Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 270727 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 327 AM EDT MON JUL 27 2015 .SYNOPSIS... RISK OF SHOWERS AND THUNDERSTORMS CONTINUING THROUGH TUESDAY. STORMS MAY PRODUCE HEAVY RAIN AND A FEW MANY BECOME STRONG TO SEVERE. HOT AND HUMID TUESDAY THROUGH THURSDAY. A COLD FRONT MAY BRING SCATTERED THUNDERSTORMS LATE THURSDAY AND THURSDAY NIGHT. WARM AND DRY WEATHER IS EXPECTED FRIDAY INTO NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... INTO THIS MORNING... BROAD AREA OF LOW PRESSURE /CONVERGENCE WITHIN/ BENEATH CYCLONIC FLOW ALOFT PREVAILING ALONG WITH ELEVATED INSTABILITY PER SPC MESO- ANALYSIS UPWARDS OF 1K J/KG CAPE THROUGH CONDITIONALLY UNSTABLE MID-LEVELS OF 6C/KM. BATCHES OF SHOWERS / THUNDERSTORMS CONTINUE WHEREVER FORCING CAN BE GENERATED. WEAKLY SHEARED ENVIRONMENT...STORMS THAT CONTINUE TO TRAIN ACROSS THE REGION OVER SE NEW ENGLAND AND THE E WATERS ARE MAINLY ASSOCIATED WITH HEAVY RAIN AND FREQUENT LIGHTNING. LOW RISK OF SMALL HAIL AND DAMAGING WINDS. FEEL THE AREA OF THESE THREATS MAY EVOLVE SLIGHTLY MORE S AND E TOWARDS MORNING...BUT FOR THE MOST PART HOLD IN PLACE. GROWING CONCERN OF POTENTIAL LOCALIZED FLOODING WHEREVER STORMS CONTINUE TO TRAIN OVER A PARTICULAR AREA. NEAR-TERM FORECAST GUIDANCE USED WITH THIS FORECAST BUT BLENDED WITH SREF PROBABILITIES AND MOS GUIDANCE. IT IS ANYONES GUESS AS TO WHERE CONVECTION WILL DEVELOP. BEST THING TO CONVEY IS THE CHANCE AND THE POTENTIAL THREATS. TODAY... SCATTERED SHOWER / THUNDERSTORM ACTIVITY TO PERSIST. UNCERTAINTY AS TO WHERE THE MORE FAVORABLE AREA OF DEVELOPMENT WILL RESIDE. PRESENT AREA OVER SE NEW ENGLAND MAY SHIFT BACK TOWARDS THE INTERIOR. SLIGHT DIFFERENCES AMONG THE HIGH-RES MODEL GUIDANCE OF WHERE THE HIGHER SW- NE LOW-LEVEL THETA-E AND INSTABILITY AXIS WILL PERSIST. BUT GOOD AGREEMENT WITH OTHER FACETS OF THE FORECAST NAMELY SOME MID-LEVEL ENERGY ROTATING THROUGH THE BROADER CYCLONIC FLOW COLLOCATED WITH CONDITIONALLY UNSTABLE MID-LEVEL LAPSE RATES IN PROXIMITY TO SE NEW ENGLAND...AS A BROAD AREA OF SURFACE LOW PRESSURE DEVELOPS ACROSS THE INTERIOR NE CONUS. WILL ALSO SEE AN ONSHORE FLOW OF HIGHER SURFACE DEWPOINT AIR LIKELY TO EXCEED 70-DEGREES IN PARTS. SO EVERYTHING TAKEN INTO CONSIDERATION BELIEVE THERE IS A CHANCE OF SHOWER / THUNDERSTORM ACTIVITY OVER ALL OF S NEW ENGLAND. THINKING SCATTERED TO WIDESPREAD. A HIGH INSTABILITY / LOW-SHEAR SETUP WITH A MEAN-WIND FLOW OUT OF THE W AT 10 MPH. MAIN THREATS OF HEAVY RAIN AND LIGHTNING WITH THE POTENTIAL FOR LOCALIZED FLOODING. SECONDARY TO THAT IS SMALL HAIL AND GUSTY WINDS. WARM AND MUGGY. HIGHS INTO THE LOW- TO MID-80S AWAY FROM THE COAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... TONIGHT... A REPEAT OF LAST NIGHT ANTICIPATED. SCATTERED SHOWER / THUNDERSTORM ACTIVITY WILL SHIFT E/SE WITH THE MEAN WIND SLOWLY. WHILE DAYTIME HEATING CONCLUDES...THERE STILL IS A LOT OF INSTABILITY AVAILABLE WITHIN THE LOW-MID LEVELS ALOFT WHERE LAPSE RATES ARE