Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 151518 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1118 AM EDT TUE APR 15 2014 .SYNOPSIS... A STRONG COLD FRONT WILL BRING A MIX OF GUSTY WINDS...SOAKING RAIN...AND POSSIBLY EVEN A BRIEF CHANGE TO A WINTRY MIX BEFORE ENDING DURING THE EARLY MORNING HOURS TOMORROW. HIGH PRESSURE BUILDING IN WILL BRING DRY BUT UNSEASONABLE CHILLY AIR TO THE REGION WED/WED NIGHT. DRY WEATHER CONTINUES THU INTO THE FIRST PART OF FRI WITH MODERATING AFTERNOON TEMPS INLAND...BUT REMAINING CHILLY ALONG THE COAST. A COUPLE WEAK WAVES OF LOW PRESSURE MAY BRING A ROUND OR TWO OF RAIN SHOWERS SOMETIME FRI NIGHT INTO SAT. && .NEAR TERM /THROUGH TONIGHT/...
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11 AM UPDATE... SHARP COLD FRONT PUSHING ACROSS MID-STATE NY/PA WHICH CAN BE SEEN WITHIN WSR-88D RADAR REFLECTIVITIES. THIS FRONT WILL PUSH EAST THIS AFTERNOON AND ACROSS NEW ENGLAND OVERNIGHT EXITING OFFSHORE AFTER MIDNIGHT. ASSOCIATED DYNAMICS AND FORCING WILL ADVECT GULF MOISTURE NORTHWARD RESULTING IN A HEAVY SOAKING RAIN ACROSS THE REGION AND THE POTENTIAL FOR ISOLATED THUNDERSTORMS. PUSHING UP AGAINST HIGH PRESSURE OFFSHORE ACROSS THE ATLANTIC...WILL ALSO SEE AN AMPLIFICATION OF WINDS ACROSS THE REGION. SPECIFIC DETAILS AND THREATS ARE OUTLINED BELOW: HEAVY RAIN/FLOODING... THE SATELLITE ANALYSIS BRANCH /NESDIS/ CLEARLY OUTLINES THE SIGNIFICANCE OF THIS EVENT...ANOMALOUS DEEP MOISTURE SURGING UP THE EAST-COAST WITH A PRECIPITABLE WATER ANOMALY 3-4 STANDARD DEVIATIONS ABOVE NORMAL. THE SOUNDING RELEASED NEAR WASHINGTON DC DULLES AIRPORT OBSERVED A 1.64-INCH PRECIPITABLE WATER AMOUNT... THE FOURTH HIGHEST EVER OBSERVED IN APRIL FOR THE AREA. AS THE COLD FRONT SLIDES EAST AGAINST HIGH PRESSURE OFFSHORE... EXPECT THE PRESSURE GRADIENT TO AMPLIFY RESULTING IN A LLJ BY AFTERNOON INTO EVENING BETWEEN 80-90 MPH...THE CONVERGENT NOSE OF WHICH WILL BE ACROSS SOUTHERN NEW ENGLAND BENEATH THE RRQ OF THE UPPER-LEVEL JET...THUS DEEP-LAYER ASCENT COMBINING WITH FRONTO- GENETICAL LIFT OF SUB-TROPICAL MOISTURE. CONSIDERING CONVECTIVE ELEMENTS ALONG WITH STEEP MID-LEVEL LAPSE RATES YIELDS THE LIKE- LIHOOD THAT WE WILL SEE WIDESPREAD RAIN WITH A FINE-LINE ALONG AND AHEAD OF THE FRONT OF EMBEDDED HEAVIER SHOWERS AND ISOLATED THUNDERSTORMS. THE FLOOD WATCH CONTINUES WITH HEIGHTENED WORDING AS A HEAVY RAIN EVENT ALONG WITH SIGNIFICANT POTENTIAL FLOODING IS ANTICIPATED. AREA AVERAGE RAINFALL AMOUNTS OF AROUND 2 INCHES ARE EXPECTED OVER ALL OF SOUTHERN NEW ENGLAND WITH LOCALLY HIGHER AMOUNTS AROUND 3 INCHES. MUCH OF THIS RAIN MAY FALL IN A SHORT WINDOW OF TIME OF ROUGHLY 6-HOURS AS NOTED BY THE SLIGHT RISK ISSUED BY WPC FOR EXCESSIVE RAINFALL. BESIDE RIVER POINTS ALREADY WITH FLOOD WARNINGS...MINOR RIVER FLOODING IS EXPECTED FOR THE CONNECTICUT...PAWCATUCK...AND MERRIMACK RIVER BASINS /SOME OF WHICH ARE SWOLLEN DUE TO UPSTREAM SNOWMELT/. SOME RIVER POINTS MAY REACH MODERATE FLOODING. EXPECTING AREA IMPACTS TO SMALL RIVERS...TRIBUTARIES...OR STREAMS /ESPECIALLY THOSE WHICH ARE NARROW AND FLASHIER/. THOSE WITH INTERESTS ALONG LOWER REACHES OF CT RIVER SHOULD PAY ATTENTION TO THE LATEST FORECASTS AND CURRENT WATER