Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 210615 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 215 AM EDT MON APR 21 2014 .SYNOPSIS...
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HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH EARLY TUESDAY. WHILE WARMER ON TUESDAY...WET WEATHER WILL FOLLOW TUESDAY NIGHT INTO WEDNESDAY BEHIND WHICH BREEZY AND COOLER CONDITIONS FOLLOW TOWARDS THE END OF THE WEEK. ANOTHER CHANCE OF WET WEATHER IS ANTICIPATED LATE FRIDAY INTO THE WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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150 AM UPDATE... OTHER THAN SOME THIN BANDS OF CIRRUS CLOUDS...SKIES WERE CLEAR AT 05Z ALONG WITH LIGHT/VRBL OR CALM WINDS. THIS IS ALLOWING RADIATIONAL COOLING TO SETTLE IN ACROSS SOME OF THE NORMALLY SUSCEPTIBLE LOCATIONS...THOUGH ALSO NOTING QUICK TEMP DROPS ALONG THE S COAST AS WELL AS ACROSS SW NH. HAVE UPDATE GRIDS TO REFLECT CURRENT CONDITIONS AND INCORPORATED INTO OVERNIGHT TRENDS.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... A HIGH PRESSURE RIDGE GRADUALLY SHIFTS SOUTHEAST THROUGH THIS PERIOD...BUT WILL STILL BE CLOSE ENOUGH TO KEEP OUR WEATHER DRY. WINDS WILL CONTINUE TO SHIFT SOUTH...AND INCREASE FOR MONDAY AFTERNOON. CURRENTLY THINKING THE PRESSURE GRADIENT WILL BE WEAK ENOUGH FOR WEAK SEA BREEZES TO DEVELOP ALONG THE EAST COAST OF MA. TEMPERATURES WILL RISE TO ABOVE NORMAL LEVELS...EXCEPT ALONG THE IMMEDIATE COASTLINE. THE PROXIMITY TO THE COLDER OCEAN WILL KEEP TEMPERATURES IN THE 50S THERE...ESPECIALLY ALONG SOUTH-FACING COASTS. ONCE THE SEA BREEZES DIE OFF TOMORROW AFTERNOON ALONG THE EAST COAST OF MA...TEMPERATURES WILL RISE QUICKLY. LATEST GUIDANCE TEMPERATURES LOOKED VERY REASONABLE. HIGHER CLOUDS INCREASE MONDAY NIGHT AHEAD OF A COLD FRONT APPROACHING SOUTHERN NEW ENGLAND. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... */ HIGHLIGHTS... - COLD FRONT AND SHOWERY WEATHER FOR LATE TUESDAY AND OVERNIGHT - BREEZY AND COOLER FOR WEDNESDAY AND THURSDAY UNDER HIGH PRESSURE - ANOTHER PERIOD OF SHOWERY WEATHER FRIDAY INTO THE WEEKEND */ OVERVIEW AND MODEL PREFERENCE... A CONSENSUS BLEND IS PREFERRED THROUGH THE MIDWEEK PERIOD AS MASS FIELDS ARE IN PRETTY GOOD BALANCE ALBEIT SOME AMPLITUDE DIFFERENCES. THEREAFTER YOU ARE IN ONE OF TWO CAMPS TOWARDS THE LATE-WEEK: EITHER AN AMPLIFYING NEGATIVELY-TILTING TROUGH OVER THE SOUTHWEST CONUS AND SUBSEQUENT SLOWER WAVE PROGRESSION...OR A FAST-STRETCHED ZONAL-FLOW REGIME. PREFER THE FORMER WITH THE 20.12Z GFS SHOWING A TIGHTENING CYCLONE TO THE LEE OF THE ROCKIES CLIMATOLOGICALLY PREFERRED THIS TIME OF YEAR. THIS SHOULD LEND TO THE WEEKEND DISTURBANCE ACROSS