Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 291106 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 706 AM EDT WED JUL 29 2015 .SYNOPSIS...
-- Changed Discussion --
HOT AND HUMID CONDITIONS TODAY THROUGH THURSDAY. A COLD FRONT WILL BRING SCATTERED THUNDERSTORMS LATE THURSDAY AND THURSDAY NIGHT. NOT AS WARM AND LESS HUMID WEATHER IS EXPECTED FRIDAY INTO THE WEEKEND AND PROBABLY INTO EARLY NEXT WEEK. WHILE FRIDAY THROUGH EARLY NEXT WEEK WILL BE MAINLY DRY...CAN/T RULE OUT AN AFTERNOON AND EVENING THUNDERSTORM EACH DAY.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 7 PM THIS EVENING/...
-- Changed Discussion --
*** HEAT ADVISORY HARTFORD/SPRINGFIELD METRO REGIONS TODAY *** 7AM UPDATE... ONLY CHANGE TO PREVIOUS FORECAST WAS TO DISCONTINUE THE DENSE FOG ADVISORY FOR THE ISLANDS AS VISIBILITIES HAVE IMPROVED. OFF TO A VERY WARM START ALREADY WITH BOSTON AT 76...WORCESTER AND PROVIDENCE 73. AS MENTIONED BELOW NEAR RECORD HIGHS TODAY WITH BDL MOST VUNERABLE OF TYING OR BREAKING THE RECORD. EARLIER DISCUSSION BELOW. ==================================================================== TODAY... MID-LEVEL RIDGE AXIS WILL CREST OVER THE REGION. THIS WILL ALLOW FOR THE MUGGY AIRMASS TO REMAIN IN PLACE. 850MB TEMPS WARM TO 18-20C THIS AFTERNOON WHICH IS SEVERAL DEGREES WARMER THEN YESTERDAY. THEREFORE HAVE HIGH CONFIDENCE THAT TEMPERATURES WILL BE SEVERAL DEGREES WARMER THEN YESTERDAY...WITH HIGHS IN THE LOW TO MID 90S WITH UPPER 90S ACROSS THE CT VALLEY. DEWPOINTS WILL BE IN THE MID 60S AND WITH LIGHT WINDS. THIS HUMIDITY COMBINED WITH NEAR RECORD TEMPERATURES WILL LEAD TO HEAT INDICES IN THE LOW TO MID 90S. HOWEVER ACROSS THE CT VALLEY REGION...ESP IN THE HARTFORD/SPRINGFIELD METRO REGIONS HEAT INDICES WILL REACH BETWEEN 98 AND 101. THEREFORE HAVE ISSUED A HEAT ADVISORY FOR THIS REGION. THERE IS THE POTENTIAL THAT THE DAY SHIFT MAY EXPAND IF TEMPS AND/OR DEWPOINTS INCREASE MORE THAN FORECASTED. ASIDE FROM THE HEAT...FORECAST SHOULD REMAIN DRY FOR MUCH OF THE DAY. CANNOT RULE OUT A SPOT SHOWER TODAY IF LOCATIONS REACH THEIR CONVECTIVE TEMPERATURES...ESP ACROSS THE HIGHER TERRAIN. HOWEVER BECAUSE IT WILL BE A ROGUE SHOWER HAVE KEPT THE FORECAST DRY.