LEVELS. ALSO ANTICIPATE URBAN AND POOR DRAINAGE FLOODING ESPECIALLY FOR THE DENSE URBAN CORRIDORS /SUCH AS I-95 AND I-195/...WITH THE EXPECTATION OF PONDING OF WATER ALONG AREA ROADWAYS WHICH WILL IMPACT THE DRIVE-HOME COMMUTE...ESPECIALLY WITH THE HEAVY RAIN THREAT FALLING POTENTIALLY IN A SHORT-WINDOW OF TIME. REMOVED THE HYDROLOGY SECTION FROM THE DISCUSSION...TYING IN THE POINTS ABOVE TO AVOID REDUNDANCY. PLEASE SEE THE COASTAL FLOODING SECTION BELOW FOR COASTAL FLOOD THREATS. WINDS... WITH THE AMPLIFICATION OF THE LLJ AND CONSIDERING PRECIP-DRAG AND POTENTIAL BOUNDARY LAYER MECHANICAL MIXING PROCESSES /DESPITE THE STOUT INVERSION PER 12Z CHATHAM SOUNDING/ THERE IS THE THREAT OF STRONG SOUTHERLY WIND GUSTS EXCEEDING 50 MPH /ESPECIALLY WITH HEAVY RAIN AND THUNDERSTORMS/ FOR THIS AFTERNOON INTO THE EVENING. WIND ADVISORY CONTINUES ACROSS CENTRAL AND EASTERN PORTION OF SOUTHERN NEW ENGLAND. EXPANSION INTO THE CONNECTICUT RIVER VALLEY IS STILL BEING CONSIDERED PER MONITORING UPSTREAM TRENDS ALONG THE FRONT. WILL NEED TO MONITOR FOR THE THREAT OF HIGH-WINDS...BUT WILL HANDLE THIS THREAT WITH SHORT-FUSED WARNINGS. WINTRY MIX/FLASH FREEZE POTENTIAL... THE BAND OF RAIN WILL MOVE E OF THE REGION ALONG WITH THE COLD FRONT AFTER MIDNIGHT AND INTO THE EARLY MORNING HOURS TOMORROW. HOWEVER...GIVEN THE STRENGTH OF THIS FRONT...COLD AIR WILL BE RAPIDLY MOVING IN FROM THE SFC TO MID LVLS DURING THIS TIME. THERE IS THE POSSIBILITY OF A CHANGE OVER TO A PERIOD OF SLEET/SNOW FROM W TO E WITH EVEN THE LOW END POTENTIAL OF SOME ACCUMULATION IN THE W AND N OF THE ROUTE 2 CORRIDOR. THIS WILL COMBINE WITH A RAPID TEMPERATURE DROP TO NEAR OR BELOW FREEZING ON WET ROADWAYS LEADING TO THE POTENTIAL FOR SLIPPERY CONDITIONS LEADING INTO THE WED MORNING COMMUTE. THE KEY WILL BE THE RACE BETWEEN THE COLD AND THE DRIER AIR EXACTLY HOW MUCH SNOW FALLS/ACCUMS...BUT THERE IS THE LOW END CHANCE OF A LIGHT COATING TO AN INCH IN SOME SPOTS IN THE EXTREME W AND HIGHER TERRAIN AS GUIDANCE HAS ONLY INCREASED BOTH THE DEPTH AND SPEED WITH WHICH THE COLD AIR COMES IN BEFORE THE PRECIPITATION ACTUALLY ENDS. TEMPERATURES... DESPITE THE CLOUD COVER...WILL LIKELY MAKE ANOTHER RUN AT 70F TODAY ACROSS THE E WHERE A BREAK OR TWO OF SUN IS POSSIBLE. ESPECIALLY SINCE THEY WILL START IN THE LOW 60S. FURTHER W WHERE CLOUDS WILL BE IN PLACE ALL DAY AND TEMPS ARE A BIT LOWER THIS MORNING...ARE LIKELY TO REMAIN IN THE MID 60S.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGHLIGHTS... * DRY BUT UNSEASONABLY CHILLY WED/WED NIGHT * DRY THU INTO FRI AFTERNOON - CHILLY COAST/MILDER AFTERNOON/S INLAND * A PERIOD OF SHOWERS POSSIBLE FRI NIGHT INTO SAT BUT LOW CONFIDENCE * NEAR OR BELOW NORMAL TEMPS CONTINUE INTO EARLY NEXT WEEK DETAILS... WEDNESDAY... AN UNSEASONABLY CHILLY AIRMASS WILL CONTINUE TO WORK INTO THE REGION AS LARGE HIGH PRESSURE BUILDS IN FROM THE WEST. ANY LEFT OVER PRECIPITATION SHOULD HAVE EXITED THE CAPE/ISLANDS BY EARLY TO MID MORNING WED...AS THE COLD FRONT WILL BE WELL OFFSHORE. NORTHWEST WINDS MAY CONTINUE TO GUST BETWEEN 30 AND 40 MPH DURING THE MORNING...BUT WILL DIMINISH SOME DURING THE AFTERNOON. ANOMALOUS 850 MB TEMPS FOR THIS TIME OF YEAR BETWEEN -6C AND -10C ARE