Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 081929 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 330 PM EDT TUE JUL 8 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 WEDNESDAY MORNING/... ***BEST SHOT FOR ORGANIZED SHOWER/THUNDERSTORM ACTIVITY WILL BE AFTER 10 PM IN OUR WESTERN ZONES*** SPC MESO-ANALYSIS SHOWING MLCAPE VALUES NEARING 1500 J/KG ALONG WITH 0 TO 6 KM SHEAR VALUES ON THE ORDER OF 30 TO 40 KNOTS. MOST OF THE SCATTERED SHOWERS/THUNDERSTORMS THAT HAVE DEVELOPED SO FAR HAVE BEEN TO OUR NORTH AND WEST OF OUR REGION....WHERE BETTER FORCING RESIDES. HOWEVER...SOME OF THE MESOSCALE MODELS DO SHOW A FEW THUNDERSTORMS WORKING ACROSS OUR REGION THROUGH EARLY EVENING. GIVEN INSTABILITY/WIND FIELDS CERTAINLY THE RISK FOR A FEW STRONG TO SEVERE THUNDERSTORMS IF THEY ARE ABLE TO FORM IN OUR REGION. WHILE THE ACTIVITY CAN/T BE RULED OUT ANYWHERE...BEST SHOT APPEARS TO BE OUR NORTHWEST ZONES CLOSER TO THE BETTER FORCING. THE MAIN THREATS WITH ANY ACTIVITY WILL BE ISOLATED STRONG TO DAMAGING STRAIGHT LINE WIND GUSTS...BUT ANY DISCRETE CELLS WOULD BE CAPABLE OF PRODUCING HAIL. GIVEN PWATS BETWEEN 1.50 AND 2 INCHES...LOCALLY HEAVY RAINFALL WILL BE THE MAIN CONCERN. ALL IN ALL...ANY STORM THAT DEVELOPS IN OUR REGION THROUGH EARLY EVENING MAY BECOME SEVERE GIVEN THE ENVIRONMENT. HOWEVER...AREAL COVERAGE MAY BE QUITE LIMITED GIVEN THE LACK OF FORCING. THE BIGGER CONCERN FOR MORE WIDESPREAD ACTIVITY WILL BE LATER TONIGHT /AFTER 10 PM/ IN OUR WESTERN ZONES WITH THE CLUSTER OF SHOWERS/THUNDERSTORMS CURRENTLY OVER THE EASTERN GREAT LAKES. MOST OF THE SHORT TERM MODELS MOVE THIS ACTIVITY EAST...BUT IT PROBABLY WON/T GET INTO OUR WESTERN ZONES UNTIL AFTER 02Z. WE NORMALLY LIKE TO SEE STEEP MID LEVEL LAPSE RATES IN PLACE FOR A SIGNIFICANT SEVERE WEATHER THREAT INTO THE OVERNIGHT HOURS. IN THIS CASE THAT IS MISSING...BUT WE DON/T WANT TO COMPLETELY LET OUR GUARD DOWN GIVEN 0 TO 6 KM SHEAR STRENGTHENING TO OVER 40 KNOTS. SO WE CAN/T RULE OUT A FEW STRONG TO SEVERE STORMS ENTERING OUR WESTERN ZONES DURING THE LATE EVENING HOURS...BUT THE HIGHER RISK FOR SEVERE WEATHER WILL BE WEST OF OUR REGION. ACTIVITY MAY EVENTUALLY FIND ITS WAY INTO OUR EASTERN ZONES IN A WEAKENED STATE...IF IT CAN SURVIVE. FINALLY...LOW CLOUDS AND FOG SHOULD DEVELOP TONIGHT ALONG THE SOUTHEAST NEW ENGLAND COAST...WHICH IS SUPPORTED BY ALL THE LATEST GUIDANCE. WILL ALSO HAVE TO WATCH FOR A TOUCH OF ELEVATED CONVECTION DEVELOPING TOWARDS 12Z NEAR CAPE/ISLANDS ON THE NOSE OF THE LOW LEVEL JET. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... 