Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 211200 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 700 AM EST FRI NOV 21 2014 .SYNOPSIS... BLUSTERY AND UNSEASONABLY COLD CONDITIONS TODAY. TEMPERATURES MODERATE SATURDAY WITH GUSTY SOUTHWEST WINDS...THEN A SIGNIFICANT WARM-UP IS IN STORE SUNDAY AND MONDAY...BUT IT WILL LIKELY BE ACCOMPANIED BY A PERIOD OF RAIN. A COASTAL STORM MAY AFFECT THE REGION SOMETIME DURING THE MIDDLE OF NEXT WEEK BUT IT IS UNCERTAIN HOW CLOSE IT WILL TRACK TO NEW ENGLAND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 7 AM UPDATE... LAST IMPULSE DIRECTLY ASSOCIATED WITH THIS COLD LONGWAVE TROF IS MOVING SE OF THE REGION THIS MORNING AS HIGH PRES BEGINS TO NOSE OVER FROM THE SW. EXPECT THE MAINLY CLEAR TO PARTLY CLOUDY SKIES TO CONTINUE THROUGH THE DAY...AND IN SPITE OF THIS...TEMPERATURES WILL REMAIN WELL ON THE COOL SIDE OF NORMAL. FORECAST ON TRACK...SO ADJUSTMENTS THIS MORNING ARE MINOR. MID LEVEL TROF AND CORE OF COLD AIR ALOFT MOVES INTO NEW ENG TODAY BUT COLUMN IS VERY DRY SO EXPECT MOSUNNY SKIES. UNSEASONABLY COLD CONDITIONS AS 850 MB TEMPS -13/14C WHICH TRANSLATES TO MAXES UPPER 20S NW HIGHER TERRAIN TO MID 30S COASTAL PLAIN. WIND WILL BE A FACTOR AS PRESSURE GRADIENT AND GOOD MIXING SUPPORTS NW WIND GUSTS TO 25-30 MPH WHICH WILL MAKE IT FEEL CONSIDERABLY COLDER IN THE TEENS AND 20S. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... TONIGHT... CENTER OF HIGH PRES MOVES TO THE MID ATLC COAST BUT RIDGE AXIS BUILDS INTO NEW ENG WHICH WILL RESULT IN CLEAR SKIES AND DIMINISHING WIND AS PRESSURE GRADIENT RELAXES. GIVEN VERY DRY AIRMASS IT WILL BE A COLD NIGHT AS DECENT RADIATIONAL COOLING DEVELOPS. MINS WILL BE MOSTLY IN THE TEENS...EXCEPT LOWER 20S ALONG THE IMMEDIATE COAST. LOW PROB FOR SOME SINGLE NUMBER MIN TEMPS W MA AND SW NH. SATURDAY... HIGH PRES BUILDS S OF NEW ENG WITH SUNSHINE GIVING WAY TO INCREASING AFTERNOON CLOUDS AS LOW AND MID LEVEL MOISTURE INCREASES FROM THE WEST. INCREASING SW FLOW BRINGS MILDER AIR INTO SNE AS PRONOUNCED LOW AND MID LEVEL WARMING OCCURS. AFTER A RATHER COLD START...TEMPS WILL RECOVER INTO THE MID 30S TO LOWER 40S. 40 KT LOW LEVEL JET DEVELOPS BY LATE DAY WHICH WILL LEAD TO GUSTY SW WINDS IN THE AFTERNOON/EVENING...ESPECIALLY NEAR THE COAST WHERE BETTER LOW LEVEL LAPSE RATES. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... OVERVIEW AND MODEL PREFERENCES... WITH THE ECMWF AND GFS OPERATIONAL RUNS CONTINUING TO SHOW MODERATE AGREEMENT THROUGH THE MID TERM...A GENERAL BLEND WILL BE USED AS A BASELINE. ITS NOT UNTIL LATER ABOUT MID WEEK THAT THE STRONGEST DIVERGENCE IN MODEL SOLUTIONS EVEN AMONG ENSEMBLES/MEANS...SO CONFIDENCE THROUGH MON-TUE REMAINS RELATIVELY HIGH WHILE CONFIDENCE BECOMES LOW FROM MID NEXT WEEK THROUGH THE THANKSGIVING HOLIDAY PERIOD. THE ISSUE IS LIKELY THE SHIFTING PATTERN THROUGH THE PERIOD...STARTING WITH BUILDING RIDGE SUN-MON AS PHASING NORTHERN AND SOUTHERN STREAM WAVES DEVELOP INTO OCCLUDING SYSTEM AROUND THE GREAT LAKES. THIS DEVELOPING TROF IS THEN EXPECTED TO GRADUALLY