EXPECTED. HOWEVER...PLENTY OF STRONG APRIL SUNSHINE WILL OFFSET THIS TO SOME DEGREE. ALL IN ALL...MUCH OF THE REGION SHOULD SEE HIGHS RECOVER WELL INTO THE 40S DURING THE AFTERNOON. WEDNESDAY NIGHT... HIGH PRESSURE OVERHEAD WILL RESULT IN AN UNSEASONABLY COLD NIGHT. WITH MAINLY CLEAR SKIES AND WINDS DIMINISHING...THE NORMALLY COLDER OUTLYING LOCATIONS OF SOUTHWEST NH/NORTHWEST MA WILL PROBABLY SEE LOWS FALL INTO THE UPPER TEENS. THE REST OF THE REGION SHOULD SEE LOW TEMPS FALL INTO THE 20S...TO THE LOWER 30S. THURSDAY AND FRIDAY... STRONG HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL GENERATE EAST TO NORTHEAST WINDS AT THE SURFACE. WHILE DRY WEATHER SHOULD PREVAIL THU INTO FRI AFTERNOON...THE ONSHORE COMPONENT TO THE WIND SHOULD HOLD HIGH TEMPS IN THE 40S ACROSS MUCH OF THE EASTERN MA COAST BOTH DAYS. FURTHER INLAND...ENOUGH HEATING SHOULD ALLOW HIGHS TO REACH WELL UP INTO THE 50S TO NEAR 60 ACROSS THE LOWER CT RIVER VALLEY. WILL ALSO HAVE TO WATCH OUT FOR SOME LOW CLOUDS AND FOG PATCHES THU NIGHT INTO FRI ALONG THE COAST. THIS WOULD BE A RESULT OF AN INCREASING MOIST ONSHORE FLOW. FRIDAY NIGHT AND SATURDAY... A COUPLE WEAK WAVES OF LOW PRESSURE WILL LIKELY PASS NEAR OR SOUTHEAST OF THE BENCHMARK. A LOT OF MODEL UNCERTAINTY ON THE TIMING AND EXACT TRACKS OF THESE WEAK WAVES. HOWEVER...THEY WILL RESULT IN A CHANCE FOR A PERIOD OR TWO OF RAIN SHOWERS FRI NIGHT AND/OR SAT. WHILE A PERIOD OF SHOWERS WILL BE POSSIBLE EVERYWHERE...HIGHEST CONFIDENCE IN A PERIOD OF WET WEATHER WILL BE ALONG THE COASTAL PLAIN. TEMPS LIKELY REMAIN AT LEAST A BIT BELOW NORMAL. SUNDAY AND MONDAY... LOW CONFIDENCE FORECAST. MUCH OF THIS TIME MAY TURN OUT DRY UNTIL LATE MONDAY OR MONDAY NIGHT...WHEN THE NEXT FRONT APPROACHES WITH THE RISK FOR RAIN SHOWERS. TEMPS WILL LIKELY AVERAGE NEAR OR BELOW NORMAL WITH THE TENDENCY FOR UPPER LEVEL TROUGHING IN THE REGION. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY/...MODERATE CONFIDENCE. DETERIORATING CONDITIONS WITH CIGS/VSBYS FALLING IFR-VLIFR WITH +RA TOWARDS THIS AFTERNOON INTO THE EVENING PERIOD. POTENTIAL FOR ISOLATED TSRA BUT WITH UNCERTAINTY WILL NOT MENTION IN TAF. STRONG S-WINDS WITH GUSTS IN EXCESS OF 40 KTS FOR S/E TERMINALS. DESPITE THIS...WILL SEE LLWS IMPACTS OVER ALL TERMINALS AS LOW-LEVEL WINDS AMPLIFYING TOWARDS THIS EVENING WITH 60-70 KT JET 2 KFT AGL. COLD FRONT PUSHES THROUGH THE TERMINALS AROUND MIDNIGHT. WILL SEE WINDS BACK WEST REMAINING GUSTY UP TO 40 KTS. CONDITIONS QUICKLY IMPROVING TO VFR. MAY SEE RAIN TRANSITION TO SNOW/SLEET BRIEFLY WITH MINOR ACCUMS. BEST CHANCES OVER NW MA INTO S NH. KBOS TERMINAL...MODERATE CONFIDENCE. KBDL TERMINAL...MODERATE CONFIDENCE. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WEDNESDAY AND THURSDAY...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS. NORTHWEST WIND GUSTS UP TO 35 KNOTS WED MORNING SHOULD DIMINISH SOME BY WED AFTERNOON AND ESPECIALLY BY WED EVENING. THURSDAY NIGHT THROUGH SATURDAY...LOW TO MODERATE CONFIDENCE. A PERIOD OF MVFR-IFR CONDITIONS IS POSSIBLE IN SOME LOW CLOUDS/FOG PATCHES AND A ROUND OR TWO OF RAIN SHOWERS. TIMING AND CONFIDENCE IS HIGHLY UNCERTAIN...BUT BEST CHANCE OF THE LOWER CONDITIONS WILL BE ALONG THE COAST.
