLY FROM 15-21Z. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY THROUGH THURSDAY... TUE...HIGH CONFIDENCE. VFR. MAINLY SOUTHWEST WINDS. CHANCE OF MVFR IN SHOWERS IN WESTERN MA/NORTHWEST CT LATE TUE AFTERNOON. TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING...MODERATE CONFIDENCE. PERIODS OF MVFR/IFR IN LOW CIGS AND VSBYS DUE TO SHOWERS. LOCALLY HEAVY SHOWERS POSSIBLE. ISOLATED THUNDER NOT OUT OF THE QUESTION. LATE WEDNESDAY MORNING THROUGH THURSDAY...HIGH CONFIDENCE. VFR. NORTHWEST WIND GUSTS TO 25-30 KT POSSIBLE WED AND 30-35 KT POSSIBLE THU.
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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 MONDAY NIGHT/...HIGH CONFIDENCE. CANCELLED THE SMALL CRAFT ADVISORY FOR THE COASTAL WATERS SOUTH AND EAST OF CAPE COD. EXPECTING WINDS AND SEAS TO REMAIN BELOW ADVISORY THRESHOLDS. OUTLOOK...TUESDAY THROUGH THURSDAY... TUE...HIGH CONFIDENCE. HIGH PRESSURE DOMINATES THE WEATHER FOR THIS PERIOD WITH FEW S/SW GUSTS AROUND 25 KTS POSSIBLE. SEAS COULD BUILD TO 5 TO 6 FT OVER THE OUTER WATERS ON TUE...INCLUDING SWELLS FROM A STORM SYSTEM WELL TO THE SOUTHEAST. TUE NIGHT INTO WED MORNING...MODERATE CONFIDENCE. COLD FRONT MOVES THROUGH THE REGION FROM WEST TO EAST WITH SHOWERS LIKELY AND POSSIBLY A RUMBLE OF THUNDER. SEAS AGAIN IN THE 4 TO 6 FT RANGE. WED AFTERNOON THROUGH THURSDAY...NW GALES ARE LIKELY...ESPECIALLY WED NIGHT AND THU...WITH GUSTS OF 30 TO PERHAPS 40 KTS OVER THE OUTER WATERS. EXPECT SEAS TO BUILD TO 6-8 FEET OVER THE OUTER WATERS...WITH 9 OR 10 FEET POSSIBLE WELL TO THE EAST OF NANTUCKET. WILL NEED TO MONITOR FOR POSSIBLE GALE WATCHES AS THE TIME GETS CLOSER.
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&& .HYDROLOGY...
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MINOR FLOODING REMAINS ALONG PORTIONS OF THE MAINSTEM CT RIVER. SEE THE LATEST FLOOD STATEMENT FOR DETAILS. FLOOD WARNINGS REMAIN POSTED ALONG CT RIVER AT... HARTFORD AND MIDDLE HADDAM
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE.
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&& $$ SYNOPSIS...BELK/GAF NEAR TERM...BELK SHORT TERM...BELK LONG TERM...GAF AVIATION...BELK/GAF MARINE...BELK/GAF HYDROLOGY...STAFF

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