Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 272303 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 703 PM EDT SUN JUL 27 2014 .SYNOPSIS... A RATHER STRONG AREA OF LOW PRESSURE BY JULY STANDARDS WILL DEVELOP OVER NY AND PA TONIGHT. ITS WARM FRONT WILL BRING A ROUND OF HEAVY SHOWERS AND THUNDERSTORMS MONDAY MORNING TO THE REGION FOLLOWED BY POSSIBLE STRONG THUNDERSTORMS MONDAY AFTERNOON TO THE AREA AS ITS ATTENDING COLD FRONT APPROACHES FROM THE WEST. BY TUE THE FRONT MOVES OFFSHORE WITH DRY AND MUCH LESS HUMID WEATHER OVERSPREADING THE REGION AND CONTINUING FOR MUCH OF THE REMAINDER OF THE WORKWEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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*** WIDESPREAD HEAVY RAIN AND T-STORMS POSSIBLE LATE TONIGHT INTO MONDAY MORNING *** 7 PM UPDATE... STILL MONITORING CONVECTION OVER WESTERN MA VICINITY OF SPRINGFIELD. STORMS HAVE A HISTORY OF PRODUCING STRONG WINDS...LARGE HAIL AND HEAVY RAINFALL. ACTIVITY WILL CONTINUE MOVING EAST- SOUTHEAST INTO CT WHERE TEMPS REMAIN IN THE L80S WITH DEW PTS IN THE U60S/L70S. THIS YIELDS ML CAPES OF AROUND 1500J/KG. STORMS WILL WEAKEN SLOWLY WITH SUNSET HOWEVER MAY PERSIST A WHILE LONGER GIVEN DEEP LAYER SHEAR OF 35 KT AND MID LEVEL LAPSE RATES OF 6-6.5C/KM. OTHERWISE REMAINDER OF THE REGION WILL REMAIN DRY. THEN LATER TONIGHT OUR ATTENTION SHIFTS TO CONVECTION CURRENTLY OVER WESTERN PA ASSOCIATED WITH ANOMALOUS SHORT WAVE TROUGH AND ASSOCIATED DEVELOPING LOW PRES AND ATTENDING WARM FRONT. THIS ACTIVITY WILL REACH CT AND WESTERN MA BETWEEN 06Z-09Z THEN THE REMAINDER OF THE REGION 09Z- 12Z. HEAVY RAIN AND A FEW STRONG STORMS ARE POSSIBLE WITH THIS NEXT ROUND. EARLIER DISCUSSION BELOW. ================================================================== ANOMALOUS POTENT SHORT WAVE TROUGH OVER THE GREAT LAKES THIS AFTERNOON WILL BRING A ROUND OF HEAVY SHOWERS/T-STORMS LATE TONIGHT INTO MON MORNING...FOLLOWED BY A SECOND ROUND OF T-STORMS /POSSIBLY STRONG TO SEVERE/ MON AFTERNOON. AS FOR THIS EVENING...WARM FRONTAL CONVECTION HAS MOVED OFFSHORE AS OF MID AFTERNOON. SPC MESOANALYSIS INDICATES MUCH DRIER MID LEVEL AIR OVER NY AND PA ADVECTING EASTWARD TOWARD NEW ENGLAND. THE LEADING EDGE OF THIS DRIER AIR IS ON THE BACKSIDE OF THE MID LEVEL TROUGH ACROSS EASTERN NY STATE AND WESTERN NEW ENGLAND. UNTIL THIS MLVL TROUGH EXITS EAST OF THE AREA THERE IS THE RISK OF AN ISOLATED TSTM WITH THE HIGHEST RISK ACROSS WESTERN CT/MA INTO SOUTHWEST NH. ELSEWHERE DRY AND HUMID CONDITIONS SHOULD PREVAIL. GIVEN THE HIGH DEW PT/THETA-E AIRMASS OVER THE