THE NE CONUS TO LINGER A BIT LONGER. */ DAY-TO-DAY DETAILS... TUESDAY INTO TUESDAY NIGHT... COLD FRONT SWEEPS THROUGH THE FORECAST REGION TOWARDS THE LATER HALF OF THE FORECAST PERIOD. INITIALLY H925 TEMPS +10-12C AND SUNSHINE SHOULD ALLOW HIGHS INTO THE 70S WITH COOLER CONDITIONS ALONG THE SHORE WITH AN E-COMPONENT OF ONSHORE FLOW. THEREAFTER SUFFICIENT LIFT-DYNAMICS SHOULD ALLOW FOR A BAND OF RAIN ALONG THE FRONT WITH EMBEDDED HEAVIER SHOWERS. PERHAPS A SLIGHT CHANCE OF THUNDER THOUGH CONVECTIVE INDICES ARE ON THE LOW-END OF THRESHOLDS. SOME HINT PER THE 20.12Z NAM OF SHOWERS BECOMING DIFFUSE ACROSS NEW ENGLAND AND PERHAPS THIS ATTRIBUTABLE TO LINGERING HIGH PRES AND DRY AIR AS WELL AS A WEAKENING JET STRUCTURE ALOFT. BUT FEEL LOW- TO MID-LEVEL ASCENT OF PWATS UP TO 1.5 INCHES WILL BE SIGNIFICANT TO YIELD THE LIKELIHOOD OF SHOWERY WEATHER ACROSS MUCH OF THE REGION. WEDNESDAY INTO THURSDAY NIGHT... HIGH PRES BUILDING ACROSS THE REGION AGAINST AN INTENSIFYING LOW ACROSS NOVA SCOTIA. BLUSTERY NW FLOW AND LIKELY SCATTERED-BROKEN CLOUD DECKS ON WEDNESDAY WILL MAKE CONDITIONS FEEL COOLER. H925 WINDS OF 30-40 KTS COUPLED WITH GOOD BOUNDARY-LAYER MIXING UP TO H85. MAY NEED CONSIDER WIND-ADVISORIES CONSIDERING THE LEVEL OF COLD ADVECTION ALOFT COUPLED WITH THE LATE-APRIL SUN. CLOUDS CLEAR OVERNIGHT INTO THURSDAY UNDER THE INCREASING INFLUENCE OF HIGH PRES. WINDS SHOULD BEGIN TO RELAX...BUT LIKELY NOT UNTIL LATE. IT WILL REMAIN BLUSTERY BUT BELOW WIND-ADVISORY THRESHOLDS. THOUGH IT WILL BE DRY WITH RH-VALUES LIKELY AROUND 30-PERCENT OVER THE INTERIOR...THE REGION IS ABOVE-NORMAL FOR PRECIP FOR THE MONTH OF APRIL. THUS AM NOT THINKING THERE WILL BE AN ELEVATED FIRE WEATHER POTENTIAL. FRIDAY INTO FRIDAY NIGHT... WARM FRONT LIFTS NE ACROSS THE REGION WITH ATTENDANT SHOWERY WEATHER SUBSEQUENT OF STRONG SW GULF-MOISTURE FLOW UNDERGOING BROAD-SCALE ASCENT AHEAD OF THE WARM-FRONT BENEATH INCREASING DIVERGENCE ALOFT. WIDESPREAD RAIN WITH PERHAPS SOME EMBEDDED HEAVIER SHOWERS. A SLIGHT CHANCE OF THUNDER THOUGH ONCE AGAIN CONVECTIVE INDICES ARE ON THE LOW-END OF THRESHOLDS. MUCH OF THIS ACTIVITY LOOKS TO OCCUR DURING THE EVENING PERIOD. SATURDAY INTO SUNDAY... PENDING BETTER MODEL CONSISTENCY...A SERIES OF COLD-FRONTS WILL USHER RENEWED CHANCES FOR SHOWERS ALBEIT MOISTURE DEPRIVED...SO EXPECT LIGHT ACTIVITY. BREEZY NW FLOW TO THE REAR RESULTS IN THE RETURN OF COOLER CONDITIONS TOWARDS THE END OF THE WEEKEND AND INTO EARLY NEXT WEEK. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/...HIGH CONFIDENCE. TODAY...VFR. EXPECT LIGHT/VRBL OR CALM WINDS FOR MOST AREAS THROUGH MID TO LATE MORNING...THEN WILL START TO PICK UP OUT OF THE SE-S UP TO AROUND 10 KT. HOWEVER...NOTING SEA BREEZES KICKING IN ALONG IMMEDIATE COAST BY MID TO LATE MORNING AND CONTINUING FOR MOST OF THE AFTERNOON. TONIGHT...VFR. LIGHT S-SW WINDS. TUESDAY...VFR. INCREASING MID TO HIGH CLOUDS DURING THE MORNING... POSSIBLY LOWERING TO MVFR ALONG S COAST AFTER 20Z. MAY SEE LOCAL MVFR VSBYS LATE IN THE DAY IN SCT SHOWERS. SW WINDS INCREASE DURING THE LATE MORNING AND AFTERNOON...GUSTING TO AROUND 20 KT MAINLY ACROSS E MA/RI. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEA BREEZE ANTICIPATED BY 16Z-18Z TODAY. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY NIGHT INTO FRIDAY... TUESDAY NIGHT...HIGH CONFIDENCE. COLD FRONT SWEEPING TERMINALS. EXPECT LOW END VFR / MVFR OVERNIGHT. SHRA. LOW CONFIDENCE TSRA. BREEZY SW FLOW...WITH GUSTS UP TO 25 KT OVER SE NEW ENGLAND...BACKING NW AND INCREASING. IMPROVING BY WEDNESDAY MORNING. WEDNESDAY INTO THURSDAY...HIGH CONFIDENCE. VFR. SCT-BKN LOW-END VFR CIGS FOR WEDNESDAY. SKC THURSDAY. BLUSTERY NW WINDS WITH GUSTS UP TO AROUND 35 KTS. FRIDAY...MODERATE CONFIDENCE. LOWERING CIGS TOWARDS LATE WITH INCREASING CHANCES FOR SHOWERS ALONG WITH INCREASING SW WINDS.
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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 MONDAY NIGHT/...HIGH CONFIDENCE. WINDS AND SEAS WILL REMAIN BELOW ADVISORY THRESHOLDS. OUTLOOK...TUESDAY INTO FRIDAY... TUESDAY INTO WEDNESDAY...HIGH CONFIDENCE. COLD FRONT SWEEPING THE WATERS BY WEDNESDAY MORNING WITH SHOWERS. NO VISIBILITY ISSUES ANTICIPATED. GUSTY SW WINDS UP TO AROUND 25 KTS POSSIBLE AHEAD OF THE FRONT. WILL SEE WAVES BUILD UP TO 5 FEET ON THE OUTER WATERS REQUIRING SMALL CRAFT ADVISORIES. WEDNESDAY NIGHT INTO THURSDAY...HIGH CONFIDENCE. WINDS BACKING NW AND GUSTING IN EXCESS OF GALE FORCE WITH GUSTS UP TO 40 KTS. WILL LIKELY NEED GALE FORCE WARNINGS FOR THE PERIOD. WAVES BUILDING UP TO AROUND 7 TO 9 FEET ON THE OUTER WATERS. GALES SHOULD DROP OFF BY THE END OF THE DAY REQUIRING CONVERSION TO SMALL CRAFT. THURSDAY NIGHT INTO FRIDAY...MODERATE CONFIDENCE. NW WINDS DIMINISHING AND TURNING OUT OF THE SW. THIS WILL ALLOW WAVE ENERGY TO DISSIPATE. SMALL CRAFT ADVISORIES SHOULD DROP OFF.
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&& .HYDROLOGY... MINOR FLOODING CONTINUES ALONG PORTIONS OF THE MAINSTEM CT RIVER. SEE THE LATEST FLOOD STATEMENT FOR DETAILS. FLOOD WARNINGS REMAIN POSTED ALONG CT RIVER AT... HARTFORD AND MIDDLE HADDAM && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...BELK/SIPPRELL NEAR TERM...EVT SHORT TERM...BELK LONG TERM...SIPPRELL AVIATION...SIPPRELL/EVT MARINE...SIPPRELL/EVT HYDROLOGY...STAFF

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