Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 071745 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 145 PM EDT MON JUL 7 2014 .SYNOPSIS... INCREASING HEAT AND HUMIDITY WILL RETURN THROUGH MIDWEEK AHEAD OF A SLOW MOVING COLD FRONT. WHILE DRY WEATHER WILL DOMINATE...A FEW THUNDERSTORMS WILL BE POSSIBLE AT TIMES THIS EVENING INTO WED WITH THE BEST CHANCE ACROSS THE INTERIOR. A FEW ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THU IF THE COLD FRONT MOVES SLOWER...BUT DRY WEATHER WITH LOWER HUMIDITY WILL ARRIVE BY THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 145 PM UPDATE... SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED AT MID AFTERNOON ACROSS EASTERN NY AND PA. ONE CLUSTER OF SHOWERS AND STORMS ACROSS EASTERN NY MAY AFFECT OUR NORTHWEST ZONES AS WE APPROACH 3 PM. ADDITIONAL SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO EXPECTED TO DEVELOP TO OUR WEST THROUGH THE AFTERNOON. INSTABILITY WILL CONTINUE TO INCREASE...SO THE BEST CHANCE FOR A FEW STRONG TO SEVERE THUNDERSTORMS WILL BE AFTER 3 OR 4 PM ACROSS SOUTHWEST NH/WESTERN MA AND UNTIL ABOUT 10 OR 11 PM. LOOKS LIKE WILL HAVE AROUND 1000 TO 1500 J/KG OF CAPE WITH 0 TO 6 KM SHEAR ON THE ORDER OF 30 TO 35 KNOTS...SO CERTAINLY THE THREAT OF A FEW STRONG TO SEVERE STORMS IN WESTERN MA/SOUTHWEST NH. THE PRIMARY THREAT WILL BE LOCALIZED STRONG TO DAMAGING WIND GUSTS GIVEN DECENT SPEED SHEAR...BUT A FEW REPORTS OF LARGE HAIL ARE ALSO POSSIBLE. IN ADDITION...PWATS ON THE ORDER OF 1.75 INCHES WILL ALSO SUPPORT BRIEF TORRENTIAL RAINFALL WITH THE STRONGEST STORMS. THE ACTIVITY SHOULD WEAKEN THIS EVENING AS IT TRIES TO ENTER EASTERN MA AND RHODE ISLAND. HOWEVER...WE CAN/T RULE OUT A FEW LEFT OVER THUNDERSTORMS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... TONIGHT... WHILE SFC INSTABILITY DIMINISHES IT DOES NOT GO AWAY COMPLETELY WHILE DEEP LAYER SHEAR INCREASES AS SHORTWAVE MOVES INTO THE REGION WHICH SHOULD ALLOW SCT SHOWERS/TSTMS TO PERSIST INTO THE EVENING...SOME OF WHICH MAY BE STRONG TO SEVERE. ALSO CANT RULE OUT A FEW SHOWERS OR A TSTM MAKING TO THE COASTAL PLAIN AS ELEVATED KI AXIS MOVES EAST ACROSS SNE. SOME DRYING EVENTUALLY MOVES IN FROM THE NORTH OVERNIGHT. MIN TEMPS MID 60S TO LOWER 70S WITH LATE NIGHT PATCHY FOG POSSIBLE. TUESDAY... PERSISTENT SW FLOW CONTINUES WITH 850 MB TEMPS NEAR 18C. WITH PT- MOSUNNY SKIES TEMPS SHOULD REACH UPPER 80S TO LOWER 90S...EXCEPT COOLER SOUTH COAST. IT WILL BE RATHER HUMID WITH DEWPOINTS NEAR 70 DEGREES. MAIN FOCUS FOR CONVECTION WILL BE TO THE WEST WHERE BETTER DYNAMICS ASSOCD WITH RIGHT ENTRANCE REGION OF UPPER JET. HOWEVER...SBCAPES INCREASE TO 1000-2000 J/KG SO SCT LATE DAY AND EVENING SHOWERS/TSTMS POSSIBLE. ANY STORMS WILL HAVE THE POTENTIAL TO BECOME SEVERE AS 0-6KM SHEAR INCREASES TO 35-40 KT BUT UPPER JET DYNAMICS SUGGEST MAIN ACTIVITY WILL REMAIN TO THE WEST THROUGH THE DAY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGHLIGHTS... * VERY WARM/HOT AND HUMID TUE NIGHT AND WED * A FEW THUNDERSTORMS POSSIBLE TUE NIGHT...WED...AND PERHAPS INTO THU * DRIER AND LESS HUMID AIR RETURNS BY THE END OF THE WEEK OVERVIEW AND MODEL PREFERENCES... THE OVERALL PATTERN ACROSS THE ERN CONUS WILL REMAIN UNDER THE INFLUENCE OF LONGWAVE TROF EXTENDING FROM HUDSON BAY INTO ONTARIO AND QUEBEC