Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 241123 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 723 AM EDT SUN MAY 24 2015 .SYNOPSIS... SOUTHWEST WINDS WILL BRING WARMER AIR INTO SOUTHERN NEW ENGLAND BEGINNING TODAY. WARM AND MUGGY CONDITIONS BUILD INTO MIDWEEK AHEAD OF INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS. COULD REMAIN WET ALL THE WAY THROUGH INTO NEXT WEEKEND. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... 730 AM UPDATE...NO MAJOR CHANGES TO THE FORECAST. MID LEVEL CLOUDS DRIFTING ACROSS N NEW ENGLAND IN ADVANCE OF WEAK SHORT WAVE DIVING SE FROM CANADA. THEY MAY GRAZE N MA. OTHERWISE PLENTY OF SUNSHINE EXPECTED TODAY AS CROSS SECTIONS SHOW DRY AIR THROUGH COLUMN. MIXING LAYER WILL DEEPEN SIGNIFICANTLY ONCE AGAIN IN RESPONSE TO DAYTIME HEATING...WITH 25-30 MPH GUSTS EXPECTED NEAR THE S COAST...CAPE COD AND ISLANDS AS WELL AS IN EASTERN MA WITH 20-25 MPH GUSTS ELSEWHERE. WINDS WILL DIMINISH TOWARD EVENING AS BOUNDARY LAYER BEGINS TO STABILIZE...ASIDE FROM S COAST WHERE IT WILL TAKE A BIT LONGER. HIGHS WILL TOP OUT IN 70S AND LOWER 80S EXCEPT 60S ON S COAST... CAPE COD AND ISLANDS DUE TO SW FLOW OFF COLDER OCEAN. && .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM MONDAY/... SW FLOW PERSISTS TONIGHT AND MON AS MODELS BRING WARM FRONT THROUGH UPSTATE NY AND NORTHERN NEW ENGLAND...WHICH SHOULD BE FOCUS FOR ANY SHOWERS OR STORMS. 00Z GFS SEEMS OVERDONE IN BRINGING PRECIPITATION THIS FAR E...ESPECIALLY GIVEN RISING 500 MB HEIGHTS AND LACK OF DEEP MOISTURE OR APPRECIABLE LIFT OVER OUR AREA. AS A RESULT WE DO EXPECT TO SEE AN INCREASE IN CLOUDINESS /MAINLY MID LEVEL/ WITH PERHAPS AN ISOLATED SHOWER OR STORM MON ACROSS NW MA. LOWS WILL DROP BACK INTO 50S TONIGHT AND ONCE AGAIN CLIMB INTO 70S/LOWER 80S MON EXCEPT 60S ON S COAST...CAPE COD AND ISLANDS. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... */ HIGHLIGHTS... - WARM MUGGY AND DRY TUESDAY INTO TUESDAY NIGHT - INCREASING SHOWER / THUNDERSTORM POTENTIAL WEDNESDAY - THURSDAY - PERHAPS A LULL IN THE WEATHER ON FRIDAY - LOOKING POTENTIALLY WET AND ACTIVE FOR NEXT WEEKEND */ DISCUSSION... FORECAST GUIDANCE STRUGGLING WITH BOTH STRENGTH AND INFLUENCE OF RIDGING ACROSS THE E-CONUS AND SUBSEQUENT ALLOWANCE OF N-STREAM ENERGY TO SLIP S. AS BEEN THE TREND THE LAST SEVERAL DAYS...THE RIDGE DEAMPLIFIES SUBSEQUENT TO THE FLATTENING MARITIME FLOW AND RETROGRADING LOW PULLING COOLER AIR CYCLONICALLY SW. THERE IS NOT MUCH SUPPORT IN MAINTAINING A RIDGING PATTERN. SO EXPECTATION THRU THE WEEK IS FOR N-STREAM ENERGY TO HAVE THE ABILITY TO TROUGH S SHIFTING THE CONVERGENT SW-FLOW ALONG WITH THETA-E / INSTABILITY AXES INTO NEW ENGLAND. ANTICIPATING INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS ESP ACROSS THE INTERIOR. SHEAR NOT IMPRESSIVE COMPARED TO INSTABILITY...SO ECHO PRIOR FORECASTER WITH CONCERN OF HEAVY RAIN AS A THREAT. WILL KEEP TUESDAY INTO TUESDAY NIGHT DRY. THOUGH THE WARM AND MUGGY CONDITIONS POTENTIALLY EXCEEDING CONVECTIVE-TEMPERATURES ACROSS THE N AND W MAY YIELD THUNDERSTORMS THAT WOULD PUSH E WITH THE STEERING FLOW...FEEL DRY AIR AND SUBSIDENCE WILL ERODE / WEAKEN ANY ACTIVITY INTO NEW ENGLAND. THE BETTER FORCING AND SW-CONVERGENT FLOW OF MOIST- INSTABILITY AXES IS WELL NW AT THIS TIME. LOW-90S POSSIBLE ACROSS INTERIOR VALLEYS. EXPECT MARINE STRATUS / FOG ALONG THE S/SE-COAST PERHAPS DEVELOPING AS EARLY AS MONDAY NIGHT INTO TUESDAY. WEDNESDAY INTO THURSDAY THE RIDGE WEAKENS ALLOWING THE FAVORABLE ENVIRONMENT FOR SHOWERS AND THUNDERSTORMS TO SHIFT SE. INCREASING POP CHANCES ACCORDINGLY. SOME