Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 240230 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1030 PM EDT THU APR 23 2015 .SYNOPSIS... UNSEASONABLY COOL WEATHER CONTINUES THROUGH THIS WEEKEND WITH SPOTTY SHOWERS OR SPRINKLES...WITH A BETTER CHANCE FOR SHOWERS EARLY NEXT WEEK AS WINDS BECOME MORE ONSHORE. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 1030 PM UPDATE... MID LEVEL SHORTWAVE FINALLY PUSHING OFF THE COAST TOWARD THE MARITIMES THIS EVENING. THE LAST OF THE SHOWERS ASSOCIATED WITH THIS SHORTWAVE WERE CROSSING CAPE COD AND THE ISLANDS...WITH ONLY A FEW HUNDREDTHS OF AN INCH OF RAINFALL BEING REPORTED. FARTHER WEST...LAKE-EFFECT SNOW WAS STAYING MAINLY WEST OF THE SPINE OF THE BERKSHIRES. CLOUDS REMAIN THE KEY TO THE FORECAST OVERNIGHT. THERE ARE ABUNDANT CLOUDS ACROSS NY STATE...WHICH IS BENEATH THE CORE OF A COLD POOL ALOFT. THESE CLOUDS WILL TRY TO ROTATE EAST INTO SOUTHERN NEW ENGLAND OVERNIGHT. SATELLITE DATA...ESPECIALLY WITHIN THE 3.9 MICRON AND 11.7 MICRON CHANNELS...SHOWING PLENTY OF BREAKS BETWEEN THE CLOUDS ASSOCIATED WITH THE SHORTWAVE AND THOSE ASSOCIATED WITH THE COLD POOL. WITH DEW POINTS IN THE LOWER 20S... SOME AREAS COULD FALL WELL BELOW FREEZING IF THE CLEARING CAN STAY IN PLACE LONG ENOUGH. WINDS CONTINUE TO DIMINISH AS WELL AWAY FROM THE HIGHER ELEVATIONS. GIVEN THESE FACTORS...KEPT THE FREEZE WARNING IN PLACE ACROSS NORTHERN CT AND NORTHWEST RI. WILL CONTINUE TO MONITOR THE LATEST TRENDS. IT IS POSSIBLE THIS WARNING COULD BE CANCELLED EARLY FRIDAY MORNING IF TOO MANY CLOUDS LINGER OVER THE WARNING AREA. REMAINDER OF FORECAST PRETTY MUCH ON TRACK...THOUGH DID MAKE SOME ADJUSTMENTS TO NEAR TERM TO REFLECT LATEST TRENDS. PREVIOUS DISCUSSION... COLD AIR AT SURFACE AND ALOFT REMAINS IN PLACE. CROSS SECTIONS SHOW PLENTY OF MOISTURE LINGERING BETWEEN 850 AND 700 MB...AS WELL AS SOME LIFT IN THIS LAYER. EXPECT CLOUDS DIMINISHING AFTER SUNSET BUT NOT COMPLETELY GOING AWAY. WEST WINDS WILL BRING AIR IN FROM THE GREAT LAKES. MIN TEMPS UPSTREAM THIS MORNING WERE IN THE UPPER 20S TO MID 30S. CLOUDS AND LINGERING WIND WILL INTERFERE WITH FROST DEVELOPMENT OUTSIDE OF ANY STRONGLY SHELTERED SPOTS. HOWEVER...AIR TEMPS AT OR A LITTLE BELOW 32F ARE EXPECTED IN WESTERN PARTS OF THE AREA. MEANWHILE...THE FROST/FREEZE SEASON HAS STARTED IN CT-RI AS WELL AS IN SOUTHEAST AND COASTAL MASS. FREEZING TEMPS ARE EXPECTED IN AT LEAST 50 PERCENT OF NORTH CENTRAL AND NORTHEAST CT. FREEZING TEMPS ARE POSSIBLE IN PARTS OF NORTHWEST RI. EXPECTED COVERAGE IS LESS IN SOUTHEAST AND COASTAL MASS. WE WILL ISSUE A FREEZE WARNING FOR HARTFORD-TOLLAND-WINDHAM COUNTIES IN CT AND WESTERN PROVIDENCE-WESTERN KENT COUNTIES IN RI FOR LATE TONIGHT/FRIDAY MORNING. IN THE RI PORTION...OUR EXPECTATION IS MOSTLY TO THE WEST AND NORTHWEST OF THE SCITUATE RESERVOIR. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... FRIDAY... WILL LIKELY SEE ANOTHER ROUND OF DIURNAL CLOUDS DEVELOP. SHOWER/SPRINKLE COVERAGE SHOULD BE LESS THAN TODAY. IT/S STILL UNSTABLE ALOFT BUT LACKING THE PASSAGE OF THE SHORTWAVE TO ORGANIZE CONVECTION. THE MIXED LAYER REACHES NEAR 800 MB AGAIN WITH 20-25 KNOT WINDS IN THE LAYER. TEMPS NEAR THE TOP OF THE LAYER WILL BE SIMILAR TO TODAY AND SO WE EXPECT MAX SFC TEMPS EITHER SIDE OF 50...PERHAPS MID 50S IN THE WARMEST SPOTS. FRIDAY NIGHT... UPPER LOW SHIFTS EAST BUT COLD POOL AND CLOUD MOISTURE LINGERS OVER NEW ENGLAND. SO WE MAY NOT CLEAR COMPLETELY...BUT PROBABLY FEWER CLOUDS THAN TONIGHT. TEMPERATURES SHOULD BE SIMILAR TO TONIGHT BUT MODEL GUIDANCE IS A DEGREE OR TWO LESS COLD. THIS LEAVES LESS ROOM FOR ANY ADDITIONAL FREEZE HEADLINES IN CT. THIS STATUS WILL BE REEVALUATED BY THE MIDNIGHT SHIFT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGHLIGHTS... * BELOW NORMAL TEMPERATURES THROUGH NEXT WEEK * SPOTTY DIURNAL SHOWERS THROUGH THIS WEEKEND * BETTER CHANCE FOR SHOWERS WITH ONSHORE WINDS MON INTO TUE * LOW CONFIDENCE FOR COASTAL SYSTEM LATE NEXT WEEK OVERVIEW AND MODEL PREFERENCES... STAGNANT UPPER LEVEL PATTERN REMAINS IN PLACE ACROSS THE LOWER 48 WITH CUTOFF LOW PRES ACROSS THE NORTHEASTERN U.S. INTO SOUTHERN QUEBEC AND WESTERN ONTARIO...RIDGING ACROSS THE CENTRAL U.S. AND ANOTHER CLOSED UPPER SYSTEM ACROSS THE PACIFIC NW. 12Z MODEL SUITE AND ENSEMBLES CONTINUE TO SIGNAL THE CLOSED UPPER LOW HOLDING IN PLACE THROUGH AT LEAST THIS WEEKEND. THE LOW TRIES TO SHIFT E SUNDAY...ONLY TO ROTATE BACK TOWARD THE REGION AND BECOMING E-W ORIENTED. THIS WILL PINCH THE WESTERN TROUGH INTO NORTHERN MEXICO AT FIRST...THEN SEND ENERGY EASTWARD ACROSS THE SOUTHERN STREAM WITH A MIGRATING CUTOFF H5 LOW. EARLY NEXT WEEK...MODELS ALONG THE EASTERN SEABOARD DIVERGE WITH THEIR HANDLING OF THE UPPER LEVEL SYSTEM LENDING TO LOWERED CONFIDENCE BEYOND MONDAY WITH THE FORECAST...THOUGH THE 12Z GFS AND ECMWF TRY TO WORK THE SOUTHERN STREAM SYSTEM INTO THE LOWER TO MID MISSISSIPPI VALLEY BY AROUND TUESDAY. FOR LATER NEXT WEEK... MODELS AND ENSEMBLES HAVE RATHER WIDE SOLUTIONS MAINLY DUE TO SPLIT PATTERN ON THE E COAST AND HANDLING PLACEMENT AND TRACK OF POSSIBLE SHORT WAVE MOVING ACROSS THE REGION WHILE A COASTAL LOW TRIES TO TAKE SHAPE SOMEWHERE FROM THE MID ATLC TO THE SE U.S. COAST WITH THE SOUTHERN STREAM ENERGY. LEANED TOWARD BLEND OF AVAILABLE GUIDANCE FOR THIS FORECAST PACKAGE WHICH GAVE GOOD CONTINUITY WITH THE PREVIOUS FORECAST. BEYOND MONDAY...LEANED TOWARD ENSEMBLES WHICH WERE A BIT MORE STABLE WITH THEIR POSITIONS AND TRACKS OF THE NORTHERN AND SOUTHERN STREAM SYSTEMS. THIS WAS CLOSER TO WPC GUIDANCE. DETAILS... SATURDAY AND SUNDAY...HIGH CONFIDENCE. STRONG H5 CUTOFF LOW CONTINUES TO SPIN ACROSS THE NORTHEAST