DEEPEN AND DIG INTO A SLOWER LONGWAVE TROF TO THE W...SIMILAR...THOUGH NOT AS COLD AS THIS WEEK/S DEEP TROUGH BUT WITH THE AXIS FURTHER TO THE W. THEREFORE...TIME-MEAN JET REMAINS SOUTHWESTERLY AND WARMING UNTIL THE CORE CAN SLIDE TO THE E LATER IN THE WEEK. AGREE WITH THE PREVIOUS FORECASTER...THAT THIS SUGGEST THE NEAR NORMAL TO WARM WEATHER CONTINUES UNTIL A COOLING TREND OCCURS LATER IN THE WEEK. DETAILS... SAT NIGHT INTO SUN EVENING... SFC WARM FRONT WILL BE NOSING IN FROM THE W WHILE SHIFTING TO THE N WITH TIME TOWARD 12Z SUN. NOTE MODEST MID LVL ISENTROPIC LIFT WITH SOME MOISTURE SUGGESTING LOW END CHANCE FOR LIGHT PRECIP ESPECIALLY N OF THE MA PIKE AND W OF I-495. TIMING WILL BE THE KEY HERE...AGREE WITH PREVIOUS FORECASTER THAT IF THE CLOUDS BUILD IN TOO QUICKLY TEMPS MAY REMAIN NEAR OR ABOVE FREEZING WHILE ALLOWANCE FOR MORE COOLING SUGGESTS THAT SFC TEMPS MAY BE A FEW DEGREES BELOW FREEZING. THEREFORE...MAY HAVE TO MONITOR FOR LIGHT FREEZING RAIN...IF THE TEMPS FALL BACK INTO THE MID-UPPER 20S LIGHT ICING IS NOT OUT OF THE QUESTION...BUT AGAIN TOTAL RAINFALL WOULD BE LIGHT AND TEMPS MAY PRECLUDE ANY IMPACTS. WILL NEED TO WATCH THIS AS WE APPROACH. OTHERWISE SUN...WARMING EXPECTED WITH AREAS REACHING THE MID 40S TO LOW 50S BY LATE IN THE DAY IN SPITE OF INCREASING CLOUDS. DWPTS ALSO RISE AS WELL. SUN NIGHT INTO MON... OCCLUDING LOW PRES TO THE W WILL PUSH 60-65 KT LLJ THROUGH THE REGION DURING THE EARLY MORNING HOURS MON. THIS WILL BE COINCIDENT WITH 1.0 INCH PWATS /ABOUT 2 STD DEVIATIONS FROM NORMAL/. THEREFORE...EXPECT SOME WIDESPREAD RAINFALL WITH MODEST CONVECTIVE ELEMENTS AS K VALUES HOVER AROUND 30...SUGGESTING HEAVY RAIN. THIS COULD ALSO YIELD SOME STRONG WINDS AND POSSIBLY EVEN A FINE-LINE DEVELOPMENT WHICH WILL NEED TO BE WATCHED. OVERALL RAINFALL VALUES OF 0.5-1.0 INCHES EXPECTED...WITH HIGHER AMOUNTS POSSIBLE. AFTER A LULL THE THREAT FOR SHOWERS CONTINUES INTO MON EVENING AS THE UPPER LVL SHORTWAVE PIVOTS THROUGH. MILD WX CONTINUES AS HIGHS COULD APPROACH THE UPPER 50S TO NEAR 60F. TUE... HIGH PRES BUILDS IN BRIEFLY FOR TUE. WARM TEMPS STILL EXPECTED AS THE CORE OF THE COLD AIR REMAINS TO THE W. EXPECT HIGHS RANGING FROM THE UPPER 40S TO UPPER 50S. WED-WED NIGHT... STILL UNCERTAINTY HERE...BUT WITH STALLED FRONTAL BOUNDARY TO THE SOUTHEAST...A DEVELOPING WAVE OF LOW PRES MAY PASS JUST CLOSE ENOUGH THE 40/70 BENCHMARK TO INITIATE TROWAL BASED PRECIP ACROSS PORTIONS OF SRN NEW ENGLAND. REGARDING THERMAL PROFILES...WHICH ARE LIKELY TO CHANGE GIVEN BOTH OPERATIONAL AND ENSEMBLE MEMBERS ARE ONLY RECENTLY CONVERGING ON THIS...TEMPS APPROACHING -6C TO -10C AT H85 SUGGEST THE POSSIBILITY OF WINTERY PRECIP IN THE INTERIOR...BUT MAY BE TOO WARM ALONG THE COAST. STILL TOO UNCERTAIN HERE TO MAKE ANY CALLS...BUT WORTH WATCHING GIVEN THE POTENTIAL TRAVEL IMPLICATIONS. THU-FRI... DEPENDENT ON THE FINAL TIMING TRACK OF THE OFFSHORE SYSTEM...HIGH PRES WOULD FOLLOW FOR THE LATE WEEK PERIOD...WITH COLDER DRIER AIR BUILDING IN FROM THE NW. && .AVIATION /11Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...HIGH