QUESTION AS TO HOW EFFECTIVELY WE CAN DESTABILIZE. COULD BE ISSUES WITH CLOUD COVER SHOULD ACTIVITY ON WEDNESDAY EXPECTED MAINLY W DRIFTS E OVERNIGHT INTO THURSDAY. WILL CONTINUE WITH WARM AND MUGGY CONDITIONS. LOW-90S POSSIBLE ACROSS INTERIOR VALLEYS ESPECIALLY WEDNESDAY. CONTINUED POTENTIAL OF MARINE STRATUS / FOG ALONG THE S/SE-COAST. FRIDAY COULD BE A LULL WITH DRY AIR AND HIGH PRESSURE IN PLACE IF YOU BELIEVE THE GFS OVER THE ECMWF. LOW CONFIDENCE. CONSENSUS OF FORECAST GUIDANCE HAS ANOTHER WAVE N PUSHING A FRONTAL BOUNDARY S AND STALLING OVER NEW ENGLAND MAKING IT A FOCUS FOR A PROLONGED PERIOD OF WET-WEATHER. HAVE SOME DOUBTS WITH CONVERGENT MASS-FIELDS N AS SURFACE REFLECTIONS FOCUS S WITH THERMAL-INSTABILITY-MOIST AXES. SHOULD HAVE A BETTER IDEA AS WE GET CLOSER IN TIME. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE. 12Z UPDATE... VFR WITH SW FLOW. 20-25 KT GUSTS LATER THIS MORNING INTO EARLY EVENING...ESPECIALLY NEAR COAST. CIGS AOA 060 LATE TONIGHT AND MONDAY WITH AN ISOLATED -SHRA/TSRA POSSIBLE ACROSS NW MA. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY NIGHT... MONDAY NIGHT INTO TUESDAY NIGHT...MODERATE CONFIDENCE. VFR. BREEZY SW-FLOW WITH 20-25 KT GUSTS. IFR STRATUS / FOG POSSIBLE ACROSS THE S/SE-COAST. WEDNESDAY INTO THURSDAY NIGHT...MODERATE CONFIDENCE. INCREASING CHANCES FOR -SHRA / TSRA. TEMPO MVFR-IFR WITH ANY ACTIVITY. SW-FLOW WITH 20 KT GUSTS AT TIMES. IFR STRATUS / FOG REMAINS POSSIBLE ACROSS THE S/SE-COAST. && .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/...HIGH CONFIDENCE. 730 AM UPDATE...SMALL CRAFT ADVISORY FOR ALL WATERS TODAY. STILL SEEING AROUND 20 KT GUSTS ON S COASTAL BAYS / SOUNDS PER COASTAL BUOYS AND MESONET OBSERVATIONS THIS MORNING...WHERE SCA REMAINS POSTED. EXPANDED SCA TO INCLUDE ALL WATERS WITH EXPECTED 25 KT GUSTS BEGINNING THIS MORNING AND INTO THIS EVENING...ESP WITHIN FEW MILES OF SHORE. SEAS WILL BUILD TO 5 FT ON OUTER WATERS...WHERE SCA REMAINS IN EFFECT THROUGH MIDNIGHT WHEN SEAS SHOULD SUBSIDE. INCREASING SW WINDS AGAINST DEPARTING TIDE ON BUZZARDS BAY AND WESTERN PORTION OF VINEYARD SOUND SHOULD LEAD TO STEEP WAVES... FIRST THROUGH SUNRISE AND AGAIN THIS AFTERNOON. GUSTS MAY BE MARGINAL ALONG E MA COAST INCLUDING BOS HARBOR BUT DECIDED TO INCLUDE THESE AREAS DUE TO INCREASE IN HOLIDAY RECREATIONAL TRAFFIC. WINDS AND SEAS DIMINISH TONIGHT. SW FLOW PERSISTS MON BUT GUSTS ARE EXPECTED TO REMAIN BELOW SCA. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY NIGHT... MODERATE CONFIDENCE. PERSISTENT SW-FETCH WITH GUSTS AROUND 20-25 KTS AT TIMES. WAVE HEIGHTS IN EXCESS OF 5-FEET MOSTLY ON THE OUTER WATERS BUT GETTING INTO THE S INNER SOUNDS. FOG ANTICIPATED LENDING TO VISIBILITY RESTRICTIONS.
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&& .FIRE WEATHER... STILL HAVE CONCERN FOR ELEVATED FIRE WEATHER SPREAD TODAY GIVEN LOW HUMIDITY /20-30 PERCENT/...GUSTY SW WINDS /20-25 MPH/ AND LACK OF SIGNIFICANT RAINFALL OVER PAST SEVERAL WEEKS. WE WILL ISSUE SPECIAL WEATHER STATEMENT TO ADDRESS THIS CONCERN. PERSISTENT SW FLOW WILL BRING GRADUAL INCREASE IN HUMIDITY THIS WEEK. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ232>235-237. SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ230- 231-236-250-251. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ254>256.
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&& $$ SYNOPSIS...SIPPRELL/JWD NEAR TERM...SIPPRELL/JWD SHORT TERM...JWD LONG TERM...SIPPRELL AVIATION...SIPPRELL/JWD MARINE...SIPPRELL/JWD FIRE WEATHER...WFO BOX STAFF

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