THIS UPCOMING WEEKEND...THOUGH IT LOOKS TO PINWHEEL AS IT TRIES TO BECOME E-W ORIENTED AND RETROGRADE BY LATE THIS WEEKEND. WHILE THERE IS ONLY WEAK SURFACE FEATURES...THE UPPER LEVEL COLD POOL WILL KEEP SOME DIURNALLY DRIVEN SHOWERS DEVELOPING. LOOKS LIKE BEST CHANCES FOR SHOWERS WILL OCCUR ACROSS CENTRAL AND NORTHERN AREAS OF MA. AM NOTING RATHER STRONG LOW PRES THAT WILL PASS S OF THE REGION THIS WEEKEND...A PIECE OF ENERGY THAT WORKED OUT OF THE DESERT SW FROM THE WESTERN LONG WAVE TROUGHING. THIS WILL ALSO KEEP MOST OF THE MOISTURE AWAY FROM THE REGION. EXPECT DAYTIME HIGHS BOTH DAYS MAINLY IN THE 50S WITH SUN EARLY BEFORE LATE MORNING AND AFTERNOON CLOUDS DEVELOP. HOWEVER...IF A FEW BREAKS OF SUN HANG INTO THE AFTERNOON...A FEW LOCATIONS MIGHT REACH 60. WITH LIGHT PRES GRADIENT...SEA BREEZES MAY ALSO DEVELOP MAINLY ALONG E COASTAL AREAS BOTH DAYS. MONDAY AND TUESDAY...MODERATE CONFIDENCE. MODELS BEGIN DO DIVERGE ON THEIR SOLUTIONS ESPECIALLY ACROSS THE WESTERN U.S. AM NOTING THE NE UPPER LOW RETURNS TO SIT AND SPIN ACROSS THE REGION. HOWEVER...ITS ORIENTATION WILL ALLOW WINDS TO SHIFT TO N-NE OVER TIME...WHICH WILL ALLOW MORE LOW LEVEL MOISTURE TO WORK ONSHORE. THIS...ALONG WITH SOME POTENT SHORT WAVES SPINNING IN THE UPPER FLOW WILL ALLOW FOR BETTER CHANCES FOR MORE ORGANIZED SHOWERS ACROSS A GOOD PORTION OF THE AREA. NOT EXPECTING HIGH RAINFALL AMOUNTS...LOOKS LIKE ON THE ORDER OF 0.1 TO 0.25 INCHES FROM 12Z MON TO 00Z WED. TEMPS WILL REMAIN COOLER THAN NORMAL FOR LATE APRIL. WEDNESDAY AND THURSDAY...LOW CONFIDENCE. WITH MODEL SOLUTIONS CONTINUING TO DIVERGE...UNCERTAINTY INCREASES DURING THIS TIMEFRAME. TWO SYSTEMS TO PONDER UPON...FIRST THE CUTOFF SITTING OVER NEW ENGLAND AND HOW THIS WILL TRACK OFFSHORE. THE SECOND IS THE CUTOFF LOW THAT WORKS E ACROSS THE SOUTHERN STREAM OUT OF THE DESERT SW. FOR NOW...LOOKS LIKE THE UPPER LOW WILL CONTINUE TO SPIN WITH SLIGHT CHANCE FOR SHOWERS WED/WED NIGHT. BIG QUESTION IS ON THURSDAY...WHETHER THE NE UPPER SYSTEM MOVES AWAY AND WHETHER LOW PRES THAT LOOKS TO DEVELOP ACROSS THE SE U.S. WILL EITHER MOVE E OR TRY TO WORK UP THE EASTERN SEABOARD. THIS DOES NOT LOOK TO HAPPEN UNTIL BEYOND THURSDAY. AT THIS POINT...KEPT PERSISTENCE GOING WITH SLIGHT CHANCE POPS AND BELOW NORMAL TEMPS. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. .SHORT TERM /THROUGH FRIDAY NIGHT/... TONIGHT...HIGH CONFIDENCE. VFR. MAY SEE PATCHY MVFR CIGS/VSBYS IN LOCAL SNOW SHOWERS ACROSS E SLOPES OF THE BERKSHIRES INTO CENTRAL PORTIONS OF THE CT VALLEY. W-NW WINDS DIMINISHING OVERNIGHT. FRIDAY...HIGH CONFIDENCE. MAINLY VFR. AS WITH TODAY...CONDITIONS MAY BRIEFLY LOWER TO MVFR IN LIGHT SHOWERS FROM MIDDAY THROUGH THE EARLY EVENING HOURS. WEST WINDS GUSTING TO 20 KNOTS DURING THE DAY. FRIDAY NIGHT...HIGH CONFIDENCE. VFR. KBOS TAF...HIGH