CONDITIONALLY UNSTABLE. THREATS OF HEAVY RAIN AND FREQUENT LIGHTNING CONTINUE AND WITH THE SLOW MOVEMENT OF THE STORM THERE IS A CONCERN FOR LOCALIZED FLOODING. A MUGGY NIGHT IN STORE WITH LOWS IN THE MID- TO UPPER- 60S. STORM ACTIVITY MAY DISSIPATE TOWARDS MORNING. TUESDAY... CONTINUED MID-LEVEL ENERGY THROUGH THE BROADER CYCLONIC FLOW ON WHAT APPEARS TO BE NNW-SSE FRONTAL BOUNDARY WHEN EVALUATING THE LOW- TO MID-LEVEL THERMAL PROFILE. SEEMS TO BE SOME LEVEL OF ENHANCED ASCENT THROUGH THE ATMOSPHERIC LAYER. COLLOCATED JET STREAK AND DECENT NNW- SSE UNIDIRECTIONAL BULK SHEAR WITH LAPSE RATES EXCEEDING 6C/KM. SURFACE REFLECTION OF A CONVERGENT BOUNDARY ALONG THE E-COASTLINE OF NEW ENGLAND APPEARS PLAUSIBLE. WITH A WARM MUGGY AIRMASS STILL IN PLACE MAY BE DEALING WITH SHOWER / THUNDERSTORM ACTIVITY ACROSS E- HALF OF NEW ENGLAND...POTENTIALLY LINE-CONVECTION ALONG THE LEADING EDGE OF THE MID-LEVEL IMPULSE. CONSIDERING SHEAR / INSTABILITY / INVERTED-V PROFILES WITHIN THE BOUNDARY-LAYER COULD BE LOOKING AT A MULTI-THREAT OUTCOME WITH ANY CONVECTION AS IT WOULD APPEAR. GOING TO HAVE TO TAKE A LOOK AT THIS MORE CLOSELY OVER THE NEXT 24-HOURS. COLLABORATING WITH OTHER WEATHER FORECAST OFFICES...WILL GO WITH ENHANCED WORDING OF HEAVY RAIN / GUSTY WINDS / SMALL HAIL. GOOD DEEP- LAYER FORCING AND NEAR A LOBE OF H5 COLDER AIR DROPPING S WITH THE MID-LEVEL VORTEX. WITH ANTICIPATED WEATHER / CLOUD COVER PERHAPS SOME ISSUES WITH HIGH TEMPERATURES. MAYBE AN ONSHORE FLOW ALONG THE E-COAST IF THE ZONE OF CONVERGENCE HOLDS OVER THE E-HALF OF NEW ENGLAND. WILL LEAN COOLER IN THIS AREA BUT GO INTO THE UPPER-80S TO THE W. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGHLIGHTS... * TRIPLE-H WEATHER WED/THU WITH HIGHS IN 90S. * SCATTERED STORMS THU/THU NIGHT. * DRIER BUT STILL VERY WARM FRI THRU SUN. LARGE SCALE PATTERN FEATURES BUILDING RIDGE OVER NORTHEAST WED/THU WHICH WILL BRING OUR NEXT SHOT OF HEAT AND HUMIDITY. HOWEVER THIS SHOULD BE RELATIVELY SHORT LIVED AS UPPER LOW DIGS ACROSS CANADIAN PRAIRIES AND EVENTUALLY BECOMES CENTERED NEAR HUDSON BAY...RESULTING IN MORE IN WAY OF CYCLONIC FLOW FOR LATER THIS WEEK INTO NEXT WEEKEND. STILL LOOKS SUMMERLIKE BEYOND THU BUT CHANGE IN UPPER AIR PATTERN SHOULD BREAK HUMIDITY AND KEEP TEMPERATURES CLOSER TO AVERAGE FOR LATE JULY. WED INTO THU...HIGH CONFIDENCE. RISING HEIGHTS SHOULD SUPPRESS CONVECTION WED SO AM CONTINUING WITH DRY FORECAST. NAM SUGGESTION OF DEVELOPMENT ALONG SEA BREEZE FRONT IS POSSIBLE BUT IS OUTLIER AT THIS POINT. HIGHS SHOULD TOP OUT IN LOW TO MID 90S AWAY FROM S COAST BUT WITH DEWPOINTS IN MID 60S TO AROUND 70 HEAT INDICES WILL PROBABLY FALL SHORT OF ADVISORY CRITERIA /100F FOR 2+ HOURS/. ANOTHER HOT/HUMID DAY EXPECTED THU BUT HIGHS SHOULD BE SLIGHTLY LOWER THAN WED GIVEN INCREASING CLOUD COVER AHEAD OF COLD FRONT APPROACHING FROM GREAT LAKES. DECENT CAPE/0-6KM SHOULD BE PRESENT ALONG WITH MARGINAL MID LEVEL LAPSE RATES...SO BETTER CHANCE OF SHOWERS/STORMS DURING AFTERNOON AND EVENING AS FRONT PROVIDES