Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 250541 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 141 AM EDT MON MAY 25 2015 .SYNOPSIS... A WARM FRONT WILL MOVE ACROSS THE REGION MONDAY FOLLOWED BY WARM AND HUMID CONDITIONS WHICH WILL LIKELY LAST INTO NEXT WEEKEND. THE THREAT FOR SCATTERED SHOWERS AND THUNDERSTORMS WILL INCREASE FROM WEDNESDAY AFTERNOON INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 140 AM UPDATE... HIGH CLOUDINESS CONTINUE TO MOVE ACROSS SOUTHERN NEW ENGLAND OVERNIGHT AHEAD OF A WARM FRONT THAT WAS PROGRESSING NORTHEASTWARD ACROSS THE APPALACHIANS. TEMPERATURES RANGED FROM THE MID 50S TO MID 60S ACROSS THE REGION AS OF 140 AM WITH SOUTHWEST WINDS 5 TO 15 MPH. LIGHT PATCHY FOG IS POSSIBLE MAINLY ALONG THE SOUTH COAST TOWARD DAYBREAK. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... MONDAY AND MONDAY NIGHT... BERMUDA HIGH SETS UP ALONG EASTERN SEABOARD. WARM FRONT DEVELOPS AS IT SHIFTS E ACROSS NY STATE DURING MONDAY. HOWEVER...WITH STRONG SUBSIDENCE IN PLACE AS WELL AS CONTINUED SW SURFACE WINDS AND H5 RIDGING BUILDING ACROSS WESTERN NEW ENGLAND...BETTER MOISTURE AND LIFT WILL REMAIN N AND W OF THE REGION. WHILE THERE WILL BE NO PRECIP WITH THIS FRONT...WILL SEE A LOT OF CLOUDINESS STREAMING ACROSS THE REGION. EXPECT THE WARM FRONT TO PUSH NE ACROSS NORTHERN NEW ENGLAND MON NIGHT. MAY SEE SOME LEFTOVER PATCHY FOG ALONG THE S COAST EARLY MON MORNING...THEN AGAIN NEAR THE S COAST AS WELL AS OUTER CAPE COD AND THE ISLANDS LATE MON NIGHT AS DEWPTS/RH VALUES INCREASE. EVEN WITH THE CLOUDS...IT WILL STILL BE WARM ON MON WITH HIGHS AROUND 80 EXCEPT IN THE UPPER 60S AND 70S ACROSS S COASTAL AREAS. READINGS WILL ONLY FALL BACK TO THE UPPER 50S TO LOWER 60S MON NIGHT...AND IT WILL BE MUGGY AS DEWPTS CONTINUE TO RISE THROUGH THE 50S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGHLIGHTS... * WARM AND HUMID INTO THE WEEKEND * INCREASING SHOWER/THUNDERSTORM POTENTIAL WED INTO THU * MORE SHOWERS AND THUNDERSTORMS POSSIBLE THIS WEEKEND OVERVIEW... MID LEVEL RIDGING ALONG THE EAST COAST WILL BE THE DOMINANT FEATURE THROUGH MUCH OF THE WEEK...ALTHOUGH NORTHERN STREAM ENERGY RIDING OVER THE TOP WILL DEAMPLIFY THE RIDGE ALLOWING FOR A WEAK FROPA AROUND THU TIMEFRAME. ABOVE NORMAL TEMPS WITH INCREASING HUMIDITY WILL BE THE THEME THROUGH THE WEEK WITH THE WARMEST TEMPS TUE/WED...WITH POTENTIAL FOR NEAR 90 DEGREES INTERIOR VALLEYS. BEST CHANCE FOR SHOWERS/TSTMS WILL BE THU WITH THE FROPA...BUT NEARBY INSTABILITY AXIS SUGGESTS POTENTIAL FOR SCT CONVECTION FOR INTERIOR LOCATIONS ON WED/FRI. LOOKING AHEAD TO THE WEEKEND...A MORE ROBUST MID LEVEL TROF WILL BE SLIDING EAST ACROSS SE CANADA BUT MODELS DIFFER ON TIMING WHICH WILL AFFECT TIMING OF A COLD FRONT AND SENSIBLE WEATHER. WE LEANED TOWARD WPC GUIDANCE WHICH IS CLOSER TO SLOWER ECMWF. TUESDAY INTO WEDNESDAY... SNE IN THE WARM SECTOR AIRMASS WITH SW FLOW BRINGING WARM AND INCREASINGLY HUMID CONDITIONS. 850 MB TEMPS 15-16C SUGGEST POTENTIAL FOR NEAR 90 DEGREES IN SOME OF THE INTERIOR VALLEYS...BUT SW WINDS OFF COOLER OCEAN WILL KEEP TEMPS IN THE 70S NEAR THE SOUTH COAST. DEWPOINTS CLIMBING TO 60+ SO IT WILL START TO FEEL A BIT HUMID COMPARED TO RECENT DAYS. REGARDING TSTM POTENTIAL...THINK TUE WILL BE MOSTLY DRY WITH POSSIBLE EXCEPTION OF FAR W NEW ENG AS MODELS GENERATE SOME MARGINAL INSTABILITY DURING THE AFTERNOON WITH SBCAPES AROUND 500 J/KG AND KI CLIMBING TO 30+. CANT RULE OUT AN ISOLD TSTM ACROSS W ZONES DURING THE AFTERNOON/EVENING...OTHERWISE MAINLY DRY TUE. MORE INSTABILITY IS FORECAST ON WEDNESDAY WITH CAPES EXCEEDING 1000 J/KG SO EXPECT SCT AFTERNOON SHOWERS/TSTMS DEVELOPING...MAINLY CONFINED TO W ZONES WHERE BEST INSTABILITY. 