Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 300705 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 305 AM EDT THU OCT 30 2014 .SYNOPSIS... SHOWERS BEHIND THE PASSING COLD FRONT WILL PUSH OFFSHORE THROUGH THE PRE DAWN HOURS. SEASONABLE AND DRIER WEATHER FOLLOWS INTO THE END OF THE WEEK UNDER HIGH PRESSURE. A COASTAL STORM WILL LIKELY DELIVER A GLANCING BLOW TO THE REGION LATE SATURDAY INTO SUNDAY...BUT THE OPPORTUNITY FOR A HIGHER IMPACT STILL EXISTS. MAINLY DRY WEATHER FOLLOWS WITH A SIGNIFICANT WARMING TREND BY NEXT TUESDAY AND WEDNESDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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210 AM UPDATE... LINE OF SHOWERS TENDING TO DISSIPATE AS IT SLOWLY SHIFTS SE ACROSS THE OUTER CAPE AND NANTUCKET AT 06Z. SCT SHOWERS MAY LINGER OVER THOSE AREAS FOR THE NEXT FEW HOURS BEFORE THE LINE FINALLY PUSHES E. BACK EDGE OF CLOUDS HAVE STEADILY PUSHED E. HOWEVER...WITH THE CLEARING SKIES AND LIGHT WINDS...TEMPS HAVE FALLEN CLOSE TO THE LOWERING DEWPTS ACROSS S NH AND DOWN THE CT VALLEY ACROSS W MA. A FEW SPOTS HAVE VSBYS BELOW 1/2SM IN THE USUAL SUSPECTS /KEEN AND KORE/. MID LEVEL CLOUDS LINGER ACROSS RI/SE MA BUT SHOULD PUSH OFFSHORE THROUGH THE REMAINDER OF THE NIGHT. TEMPS HAVE FALLEN TO THE MID AND UPPER 30S WHERE SKIES HAVE CLEARED AND CALM WINDS...MAINLY ACROSS THE MID AND UPPER CT VALLEY...RANGING TO THE LOWER-MID 50S WHERE CLOUDS REMAIN ON THE S COAST...CAPE COD AND THE ISLANDS AT 06Z. LIGHT PRES GRADIENT WILL KEEP WINDS LIGHT THROUGH 12Z. DEWPTS WILL TAKE THEIR TIME FALLING WITH THE LIGHT WINDS. HAVE UPDATED NEAR TERM FORECAST TO BRING CONDITIONS CURRENT. MAIN CHANGES WERE TO LOWER DEWPTS A BIT. SHORT RANGE MODELS NOT HANDLING THE LOWER DEWPTS ALREADY IN THE CT VALLEY EXCEPT FOR SOME OF THE NEAR TERM BIAS CORRECTED DATA.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... TODAY... HIGH PRESSURE CONTINUES TO BUILD E. SUBSIDENCE AND SINKING AIR IN CONTROL OF THE REGIONS WEATHER. WITH A COOLER AIRMASS CONTINUING TO BUILD WITHIN THE LOW-LEVELS /H85 JUST BELOW THE FREEZING MARK/ EXPECT A WELL-MIXED BOUNDARY-LAYER ALLOWING FOR DRIER AIR TO MIX- DOWN /DEWPOINTS INTO THE MID-30S/ AND DEVELOPMENT OF A SCATTERED CUMULUS DECK AROUND 5-6 KFT. HIGHS AROUND THE 50S EXPECTED WHICH IS JUST ABOUT NORMAL FOR THIS TIME OF YEAR ACROSS SOUTHERN NEW ENGLAND. LIGHT WESTERLY WINDS. TONIGHT... HIGH PRESSURE ACROSS NEW ENGLAND. LIGHT AND VARIABLE WINDS. COLD AIRMASS BELOW FREEZING REMAINS ALOFT. A GOOD CASE FOR EFFECTIVE RADIATIONAL COOLING...THAT IS IF CLOUDS DO NOT BECOME AN ISSUE. CONSIDERING DEWPOINTS AROUND THE MID-30S ON THURSDAY...IT IS POSSIBLE LOCATIONS COULD COOL BELOW THE CROSSOVER THRESHOLD IF THE CONDITIONS ARE RIGHT AND WE ARE ALLOWED TO RADIATE OUT EFFECTIVELY. BUT BENEATH CYCLONIC FLOW THROUGH WHICH WEAK IMPULSES WILL GLIDE... THERE IS ALWAYS THAT POTENTIAL FOR ENHANCEMENT OF MID-LEVEL LIFT AND