FOCUS FOR LIFT. FRI THROUGH SUN...MODERATE CONFIDENCE. HIGH PRESSURE BUILDS ACROSS NORTHEAST AS UPPER FLOW BECOMES MORE CYCLONIC. THIS WILL BRING SOME RELIEF FROM HEAT/HUMIDITY BUT HIGHS SHOULD STILL TOP OUT WELL INTO 80S AWAY FROM S COAST. GOING WITH DRY FORECAST AS ENSEMBLES SHOW FAIRLY LOW PROBABILITIES OF MEASURABLE RAINFALL DURING THIS TIME FRAME. && .AVIATION /07Z 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/... TOWARDS 12Z... SCT SHRA/TSRA OVER E/SE-PORTIONS OF S NEW ENGLAND. +RA WITH LIGHTNING MAIN THREATS. TEMPO MVFR TO IFR POSSIBLE ALONG WITH SOME WIND GUSTS. TO THE N/W: LIGHT S-FLOW WITH THE POTENTIAL FOR IFR FOG. OTHERWISE A MIX OF VFR-MVFR. MONDAY AND MONDAY NIGHT... OVERALL LOW-END VFR. SCT SHRA/TSRA OVER ALL SNE. WILL PREVAIL VCSH AND NARROW DOWN SPECIFIC IMPACTS WITH LATER TAFS. AWW/S MAY BE NEEDED. TEMPO MVFR- IFR IMPACTS. THREATS OF SMALL HAIL / WINDS / +RA / LIGHTNING ALL ANTICIPATED. BREEZY S/SW-WINDS. TUESDAY... LOW-END VFR. FOCUS OVER E-HALF OF S NEW ENGLAND WHERE RENEWED CHANCES OF SHRA/TSRA. THREATS OF SMALL HAIL / WINDS / +RA / LIGHTNING ALL ANTICIPATED. ONSHORE FLOW EXPECTED ALONG E-COAST. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. MAINLY VFR. SHRA/TSRA WILL BE POSSIBLE THROUGH TUESDAY. WILL PREVAIL VCSH AND FOCUS ON SPECIFICS WITH LATER TAF ISSUANCES. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. MAINLY VFR. SHRA/TSRA WILL BE POSSIBLE THROUGH TUESDAY. WILL PREVAIL VCSH AND FOCUS ON SPECIFICS WITH LATER TAF ISSUANCES. OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/... TUESDAY NIGHT AND WEDNESDAY...HIGH CONFIDENCE. MVFR/IFR IN SCT SHRA/TSRA TUESDAY EVENING...OTHERWISE VFR. THURSDAY...MODERATE CONFIDENCE. MVFR/IFR IN SCT SHRA/TSRA MAINLY DURING AFTERNOON AND EVENING. FRIDAY...MODERATE CONFIDENCE. VFR. && .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. SCATTERED SHOWERS / THUNDERSTORMS TO PERSIST OVER ALL OF THE S NEW ENGLAND REGION WHICH WILL AT TIMES IMPACT THE WATERS. ANTICIPATE HEAVY RAIN AND FREQUENT LIGHTNING WITH ANY STORMS. CAN NOT RULE OUT THE POSSIBILITY OF SMALL HAIL ALONG WITH GUSTY WINDS...THOUGH THINKING BELOW GALE FORCE. OTHERWISE SEAS REMAINING BELOW 4-FEET AS WINDS PREDOMINANTLY REMAIN OUT OF THE S. OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/... TUESDAY NIGHT AND WEDNESDAY...HIGH CONFIDENCE. WINDS AND SEAS REMAIN BELOW SCA. SCA. MAY SEE LEFTOVER SHOWERS/STORMS ON WATERS DURING EVENING. THURSDAY...MODERATE CONFIDENCE. INCREASING S/SW WINDS EXPECTED AHEAD OF COLD FRONT...BUT GUSTS SHOULD PEAK AROUND 20KT MAINLY ON S COASTAL WATERS. BUILDING S SWELL MAY REACH 5 FT ON OUTER WATERS S OF ISLANDS. MAY SEE THUNDERSTORMS LATER IN DAY AND THU EVENING. FRIDAY...MODERATE CONFIDENCE. HIGH PRESSURE BUILDS OVER WATERS. WINDS AND SEAS BELOW SCA. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...SIPPRELL/JWD NEAR TERM...SIPPRELL/JWD SHORT TERM...SIPPRELL LONG TERM...JWD AVIATION...SIPPRELL/JWD MARINE...SIPPRELL/JWD

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