Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 090558 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 158 AM EDT WED JUL 9 2014 .SYNOPSIS... VERY WARM TO HOT WEATHER WILL CONTINUE THROUGH WEDNESDAY WITH A FEW THUNDERSTORMS POSSIBLE...BUT DRY WEATHER WILL DOMINATE. MUCH LOWER HUMIDITY AND SEASONABLE WEATHER RETURNS THURSDAY INTO SATURDAY AS HIGH PRESSURE BUILDS IN BEHIND A COLD FRONT. THE HIGH PRESSURE SYSTEM WILL MOVE OFF THE COAST EARLY NEXT WEEK ALLOWING HUMIDITY TO RETURN ALONG WITH THE RISK OF A FEW SHOWERS/THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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200 AM UPDATE... RADAR HAS QUIETED DOWN OVER THE PAST HOUR LEAVING TO JUST A FEW SCATTERED SHOWERS ACROSS THE CENTRAL HILLS AND SOUTHERN NEW ENGLAND. OTHERWISE THE MAIN FOCUS IN ON THE LOW LEVEL CLOUDS AND FOG POTENTIAL ACROSS THE CAPE AND THE ISLANDS. HOWEVER AS PRE-FRONTAL TROUGH PUSHES EASTWARD...BELIEVE THAT FOG WILL MIX OUT AND LOW LEVEL CLOUDS WILL LIFT. GUSTY SW WINDS WILL CONTINUE INTO THE OVERNIGHT HOURS AS LLJ BEGINS TO INCREASE. BECAUSE OF THE UPPER 60S TO LOW 70S DEWPOINTS ACROSS THE REGION CANNOT RULE OUT A FEW SCATTERED SHOWERS/THUNDER NEAR DAY BREAK ON THE NOSE OF THE LOW LEVEL JET. WILL NEED TO MONITOR THIS POTENTIAL OVERNIGHT. OTHERWISE BULK OF THE FORECAST REMAINS ON TRACK. TEMPS WILL REMAIN IN THE 70S ACROSS THE REGION WITH GUSTY SW WINDS AT 20-25 MPH.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... WEDNESDAY AND WEDNESDAY NIGHT... ANOTHER VERY WARM TO HOT DAY ON TAP FOR THE REGION. ONCE AGAIN HIGHS ARE EXPECTED TO TOP OUT IN THE UPPER 80S AND LOWER 90S. IT WON/T BE QUITE AS HUMID AS THE PAST FEW DAYS AS LOW LEVEL MOISTURE BEGINS TO MIX OUT. LOW CONFIDENCE ON CONVECTIVE POTENTIAL WEDNESDAY AFTERNOON AND EVENING. WILL PROBABLY SEE ABOUT 1000 TO 1500 J/KG OF CAPE...BUT NOT AS MUCH AS THE LAST TWO DAYS WITH LESS LOW LEVEL MOISTURE. 0 TO 6 KM SHEAR IS QUITE IMPRESSIVE FOR JULY STANDARDS ON THE ORDER OF 40 TO 50 KNOTS. HOWEVER...DRY MID LEVEL AIR MAY SIGNIFICANTLY LIMIT UPDRAFT AND CONVECTIVE POTENTIAL. WHILE WE NEVER BASE A FORECAST ON QPF...BELIEVE THIS IS ONE BIG REASON WHY THE MODELS SHOW VERY LITTLE OF IT. WITH ALL THAT SAID...GIVEN VERY HIGH SHEAR AND FRONTAL BOUNDARY SLOWLY WORKING INTO THE REGION THINK WE WILL SEE ISOLATED STORMS BUT WITH LIMITED AREAL COVERAGE. ANY STORM THAT IS ABLE TO DEVELOP COULD BE STRONG TO SEVERE SO STILL NEED TO KEEP A CLOSE EYE ON POTENTIAL. SHOULD SEE DRIER AIR WORK IN BEHIND THE COLD FRONT DURING WEDNESDAY NIGHT...ENDING THE RISK FOR ANY CONVECTION IN MOST AREAS. THE EXCEPTION MAY BE THE SOUTH COAST/CAPE AND ISLANDS...WHERE SCATTERED SHOWERS AND THUNDERSTORMS MAY DEVELOP ON THE NOSE OF THE LOW LEVEL JET AND FRONTAL BOUNDARY PUSHING INTO THE REGION. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... HIGHLIGHTS... * FAIR WEATHER THU AND FRI WITH LOWER HUMIDITY. * SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS LATE SAT/EARLY SUN ALONG WITH THE RETURN OF A MORE HUMID AIRMASS. * BETTER CHANCE OF SHOWERS AND THUNDERSTORMS LATE SUN THROUGH TUE WITH LOCALIZED FLASH FLOODING THE MAIN CONCERN AT THIS TIME. * SEASONABLE TEMPERATURES THROUGH THE PERIOD. OVERVIEW AND MODEL PREFERENCES... AT THE MID LEVELS...A RIDGE OVER WESTERN NOAM AND A MORE PERSISTENT RIDGE OVER THE DAVIS STRAIGHT WILL SUPPORT A MEAN TROUGH INVOF HUDSONS BAY THROUGH THE PERIOD. THIS TROUGH WILL EVOLVE INTO AN ANOMALOUS DEEP /-2 TO -3 SD/ CUT-OFF LOW OVER SOUTHERN CANADA IN THE MON-TUE TIMEFRAME. BOTH GFS AND EC OPERATIONAL RUNS AND THEIR RESPECTIVE ENSEMBLES ARE IN FAIRLY GOOD AGREEMENT ON THIS FEATURE... ALTHOUGH THE OPERATIONAL RUNS ARE A BIT MORE AMPLIFIED AND FURTHER SOUTH. THERE IS UNCERTAINTY WITH REGARD TO THE TIMING AND AMPLITUDE OF SHORTWAVE ENERGY ROTATING THROUGH THIS TROUGH...ESPECIALLY LATE SAT INTO EARLY SUNDAY. THE EC/ECENS INDICATES A DEEPER SHORTWAVE MOVING THROUGH THE AREA WHILE THE GFS SHOWS A WEAKER SHORTWAVE... ALTHOUGH SOME OF THE INDIVIDUAL GEFS ENSEMBLE MEMBERS DO SUPPORT THE EC/ECENS SOLUTION. THE NEXT FEATURE IS A COOL FRONT THAT IS PROGGED TO MOVE THROUGH THE REGION ON TUESDAY. DETAILS... THURSDAY...COOL FRONT SHOULD BE IN THE VICINITY OF CAPE COD CANAL AROUND 12Z...BUT MAY BE SLOW TO EXIT...DUE TO FLOW ALOFT BEING INITIALLY PARALLEL TO IT. THIS MAY CAUSE CLOUDS AND SHOWERS TO LINGER ACROSS COASTAL AREAS EARLY IN THE DAY BUT EXPECT A GRADUAL CLEARING TREND AS THE FRONT MAKES SLOW PROGRESS OFFSHORE. THE FLOW REMAINS CYCLONIC ALOFT...BUT WITH A MUCH DRIER AIRMASS FILTERING INTO THE REGION...EXPECT IT TO BE A DRY DAY OTHERWISE. FRIDAY...A WEAK SHORTWAVE MOVES THROUGH EARLY IN THE MORNING BUT THE COLUMN IS DRY SO NOT EXPECTING ANY PRECIP. WEAK RIDGING THEN BUILDS IN ALOFT DURING THE DAY...AND WITH HIGH PRESSURE CENTERED OVER THE REGION AT THE SURFACE...EXPECTING A DRY DAY. SEA-BREEZES LOOK LIKELY ALONG COASTAL AREAS DUE TO A WEAK GRADIENT. SATURDAY AND SUNDAY...HIGH PRESSURE RIDGE MOVES OFFSHORE AND RETURN FLOW WILL LEAD TO A MORE HUMID AIRMASS BEGINNING SATURDAY. LATE SAT AND INTO SUNDAY...A SHORTWAVE IS PROGGED TO MOVE THROUGH...LEADING TO THE CHANCE OF SHOWERS AND THUNDERSTORMS DURING THIS TIMEFRAME. HOWEVER THE TIMING AND AMPLITUDE OF THIS FEATURE IS UNCERTAIN. MONDAY THROUGH TUE... SEVERAL SHORTWAVE DISTURBANCES WILL ROTATE THROUGH AN ANOMALOUSLY DEEP CUT-OFF LOW IN SOUTHERN CANADA WITH SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS POSSIBLE. ALTHOUGH SEVERE WEATHER POTENTIAL AT THIS TIMEFRAME IS HIGHLY UNCERTAIN... THIS TYPE OF PATTERN DOES FAVOR FLASH FLOODING...SO THIS POTENTIAL WILL NEED TO BE MONITORED. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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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 THURSDAY/... BEFORE 12Z...HIGH CONFIDENCE. VFR CONDITIONS. HOWEVER...MVFR/IFR LOW CLOUDS AND FOG WILL LINGER UNTIL 10-12Z ACROSS THE SOUTHEAST NEW ENGLAND COAST. GUSTY SW WINDS WILL CONTINUE AT AROUND 25 KTS. TODAY AND TONIGHT...MODERATE CONFIDENCE. LOW CLOUDS AND FOG ALONG SOUTHEAST NEW ENGLAND COAST WILL BURN OFF TEMPORARILY DURING THE LATE MORNING AND AFTERNOON...BUT SHOULD REFORM TONIGHT. ACROSS THE REST OF THE REGION MAINLY VFR OUTSIDE A FEW SPOT THUNDERSTORMS THIS AFTERNOON AND EVENING. THURSDAY...HIGH CONFIDENCE. VFR CONDITIONS EXPECT ACROSS THE CAPE AND ISLAND WHERE LINGERING MVFR CLOUDS AND FOG WILL OCCUR. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... FRIDAY THROUGH SUNDAY...LOW CONFIDENCE. VFR...EXCEPT MVFR/IFR POSSIBLE IN SHRA/TSRA OVER THE FAR NORTHWEST INTERIOR..
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...MODERATE TO HIGH CONFIDENCE. GUSTY SOUTHWEST WINDS WILL CONTINUE INTO THE EVENING ACROSS SOME OF OUR NEAR SHORE WATERS...SO THESE SCA HEADLINES WILL CONTINUE INTO PART OF THE EVENING. MEANWHILE...ACROSS THE SOUTHERN OPEN WATERS LONG SOUTHWEST FETCH WILL ALLOW PERSISTENT 4 TO 7 FOOT SEAS INTO AT LEAST WEDNESDAY EVENING. IN ADDITION...AREAS OF FOG ARE EXPECTED LATE TONIGHT INTO WED MORNING AND DEVELOP AGAIN WEDNESDAY NIGHT ACROSS THE SOUTHERN WATERS. THERE ALSO IS A LOW RISK OF A STRONG THUNDERSTORM OR TWO WITH GUSTY WINDS ACROSS THE EASTERN WATERS THIS EVENING. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY...MODERATE CONFIDENCE. A COOL FRONT WILL BE MOVING THROUGH THE WATERS EARLY IN THE DAY WITH A CHANCE SHOWERS AND THUNDERSTORMS. SEAS WILL BE AT SCA THRESHOLDS /5-6 FEET/ BUT DECLINING THROUGH THE DAY. FRIDAY THROUGH SUNDAY...HIGH CONFIDENCE. HIGH PRESSURE BUILDS INTO THE REGION...EXCEPT WINDS AND SEAS BELOW SCA THRESHOLDS. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ235-237. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ254>256.
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&& $$ SYNOPSIS...FRANK NEAR TERM...DUNTEN SHORT TERM...FRANK LONG TERM...99 AVIATION...DUNTEN/99 MARINE...FRANK/99

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