000 FXUS61 KBOX 011307 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 907 AM EDT FRI NOV 1 2013 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE REGION TODAY AND STALL NEAR THE COAST TONIGHT AS A WEAK WAVE OF LOW PRESSURE DEVELOPS SOUTH OF NEW ENGLAND. UNSEASONABLY MILD AND WINDY TODAY WITH A BAND OF SHOWERS MOVING ACROSS THE REGION. ANOTHER PERIOD OF SHOWERS AFFECT THE CAPE AND ISLANDS TONIGHT INTO EARLY SATURDAY...THEN COLDER AND BLUSTERY CONDITIONS ARRIVE FOR SUNDAY INTO EARLY NEXT WEEK. HIGH PRESSURE BY THE MIDDLE OF THE WEEK WILL ALLOW FOR MODERATING TEMPERATURES. PETER CREEDON WILL HAVE YET ANOTHER RAINY BIRTHDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 9 AM UPDATE... FINE LINE OF LOW TOP CONVECTION ACROSS EASTERN NY STATE AND WESTERN NJ WILL WEAKEN AND BECOME FRAGMENTED AS IT APPROACHES AND ENTERS WESTERN NEW ENGLAND. THIS WILL BE ESPECIALLY TRUE FOR THE NORTHERN PORTION OF THE LINE...AS BEST INSTABILITY AND FORCING FOR ASCENT WILL SLIDE SOUTH OF NEW ENGLAND ACROSS NYC/LONG ISLAND AND THE SOUTHERN NEW ENGLAND COASTAL WATERS. NEVERTHELESS WIND THREAT REMAINS HIGH AS OUR KBOX RADAR VAD WIND PROFILE DETECTING 60 KT OF WIND AT 2 KFT HERE IN TAUNTON MA. CORE OF 60-70 KT LOW LEVEL JET WILL REMAIN OVER RI AND SOUTHEAST MA THROUGH 15Z/11AM...THEN BEGINNING TO SLIDE OFFSHORE. HOWEVER WIND THREAT REMAINS HIGH ACROSS THE ENTIRE REGION AS HEAVIER SHOWERS WILL HELP TRANSPORT STRONGER WINDS ALOFT TO THE SURFACE. ALSO HIGHER TERRAIN REMAIN AT RISK GIVEN CLOSER PROXIMITY TO STRONGER WINDS ALOFT. STRONG WINDS WILL PERSIST BEHIND FRONTAL PASSAGE AND DEPARTURE OF SHOWERS THIS AFTERNOON...AS LOW LEVEL LAPSE RATES STEEPEN IN POST FRONTAL AIRMASS YIELDING GUSTS UP TO 50 MPH. STRONGEST WINDS THIS AFTERNOON WILL BE ACROSS NORTHERN MA INTO SOUTHWEST NH. THUS EXPECT A WINDY DAY FROM START TO FINISH WITH WINDS FINALLY EASING AROUND SUNSET. ONLY CHANGE TO FORECAST WILL BE TO INCREASE HIGH TEMPS AS 9 AM READINGS ARE ALREADY NEAR 70 /70 AT MARSHFIELD/! WILL KEEP AN EYE ON RECORD HIGHS FOR TODAY WHICH ARE IN THE U70S /BOS AND PVD/ L70S FOR ORH AND L80S FOR BDL. NOT SURPRISING REGARDING THIS NEAR RECORD WARMTH GIVEN STRENGTH OF LOW LEVEL JET BEING +3 STD FROM CLIMO. EARLIER DISCUSSION BELOW. ------------------------------------------------------------------ PREVIOUS DISCUSSION... DRY SLOT AND PRECIP LULL LIFTING NWD ACROSS SNE EARLY THIS MORNING WHICH IS WELL FORECAST BY SHORT RANGE MODEL SUITE INCLUDING HRRR. EDGE OF THE DRY SLOT WILL BE ACROSS FAR NW ZONES WHERE OCCASIONAL SHOWERS WILL CONTINUE...WITH THESE SHOWERS MOVING BACK TO THE EAST TOWARD DAYBREAK. WARM SECTOR AIRMASS IN WELL ENTRENCHED WITH TEMPS UPPER 50S TO MID 60S. ANOMALOUS LOW PRES -4SD LIFTS NE FROM GT LAKES TODAY WITH +3SD LOW LEVEL JET MOVING ACROSS SNE TODAY. PWAT ANOMALY ALSO +3SD. THIS WILL RESULT IN A PERIOD OF LOCALLY HEAVY SHOWERS MOVING WEST TO EAST THIS MORNING INTO THE AFTERNOON ASSOCD WITH IMPRESSIVE LOW LEVEL MOISTURE TRANSPORT AND RIGHT ENTRANCE REGION OF THE UPPER JET. ALSO CONCERNED WITH A