Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 282352 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 752 PM EDT TUE JUL 28 2015 .SYNOPSIS... ISOLATED TO SCATTERED THUNDERSTORMS WILL COME TO AN END THIS EVENING. OTHERWISE...HOT AND HUMID CONDITIONS EXPECTED THROUGH THURSDAY. A COLD FRONT WILL BRING SCATTERED THUNDERSTORMS LATE THURSDAY AND THURSDAY NIGHT. WARM AND LESS HUMID WEATHER IS EXPECTED FRIDAY INTO THE WEEKEND. THERE WILL BE CHANCES FOR MORE SHOWERS AND THUNDERSTORMS LATE THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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730 PM UPDATE... LAST OF WEAKENING SHOWERS HAVE MOVED OFF THE RI COAST AND IN THE VICINITY OF KBID AT 2330Z. THE ISOLD SHOWERS THAT DEVELOPED INLAND W OF KORH AND NEAR KBED HAVE ALSO MOSTLY DISSIPATED. NOTING LEFTOVER DEBRIS CLOUDS FROM THE CONVECTION HANGING ACROSS INTERIOR MA/RI/NE CT ON LATEST IR SATELLITE IMAGERY. SHOULD SEE THOSE CLOUDS TEND TO DISSIPATE. HOWEVER...MORE CLOUDS MOVE MAY TRAVERSE ACROSS THE REGION IN THE N-NW FLOW ALOFT OUT OF N NEW ENGLAND AND UPSTATE NY OVERNIGHT. NOTING LOW CLOUDS ALREADY AT KACK...SO WILL LIKELY SEE LOW CLOUDS EXPAND ALONG THE S COAST IN THE SOUPY AIRMASS. PATCHY FOG WILL LIKELY DEVELOP ESPECIALLY IN AREAS WHERE RAIN FELL THIS AFTERNOON INTO THE EVENING. HAVE UPDATED NEAR TERM FORECAST TO BRING CONDITIONS CURRENT. PREVIOUS DISCUSSION... EXPECT DRY WEATHER TO PREVAIL FOR THE REST OF THE NIGHT. LOW TEMPS WILL RANGE FROM THE LOWER TO MIDDLE 60S IN THE OUTLYING LOCATIONS WITH UPPER 60S TO LOWER 70S IN THE URBAN HEAT ISLANDS OF DOWNTOWN BOSTON AND PROVIDENCE.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... ***HOT BUT DRY WEATHER ON WEDNESDAY*** UPPER LEVEL RIDING WILL BUILD ACROSS SOUTHERN NEW ENGLAND. THIS SHOULD RESULT IN PARTLY TO MOSTLY SUNNY SKIES...DESPITE SOME DIURNAL CUMULUS CLOUDS. 850 MB TEMPS AROUND +18C WILL YIELD HIGHS BETWEEN 90 AND 95 ACROSS MOST OF THE REGION. WEAK PRESSURE GRADIENT WILL RESULT IN TEMPS A BIT COOLER ALONG PORTIONS OF THE COAST. WHILE THERE IS A LOW RISK OF A VERY ISOLATED SHOWER/THUNDERSTORM...GIVEN UPPER LEVEL RIDGING OPTED FOR A DRY FORECAST. EVEN IF ONE WERE TO HAPPEN IT PROBABLY WOULD BE VERY BRIEF AND COVER SUCH A SMALL AREA OF OUR REGION...NOT WORTH A MENTION AT THIS POINT. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... SYNOPTIC OVERVIEW AND MODEL PREFERENCES... AS H5 CUTOFF LOW SETS UP ACROSS HUDSON BAY/ONTARIO/W QUEBEC AND A NEGATIVE NAO PATTERN IN PLACE...A FAST UPPER FLOW WILL CONTINUE ACROSS THE NORTHERN STREAM THROUGH THIS PERIOD. SHORT WAVES IN THIS FLOW WILL BRING CHANCES FOR SHOWERS/THUNDERSTORMS...THOUGH TIMING OF EACH INDIVIDUAL SYSTEM IS IN QUESTION BEYOND FRIDAY DUE TO THE FAST FLOW. MAY START TO SEE THIS LONG WAVE PATTERN BREAK DOWN EARLY NEXT WEEK...THOUGH LOW CONFIDENCE ON THIS TIMING THIS FAR OUT. NOTED VERY GOOD CONTINUITY AND TIMING OF APPROACHING SYSTEM LATE THIS WEEK AMONGST THE MEDIUM MODEL SUITE...THEN TIMING AND PLACEMENT OF SYSTEMS THIS WEEKEND INTO EARLY NEXT WEEK IN QUESTION. SO... WENT WITH A BLEND OF 12Z GFS/00Z ECMWF OP MODEL RUNS THROUGH FRIDAY NIGHT...THEN TRANSITIONED