CONVERGENCE YIELDING A BLANKETING CLOUD BASE. IF CONDITIONS REMAIN CLEAR...THERE IS ENOUGH CONFIDENCE TO SPECULATE THAT SHALLOW GROUND FOG WILL DEVELOP WHEREVER SOILS ARE SATURATED /I.E. SWAMPY BOGS/. LOWS WOULD BOTTOM DOWN AROUND THE MID-30S...LOW- 30S FOR THOSE AREAS THAT RADIATE. WARMEST CONDITIONS ALONG THE SHORES. BUT WILL GO CONSERVATIVE WITH THIS FORECAST CONSIDERING THE POTENTIAL FOR MID-LEVEL CLOUD DECKS AND HOLD WITH LOWS AROUND THE UPPER-30S. WILL NEED TO MONITOR FOR FROST / FREEZE HEADLINES MAY BE NECESSARY FOR S/E COASTAL MA AND RI. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... HIGHLIGHTS... * COOL ON FRIDAY * GLANCING BLOW FAVORED SAT/EARLY SUN BUT HIGHER IMPACT POSSIBLE * BIGGEST CONCERN IS STRONG WINDS LATE SAT/SUN ESP CAPE COD * ACCUMULATING SNOW IS STILL POSSIBLE BUT A RATHER LOW PROBABILITY * MUCH MILDER WEATHER RETURNS BY NEXT TUE AND WED DETAILS... FRIDAY... AN ELONGATED HIGH PRESSURE SYSTEM ACROSS EASTERN CANADA WILL RESULT IN A RATHER CLOUDY/COOL DAY WITH EASTERLY WINDS. A SPOT SHOWER AND PERHAPS EVEN SOME DRIZZLE WILL BE POSSIBLE ALONG THE COAST DURING THE AFTERNOON...BUT THE MAJORITY OF THE DAY WILL BE DRY. HIGHS WILL MAINLY BE IN THE UPPER 40S ACROSS THE HIGHER TERRAIN...TO THE LOWER TO MIDDLE 50S ELSEWHERE. SATURDAY AND SUNDAY... FORECAST CONFIDENCE REMAINS QUITE LOW OVER THIS TIME. ENSEMBLE SENSITIVITY PLOTS SHOW THE ENERGY RESPONSIBLE FOR DEVELOPING THE EVENTUAL STORM IS STILL NEAR THE ARCTIC CIRCLE. THIS LEAVES PLENTY OF UNCERTAINTY IN THE TRACK/STRENGTH AND IMPACTS ACROSS THE REGION. WITH THAT SAID...CURRENT MODEL CONSENSUS FAVORS A GLANCING BLOW AND NOT A DIRECT HIT FOR OUR REGION. THE BIGGEST CONCERN RIGHT NOW IS FOR STRONG TO PERHAPS DAMAGING WINDS...ESPECIALLY ACROSS THE CAPE AND NANTUCKET. THERE ARE TWO MAIN SHORTWAVES INVOLVED IN STORM FORMATION. INITIALLY...MOST MODELS FORM AN ELONGATED LOW PRESSURE SYSTEM OR EVEN TWO CENTERS BEFORE CONSOLIDATING INTO ONE STORM. CURRENT INDICATIONS ARE THAT THIS HAPPENS TOO LATE FOR A SIGNIFICANT RAIN/SNOW EVENT IN SOUTHERN NEW ENGLAND. A BIG CAVEAT IS THAT THIS EVENT IS CURRENTLY PROGGED BETWEEN 72 AND 96 HOUR OUT...WHICH IS QUITE A BIT OF TIME IN THE MODEL WORLD. IF THE INITIAL SHORTWAVE IS WEAKER THAN CURRENTLY DEPICTED...THE STORM WILL INTENSIFY EARLIER AND CLOSER TO THE COAST. WHILE THIS IS A LOWER PROBABILITY AT THIS POINT...ITS CERTAINLY IN THE REALM OF POSSIBILITIES. WHAT EVER HAPPENS...WE CAN SAY THAT EASTERN NEW ENGLAND WILL HAVE MORE OF AN IMPACT THAN THE INTERIOR. PTYPE AND TIMING... A LOT OF THIS WILL DEPEND ON HOW FAR WEST THE MAIN PRECIPITATION SHIELD REACHES. INITIALLY...ALL PRECIPITATION WILL BE IN THE FORM OF RAIN OR JUST SCATTERED SHOWERS SATURDAY. IN FACT...MOST OF THE PRECIPITATION WILL BE IN EASTERN NEW ENGLAND...WITH JUST A FEW SHOWERS ACROSS WESTERN SECTIONS IF THE CURRENT TRACK VERIFIES. IF THE TRACK SHIFTS WEST AND WE END UP GETTING INTO HEAVIER