Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 151803 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 203 PM 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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200 PM UPDATE... COLD FRONT PUSHING INTO THE HUDSON RIVER VALLEY. SUB-TROPICAL MOISTURE CONVERGENCE COUPLED WITH STRONG LIFT AND DYNAMICS COMING TOGETHER ACROSS SOUTHERN NEW ENGLAND. BEGINNING TO SEE AN AREAL INCREASE IN RAIN COVERAGE WITH EMBEDDED HEAVIER SHOWERS AND AN ISOLATED THUNDERSTORM. H925 WINDS FROM VERTICAL WIND PROFILERS VIA WSR-88D SHOWING ENHANCING S-WINDS OF 60-70 KTS. WILL LIKELY SEE AN INCREASE IN IMPACTS DUE TO THE ATTRIBUTABLE THREATS OUTLINED BELOW: HEAVY RAIN/FLOODING... FLOOD WARNINGS HAVE BEEN ISSUED FOR MULTIPLE POINTS ALONG THE CONNECTICUT RIVER BASIN WITH THE EXPECTATION OF MINOR RIVER FLOODING...PERHAPS MODERATE FLOODING AT MIDDLE HADDAM. AN AREAL FLOOD ADVISORY HAS BEEN ISSUED FOR ALL OF RI AND THE SURROUNDING AREA. EARLIER...THE SATELLITE ANALYSIS BRANCH NOTED ANOMALOUS DEEP MOISTURE SURGING NORTH FROM THE GULF ON THE ORDER OF 3-4 STANDARD DEVIATIONS ABOVE NORMAL WHILE WPC PUT OUT A SLIGHT RISK TO THE WEST OF THE REGION OF EXCESSIVE RAINFALL AND FLASH FLOODING. LATEST SPC MESOANALYSIS HIGHLIGHTS A SURGE OF 1.5 INCH PWATS INTO SOUTHERN NEW ENGLAND COLLOCATED WITH STRONG CONVERGENT H85 MOISTURE TRANSPORT. COUPLING WITH AN AMPLIFYING LLJ ALREADY OBSERVED BY THE EARLIER MENTIONED VERTICAL WIND PROFILERS THE CONVERGENT NOSE OF WHICH LIES OVER SOUTHERN NEW ENGLAND BENEATH THE RRQ OF AN UPPER-LEVEL JET...AND CONSIDERING THE APPROACH OF A SHARP COLD FRONT AND DEEP FRONTOGENETICAL LIFT...AND YOU HAVE A PRETTY GOOD SETUP FOR HEAVY RAIN AND FLOODING. CONVECTIVE ELEMENTS AND MOIST ADIABATIC LAPSE RATES...AND THERE IS SOME CONDITIONAL INSTABILITY TO WARRANT THE THREAT OF ISOLATED THUNDERSTORMS. THUS THE FLOOD WATCH CONTINUES WITH THE EXPECTATIONS AS OUTLINED ABOVE. AVERAGE STORM-TOTAL RAINFALL AMOUNTS ARE FORECAST AROUND 2 INCHES AND EXPECT LOCALLY HIGHER AMOUNTS OF AROUND 3 INCHES IN A TIMEFRAME OF AROUND 6-HOURS. THE BASIS FOR THE FLOOD WATCH IS DUE TO ALREADY SWOLLEN RIVERS FROM UPSTREAM SNOWMELT TAKING ON ADDITIONAL WATER AND LIKELY GOING INTO MINOR FLOOD...POSSIBLY INTO MODERATE FLOOD. RIVER BASINS OF CONCERN INCLUDE CONNECTICUT/MERRIMACK/PAWCATUCK. ALSO ANTICIPATE IMPACTS TO LOCAL STREAMS/CREEKS/TRIBUTARIES...ESPECIALLY THOSE THAT ARE NARROWER AND FLASHIER. THOSE WITH INTERESTS ALONG AREA RIVERS SHOULD PAY ATTENTION TO THE LATEST FORECASTS AND CURRENT WATER LEVELS. THE FLOOD WATCH ALSO INCLUDES URBAN AND POOR DRAINAGE ISSUES THE HEIGHT OF WHICH WILL CENTER AROUND THE DRIVE-HOME COMMUTE FOR MOST ROADWAYS THROUGHOUT SOUTHERN NEW ENGLAND. CONCERNED FOR THE I-91 CORRIDOR SURROUNDING SPRINGFIELD MA AND HARTFORD CT...AS WELL AS THE I-95/I-195 CORRIDORS AROUND BOSTON AND PROVIDENCE...EVEN OUT I-90 INCORPORATING WORCESTER. PONDING OF WATER ALONG AREA ROADWAYS WILL LIKELY BE A BIG ISSUE TO AREA TRAFFIC. PLEASE SEE THE COASTAL FLOODING SECTION BELOW FOR COASTAL FLOOD THREATS. WINDS... SEVERAL LOCATIONS ACROSS CENTRAL/EASTERN NEW ENGLAND