CONFIDENCE IN OVERALL TAF. MODERATE CONFIDENCE IN TIMING OF SHOWERS. KBDL TAF...HIGH CONFIDENCE IN OVERALL TAF. MODERATE CONFIDENCE IN TIMING OF SHOWERS. OUTLOOK...SATURDAY THROUGH TUESDAY... SATURDAY AND SUNDAY...HIGH CONFIDENCE. MAINLY VFR. CONDITIONS COULD LOWER TO MVFR QUICKLY IN A FEW BRIEF SHOWERS FROM LATE MORNING THROUGH AROUND SUNSET EACH DAY. SEA BREEZE DEVELOPMENT IS POSSIBLE ALONG THE EAST COAST EACH DAY. MONDAY AND TUESDAY...MODERATE CONFIDENCE. MAINLY VFR. PATCHY MVFR CONDITIONS IN SCT SHOWERS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... TONIGHT...HIGH CONFIDENCE. A WEAK FRONT SWEEPS ACROSS THE WATERS. WEST WINDS GUSTING NEAR 25 KT EARLY AND 15-20 KNOTS LATE. SEAS AT 5-7 FEET ON THE OUTER WATERS AND RI WATERS WILL DIMINISH OVERNIGHT. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR MOST OF THE COASTAL WATERS OVERNIGHT. FRIDAY...HIGH CONFIDENCE. WEST-NORTHWEST WINDS WILL GUST TO 20 KNOTS. A FEW SPOTS MAY APPROACH 25 KNOTS...PRIMARILY SOUTH OF BLOCK ISLAND. SEAS LINGER AT 5 FEET ON THE SOUTHERN AND SOUTHEAST OUTER WATERS. A SMALL CRAFT ADVISORY WILL CONTINUE MAINLY ON THOSE OUTER WATERS. FRIDAY NIGHT...HIGH CONFIDENCE. WEST-NORTHWEST WINDS WILL CONTINUE TO GUST NEAR 20 KNOTS. SEAS WILL LINGER BETWEEN 4-5 FEET. OUTLOOK...SATURDAY THROUGH TUESDAY... SATURDAY THROUGH MONDAY...HIGH CONFIDENCE. EXPECT W WINDS GUSTING TO 20 KT SAT/SAT NIGHT MAINLY OVER THE OUTER WATERS...THEN WILL DIMINISH SUNDAY AND MONDAY. E SWELLS WILL BEGIN TO APPROACH THE WATERS LATE MONDAY INTO MONDAY NIGHT...WITH SEAS INCREASING TO AROUND 5-6 FT. TUESDAY...MODERATE CONFIDENCE. WINDS GENERALLY N-NE WITH GUSTS UP TO 20 KT...POSSIBLY UP TO 25 KT ON THE EASTERN OUTER WATERS. SEAS BUILD UP TO 6-8 FT...HIGHEST ON THE EASTERN OPEN WATERS. && .HYDROLOGY... A COMBINATION OF RAINFALL AND SNOWMELT ACROSS NORTHERN NEW ENGLAND WAS MAKING ITS WAY DOWN THE CONNECTICUT RIVER. THIS COMBINED WITH TIDAL INFLUENCES AT THE MOUTH OF THE RIVER WILL RESULT IN MINOR FLOODING ACROSS PORTIONS OF THE LOWER CONNECTICUT RIVER. THE RIVER NEAR MIDDLE HADDAM IS UNDER STRONG TIDAL INFLUENCE. AS A RESULT... THE RIVER IS ABOVE FLOOD STAGE AT HIGH TIDE AND NEAR FLOOD STAGE AT LOW TIDE. THIS IS EXPECTED TO TREND LOWER THE NEXT COUPLE OF CYCLES...WITH A HIGH TIDE CREST BELOW FLOOD STAGE LATE FRIDAY AFTERNOON. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...FREEZE WARNING FROM 3 AM TO 8 AM EDT FRIDAY FOR CTZ002>004. MA...NONE. RI...FREEZE WARNING FROM 3 AM TO 8 AM EDT FRIDAY FOR RIZ001-003. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ235-237. SMALL CRAFT ADVISORY UNTIL NOON EDT FRIDAY FOR ANZ250-254>256. && $$ SYNOPSIS...WTB/EVT NEAR TERM...WTB/BELK/EVT SHORT TERM...WTB LONG TERM...EVT AVIATION...WTB/EVT MARINE...WTB/BELK/EVT HYDROLOGY...STAFF

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