REGION...LOW CLOUDS AND FOG SHOULD DEVELOP AFTER SUNSET AS THE BLYR COOLS. OVERNIGHT...INITIAL SHORT WAVE RIDGING AND MID LEVEL DRY AIR SHOULD KEEP SOUTHERN NEW ENGLAND DRY THROUGH ABOUT 06Z/2AM. THEREAFTER POTENT SHORT WAVE TROUGH OVER THE GREAT LAKES APPROACHES FROM THE SOUTHWEST. THIS FEATURE INDUCES CYCLOGENESIS OVER PA/NY STATE. A BAND OF WARM FRONTAL PRECIP/CONVECTION WILL SWEEP ACROSS THE REGION BETWEEN 09Z-12Z FROM SW TO NE. HEAVY DOWNPOURS AND A FEW OF THE STRONGER STORMS MAY CONTAIN GUSTY WINDS AS MUCH OF THE MDL GUID INDICATES 500-1000 J/KG OF CAPE TOWARD 12Z. HOWEVER THE GREATEST RISK IS ISOLATED POOR DRAINAGE FLOODING. THINK RISK OF FLASH FLOODING IS LOW GIVEN HOW QUICKLY SYSTEM IS MOVING AND PWATS ARE ONLY +1 SD ABOVE CLIMO. NEVERTHELESS HEAVY SHOWERS/TSTMS MAY IMPACT THE MORNING COMMUTE. IT WILL BE A WARM AND MUGGY WITH DEW PTS IN THE 60S TO AROUND 70.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... *** FEW STRONG TO SEVERE STORMS POSSIBLE MON AFTERNOON *** IMPRESSIVE SHORT WAVE TROUGH SWINGS ACROSS THE AREA MON WITH 500 MB HEIGHTS ON THE ORDER OF -3 SD FROM CLIMO! SURFACE LOW PRES TRACKS FROM PA/NY BORDER THEN ACROSS CENTRAL NEW ENGLAND IN THE AFTERNOON. WARM FRONTAL CONVECTION WITH HEAVY RAIN IS LIKELY IN THE MORNING BUT SHOULD LIFT QUICKLY NORTHEAST AND EXIT THE REGION 12Z-15Z FROM SW TO NE. WARM SECTOR THEN OVERSPREADS EASTERN HALF OF THE REGION WITH TEMPS RISING INTO THE 80S AND DEW PTS 65-70. THIS WILL YIELD SB CAPES OF 1000-2000J/KG ALONG WITH MID LEVEL LAPSE RATES OF 6-6.5C/KM AS COOLING OCCURS ALOFT. DEEP LAYER SHEAR IS STRONG AS WELL WITH 0-6 KM 35 TO 40 KT. FORCING FOR ASCENT WILL BE PROVIDED BY STRONG FRONTAL CONVERGENCE AS COLD FRONT APPROACHES FROM THE WEST. IN ADDITION LFQ OF ANOMALOUS UPPER LEVEL JET OVER THE AREA WILL PROVIDE ENHANCED QG FORCING. THE ONLY WRINKLE IS THE EXACT TIMING AND TRAJECTORY OF THE DRY SLOT WHICH MUCH OF THE GUID SUGGEST WILL BE OVER SOUTHEAST MA AND VCNTY. THUS THE GREATEST THREAT OF STRONG TO SEVERE TSTMS MAY BE FROM INTERIOR CT NORTHEAST INTO CENTRAL AND NORTHEAST MA INCLUDING SOUTHERN NH. SPC HAS PLACED THIS REGION IN A SEE TEXT. MAIN THREATS WILL BE STRONG TO DAMAGING WINDS/LARGE HAIL AND LOW RISK OF AN ISOLATED TORNADO GIVEN STRONG LOW LEVEL SHEAR AND HIGH DEW PTS/LOW LCL. MON NIGHT... BIG IMPROVEMENT BEHIND THE FRONTAL PASSAGE WITH MUCH LESS HUMID AIRMASS OVERSPREADING THE REGION WITH DEW PTS FALLING INTO THE 50S! THIS WILL SUPPORT LOW TEMPS BY TUE MORNING IN THE MU50S INLAND AND LOW TO MID 60S ALONG THE COAST. && .LONG TERM /TUESDAY THROUGH SUNDAY/...