POSSIBLE FINE LINE OF CONVECTION ALONG THE FRONT LATER THIS MORNING PER HRRR SOLUTION. MODELS ARE GENERATING MARGINAL INSTABILITY WITH SBCAPES 200-400 J/KG SO THIS SCENARIO SEEMS PLAUSIBLE. LOW RISK OF ISOLD THUNDER AND IF FINE LINE DOES DEVELOP THIS WOULD ENHANCE THE RISK OF STRONGER WINDS MIXING DOWN TO THE SURFACE. THE SPEED OF THIS SYSTEM AND MARGINAL INSTABILITY WILL LIMIT RAINFALL AMOUNTS WITH QPF LESS THAN 0.5 FOR MOST LOCATIONS...WITH UP TO 1 ACROSS FAR W ZONES. LOCALIZED MINOR URBAN AND POOR DRAINAGE FLOODING IS POSSIBLE THIS MORNING...MAINLY IN THE INTERIOR. SHOWERS WILL BE EXITING W ZONES LATE MORNING TO MIDDAY...AND EARLY AFTERNOON IN THE COASTAL PLAIN. BUT SHOWERS COULD LINGER THROUGH THE DAY OVER THE OUTER CAPE/ISLANDS AS FRONT STALLS. WIND THREAT...CORE OF THE LOW LEVEL JET WILL BE MOVING ACROSS SNE 12-18Z. SOUNDINGS INDICATE VERY SHALLOW PREFRONTAL MIXING BUT POTENTIAL FOR GUSTS TO 40+ KTS THIS MORNING. HEAVIER SHOWERS AND POTENTIAL FINE LINE WOULD ALSO AID IN TRANSPORTING STRONGER WINDS TO THE SURFACE. STRONGEST WINDS WILL LIKELY BE ACROSS PORTIONS OF RI AND INTERIOR E MA WHERE MILDEST TEMPS INTO THE LOWER 70S PROMOTE DEEPER MIXING. SOUNDINGS INDICATE THE POTENTIAL FOR ANOTHER PULSE OF STRONG POST-FRONTAL WINDS TO 40+ KTS THIS AFTERNOON AS BOUNDARY LAYER MIXING DEEPENS. STRONGEST POST- FRONTAL WINDS MORE LIKELY ACROSS THE INTERIOR WITH LESS WIND ALONG THE COAST. WIND ADVISORY WILL CONTINUE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... FRONT STALLS NEAR THE COAST TONIGHT AS A WAVE IS FORECAST TO DEVELOP S OF NEW ENG. THIS WILL KEEP THE THREAT OF SHOWERS GOING TONIGHT ACROSS SE COASTAL NEW ENG...ESPECIALLY THE OUTER CAPE AND ISLANDS WHILE DRY CONDITIONS PREVAIL IN THE INTERIOR. AMERICAN MODELS KEEP MOST OF THE RAIN OFFSHORE WHILE INTERNATIONAL MODELS BRING A DECENT SLUG OF RAIN TO THE OUTER CAPE/ISLANDS LATE TONIGHT. WITH FRONT STALLING NEAR THE COAST...WE TRENDED FORECAST TOWARD WETTER SOLUTION AND HAVE LIKELY POPS TO ACK WITH CHC POPS TO THE CAPE AND S COASTAL MA. LOW PROB THAT SHOWERS COULD BACK IN TO THE BOS-PVD CORRIDOR LATE TONIGHT BUT WE KEPT IT DRY FOR NOW. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGHLIGHTS... * COASTAL LOW DEVELOPS FOR SATURDAY...CLIPPING THE CAPE AND ISLANDS * COLDER AND BLUSTERY CONDITIONS WILL RETURN ON SUNDAY AND MONDAY * MODERATING TEMPERATURES AND DRY WEATHER BY MID NEXT WEEK. * POSSIBLE SYSTEM APPROACHING THURSDAY/FRIDAY CONFIDENCE LEVEL/MODEL GUIDANCE... MODERATE CONFIDENCE IN THE OVERALL FORECAST. HAVE HIGH CONFIDENCE IN THE OVERALL TRENDS YET LOW CONFIDENCE ON EXACT PRECIP TIMING. LONG WAVE TROUGH IS STILL PROGGED TO IMPACT NEW ENGLAND WITH SEVERAL SHORTWAVES MOVING THROUGH THE FLOW. THE FIRST ONE IS MOVING THROUGH TODAY WITH A SECOND SHORTWAVE APPROACHING THE REGION BY TOMORROW. EXPECT THIS EXPANSIVE NEGATIVE HEIGHT ANOMALY TO INDUCE AN AREA OF LOW PRESSURE ALONG THE MID-ATLANTIC COAST WHICH WILL SLIDE NORTHWARD TOWARD THE CANADIAN MARITIMES. 