Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 301130 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 730 AM EDT SAT AUG 30 2014 .SYNOPSIS... HIGH PRESSURE OVER NEW ENGLAND MOVES OFFSHORE TODAY. WARMER MORE HUMID AIR WILL THEN MOVE UP FROM THE SOUTH AND SOUTHWEST WITH SUMMERTIME HUMIDITY STARTING SUNDAY. AN UPPER LEVEL DISTURBANCE A FRONT WILL SLOWLY PUSH ACROSS NEW ENGLAND THROUGH MONDAY BRINGING A PERIOD OF SHOWERS AND SCATTERED THUNDERSTORMS. ANOTHER FAST MOVING FRONT MAY BRING A FEW MORE SHOWERS AND THUNDERSTORMS TUESDAY... MAINLY ACROSS THE INTERIOR. HIGH PRESSURE TAKES OVER LATE NEXT WEEK WITH DRY AND WARM CONDITIONS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 725 AM UPDATE... A FEW OF THE NORMALLY PRONE SPOTS REPORTED LOW CLOUDS AND BRIEF PATCHY FOG AROUND SUNRISE THIS MORNING...AND SOME STILL HAVE SOME LOW CLOUDS AT 11Z. EXPECT THIS TO BURN OFF BY MID MORNING...THEN WILL SEE HIGH CLOUDS FILTER IN THROUGH MIDDAY. WILL ALSO SEE SOME FAIR WEATHER CUMULUS CLOUDS DEVELOP DURING THE DAY. WITH THE MAINLY CLEAR SKIES AND CALM WINDS...SOME SPOTS ACROSS THE REGION WERE DOWN RIGHT CHILLY. AT 6 AM...KMVY REPORTED AT TEMP OF 39 DEGREES! OTHER COOL SPOTS INCLUDED 44 DEGREES AT KTAN...45 AT KOWD...47 AT KEWB...48 DEGS AT KPVC AND 49 AT KPYM. EXPECT READINGS TO REBOUND QUICKLY AS S WINDS PICK UP THIS MORNING. REMAINDER OF GRIDS WERE IN GOOD SHAPE...BUT HAVE UPDATED TO BRING CONDITIONS CURRENT. PREVIOUS DISCUSSION... FOR TODAY...GENERAL SUBSIDENCE UNDER THE HIGH SHOULD PROVIDE A SUNNY DAY. A MOIST LAYER WITH 75 PERCENT RH WILL LINGER BETWEEN 850 AND 900 MB WITH MIXING EXPECTED TO REACH TO 900 MB OR A LITTLE ABOVE. THIS SHOULD AGAIN GENERATE DIURNAL CUMULUS LATER THIS MORNING AND AFTERNOON. TEMPS AT THE TOP OF THE LAYER WILL SUPPORT MAX SFC TEMPS OF 73 TO 79F...A FEW SPOTS MAY TOUCH 80F. SOUTH WINDS COMING OFF THE OCEAN WILL KEEP THE SOUTH COAST A LITTLE COOLER...70 TO 75F. WINDS IN THE MIXED LAYER WILL BE AROUND 15-18 KNOTS...SO EXPECT SOME GUSTS TO THIS RANGE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... TONIGHT... WITH HIGH PRESSURE OFFSHORE...SOUTH WINDS WILL BRING WARMER MORE HUMID AIR TOWARD NEW ENGLAND. THIS WILL MEAN INCREASING CLOUDS AS THE HIGHER HUMIDITY AIR RIDES UP OVER THE COOLER AIRMASS AT THE SURFACE. THE MOIST LAYER WILL BE CONCENTRATED BELOW 950 MB WITH AT BEST WEAK LIFT...SO EXPECT CLOUDS AND FOG WITH SOME DRIZZLE POSSIBLE. SUNDAY... SHORTWAVE MOVING THROUGH THE UPPER FLOW WILL START THE DAY OVER THE GREAT LAKES. AN 85-90 KNOT JET WILL DRIVE THE SYSTEM EAST INTO NEW ENGLAND BY LATER IN THE DAY. THE DYNAMICALLY FAVORABLE ZONES