THROUGH MUCH OF THE LONG TERM. INITIALLY...THE BASE OF THIS TROF LIES ACROSS THE GREAT LAKES...LEAVING NEW ENGLAND IN SW FLOW AND THEREFORE WARMING TEMPS AND HIGHER DWPT AIR. IT/S NOT UNTIL THIS BASE SHIFTS FURTHER E BY LATE IN THE WEEK...THAT THE COOLER/DRIER AIR IS ALLOWED TO MOVE IN ALONG WITH SFC HIGH PRES. HOWEVER...EVEN WITH THE WEAK RIDGE ASSOCIATED WITH THE HIGH PRES MOVING IN FOR THE WEEKEND...S FEW CUTOFF LOW PRES CENTERS CONTINUE TO FUJIWHARA AROUND HUDSON BAY...ALLOWING YET ANOTHER LONGWAVE TROF TO DEVELOP BY EARLY NEXT WEEK. ALTHOUGH THERE ARE SOME SLIGHT DIFFERENCES...MUCH OF THE AVAILABLE LONG RANGE GUIDANCE IS IN AGREEMENT WITH THESE SYNOPTIC SCALE FEATURES. THEREFORE...A BLEND OF GUIDANCE WILL BE USED AS A BASELINE. THE ONLY CAVEAT WILL BE THU...WHERE MORE WEIGHT WILL BE GIVEN TO THE ECMWF DUE TO ITS CONSISTENCY WITH COLD FRONTAL TIMING...SOMETHING THE GFS AND MANY ENSEMBLE MEMBERS ARE BEGINNING TO AGREE WITH. DETAILS... TUE NIGHT INTO WED... SHORTWAVE ENERGY IS LIKELY TO PASS BY TUE NIGHT...SO ITS POSSIBLE THE BULK OF CONVECTION ASSOCIATED WITH VERY MOIST/UNSTABLE AIRMASS IN PLACE HOLDS OFF UNTIL MAINLY THE OVERNIGHT HOURS ON TUE. INDEED THE 1000+ J/KG SB CAPE DOES NOT DIP TOO MUCH AFTER 00Z WED...K VALES AND PWATS WELL ABOVE 1.5 INCHES ALSO SUGGEST A LOT OF MOISTURE REMAINS THROUGH THE COLUMN. FINALLY...W ORIENTED SHEAR REMAINS AROUND 30-35 KT. THEREFORE...SOME NOCTURNAL CONVECTION IS POSSIBLE...SO WILL MAINTAIN POPS AND HEAVY RAIN WORDING AT LEAST THROUGH 06Z AS THE SHORTWAVE MOVES THROUGH. OVERNIGHT MINS REMAIN ELEVATED...UPPER 60S AND LOW 70S. FOR WED...ITS TRICKY. SOUNDINGS SUGGEST DRY AIR BEGINS TO MOVE IN ALOFT...HOWEVER THE SAME MOIST/WARM AIRMASS REMAINS IN PLACE AT THE SFC...YIELDING 1000-2000J/KG SB CAPE VALUES ONCE AGAIN. HOWEVER...SHEAR IS QUITE HIGH...ON THE ORDER OF 45 KT. THE ISSUE AT HAND IS WHETHER OVERNIGHT CONVECTION...THE DRY AIR ALOFT OR THE RELATIVE LACK OF A TRIGGER WILL BE ENOUGH TO PRECLUDE CONVECTIVE ACTIVITY. THERE IS SOME SUPPORT AS THE RIGHT ENTRANCE REGION OF STRONG UPPER JET LINES UP ACROSS SRN NEW ENGLAND. FOR NOW...WILL CONTINUE TO SUGGEST SLIGHT TO CHANCE POPS WITH TS. THIS WILL DEFINITELY HAVE TO BE WATCHED HOWEVER...AS ANOTHER ROUND OF HIGH INSTABILITY COMBINED WITH THE VERY STRONG SHEAR AND VENTING JET SETUP ALOFT...IF ANYTHING FIRES...COULD YIELD MORE WIDESPREAD OR STRONGER SEVERE WX. THERE ARE JUST SOME MITIGATING FACTORS TO WORK THROUGH. THU... AS MENTIONED ABOVE...THE KEY FOR THU WEATHER WILL BE THE TIMING OF THE COLD FRONT WHICH WILL ALLOW DRIER/COOLER AIR TO FINALLY FILTER INTO SRN NEW ENGLAND. WILL LEAN ON THE ECMWF WHICH HAS BEEN MORE CONSISTENT...AND OTHER GUIDANCE LOOKS LIKE IT MAY BE CATCHING UP. THEREFORE...THE FRONT IS LIKELY TO MOVE THROUGH SLOWLY DURING THE DAY...AND MAY NOT EVEN BE OFFSHORE UNTIL THU NIGHT. THEREFORE...WILL MAINTAIN THE HIGHER THAN NORMAL DWPTS AND HUMIDITY THROUGH THE DAY AND KEEP POPS/TS RISK. NOT QUITE AS CONCERNED AT THIS POINT ABOUT SEVERE WX FOR THU AS DRIER AIR AND SUBSIDENCE INVERSION MAY LIMIT CAPE VALUES...BUT IT WILL STILL HAVE TO BE WATCHED. FRI INTO SAT... HIGH PRES MOVES IN FROM THE NW AS BASE OF LONGWAVE TROF MOVES THROUGH NEW ENGLAND. THIS ALLOWS DRIER AND COOLER W-NW FLOW TO DEVELOP ACROSS THERE REGION...YIELDING A RELIEF FROM THE HEAT AND HUMIDITY AND MAINLY DRY WX. TEMPS ARE LIKELY TO BE CLOSE TO SEASONAL NORMALS BASED ON CURRENT MID LVL TEMPS. SUN INTO MON... ANOTHER GRADUAL LONGWAVE TROF DEVELOPMENT IS FAVORED...THANKS TO STRONG SHORTWAVE MOVING THROUGH THE ZONAL FLOW ACROSS THE NRN HALF OF THE CONUS. WHILE THERE REMAINS UNCERTAINTY HERE...THE BULK OF AVAILABLE GUIDANCE FAVORS A RETURN TO MORE UNSETTLED AND POTENTIALLY WET WX. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/... THROUGH TODAY...HIGH CONFIDENCE. MAINLY VFR...ONLY ISSUE WOULD BE LATE DAY MVFR/IFR BRIEFLY IN ANY T-STORMS/SHRA THAT DEVELOP FOR WRN NEW ENGLAND TERMINALS. SW WINDS GUSTING 25-30 KT AT TIMES THROUGH THE DAY...MAINLY IN THE COASTAL PLAIN. TONIGHT...MODERATE CONFIDENCE. SCT SHOWERS/TSTMS INTERIOR WITH LOCAL MVFR- IFR CONDITIONS POSSIBLE IN THE EVENING. OTHERWISE MAINLY VFR...BUT PATCHY MVFR/IFR FOG MAY DEVELOP OVERNIGHT. TUESDAY...MAINLY VFR. SCT LATE DAY SHOWERS/TSTMS DEVELOPING WITH LOCAL MVFR-IFR CONDITIONS POSSIBLE. SW WIND GUSTS TO 20-25 KT. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... TUESDAY NIGHT THROUGH WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR...EXCEPT IN PATCHY LATE NIGHT/EARLY MORNING STRATUS/FOG. IN ADDITION...LOCALIZED BRIEF MVFR-IFR CIGS/VSBYS ARE POSSIBLE IN A FEW SHOWERS/THUNDERSTORMS LATE TUE INTO WED. THURSDAY...MODERATE CONFIDENCE. MAINLY VFR AGAIN...BUT THERE IS STILL AN ISOLATED THREAT FOR BRIEF MVFR/IFR CONDITIONS IN SHOWERS/THUNDERSTORMS DURING THE AFTERNOON...ESPECIALLY SOUTH AND EAST OF A BDL-ORH-BOS LINE. FRIDAY...HIGH CONFIDENCE. VFR CONDITIONS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/...HIGH CONFIDENCE. LOW LEVEL JET DEVELOPING ACROSS THE WATERS WILL RESULT IN SW WIND GUSTS INCREASING TO 25-30 KT THIS AFTERNOON...STRONGEST OVER THE SOUTH COASTAL NEARSHORE WATERS WHERE MIXING IS GREATEST. WINDS WILL DIMINISH A BIT TONIGHT BUT STILL POTENTIAL FOR G20-25KT. ANOTHER PULSE OF STRONGER WINDS DEVELOP TUE AFTERNOON WITH POTENTIAL FOR A FEW G25KT. THE INCREASING SW FLOW WILL RESULT IN SEAS BUILDING TO 5-7 KT OVER THE SOUTHERN WATERS. SMALL CRAFT ADVISORIES REMAIN IN EFFECT. PATCHY FOG MAY REDUCE VSBYS LATE TONIGHT AND TUE. OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY... TUE NIGHT INTO WED...MODERATE CONFIDENCE. SW FLOW CONTINUES MAINLY 10-15 KT WITH GUSTS TO 20 BUT A FEW GUSTS AROUND 25 KT ARE POSSIBLE. IN ANY CASE...SMALL CRAFT ADVISORIES ARE LIKELY TO CONTINUE ON THE OUTER WATERS THANKS TO A 5-6 FT S SWELL LINGERING. SOME FOG OVER THE WATERS TUE NIGHT WITH LOW VSBYS...ALONG WITH OCCASIONAL THUNDERSTORMS INTO THE DAY WED. THU...MODERATE CONFIDENCE. ONE MORE ROUND OF POTENTIAL THUNDERSTORMS OVER THE S WATERS ESPECIALLY. OTHERWISE...GRADUAL IMPROVEMENT LATE THU AS WINDS SHIFT TO THE NW. SEAS MAY FINALLY DROP BELOW SCA THRESHOLDS BY THU NIGHT. FRI...HIGH CONFIDENCE. HIGH PRESSURE BUILDS IN KEEPING WINDS/SEAS BELOW SCA THRESHOLDS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ230- 236-251. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ235-237-250. SMALL CRAFT ADVISORY UNTIL 6 PM EDT TUESDAY FOR ANZ254>256. && $$ SYNOPSIS...KJC/DOODY NEAR TERM...FRANK SHORT TERM...KJC LONG TERM...DOODY AVIATION...KJC/DOODY MARINE...KJC/DOODY

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