OVER TO AN OVERALL BLEND OF AVAILABLE GUIDANCE INCLUDING GEFS/ECENS LATER IN THE PERIOD WHICH GAVE GOOD CONSISTENCY. WEDNESDAY NIGHT... WEAK SHORT WAVE RIDGING WILL CROSS THE REGION WED NIGHT. WILL SEE SULTRY CONDITIONS...WHICH WILL LIKELY LEAD TO PATCHY FOG WHICH MAY BECOME LOCALLY DENSE ALONG THE S COAST...CAPE COD AND THE ISLANDS AFTER MIDNIGHT. EXPECT OVERNIGHT LOWS IN THE UPPER 60S TO LOWER 70S THOUGH A BIT MILDER IN THE URBAN CENTERS. THURSDAY THROUGH FRIDAY NIGHT... PRETTY VIGOROUS H5 SHORT WAVE MOVES ALONG IN W-NW FLOW ALOFT. CURRENT TIMING SUGGESTS ARRIVING AFTER 18Z THU ACROSS THE E SLOPES OF THE BERKSHIRES THAN PUSHING INTO THE CT VALLEY LATE IN THE DAY. LOOKS LIKE MOST ACTION WILL OCCUR THU NIGHT INTO FRI AS FRONT MOVES SLOWLY BUT STEADILY ACROSS. WITH GOOD PUSH OF DRIER AIR BEHIND THIS FRONT...NOTING PWATS INCREASE TO 1.9 TO 2.1 INCHES DURING THE NIGHT WITH HIGHEST VALUES ACROSS S COASTAL AREAS. ALSO GOOD ELEVATED CONVECTION SIGNALS...WITH TQ VALUES IN THE LOW 20S ALONG WITH K INDICES IN THE MID 30S. SPC HAS ALSO MENTIONED MARGINALLY SEVERE CONDITIONS AS THE PRECIP MOVES INTO FAR WESTERN AREAS LATE IN THE DAY. SOMETHING TO BE WATCHED. HAVE LIKELY SHOWERS/SCT TSTMS MOVING ACROSS THE REGION OVERNIGHT. ALSO USED ENHANCED WORDING FOR HEAVY RAINFALL. EXPECT FRONT TO CLEAR THE COAST FRI MORNING. ISOLD THUNDER MAY LINGER THROUGH MID MORNING AS BEST INSTABILITY MOVES OFFSHORE. SOME SHOWERS MAY LINGER ACROSS THE CAPE AND ISLANDS UNTIL AROUND MIDDAY THEN SHOULD EXIT. NOTING A BRIEF BREAK IN THE HUMID CONDITIONS AS DEWPTS FALL BACK TO THE 50S AWAY FROM THE COAST. TEMPS WILL STILL BE WARM THOUGH...WITH HIGHS MAINLY IN THE LOWER- MID 80S. FRIDAY NIGHT WILL BE DRY AND COMFORTABLE ESPECIALLY ACROSS CENTRAL AND W MA INTO N CT. EXPECT LOWS IN THE 60S...THOUGH MAY LINGER AROUND 70 ACROSS THE OUTER CAPE AND ISLANDS. SATURDAY-SUNDAY... NOTING ANOTHER DIP IN THE LONG WAVE TROUGH ACROSS THE GREAT LAKES AS A SHORT WAVE MOVES IN THE UPPER FLOW. OPERATIONAL MODELS HAVING TROUBLE HANDLING THIS FEATURE...THOUGH DOES LOOK LIKE THERE MAY BE SOME ISOLD SHOWER/TSTM ACTIVITY AS WEAK FRONT CROSSES SAT NIGHT INTO SUN MORNING. LOOKS LIKE BEST SHOT FOR NOW WILL BE ACROSS THE CT VALLEY AND ALONG E COAST...THOUGH COULD SEE ISOLD ACTIVITY ANYWHERE. SOMEWHAT LOWER CONFIDENCE DURING THIS TIMEFRAME. MONDAY-TUESDAY... THE H5 CLOSED LOW OVER HUDSON/JAMES BAYS HINTS IN SHIFTING SLOWLY E ACROSS N QUEBEC DURING THIS TIMEFRAME...BUT STILL SEEING LONG WAVE TROUGHING ACROSS THE GREAT LAKES. MAY SEE PERIODS OF SHOWERS/TSTMS MAINLY DURING THE DAYLIGHT HOURS BOTH MON AND TUE...THOUGH SOME QUESTION ON EXACT TIMING THIS FAR OUT. WILL REMAIN WARM AND HUMID DURING THIS TIMEFRAME. && .AVIATION /00Z 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 WEDNESDAY AFTERNOON/... TONIGHT...MODERATE CONFIDENCE. EXPECT MAINLY VFR CONDITIONS. WILL LIKELY SEE PATCHY FOG DEVELOP ALONG S COAST AND TYPICALLY PRONE INLAND LOCATIONS WITH LOCAL MVFR-IFR VSBYS. MAY ALSO SEE IFR-LIFR CIGS MAINLY ACROSS CAPE COD AND THE ISLANDS. ANY ISOLATED TO SCATTERED CONVECTION SHOULD COME TO AN END BY 7 OR 8 PM. OTHERWISE...VFR FOR MOST SITES EXCEPT FOR SOME PATCHY