0-6KM SHEAR IS WEAK...LESS THAN 25 KT SO MAIN THREAT IS LOCALLY HEAVY RAINFALL GIVEN HIGH PWATS. THURSDAY AND FRIDAY... NOT MUCH CHANGE IN AIRMASS WITH CONTINUED THREAT OF SHOWERS/TSTMS...MAINLY INTERIOR. IT APPEARS BEST CHANCE OF CONVECTION WILL BE THU AS SHORTWAVE PASSES TO THE NORTH WITH SUBTLE MID LEVEL COOLING AND WEAK FROPA MOVING INTO THE REGION. CAPES 1000+ J/KG AND SOME CONVERGENCE SUGGESTS A MORE ACTIVE DAY AND 0-6KM SHEAR IS A BIT STRONGER AS WELL BUT STILL LESS THAN 30 KT. HEAVY RAIN IS MAIN THREAT BUT A FEW STRONG TO SEVERE STORMS POSSIBLE THU. TEMPS ABOVE NORMAL...WARMEST 80S IN THE INTERIOR. SATURDAY AND SUNDAY... GFS IS CONSIDERABLY FASTER THAN ECMWF WITH COLD FRONT WITH SHOWERS/TSTMS SAT THEN DRYING OUT SUNDAY AS HIGH PRES BUILDS TO THE N. ECMWF HAS FRONT MOVING THROUGH SUN AFTERNOON/EVENING WITH BEST CHANCE OF CONVECTION DURING THIS TIME. WPC CONSENSUS FAVORED LOWER SOLUTION. A LOW CONFIDENCE FORECAST AT THIS TIME RANGE AND TIMING OF FRONT WILL DICTATE WHICH WEEKEND DAY HAS BETTER CHANCE OF CONVECTION. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH MONDAY NIGHT/...HIGH CONFIDENCE. OVERNIGHT...VFR. CIGS 10KFT OR ABOVE OVERNIGHT. MAY SEE PATCHY FOG WITH MVFR TO LOCAL IFR VSBYS ACROSS THE ISLANDS...POSSIBLY UP TO THE IMMEDIATE S COAST. MONDAY AND MONDAY NIGHT...VFR. MAY SEE PATCHY FOG WITH MVFR VSBYS EARLY MON MORNING AND AGAIN AFTER MIDNIGHT MON NIGHT...MAINLY NEAR THE S COAST AND OUTER CAPE COD/NANTUCKET. SW WINDS INCREASE MON NIGHT...GUSTING TO 20-25 KT. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY THROUGH FRIDAY...MODERATE CONFIDENCE. MOSTLY VFR CIGS. BUT BRIEF MVFR/IFR IN ANY SHOWERS/THUNDERSTORMS WED THROUGH FRIDAY. LOW CONFIDENCE ON DURATION AND AREAL EXTENT OF ANY IFR STRATUS AND FOG DURING THE LATE NIGHT AND MORNING PERIODS. SW GUSTS TO 25 KT ALONG SE NEW ENG COAST TUE/WED. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH MONDAY NIGHT/...HIGH CONFIDENCE. OVERNIGHT...SOUTHWEST WINDS 10 TO 20 KT ACROSS THE COASTAL WATERS. MAY SEE PATCHY FOG DEVELOP LATE TONIGHT ACROSS PORTIONS OF THE SOUTHERN WATERS WITH LOCALLY REDUCED VSBYS. MONDAY-MONDAY NIGHT...SW WINDS CONTINUE...GUSTING UP TO 20 KT DURING MON. SEAS SHOULD REMAIN BELOW 5 FT DURING THE DAY. EXPECT SW WIND GUSTS TO PICK UP TO 20-25 KT MON NIGHT. SEAS ALSO BUILD TO 5-6 FT ON THE SOUTHERN WATERS AS WELL AS THE EASTERN OUTER WATERS. OUTLOOK...TUESDAY THROUGH FRIDAY...MODERATE CONFIDENCE. PERSISTENT SW FLOW WITH GUSTS AROUND 20-25 KTS AT TIMES. STRONGEST WINDS OVER THE NEARSHORE WATERS. INCREASING SWELL AND WIND WAVE WILL RESULT IN SEAS BUILDING TO 5-6 FT OVER S COASTAL WATERS. FOG ANTICIPATED DURING THE OVERNIGHT AND MORNING LENDING TO VISIBILITY RESTRICTIONS. && .FIRE WEATHER... 4 PM UPDATE... EXPECT DEWPTS TO SLOWLY BUT STEADILY RISE OVERNIGHT AND MONDAY WITH PERSISTENT SW WINDS IN PLACE. FORECASTED MINIMUM RH VALUES WILL BE FROM 35 TO 60 PERCENT ON MONDAY...LOWEST ACROSS INTERIOR AREAS. WITH THE INCREASING HUMIDITY...EXPECT LOWERED FIRE WEATHER RISK SO WILL NOT BE ISSUING A STATEMENT AT THIS TIME. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...KJC/EVT NEAR TERM...GAF SHORT TERM...EVT LONG TERM...KJC AVIATION...KJC/EVT/GAF MARINE...KJC/EVT/GAF FIRE WEATHER...STAFF

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