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*/ HIGHLIGHTS... - SLIGHTLY COOL AND DRY INTO THE END OF JULY! - SCATTERED STORMS POSSIBLE ACROSS INTERIOR NEW ENGLAND FOR THURSDAY - DECENT CHANCES FOR WET WEATHER FRIDAY INTO SATURDAY - POSSIBLE DAILY OCCURRENCES OF INTERIOR STORMS INTO NEXT WEEK */ OVERVIEW AND MODEL PREFERENCE... INCREDIBLE PATTERN FOR MID-SUMMER! ENSEMBLE SIGNALS AVERAGING WELL- BELOW NORMAL /-4 TO -5 SD/ FOR BOTH TEMPERATURE AND HUMIDITY ACROSS THE NE CONUS AS A BUCKLED PATTERN PREVAILS WITH PREFERRED TROUGHING ACROSS THE GREAT LAKES NEIGHBORED BY STRONG RIDGING. ANTICIPATING A COOL TO SEASONABLE PATTERN LACKING OF HEAT AND HUMIDITY. GOING DEEPER...SLIGHTLY NEGATIVE NAO/AO INDICES INTO THE EARLY-HALF OF AUGUST AS THE ENSEMBLE SPREAD OF THE PNA EXHIBITS AN OVERALL POSITIVE TREND SIGNALS CONTINUED RIDGING OVER THE E-PACIFIC WITH PREFERRED TROUGHING E. NO SURPRISE THAT THE NAEFS/GEFS ANALOGS ALONG WITH THE EC-ENSEMBLE HOLD A BUCKLED PATTERN ACROSS THE REGION AS THE W-ATLANTIC RIDGE REMAINS STOUT. TREND OF ANOMALOUS BELOW-NORMAL CONDITIONS PREVAILS. THOUGH...PER AFOREMENTIONED ANALOGS/ENSEMBLES...THERE IS A POTENTIAL TREND TOWARDS DEAMPLIFICATION. THIS RESONATES WITHIN GLOBAL FORECAST SOLUTIONS HIGHLIGHTING A PHASE-SHIFT IN THE MJO CLIMATOLOGICALLY RESULTING IN A MORE ZONAL PATTERN WITH WARMER TEMPERATURE ANOMALIES OVER NORTH AMERICA. SOME UNCERTAINTY WITH A CONTINUED LOW ANOMALY OVER NE CANADA. WILL HAVE TO WAIT AND SEE. AS TO THE FORECAST...WILL TREND WITH MORE SEASONABLE CONDITIONS AS CYCLONIC FLOW ALOFT PREVAILS USHERING MUCH COOLER AIR S OUT OF CANADA. PRECIPITATION CHANCES VARY...BUT WILL NEED TO CLOSELY MONITOR INDIVIDUAL IMPULSES AND ACCOMPANYING JET STREAKS THROUGH THE OVERALL TROUGH PATTERN. ITS PLAUSIBLE TO SEE PERIODS OF WET WEATHER SHOULD THE TROUGH WOBBLE PARENT WITH ITS NEIGHBORING RIDGE AXES. WILL BREAK DOWN THE HIGHLIGHTS/CONFIDENCE WITHIN THE DAILY DISCUSSION BELOW. */ DAY-TO-DAY DETAILS... TUESDAY INTO WEDNESDAY... MID- TO UPPER-LEVEL CYCLONIC FLOW USHERS +8-10C H85 AIR INTO S NEW ENGLAND AS THE MAJORITY OF ACTIVITY/DYNAMICS IS SHUNTED OFFSHORE. WEAK HIGH PRESSURE WITH LIGHT WINDS SLOWLY TURNING S TOWARDS THE END OF THE PERIOD. LOTS OF DRY AIR IN PLACE AS IT CONTINUALLY WRAPS INTO THE OCCLUSION AS NEW ENGLAND FINDS ITSELF WITHIN THE LFQ OF THE UPPER-LEVEL JET...A FAVORABLE REGION OF SUBSIDENCE. WILL PREVAIL WITH SEASONABLE CONDITIONS WITH SEA-BREEZES ALONG THE SHORES. A DRY FORECAST WITH ACTIVITY HELD WELL N/W PARENT WITH THE OCCLUSION AND BETTER COLD-POOL. PARTLY CLOUDY CONDITIONS DURING THE DAY WITH DIURNAL CUMULUS. THURSDAY... MAIN IMPULSE ASSOCIATED WITH THE OCCLUSION EJECTS CYCLONICALLY OVER THE E GREAT LAKES. EXPECT SUBSEQUENT FALLING HEIGHTS COLOCATED WITH