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 THROUGH TUESDAY/... HIGHLIGHTS... * A FEW THUNDERSTORMS POSSIBLE WED NIGHT INTO THU * DRIER AND LESS HUMID AIR RETURNS BY THE END OF THE WEEK OVERVIEW AND MODEL PREFERENCES... OVERALL...BOTH OPERATIONAL AND ENSEMBLE MODELS ARE IN FAIR AGREEMENT THROUGH THE LONG TERM. LONGWAVE TROF WILL BE LIFTING THROUGH NEW ENGLAND THROUGH THE...AS THE SFC REFLECTION...A COLD FRONT SLIDES FURTHER OFFSHORE. THE UPPER PATTERN SHIFT FORCES A ZONAL FLOW ACROSS THE REGION...ALLOWING DRIER AND MORE SEASONAL AIRMASS TO MOVE INTO PLACE. THEN YET ANOTHER DEEP CUTOFF TRIES TO DEVELOP THANKS TO SHORTWAVE ENERGY DIVING S FROM N CENTRAL CANADA. WHILE THERE IS SOME DISAGREEMENT ON WHERE THE CORE OF THIS CUTOFF ULTIMATELY RESIDES BY THE TIME IT SETTLES NEXT WEEK...THEY ARE ALL IN AGREEMENT THAT THIS CUTOFF WILL FORM TO OUR W. THEREFORE...WILL LIKELY SEE ANOTHER ROUND OF SW FLOW AND POTENTIAL FOR UNSETTLED AND WET CONDITIONS BY NEXT WEEK. GIVEN THE AGREEMENT...ANOTHER BLEND OF GUIDANCE WILL BE USED AS BASELINE. DETAILS... WED NIGHT INTO THU... CURRENT TIMING OF THE FINAL COLD FRONT HAS IT SLIDING ACROSS SRN NEW ENGLAND SLOWLY...MAINLY BETWEEN 00Z AND 12Z THU. AHEAD OF THE FRONT...HIGH DWPTS IN THE UPPER 60S TO AROUND 70 STILL SUPPORT 500-800J/KG OF ML CAPE COINCIDENT WITH REMAINING 40 KT OF 0-6KM SHEAR. THEREFORE...NOT OUT OF THE QUESTION THAT SOME CONVECTIVE ACTIVITY MAY CONTINUE INTO THE OVERNIGHT HOURS ESPECIALLY S OF THE MASS PIKE AND ALONG THE WATERS. HIGH SHEAR MAY PROMOTE GUSTY WINDS OR HAIL AS WELL. THE MAIN FLY IN THE OINTMENT IS DRYING IN THE MID LVLS WHICH MAY PRECLUDE CONVECTION SOMEWHAT...SO FOR NOW MOST POPS ARE CHANCE OR BELOW. THE KEY MAY BE ANYTHING THAT FORMS DURING THE AFTERNOON/EVENING WED WHICH WOULD BE WITHIN A MOIST COLUMN AND IS HELD TOGETHER BY THE SHEAR. BY THU...THE THREAT FOR SHOWERS OR AN ISOLATED STORM MAY LINGER UNTIL THE FRONT IS ABLE TO PUSH FURTHER OFFSHORE. THEREFORE...HAVE GRADUALLY LOWERING POPS THROUGH THE DAY. STILL WARM ON THU LIKELY AS THE MID LVL TEMPS ARE LIKELY TO BE SLOW TO CHANGE. SO WILL CONTINUE WITH HIGHS ABOVE NORMAL. FRI AND SAT... HIGH PRES MOVES IN FROM THE W AS W-E ZONAL FLOW DEVELOPS ALOFT. THIS NW FLOW WILL ALLOW THE PERSISTENT HUMIDITY EARLY THIS WEEK TO FINALLY BREAK WITH DWPTS BEING ALLOWED TO FALL INTO THE LOW-MID 50S. H85 TEMPS EACH DAY RANGE AROUND +12 TO +14C...WHICH SUGGEST HIGHS NEAR SEASONAL NORMALS OR IN THE LOW-MID 80S. SUN INTO MON... A GRADUALLY DEVELOPING CUTOFF TO THE W WILL YIELD INCREASING RETURN FLOW THROUGH THE PERIOD. THEREFORE...EXPECT INCREASING HUMIDITY AND COLUMN MOISTURE THROUGH THE PERIOD...AS WELL AS WARMER TEMPERATURES. ENSEMBLES SUGGEST THAT BY MON...PWATS MAY APPROACH 2 STD DEVIATIONS FROM NORMAL. ALTHOUGH THERE ARE SOME DISAGREEMENTS ON EXACTLY HOW IT TURNS OUT. BY SUN...WARM FRONT WILL MOVE INTO NRN NEW ENGLAND YIELDING THE POSSIBILITY OF SHOWERS OR POSSIBLY AN ISOLATED RUMBLE OF THUNDER. THE HIGHER THREAT LOOKS TO BE MON INTO TUE...AS ANOTHER SLOW MOVING COLD FRONT APPROACHES FROM THE W...IN WHAT COULD BE A MOISTURE RICH AND POTENTIALLY UNSTABLE AIRMASS. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY NIGHT/... THIS AFTERNOON INTO TONIGHT...MODERATE CONFIDENCE. TO THE NORTHWEST OF I-95 MAINLY VFR CONDITIONS EXPECTED OUTSIDE OF ANY CONVECTION. TO THE SOUTHEAST OF I-95...IFR CONDITIONS EXPECTED TO DEVELOP IN LOW CLOUDS AND FOG ON SOUTHWEST WINDS TONIGHT. AS FOR CONVECTIVE POTENTIAL...A FEW ISOLATED THUNDERSTORMS ARE POSSIBLE THROUGH EARLY EVENING.. BETTER SHOT AFTER 2Z THIS EVENING WHEN A LINE OF SHOWERS/THUNDERSTORMS MAY APPROACH OUR WESTERN ZONES. LOCALLY STRONG WIND GUSTS AND HEAVY RAIN ARE STILL POSSIBLE. ACTIVITY SHOULD WEAKEN AS IT MOVES EAST. WEDNESDAY AND WEDNESDAY NIGHT...MODERATE CONFIDENCE. LOW CLOUDS AND FOG ALONG SOUTHEAST NEW ENGLAND COAST MAY BURN OFF TEMPORARILY DURING THE LATE MORNING AND AFTERNOON...BUT SHOULD REFORM WED NIGHT. ACROSS THE REST OF THE REGION MAINLY VFR OUTSIDE A FEW SPOT THUNDERSTORMS THIS AFTERNOON AND EVENING. KBOS TAF...HIGH CONFIDENCE IN TAF. LOW PROBABILITY OF A THUNDERSTORM THIS EVENING. KBDL TAF...HIGH CONFIDENCE IN TAF. A LINE OF STRONG THUNDERSTORMS MAY WORK INTO THE REGION AFTER 2Z. OUTLOOK...THURSDAY THROUGH SATURDAY... THU...MODERATE CONFIDENCE. MAINLY VFR. SHOWERS OR AN ISOLATED THUNDERSTORM POSSIBLE MAINLY NEAR THE S COAST WITH BRIEF MVFR/IFR CONDITIONS. ALL VFR EXPECTED BY LATE IN THE DAY THU. FRI INTO SAT...HIGH CONFIDENCE. MAINLY VFR. && .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... WEDNESDAY NIGHT INTO THURSDAY...MODERATE CONFIDENCE. A COLD FRONT WILL BE MOVING OFF THE SRN WATERS WED NIGHT. THIS MEANS SHOWERS AND AN ISOLATED THUNDERSTORM IS POSSIBLE THROUGH ABOUT MID DAY THU. OTHERWISE...SEAS WILL GRADUALLY BE DECLINING THROUGH THE PERIOD FROM ABOUT 5-6 FT ON THE OCEAN WATERS. THEREFORE...OUTSIDE OF ANY STORMS...SMALL CRAFT ADVISORIES ARE LIKELY TO BE COMING DOWN INTO EARLY THU. FRI AND SAT...HIGH CONFIDENCE. MAINLY QUIET BOATING WEATHER WITH HIGH PRESSURE. WINDS AND SEAS BELOW SMALL CRAFT THRESHOLDS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT WEDNESDAY FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ230- 236-251. SMALL CRAFT ADVISORY UNTIL 9 PM EDT WEDNESDAY FOR ANZ235-237- 254>256. && $$ SYNOPSIS...FRANK NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY MARINE...FRANK/DOODY

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