PRECIPITATION SAT NIGHT AND EARLY SUN...DYNAMIC COOLING WOULD CHANGE PTYPE TO SNOW AT LEAST IN THE HIGHER TERRAIN. AGAIN...BASED ON EXPECTED TRACK...ACCUMULATING SNOW IS A RATHER LOW PROBABILITY...BUT STILL CAN/T BE RULED OUT. WHAT EVER HAPPENS...MOST PRECIPITATION SHOULD HAVE EXITED THE REGION BY MID MORNING ON SUNDAY. STRONG WINDS... STRONG WINDS ARE THE ONE THING WE ARE FAIRLY CONFIDENT THAT WILL DEVELOP. EXCELLENT MIXING ON THE BACKSIDE OF THE STORM SHOULD RESULT IN NORTH TO NORTHWEST WIND GUSTS OF 40 TO 50 MPH DEVELOPING LATE SAT AND ESPECIALLY SUN AS MIXING INCREASES. ACROSS THE CAPE AND NANTUCKET...DEPENDING ON THE TRACK OF THE STORM MAY SEE A PERIOD OF 50 TO 60 MPH WIND GUSTS. WIND ADVISORIES MAY BE NEEDED FOR MUCH OF THE REGION AND PERHAPS HIGH WIND WATCHES/WARNINGS FOR THE CAPE AND NANTUCKET. GIVEN MANY TREES STILL HAVE AT LEAST SOME LEAVES ON THEM...THE RISK FOR TREE DAMAGE AND ISOLATED POWER OUTAGES WILL BE ENHANCED. MONDAY THROUGH WEDNESDAY... DEEP UPPER TROUGH LIFTS NORTHEAST OF THE REGION AND WE ENTER AN AREA OF UPPER LEVEL RIDGING. A SIGNIFICANT WARMING TREND EXPECTED WITH SOME OF THE COASTAL PLAIN POSSIBLY SEEING HIGHS BREAK 60 BY TUE OR WED. MAINLY DRY WEATHER OVER THIS TIME...BUT A SPOT SHOWER OR TWO IS POSSIBLE. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE THROUGH TONIGHT...THEN MODERATE CONFIDENCE FRIDAY. THROUGH 12Z...MAINLY VFR. PATCHY FOG ACROSS CT VALLEY OF SW NH AND W MA WITH LOCAL IFR-LIFR CIGS/VSBYS AT NORMALLY PRONE AREAS THROUGH 12Z. LOW PROB OF LOCAL MVFR-IFR CIGS/VSBYS ACROSS INTERIOR E MA INTO NE CT BETWEEN 08Z-12Z. TODAY...MVFR-IFR VSBYS IMPROVE BY 14Z ACROSS CT VALLEY...OTHERWISE VFR. SCT-BKN CLOUDS 4-5KFT FROM LATE MORNING THROUGH THE AFTERNOON. TONIGHT...VFR. INCREASING CLOUDS AFTER MIDNIGHT. MAY SEE LOCAL MVFR-IFR ACROSS SW NH INTO NW MA LATE. SHALLOW PATCHY GROUND FOG POSSIBLE AT PRONE TERMINALS. FRIDAY...MAINLY VFR. WINDS SHIFT TO E-NE DURING DAY...INCREASING ALONG COAST TO 10-15 KT WITH SOME GUSTS TO 20 KT LATE IN DAY. MAY SEE MVFR CIGS DEVELOP ALONG E COAST TERMINALS DURING THE AFTERNOON. WIDELY SCT SHOWERS ALONG S COAST POSSIBLE LATE. KBOS...HIGH CONFIDENCE IN TAF. KBDL...HIGH CONFIDENCE IN TAF. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRIDAY NIGHT...MODERATE CONFIDENCE. VFR TO START BUT ONSHORE FLOW MAY RESULT IN MVFR CIGS DEVELOPING. A SPOT SHOWER OR TWO POSSIBLE. SATURDAY AND SUNDAY...LOW CONFIDENCE BASED ON UNCERTAINTY OF TRACK/STRENGTH AND TIMING OF COASTAL LOW PRESSURE SYSTEM. MOST LIKELY SCENARIO IS VFR TO BE MIXED IN AT TIMES WITH MVFR SAT INTO SAT NIGHT. LOWER CONDITIONS MOST LIKELY AT THE COAST WITH RAIN OR SCATTERED SHOWERS. LOW PROBABILITY FOR A CHANGE TO SNOW AT THE END. CONDITIONS IMPROVE TO VFR BY SUNDAY...BUT NORTH TO NORTHWEST WIND GUSTS OF 30 TO 40 KNOTS EXPECTED. STRONGEST WINDS CAPE AND NANTUCKET WITH GUSTS OF 40 TO 50 KNOTS POSSIBLE. MONDAY...MODERATE TO HIGH CONFIDENCE IN VFR.