FOG IN THE TYPICALLY PRONE LOCATIONS. ALSO...CANNOT RULE OUT IFR IN STRATUS AND FOG ACROSS FAR SE MASS INCLUDING THE CAPE AND ISLANDS...BUT CONFIDENCE IN THAT IS LOW. WEDNESDAY...HIGH CONFIDENCE IN VFR CONDITIONS. KBOS TERMINAL...HIGH CONFIDENCE IN MAINLY VFR THROUGH TONIGHT. CONVECTION WILL LIKELY REMAIN WEST OF THE BOSTON TERMINAL...BUT STILL A LOW RISK THAT SOMETHING COULD DEVELOP THROUGH 8 PM KBDL TERMINAL...HIGH CONFIDENCE IN MAINLY VFR THROUGH TONIGHT. VERY LOW RISK OF AN ISOLATED THROUGH 8 PM. OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/... WEDNESDAY NIGHT...MODERATE TO HIGH CONFIDENCE. WILL SEE PATCHY FOG WITH MVFR-IFR CONDITIONS MAINLY NEAR OR AFTER MIDNIGHT. THURSDAY...MODERATE CONFIDENCE. PATCHY MVFR-IFR IN FOG IMPROVING TO VFR BY MID MORNING. HOWEVER...LOW PROB THAT MVFR-IFR IN LOW CLOUDS AND PATCHY FOG MAY LINGER ALONG THE SOUTH COAST. CHANCE OF SHOWERS AND THUNDERSTORMS MOVE INTO WESTERN AREAS AFTER 18Z...THEN SHIFTING E BY EVENING. THURSDAY NIGHT...MODERATE CONFIDENCE. PATCHY MVFR CIGS/VSBYS IN SCATTERED SHOWERS/THUNDERSTORMS. LOCALLY HEAVY RAINFALL LIKELY... ESPECIALLY ACROSS RI/SE MA AROUND OR AFTER MIDNIGHT. IMPROVING CONDITIONS AFTER MIDNIGHT ACROSS N CENTRAL AND W MA INTO N CENTRAL CT. FRIDAY AND SATURDAY...MODERATE TO HIGH CONFIDENCE. LINGERING SHOWERS/ISOLD THUNDERSTORMS AND PATCHY FOG ALONG S COAST... OTHERWISE MAINLY VFR THROUGH THE REMAINDER OF FRIDAY THROUGH SAT. ISOLD SHOWERS/TSTMS POSSIBLE SAT NIGHT WITH LOCAL MVFR CONDITIONS. LOWER CONFIDENCE ON TIMING. SUNDAY...MODERATE CONFIDENCE. MAINLY VFR.
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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 AFTERNOON/...HIGH CONFIDENCE. WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH WEDNESDAY AFTERNOON. MAIN CONCERN WILL BE A FEW STRONG TO SEVERE STORMS ACROSS THE ADJACENT SOUTH COASTAL WATERS THROUGH 7 OR 8 PM. LOCALLY STRONG WIND GUSTS AND PERHAPS ISOLATED HAIL ARE THE MAIN CONCERNS. ALSO...SOME PATCHY FOG IS POSSIBLE THIS EVENING NEAR THE ISLANDS BUT VISIBILITIES SHOULD IMPROVE AFTER MIDNIGHT AS WINDS TURN WEST. OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/... WEDNESDAY NIGHT AND THURSDAY...EXPECT LIGHT SW WINDS WED NIGHT INTO THU...THEN PICKING UP DURING THU AFTERNOON. MAY SEE GUSTS TO 20 KT. SEAS 4 FT OR LESS. PATCHY FOG WED NIGHT INTO THU MORNING LOWERING VSBYS. THURSDAY NIGHT...SW WINDS GUSTING TO 20 KT MAINLY OVER THE OPEN WATERS. SEAS REACHING AROUND 5 FT. PATCHY FOG ALONG WITH SCT SHOWERS/TSTMS LOWERING VSBYS. FRIDAY AND SATURDAY...COLD FRONT SLOWLY MOVES OFFSHORE. ANOTHER WEAK FRONT MAY ENTER THE WATERS LATE SAT OR SAT NIGHT. SEAS OVER THE OPEN WATERS UP TO AROUND 5 FT DURING FRI...SUBSIDING FRI NIGHT BUT MAY BUILD AGAIN SAT NIGHT. SUNDAY...WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...AIR QUALITY ALERT FROM 11 AM TO 11 PM EDT WEDNESDAY FOR MAZ017>024. RI...AIR QUALITY ALERT FROM 11 AM TO 11 PM EDT WEDNESDAY FOR RIZ005>008. MARINE...NONE. && $$ SYNOPSIS...FRANK/EVT NEAR TERM...FRANK/EVT SHORT TERM...FRANK LONG TERM...EVT AVIATION...FRANK/EVT MARINE...FRANK/EVT

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