FOR LIFT ASSOCIATED WITH THE JET WILL BE WELL TO OUR WEST IN THE MORNING...BUT THEN SHIFT INTO OUR AREA DURING THE AFTERNOON WITH THE BEST SUPPORT IN WESTERN MASS/SOUTHERN NH LATE IN THE DAY. CLOUDS MAY THIN IN THE MORNING BUT SHOULD THICKEN AGAIN THROUGH THE DAY AS SHORTWAVE AND ITS DEEPER MOISTURE MOVE IN. LAPSE RATE IN THE 850-500 MB LAYER IS SO-SO AT 5.5C/KM. TOTALS CLIMB TO THE MID 40S. WINDS AT 850 MB REACH 30 KNOTS WHILE 500 MB WINDS REACH 40-45 KNOTS. PRECIPITABLE WATER VALUES WILL CLIMB THROUGH THE DAY WITH AFTERNOON VALUES OF 2.0 TO 2.25 INCHES...MOVE THAN 2 STD DEVIATIONS ABOVE NORMAL AND POTENTIALLY NEAR 3. THIS FAVORS SHOWERS AND SCATTERED THUNDERSTORMS WITH POTENTIAL FOR STRONG WIND GUSTS AND HEAVY DOWNPOURS. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... OVERVIEW AND MODEL PREFERENCES... MEDIUM RANGE MODELS AND THEIR ENSEMBLES CONTINUE TO SHOW PRETTY GOOD CONTINUITY WITH THIS FORECAST PACKAGE...THOUGH SOME TIMING DIFFERENCES WORK IN BEGINNING AROUND THE TUESDAY TIMEFRAME THROUGH THE REMAINDER OF NEXT WEEK AS THE FLAT UPPER LEVEL WIND FLOW ACROSS THE NORTHERN TIER STATES TENDING TO CAUSE OPERATIONAL MODEL RUNS TO EXACERBATE TIMING ISSUES WITH FAST MOVING SYSTEMS IN THIS FLOW. UPPER LEVEL PATTERN FOR THIS PORTION OF THE FORECAST STARTS OFF WITH RATHER HIGH AMPLITUDE RIDGE FROM THE NORTHEAST INTO QUEBEC IN THE NORTHERN STREAM WIND FLOW...WHILE A TROUGH DIGS OUT OF THE NORTHERN PLAINS. OVERALL...THIS NORTHERN STREAM HAS BEEN GENERALLY FLATTER THAN THE LAST SEVERAL MONTHS /WITH HIGH AMPLITUDE SLOW MOVING PATTERNS/...WHICH SIGNALS A FASTER FLOW OF SURFACE SYSTEMS WITHIN THIS FLOW. EARLY IN THIS FORECAST...WILL SEE A SHORT WAVE RIDE ACROSS IN THE FLATTER PORTION OF THE RIDGE ACROSS THE REGION... WHICH WILL KEEP UNSETTLED CONDITIONS INTO THE HOLIDAY. ONCE THIS MOVES E...EXPECT A SOMEWHAT AMPLIFIED BUT PROGRESSIVE PATTERN THROUGH THE REMAINDER OF NEXT WEEK. ONE THING THAT IS CONSISTENT IS A CONTINUED MILDER THAN NORMAL TEMPERATURE REGIME WITH RATHER HIGH HUMIDITY TO START OFF...THEN WILL SLOWLY DROP BUT REMAIN SOMEWHAT UNCOMFORTABLE...OUR SHOT FOR LATE SUMMER CONDITIONS. LEANED TOWARD A BLEND OF AVAILABLE GUIDANCE INTO EARLY TUESDAY AS A PRETTY GOOD CONSENSUS CONTINUES. FROM LATER TUESDAY THROUGH THE END OF NEXT WEEK...TRANSITIONED OVER TO THE ENSEMBLE MEANS WHICH HAVE BEEN MORE STABLE THAN THE OPERATIONAL MODEL RUNS DUE TO TIMING ISSUES WITH THE FAST FLOW ALOFT. HAVE LOWER CONFIDENCE IN THE FORECAST BEYOND EARLY TUESDAY. DETAILS... SUNDAY NIGHT THROUGH MONDAY NIGHT... EXPECT SHOWERS AND SOME THUNDERSTORMS TO CONTINUE THROUGH MOST OF THIS TIMEFRAME