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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 TUESDAY/...HIGH CONFIDENCE. S-SW WINDS CONTINUE TO INCREASE THROUGH THE DAY SUCH THAT GALE FORCE WINDS ARE LIKELY BY THIS AFTERNOON...CONTINUING INTO THE OVERNIGHT HOURS. GALE WARNINGS CONTINUE FOR THIS THREAT. THESE WINDS WILL SHIFT TO THE W-NW EARLY WED MORNING BUT CONTINUE WITH GALE FORCE GUSTS UNTIL THEY SUBSIDE BY MID MORNING WED. SOME HEAVY RAIN/FOG AND ISOLATED THUNDERSTORMS ARE POSSIBLE MAINLY THIS AFTERNOON AND EVENING AS WELL. SEAS INCREASE TO 10-12 FT. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WEDNESDAY...HIGH CONFIDENCE. NORTHWEST WIND GUSTS UP TO 35 KNOTS IN THE MORNING SHOULD LOWER TO SCA LEVELS BY AFTERNOON. SEAS ACROSS THE OPEN WATERS WILL REMAIN ABOVE SCA THRESHOLDS GIVEN PLENTY OF LEFT OVER SOUTHERLY SWELL. THURSDAY AND FRIDAY...MODERATE TO HIGH CONFIDENCE. HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RESULT IN NORTHEAST WIND GUSTS OF 20 TO 25 KNOTS MUCH OF THE TIME. IN ADDITION...SEAS ACROSS THE OUTER- WATERS WILL LIKELY REMAIN NEAR OR ABOVE SCA THRESHOLDS. SATURDAY...MODERATE CONFIDENCE. POTENTIAL FOR NORTHEAST WIND GUSTS OF 20 TO 25 KNOTS AND MARGINAL SCA SEAS CONTINUES. HOWEVER...EXACT WIND SPEEDS AND WAVE HEIGHTS WILL DEPEND ON THE TRACK OF A COUPLE WEAK WAVES OF LOW PRESSURE WHICH REMAINS UNCERTAIN AT THIS TIME.
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&& .TIDES/COASTAL FLOODING...
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STRONG SOUTHERLY WINDS OVER THE WATERS GUSTING 30 TO 40 MPH WILL YIELD AN AVERAGE 1.5 FOOT SURGE ALONG THE SOUTH COAST. COMBINED WITH HIGH TIDE AROUND 9-10 PM /NOT ASTRONOMICALLY HIGH/...THERE IS THE POSSIBILITY OF SPLASHOVER ALONG LOW-LYING AREAS...BUT AT THIS PRESENT TIME WE ARE NOT CONSIDERING MINOR COASTAL FLOODING.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR CTZ002>004. MA...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR MAZ002>021-026. WIND ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR MAZ004>007- 012>024-026. NH...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR NHZ011-012-015. RI...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR RIZ001>007. WIND ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR RIZ001>008. MARINE...GALE WARNING FROM 2 PM THIS AFTERNOON TO NOON EDT WEDNESDAY FOR ANZ232-233-235-237-250-254>256. GALE WARNING UNTIL NOON EDT WEDNESDAY FOR ANZ230-231-234-236- 251.
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&& $$ SYNOPSIS...FRANK/DOODY NEAR TERM...SIPPRELL LONG TERM...FRANK AVIATION...FRANK/DOODY MARINE...FRANK/DOODY TIDES/COASTAL FLOODING...SIPPRELL

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