-- End Changed Discussion --
&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM THURSDAY/... TONIGHT... DRY WEATHER WILL RESUME TONIGHT. HOWEVER THERE COULD BE ANOTHER ROUND OF FOG ESP FOR THE SOUTH COAST...CAPE AND ISLANDS WHERE DEWPOINTS WILL BE HIGHEST. OTHERWISE A MUGGY AND MILD NIGHT WILL BE ON TAP WITH TEMPS DROPPING INTO THE LOW 70S. TOMORROW... DESCENT SHORTWAVE WILL MOVE THROUGH THE FLOW ON THURSDAY PUSHING A COLD FRONT ACROSS THE AREA. WARM...HUMID AIRMASS WITH SOUTHERLY FLOW WILL BE IN PLACE AHEAD OF THIS APPROACHING FRONT. THE SOUTHERLY FLOW WILL ALLOW FOR MUCH OF THE REGION TO HAVE 70+ DEWPOINTS. THIS WILL HELP KEEP TEMPS SLIGHTLY LOWER...IN THE UPPER 80S TO LOW 90S. HEAT INDICES WILL STILL BE HIGH...REACHING INTO THE LOW TO MID 90S. 00Z GUIDANCE IS IN GOOD AGREEMENT ON TIMING OF THE FRONT. IN FACT MOST MODELS HAVE SPED THIS SYSTEM UP BY ABOUT 6+ HOURS. SHOWERS AND THUNDERSTORMS WILL BEGIN TO MOVE INTO THE REGION AROUND 18Z AND PUSH ACROSS THE AREA BY THURSDAY NIGHT. A FEW STRONG TO A SEVERE STORM IS POSSIBLE AS INSTABILITY WILL BE QUITE HIGH WITH MARGINAL MID-LEVEL LAPSE RATES. SHEAR VALUES LOOK TO BE ALONG OR BEHIND THE FRONT...WHICH COULD LIMIT STRONG/SEVERE POTENTIAL. BIGGEST THREAT WITH THESE STORMS APPEARS TO BE HEAVY DOWNPOURS LEADING TO NUISANCE FLOODING AS PWAT VALUES ARE ABOUT 2+ INCHES. GUSTY WINDS/LOCALIZED DOWNBURST ALSO CANNOT BE RULE OUT DUE TO THE INVERTED-V SOUNDINGS. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... HIGHLIGHTS... * PATTERN CHANGE TO MORE SEASONABLE TEMPS IS ACCOMPANIED BY SHOWERS AND THUNDERSTORMS THU NIGHT * NOT AS WARM AND HUMID FRIDAY AND BEYOND * MAINLY DRY WEATHER PREVAILS FRIDAY THRU TUESDAY SYNOPTIC OVERVIEW AND MODEL PREFERENCES... IMPRESSIVE AND ANOMALOUS VORTEX CURRENTLY OVER SOUTHERN MANITOBA AS SEEN ON THE LATEST WATER VAPOR IMAGERY WILL BECOME THE MAIN WEATHER FEATURE THIS PERIOD...AS IT EVOLVES INTO A MUCH BROADER CIRCULATION OVER JAMES AND HUDSON BAY THIS WEEKEND AND NEXT WEEK. THIS RESULTS IN A BROAD MEAN LONG WAVE TROUGH SETTING UP ACROSS THE GREAT LAKES AND THE NORTHEAST. THIS WILL SUPPRESS EXCESSIVE HEAT AND HUMIDITY AIRMASS CURRENTLY OVER THE AREA SOUTHWARD BEGINNING FRIDAY AND LASTING THRU THE WEEKEND INTO EARLY NEXT WEEK. GIVEN GOOD MULTI MODEL AGREEMENT AMONG DETERMINISTIC AND ENSEMBLE GUIDANCE REGARDING THE LARGE SCALE FLOW THIS PERIOD...FORECAST CONFIDENCE IS ABOVE AVERAGE. DAILY SENSIBLE WEATHER DETAILS... THURSDAY NIGHT... NORTHERN STREAM SHORT WAVE AND ATTENDING COLD FRONT MOVE ACROSS THE AREA. MODEST SYNOPTIC SCALE FORCING ASSOCIATED WITH THIS FEATURE. WHILE INSTABILITY AND SHEAR IS MARGINAL IN THE PREFRONTAL ENVIRONMENT...PWATS CLIMB TO 2+ INCHES /+2 STD DEVIATIONS ABOVE CLIMO/. THUS GREATER RISK OF HEAVY DOWNPOURS AND LOCALIZED FLOODING. WARM AND MUGGY CONDITIONS PREVAIL AS POST FRONTAL AIRMASS DOESN/T ARRIVE UNTIL FRIDAY. FRIDAY THRU TUESDAY... TREND TOWARD MORE SEASONABLE TEMPERATURES AND LOWER HUMIDITY ARRIVES FRIDAY BEHIND DEPARTING COLD FRONT WITH HIGHS IN THE 80S AND LOWS IN THE 60S. TOO DIFFICULT AT THIS TIME RANGE TO TIME INDIVIDUAL SHORT WAVES EMBEDDED IN THE CYCLONIC FLOW. SO BEST WORDING WOULD BE MANY HOURS OF DRY WEATHER THIS PERIOD BUT CYCLONIC FLOW AND COOLER TEMPS ALOFT WILL RESULT IN THE RISK OF A THUNDERSTORM DURING PEAK HEATING HOURS EACH DAY. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY/... 7 AM UPDATE... NO MAJOR CHANGES FROM 06Z AND 09Z TAFS. EARLIER DISCUSSION BELOW. ================================================================= TONIGHT...MODERATE CONFIDENCE. VFR FOR MANY SITES...HOWEVER ANTICIPATE PATCHY DENSE FOG HAS DROPPED SOME SITES DOWN TO IFR OR EVEN LIFR. BEST LOCATIONS IS ACROSS THE CAPE...ISLANDS AND SOUTH COAST WHERE DEWPOINTS ARE IN THE 70S. TODAY INTO TONIGHT...HIGH CONFIDENCE IN VFR CONDITIONS. MAY SEE PATCHY FOG OVERNIGHT DROPPING CONDITIONS TO IFR. THURSDAY...VFR TO START CONDITIONS DROPPING TO MVFR IN -SHRA/TSRA BETWEEN 18-00Z. A FEW STRONG STORMS ARE POSSIBLE. KBOS TERMINAL...HIGH CONFIDENCE. SEA BREEZE DEVELOPS BETWEEN 14-15Z. KBDL TERMINAL...HIGH CONFIDENCE. OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/... THURSDAY NIGHT...MVFR AND IFR IN SCATTERED SHOWERS/T-STORMS AND FOG. MODERATE TO HIGH FORECAST CONFIDENCE. FRIDAY AND SATURDAY...MODERATE TO HIGH CONFIDENCE IN VFR CONDITIONS. VERY LOW RISK FOR AN AFTERNOON T-STORM SATURDAY. SUNDAY...MODERATE CONFIDENCE FOR MAINLY VFR.
-- End Changed Discussion --
&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH THURSDAY/...HIGH CONFIDENCE. WINDS AND SEAS BELOW SCA TODAY AND TONIGHT HAS HIGH PRESSURE WILL BE IN PLACE. APPROACHING COLD FRONT ON THURSDAY WILL INCREASE WINDS ALONG THE SOUTHERN WATERS. COULD SEE SOME GUSTY NEAR 25 KTS. PERSISENT SOUTHERLY SWELL WILL INCREASE SEAS BETWEEN 4-6 FEET. A SCA MAY BE NEEDED ON THURSDAY. OUTLOOK /THURSDAY NIGHT THROUGH SATURDAY/... THURSDAY NIGHT...SW WINDS 15 TO 20 KT WITH GUSTS UP TO 25 KT POSSIBLE. ROUGH SEAS ON SOUTH OCEAN WATERS WITH WIND WAVES OF 3 TO 6 FT POSSIBLE. VSBY REDUCED IN SCATTERED SHOWERS/TSTMS AND FOG. MODERATE TO HIGH FORECAST CONFIDENCE. FRIDAY/SATURDAY AND SUNDAY...COLD FRONT SLOWLY MOVES OFFSHORE WITH WIND SHIFT FROM SSW TO WSW. DRY WEATHER AND GOOD VSBY. HIGH FORECAST CONFIDENCE. LEFTOVER SOUTHERLY SWELLS ON SOUTH OCEAN WATERS FROM THU NIGHT LINGER FRI BUT SLOWLY DIMINISH. && .CLIMATE... RECORD HIGHS FOR 7/29: BOSTON97 ON 1933 & 1931 PROVIDENCE95 ON 2002 & 1949 BRADLEY96 ON 1933 WORCESTER94 ON 1892 && .BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...HEAT ADVISORY FROM NOON TODAY TO 7 PM EDT THIS EVENING FOR CTZ002. MA...AIR QUALITY ALERT FROM 11 AM THIS MORNING TO 11 PM EDT THIS EVENING FOR MAZ017>024. HEAT ADVISORY FROM NOON TODAY TO 7 PM EDT THIS EVENING FOR MAZ011. RI...AIR QUALITY ALERT FROM 11 AM THIS MORNING TO 11 PM EDT THIS EVENING FOR RIZ005>008. MARINE...NONE.
-- End Changed Discussion --
&& $$ SYNOPSIS...NOCERA/DUNTEN NEAR TERM...DUNTEN SHORT TERM...DUNTEN LONG TERM...NOCERA AVIATION...NOCERA/DUNTEN MARINE...NOCERA/DUNTEN CLIMATE...

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.