STRONG ENHANCED ASCENT AND DEEP-LAYER LIFT /ESPECIALLY WITHIN THE LFQ OF AN ATTENDANT JET STREAK/. SHOULD SEE DIURNALLY-DRIVEN ACTIVITY DEVELOP ACROSS INTERIOR NEW ENGLAND BENEATH COOLER AIR ALOFT AND CYCLONIC FLOW. SEVERITY SHOULD BE LIMITED LACK OF INSTABILITY WITH POOR LAPSE RATES AND ABUNDANCE OF DRY AIR...DESPITE DECENT SW-NE UNI-DIRECTIONAL SHEAR. EXPECT ISOLATED TO SCATTERED ACTIVITY AWAY FROM THE SHORELINES WHICH SHOULD REMAIN FAIRLY QUIET UNDER THE INFLUENCE OF ONSHORE MARITIME AIR. FRIDAY INTO SATURDAY... PACIFIC-ORIGIN ENERGY ROUNDING THE BROADER TROUGH PATTERN STREAMS NE ACROSS NEW ENGLAND. MID- TO UPPER-LEVEL TIGHTENING OF THE PRESSURE GRADIENT RESOLVES A FASTER JET STREAK SUBSEQUENTLY. SHOULD SEE A BROADSCALE REGION OF FAVORABLE ASCENT DEVELOP ACROSS NEW ENGLAND. BUT CHALLENGES PREVAIL BETWEEN LIKELY DIURNALLY DRIVEN ACTIVITY ACROSS INTERIOR NE-CONUS AND LINGERING OFFSHORE FRONTAL BOUNDARY. ANTICIPATING A REGION BETWEEN OF DRIER WEATHER...JUST WHERE AND HOW IT EVOLVES ENTERTAINS A FAIR AMOUNT OF UNCERTAINTY. EC/GEFS TREND WITH ACTIVITY MAINLY ACROSS THE INTERIOR WHEREAS THE 27.12Z GFS RETROGRADES THE OFFSHORE FRONT PARENT WITH A FRONTAL LOW CONSEQUENTIAL OF THE AFOREMENTIONED PACIFIC ENERGY. ALL SOLUTIONS SHOW THE MAIN LOW OVER THE GREAT LAKES LIFTING OUT OF THE REGION TO THE NE. SUNDAY INTO EARLY NEXT WEEK... THOUGH PATTERN DEAMPLIFICATION IS POSSIBLE...CYCLONIC FLOW PREVAILS BEHIND THE EARLIER PACIFIC IMPULSE. WILL HOLD WITH THE TYPICAL SUMMER-TIME PATTERN OF CONVECTION ACROSS THE INTERIOR WITH QUIET WEATHER ALONG THE SHORES.
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&& .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 7 PM UPDATE... ONLY CHANGE TO 18Z TAFS WAS TO ACCOUNT FOR TSTMS VICINITY OF BAF/BDL THRU 00Z/01Z. OTHERWISE NO CHANGES. EARLIER DISCUSSION BELOW. ================================================================ MODERATE CONFIDENCE THROUGH MON...THEN INCREASING CONFIDENCE MON NIGHT. THRU 00Z...SHOWERS AND SCATTERED TSTMS EXIT EASTERN MA 3PM OR 4PM...THEN ANY NEW CONVECTION SHOULD BE VERY ISOLATED IF AT ALL. ANY LINGERING MVFR ACROSS EASTERN MA WILL IMPROVE TO LOW END VFR BY 4 PM. TONIGHT...MARGINAL MVFR/VFR TO START THEN LOWERING TO MVFR/IFR AS THE NIGHT PROGRESS AS FOG DEVELOPS. ANOTHER ROUND OF HEAVY SHOWERS WITH SCT TSTMS DEVELOPS 07Z-10Z FROM SW TO NE. HEAVY RAIN AND GUSTY WINDS ARE THE MAIN THREATS. MONDAY...IFR/LIFR IN THE MORNING WITH SCT SHRA/TSTMS LIFTS NE INTO ME 12Z TO 15Z FROM SW TO NE. THEN LOW END VFR MOST TERMINALS BY AFTERNOON WITH ANOTHER ROUND OF TSTMS POSSIBLE EXPECT ACROSS RI AND SOUTHEAST MA WHERE RISK OF SHRA/TSTMS IS MUCH LOWER. A FEW STRONG STORMS ARE POSSIBLE WITH HEAVY RAIN AND GUSTY WINDS. MONDAY NIGHT...IMPROVING WEATHER AFTER 03Z OR