OBSERVING WIND GUSTS IN EXCESS OF 40 KTS /46 MPH/. WSR-88D VERTICAL WIND PROFILERS SHOWING WINDS AT H925 AMPLIFYING TO 70 KTS. INCREASING AREAL COVERAGE OF RAIN WITH EMBEDDED HEAVIER SHOWERS AIDING IN THE PRECIP-DRAG / MECHANICAL MIXING OF FASTER MOMENTUM ALOFT DOWN TO THE SURFACE. SHOULD SEE THESE WINDS CONTINUE INTO THE EVENING HOURS. WIND ADVISORIES CONTINUE ACCORDINGLY. ANY HIGH-WINDS TO WHICH WE CONTINUE TO MONITOR FOR WILL BE HANDLED WITH SHORT-FUSED WARNINGS. THOSE TRAVELING OVER BRIDGES /THINKING THE SAGAMORE AND BOURNE/ SHOULD BE AWARE OF FIERCE CROSSWINDS. GUSTS IN EXCESS OF 50 MPH WILL BE POSSIBLE. ALREADY RECEIVING NUMEROUS REPORTS OF TREES AND WIRES DOWN...BLOWN TRANSFORMERS AND POWER OUTAGES. THESE IMPACTS AND THREATS WILL CONTINUE OVER THE NEXT SEVERAL HOURS AHEAD OF THE COLD FRONT SWEEPING THROUGH THE REGION. WINTRY MIX/FLASH FREEZE POTENTIAL... TEMPERATURES QUICKLY FALLING IMMEDIATELY BEHIND THE COLD FRONT. CONSIDERING THE STRONG DYNAMICS AND LIFT ASSOCIATED WITH THE RRQ OF THE UPPER-LEVEL JET ACROSS AND TO THE REAR OF THE FRONT... THERE IS THE POTENTIAL FOR LINGERING PRECIPITATION WITHIN THE SHALLOW COLD-AIR MASS. THUS THERE REMAINS THE POSSIBILITY OF A BRIEF CHANGEOVER TO A SNOW/SLEET MIX...MAINLY ACROSS PORTIONS OF N MA AND S NH ALONG AND NORTH OF THE ROUTE 2 CORRIDOR. ANY ACCUMULATIONS WILL BE LIGHT AROUND A TRACE TO PERHAPS A TENTH OR TWO...ENOUGH TO MAKE FOR SLIPPERY CONDITIONS. DRIER AIR WILL WORK INTO THE REAR OF THE STORM RESULTING IN THE BACK EDGE OF PRECIP TO DISSIPATE. SHOULD ALSO SEE THIS DRY AIR AT THE SURFACE. THUS IT IS A QUESTION AS TO WHETHER WET SURFACES FROM THE RAIN WILL FREEZE AHEAD OF EVAPORATING. EITHER WHICH WAY...THERE IS THE POTENTIAL FOR BLACK-ICE AND SLIPPERY CONDITIONS THAT MAY EXIST FOR THE WEDNESDAY MORNING COMMUTE.
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&& .SHORT TERM /WEDNESDAY/...
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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...AS THE COLD FRONT WILL BE WELL OFFSHORE. NORTHWEST WINDS CONTINUE TO GUST BETWEEN 30 AND 40 MPH DURING THE MORNING...BUT WILL DIMINISH 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.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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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 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.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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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 CONTINUING 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 ARE AMPLIFYING TO 60-70 KT 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... 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. && .TIDES/COASTAL FLOODING... 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. && .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 UNTIL 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 SHORT TERM...SIPPRELL LONG TERM...FRANK AVIATION...FRANK/SIPPRELL MARINE...FRANK/DOODY TIDES/COASTAL FLOODING...SIPPRELL

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