CONFIDENCE. NO MAJOR CHANGES WITH 12Z UPDATE. TODAY... VFR. GUSTY NW WINDS TO 25 KT. TONIGHT...VFR WITH DIMINISHING WIND. SATURDAY...VFR. INCREASING SW WINDS IN THE AFTERNOON WITH GUSTS TO 25-30 KT DEVELOPING IN THE COASTAL PLAIN. KBOS TERMINAL...HIGH CONFIDENCE. KBDL TERMINAL...HIGH CONFIDENCE. OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY... SATURDAY NIGHT...MODERATE CONFIDENCE. CLOUDS MOVE IN AT NIGHT...BRIEF MVFR POSSIBLE OVERNIGHT IN LIGHT SPRINKLES ESPECIALLY NORTH OF THE MASS PIKE. COULD BE LIGHT FREEZING DRIZZLE/FREEZING SPRINKLES NORTH AND WEST OF I-495. SUNDAY...HIGH CONFIDENCE. VFR. DIMINISHING WIND. SUNDAY NIGHT-MONDAY...CIGS/VSBYS LOWER TO MVFR/IFR IN RAIN/FOG. SOUTH WIND AT 2000 FEET INCREASES TO 60-65 KNOTS ALONG THE COASTAL PLAIN LATE NIGHT AND MONDAY MORNING AND MAY GENERATE ANOTHER ROUND OF LOW LEVEL WIND SHEAR IN THAT AREA. CONDITIONS THEN IMPROVE TO VFR IN THE AFTERNOON WITH GUSTY SOUTHWEST WINDS. A COLD FRONT MOVES INTO SOUTHERN NEW ENGLAND AT NIGHT AND SHOULD GENERATE BRIEF MVFR IN SHOWERS. WIND WILL SHIFT FROM SSW TO WSW WITH THE WIND SHIFT. TUESDAY...VFR. A FEW BRIEF SHOWERS POSSIBLE IN EASTERN MASS/RI && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH FORECAST CONFIDENCE THRU SATURDAY. TODAY...WE CONVERTED GALE WARNINGS TO SMALL CRAFT ADVISORIES FOR ALL WATERS. EXPECT WIND GUSTS TODAY WILL FALL JUST SHY OF GALES WITH NW GUSTS TO 30 KT. TONIGHT...WINDS GRADUALLY DIMINISH WITH SPEEDS DROPPING BELOW 20 KT LATE TONIGHT. SATURDAY...EXPECT INCREASING SW WINDS IN THE AFTERNOON AS DECENT LOW LEVEL JET DEVELOPS ACROSS THE REGION. GIVEN STILL WARM SST... GOOD MIXING OVER WATER SUPPORTS WIND GUSTS TO 30 KT WITH MARGINAL GALES POSSIBLE BY EVENING. OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY... SAT NIGHT...SOUTHWEST WINDS CONTINUE TO GUST TO 35 KNOTS DURING THE DAY AND THEN DIMINISH IN THE EVENING. SEAS 5-8 FEET WILL DIMINISH IN THE EVENING. SUNDAY-MONDAY...A WARM FRONT MOVES UP ACROSS THE WATERS. VSBYS WILL LOWER TO 1-3 MILES IN RAIN AND FOG STARTING AROUND MIDNIGHT CONTINUING INTO THE MORNING. STRONG SOUTH WINDS...ROUGHLY 60-65 KNOTS...AT 2000 FEET ALTITUDE WILL MOVE OVER THE WATERS AFTER MIDNIGHT AND THROUGH MONDAY MORNING. SOME OF THIS WIND MAY BE DRAWN TO THE SURFACE IN HEAVIER BURSTS OF RAIN. AT THE LEAST...SOUTH WINDS WILL BE ON THE HIGH END OF SMALL CRAFT ADVISORY THRESHOLDS AT OR NEAR GALE. THIS WILL DRIVE SEAS TO 5-10 FEET ON THE EXPOSED WATERS. TUESDAY...SOUTHWEST WINDS WILL GUST NEAR SMALL CRAFT THRESHOLDS. SEAS WILL SLOWLY DIMINISH BUT REMAIN ABOVE 5 FEET ON THE EXPOSED WATERS. SMALL CRAFT ADVISORY WILL BE NEEDED. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST SATURDAY FOR ANZ230- 232>237. SMALL CRAFT ADVISORY UNTIL 3 AM EST SATURDAY FOR ANZ231-251- 255-256. SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR ANZ250-254. && $$ SYNOPSIS...KJC/DOODY NEAR TERM...KJC/DOODY SHORT TERM...KJC LONG TERM...DOODY AVIATION...KJC/DOODY MARINE...KJC/DOODY

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