AS AN UPPER LEVEL FEATURE AND SURFACE REFLECTION REMAINS PARALLEL TO THE SW UPPER FLOW. AS THE FLOW FLATTENS OUT LATE MON INTO MON NIGHT...THE LEFTOVER ENERGY WILL SHIFT OFFSHORE BUT MAY LINGER ACROSS SOUTHERN AREAS. MODELS CONTINUE TO SIGNAL HIGH PWATS...ON ORDER OF 2.2 TO 2.3 INCHES...SO SOME RAINFALL MAY BE HEAVY AT TIMES ESPECIALLY IN ANY THUNDERSTORMS. ANTECEDENT CONDITIONS HAVE BEEN PRETTY DRY OVER THE LAST SEVERAL WEEKS...EXCEPT FOR A FEW SPOTS THAT DID HAVE SOME LOCALLY HEAVY RAINFALL AROUND 8/27-28 /CENTRAL MA AND S CENTRAL CT/. THERE MAY BE A FEW LOCALIZED AREAS THAT ARE PRONE TO POOR DRAINAGE FLOODING THAT MIGHT HAVE SOME PROBLEMS SUN NIGHT INTO MON MORNING...BUT ONLY A LOW PROBABILITY FOR THIS. ALSO NOTING H85 WINDS UP TO 35-40 KT...SO SOME COULD MIX DOWN WITH ANY STORMS EARLY SUN NIGHT ACROSS THE INTERIOR. SHOULD START TO SEE IMPROVING CONDITIONS ACROSS S NH/N MA EARLY MON NIGHT...THEN WILL SHIFT SOUTHWARD OVERNIGHT. ONLY QUESTION WILL BE TIMING THE PRECIP EXIT ALONG THE S COAST...WHICH IT MAY LINGER A BIT LONGER. SHOULD SEE THIS AREA IMPROVE AROUND OR AFTER MIDNIGHT. EXPECT WARM AND HUMID CONDITIONS WITH S-SW WINDS IN PLACE. DEWPTS WILL BE STEAMY...IN THE 65 TO 70 DEGREE RANGE...THOUGH MAY DROP A BIT INLAND AS CONDITIONS IMPROVE MON NIGHT. TUESDAY AND TUESDAY NIGHT... ANOTHER FRONT WILL QUICKLY PUSH TOWARD THE REGION. WILL SEE ANOTHER ROUND OF SCT SHOWERS MAINLY ACROSS THE INTERIOR WHERE THE BEST ENERGY AND DYNAMICS OCCUR. CAN NOT RULE OUT A COUPLE OF THUNDERSTORMS AS WELL. SHOULD SEE IMPROVING CONDITIONS AFTER LEFTOVER SHOWERS WILL LIFT NE TUE NIGHT. WARM AND HUMID CONDITIONS WILL CONTINUE WITH HIGHS IN THE LOWER- MID 80S. IT WILL REMAIN STICKY TUE NIGHT...THOUGH DEWPTS MAY DROP A FEW DEGS WELL INLAND. WEDNESDAY THROUGH FRIDAY... HIGH PRES WILL MOVE ACROSS THE REGION THROUGH MOST OF THIS TIMEFRAME. WITH CONTINUED W-SW WINDS IN PLACE...TEMPS WILL REMAIN SEVERAL DEGS WARMER THAN SEASONAL NORMS FOR EARLY SEPTEMBER. DOES LOOK LIKE DEWPTS WILL BE A BIT MORE COMFORTABLE ON THURSDAY... FORECAST IN THE MID 50S TO AROUND 60 /VS. 65 TO 70 EARLY IN THE WEEK/. HIGHS WILL CONTINUE IN THE LOWER-MID 80S. MAY SEE ANOTHER FRONT TRY TO APPROACH LATER FRIDAY...THOUGH TIMING IS IN QUESTION. HAVE KEPT A DRY FORECAST DURING THE DAY FOR NOW...BUT MIGHT SEE SOME SHOWERS TRY TO MOVE IN FRI NIGHT. LOWER CONFIDENCE ON THIS PORTION OF THE FORECAST. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /THROUGH SUNDAY/...HIGH CONFIDENCE. TODAY...GENERALLY VFR. LOCAL MVFR-IFR THROUGH 13Z-14Z IN NORMALLY PRONE AREAS OF S NH/NE CT/E INTERIOR MA. EXPECT LIGHT/VRBL OR CALM WINDS AT 12Z TO BECOME S AT 5-10 KT. TONIGHT...VFR EARLY. INCREASING RISK OF MVFR CIGS/VSBY IN DEVELOPING CLOUD COVER AND FOG/DRIZZLE...MAINLY AFTER MIDNIGHT. SUNDAY... MVFR/IFR EARLY IN FOG AND LOW CLOUDS. VSBY SHOULD IMPROVE TO VFR DURING THE MORNING EXCEPT ALONG THE SOUTH COAST WHERE IFR MAY LINGER. MVFR AND LOW-END VFR CEILINGS AWAY FROM THE SOUTH COAST DURING THE AFTERNOON. THUNDERSTORMS EXPECTED TO DEVELOP IN THE AFTERNOON...MOSTLY IN THE CT VALLEY AND SOUTHERN NH. POTENTIAL FOR HEAVY DOWNPOURS AND STRONG WIND GUSTS WITH ANY THUNDERSTORMS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY... SUNDAY NIGHT AND MONDAY...LOW CONFIDENCE. LOW END VFR GENERALLY...THOUGH WILL SEE POCKETS OF MVFR-IFR CIGS/VSBYS IN AREAS OF SHOWERS. POSSIBLE TSRA AT SOME TERMINALS ESPECIALLY INLAND EARLY SUN NIGHT. S-SW WINDS CONTINUE. PATCHY FOG DEVELOPS WITH MVFR-IFR VSBYS LATE SUN NIGHT INTO MON MORNING. TUESDAY...MODERATE CONFIDENCE. ANOTHER FRONT PUSHES ACROSS THE REGION TUE NIGHT. MAINLY LOW END VFR CONDITIONS. SCT SHOWERS ACROSS THE INTERIOR TUE AFTERNOON/EARLY TUE NIGHT...THEN SHOULD LIFT NE. LOW RISK FOR TSRA. WINDS VEER TO W LATE TUE NIGHT. MAY SEE PATCHY FOG AFTER MIDNIGHT IN NORMALLY PRONE VALLEY AREAS. WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR. PATCHY FOG EARLY WED MORNING WITH LOCAL MVFR-IFR VSBYS WILL IMPROVE BY MID MORNING. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY...HIGH PRESSURE OVER THE WATERS WILL MEAN FAIR SKIES AND LIGHT SOUTH WINDS. SOME PATCHY FOG POSSIBLE AROUND SUNRISE. TONIGHT... WARM HUMID AIR MOVES UP FROM THE SOUTH AND ACROSS THE WATERS. THIS WOULD FAVOR PATCHY FOG AND POSSIBLY LIGHT DRIZZLE. SUNDAY...INCREASING SOUTHWEST WIND WITH GUSTS 20-22 KNOTS. BUILDING SEAS...BUT HEIGHTS BELOW 5 FEET UNTIL EVENING. SHOWERS/TSTMS WILL DEVELOP WEST AND NORTHWEST OF MASSACHUSETTS. THERE IS A LOW END CHANCE THESE COULD REACH THE WATERS LATE SUNDAY WITH HEAVY DOWNPOURS AND STRONG WIND GUSTS. OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY... SUNDAY NIGHT AND MONDAY...MODERATE CONFIDENCE. S-SW WINDS GUSTING UP TO 20 KT. MAY SEE A FEW GUSTS CLOSE TO 25 KT ON THE OUTER WATERS SUN NIGHT. SEAS BUILD TO AROUND 5 FT MAINLY ON THE SOUTHERN OUTER WATERS. MAY SEE PATCHY FOG DEVELOP LATE SUN NIGHT INTO MON MORNING. TUESDAY AND WEDNESDAY...MODERATE CONFIDENCE. EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. SW WINDS WILL VEER TO W LATE TUE NIGHT INTO WED. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/EVT NEAR TERM...WTB/EVT SHORT TERM...WTB LONG TERM...EVT AVIATION...WTB/EVT MARINE...WTB/EVT

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