SO AS COLD FRONT SWEEPS ACROSS THE AREA ALONG WITH A WIND SHIFT TO THE WNW. ANY LINGERING SHOWERS/TSTMS ACROSS NORTHERN MA AND SOUTHWEST NH AND MVFR CONDITIONS WILL IMPROVE TO VFR AFTER 03Z OR SO. KBOS TAF...MODERATE CONFIDENCE. SHOWERS/STORMS JUST ABOUT OFFSHORE AS OF 230 PM. LITTLE IF ANY NEW CONVECTION UNTIL 09Z-12Z MON. LOWERING TO MVFR/IFR TONIGHT IN FOG...THEN IMPROVING TO VFR MON MIDDAY. A FEW STRONG STORMS POSSIBLE MON AFTN. KBDL TAF...MODERATE CONFIDENCE. BRIEF MVFR CONDITIONS IN STORMS THRU 00Z-01Z THEN IMPROVING TO VFR. THEN CONDITIONS LOWER 06Z-09Z TO MVFR/IFR IN SHOWERS AND TSTMS. HEAVY RAIN AND GUSTY WINDS POSSIBLE. CONDITIONS IMPROVE TO VFR MON MIDDAY WITH ANOTHER ROUND OF AFTN T-STORM POSSIBLE. A FEW STRONG STORMS POSSIBLE. OUTLOOK...TUESDAY THROUGH FRIDAY...MODERATE CONFIDENCE. TUESDAY AND WEDNESDAY...HIGH CONFIDENCE. VFR WITH LIGHT WINDS GRADUALLY TURNING S. SEA-BREEZES ALONG THE SHORES. THURSDAY...MODERATE CONFIDENCE. ISOLATED-SCATTERED SHRA/TSRA POSSIBLE OVER INTERIOR TERMINALS WITH MIX OF MVFR-IFR CONDITIONS. SEA-BREEZES ALONG THE SHORES. FRIDAY...LOW CONFIDENCE. SCATTERED-WIDESPREAD SHRA/TSRA. MAIN FOCUS ACROSS SE/W/CENTRAL NEW ENGLAND. COULD BE A LULL IN ACTIVITY AROUND THE BOS-PVD CORRIDOR.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. MODERATE CONFIDENCE THROUGH MON NIGHT TONIGHT...PATCHY DENSE FOG POSSIBLE. SHOWERS AND TSTMS REDEVELOP TOWARD DAYBREAK. A FEW STRONG STORMS POSSIBLE ALONG WITH VERY HEAVY RAIN. MONDAY...PATCHY DENSE FOG IN THE MORNING BURNS OFF/ERODES BY EARLY AFTERNOON. EARLY MORNING SHOWERS AND TSTMS TAPER OFF FOLLOWED BY A NEW ROUND OF SHOWERS/TSTMS MID TO LATE AFTERNOON. A FEW OF THESE STORMS MAY BE STRONG ALONG WITH HEAVY DOWNPOURS. SSW WINDS MAY APPROACH 25 KT AS THE AFTERNOON PROGRESSES ESPECIALLY NEAR SHORE. MON NIGHT...COLD FRONT SWEEPS ACROSS THE WATERS WITH A WIND SHIFT TO THE WNW ALONG WITH DRY WEATHER AND GOOD VSBY. OUTLOOK...TUESDAY THROUGH FRIDAY...MODERATE CONFIDENCE. TUESDAY THROUGH THURSDAY...MODERATE CONFIDENCE. LIGHT WINDS ASSOCIATED WITH HIGH PRESSURE SHOULD ALLOW FOR TRANQUIL BOATING WEATHER AS SEAS DIMINISH. FRIDAY...MODERATE CONFIDENCE. WHILE BOATING CONDITIONS REMAIN TRANQUIL...WILL SEE INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS DEVELOP ACROSS THE WATERS. && .EQUIPMENT...
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OUR DOPPLER RADAR IS DOWN. A TECHNICIAN IS ON THE WAY IN. WE APOLOGIZE FOR ANY INCONVENIENCE.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 7 AM TO 7 PM EDT MONDAY FOR ANZ235-250-254>256. && $$ SYNOPSIS...NOCERA NEAR TERM...NOCERA SHORT TERM...NOCERA LONG TERM...SIPPRELL AVIATION...NOCERA/SIPPRELL MARINE...NOCERA/SIPPRELL EQUIPMENT...NOCERA

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