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&& .MARINE...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE. THROUGH 12Z...LEFTOVER 5-6 FT SEAS AND GUSTS TO 25 KT WILL DIMINISH TOWARD DAYBREAK. TODAY...LEFTOVER 5 FT SEAS ON THE OUTER WATERS E AND S OF CAPE COD SHOULD SUBSIDE BY MID MORNING. OTHERWISE...EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA. TONIGHT...LIGHT NE WINDS AND SEAS UP TO 3 FT. FRIDAY...WINDS BECOME E-NE BUT WILL REMAIN BELOW SMALL CRAFT CRITERIA. SEAS SLOWLY INCREASE TO 3 FT ON SOUTHERN OUTER WATERS. OUTLOOK...FRIDAY NIGHT THOUGH MONDAY... ***STORM FORCE WIND GUSTS AND 20 FOOT SEAS POSSIBLE LATE SAT INTO SUNDAY ACROSS THE OPEN ATLANTIC WATERS EAST OF MASSACHUSETTS*** FRIDAY NIGHT...HIGH CONFIDENCE. INCREASING NE WINDS. GUSTS UP TO 25-30 KT WITH SEAS BUILDING TO AROUND 5 FT ON THE OUTER WATERS. SATURDAY AND SUNDAY...MODERATE CONFIDENCE. HIGH IMPACT MARINE EVENT EXPECTED. WHILE UNCERTAINTY REMAINS ON THE EXACT TRACK AND TIMING OF COASTAL LOW PRESSURE...GALE FORCE NORTHERLY WIND GUSTS ACROSS MOST WATERS ARE PRETTY MUCH A SLAM DUNK LATE SAT INTO SUN. IN FACT...DECENT CHANCE IN A PERIOD OF STORM FORCE WIND GUSTS WITH 20 FOOT SEAS ACROSS THE OPEN ATLANTIC WATERS EAST OF MASSACHUSETTS. EXACT WIND SPEEDS AND WAVE HEIGHTS WILL DEPEND UPON THE EXACT TRACK/INTENSITY OF COASTAL LOW PRESSURE...BUT APPEARS THERE IS A GOOD CHANCE OF A HIGH IMPACT MARINE EVENT. A MARINE WEATHER STATEMENT WAS ISSUED TO ADDRESS THESE CONCERNS. MONDAY...MODERATE CONFIDENCE. NORTHWEST SCA WIND GUSTS AND SEAS WILL LIKELY CONTINUE MUCH OF THE DAY WITH GOOD MIXING IN THE COLD AIR ADVECTION PATTERN.
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&& .TIDES/COASTAL FLOODING... ASTRONOMICAL HIGH TIDES ARE NOT THAT IMPRESSIVE LATE SAT INTO SUN. NONETHELESS...THERE IS AT LEAST A LOW PROBABILITY FOR MINOR COASTAL FLOODING/EROSION ALONG THE EASTERN MA COAST AS WELL AS PORTIONS OF THE CAPE AND NANTUCKET. THE CONCERN IS FOR THE EARLY MORNING HIGH TIDE ON SUNDAY. IF WE END UP REALIZING 20 FOOT SEAS OVER THE OPEN OCEAN AND NORTHERLY WIND GUSTS OF 40 TO 50 KNOTS...THERE COULD BE SOME MINOR COASTAL FLOODING AND EROSION. SOME OF THE HOT SPOTS WOULD BE SALISBURY AND PLUM ISLAND...HULL...SCITUATE AND PERHAPS SANDWICH HARBOR AND NANTUCKET HARBOR. AGAIN...IT WILL DEPEND ON EXACT WIND SPEEDS/WAVE HEIGHTS OUT OVER THE OCEAN DURING THE EARLY MORNING SUNDAY HIGH TIDE CYCLE. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ254>256.
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&& $$ SYNOPSIS...FRANK/SIPPRELL NEAR TERM...EVT SHORT TERM...SIPPRELL LONG TERM...FRANK AVIATION...FRANK/EVT MARINE...FRANK/EVT TIDES/COASTAL FLOODING...STAFF

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