00Z MODEL GUIDANCE ALL AGREE WITH THIS COASTAL LOW DEVELOPMENT...WHICH COULD BRING MORE SHOWERS ACROSS THE IMMEDIATE SOUTH COAST...CAPE AND ISLANDS ON SATURDAY. THERE ARE SOME MODEL DISCREPANCIES ON EXACT PLACEMENT OF THE LOW...WITH THE EC ON THE FASTER END AND THE GFS ON THE SLOW SIDE. TRENDED IN THE MIDDLE FOR NOW. FINALLY THE LAST IMPULSE WILL PUSH A STRONG COLD FRONT THROUGH THE REGION ON SUNDAY DROPPING TEMPS BACK TOWARDS SEASONABLE. BY EARLY NEXT WEEK MODELS CONCUR WITH A WESTERN TROUGH TO STRONGLY AMPLIFY RESULTING IN RIDGING TO BUILD OVER THE EASTERN HALF OF THE U.S. HOWEVER THIS WESTERN TROUGH WILL APPROACH NEW ENGLAND BY THURSDAY BRINGING ANOTHER ROUND OF RAIN AND WIND. EXACT TIMING FOR THIS SYSTEM IS STILL UNCERTAIN. DETAILS... SATURDAY... MID-ATLANTIC LOW WILL DEVELOP AND HEAD TOWARDS SOUTHERN NEW ENGLAND DURING THE MORNING HOURS. AS MENTIONED BEFORE...TRENDED TOWARDS THE MIDDLE OF THE ROAD COMPARED TO THE GFS AND EC. BELIEVE THERE WILL BE A SHARP CUT OFF IN TERMS OF WHERE THE RAIN WILL AND WILL NOT FALL. HAVE THE HIGHEST CONFIDENCE THAT THIS SYSTEM WILL BRING SOME SHOWERS ACROSS THE IMMEDIATE SOUTH COAST...CAPE AND ISLANDS. HOWEVER WITH THE ONSHORE FLOW...COULD SEE A SHOWER OR TWO ACROSS THE SOUTHEAST COASTAL SIDE OF MASSACHUSETTS. THIS COASTAL LOW WILL MOVE UP TO THE MARITIMES BY THE SATURDAY NIGHT SO CHANCE OF PRECIP WILL WANE BY THE AFTERNOON HOURS. REGARDLESS SATURDAY WILL STILL BE MILD WITH TEMPS IN THE 60S AND LESS WINDY. DEFINITELY AN IMPROVEMENT COMPARED TO TODAY. SUNDAY... THE UNSEASONABLE WARM WEATHER WILL COME TO AN END ON SUNDAY AS THE THIRD AND LAST IMPULSE PUSHES A STRONG COLD FRONT THROUGH THE REGION BY LATE SATURDAY/EARLY SUNDAY. THIS FRONT WILL HAVE STRONG CAA BEHIND IT DROPPING TEMPERATURES ACROSS THE REGION CLOSER TO SEASONABLE. IN FACT 850 MB TEMPS DROP BETWEEN -6 TO -9C RESULTING IN HIGH TEMPS TO BE BE IN THE MID 40S TO LOW 50S. WITH COASTAL LOW WAY OUT IN THE MARITIMES AND CANADIAN HIGH BUILDING ACROSS THE NORTH COUNTRY...DUE NORTH WINDS ARE ANTICIPATED. THESE NORTHERLY WINDS WILL ALLOW FOR SOME POSSIBLE OCEAN EFFECT SHOWERS TO DEVELOP AND MOVE ALONG THE EAST COAST LINE AND ACROSS THE CAPE AND ISLANDS. HAVE KEPT A SLIGHT CHANCE MENTIONED FOR NOW. THESE SHOWERS WILL BE VERY ISOLATED IN NATURE. ALTHOUGH TEMPS ALOFT ARE DROPPING QUICKLY...BELIEVE LIQUID PRECIP WILL HOLD OUT AS SURFACE AND BL TEMPS WILL STILL STAY ABOVE FREEZING. SUNDAY NIGHT INTO WEDNESDAY.... CANADIAN HIGH PRESSURE WILL BEGIN TO MOVE INTO THE REGION LATE SUNDAY NIGHT INTO MONDAY...AND BUILD OVER THE NORTHEAST THROUGH AT LEAST WEDNESDAY. THIS HIGH PRESSURE WILL ALLOW FOR LIGHT WINDS AND CLEAR SKIES ESP DURING THE OVERNIGHT HOURS. THIS WILL ALLOW FOR RADIATIONAL COOLING ON SUNDAY NIGHT AND ON MONDAY NIGHT. SUNDAY NIGHT APPEARS TO BE THE COLDEST WITH TEMPS DROPPING INTO THE MID TEENS TO MID 20S. MONDAY WILL BE THE COOLEST THE REGION HAS SEEN IN AWHILE WITH HIGHS BELOW AVERAGE...LOW TO MID 40S. AN UPPER LEVEL RIDGE WILL BEGIN TO BUILD ACROSS THE EASTERN SEABOARD RESULTING IN DRY WEATHER AND A WARMING TREND. IN FACT MID 60S RETURN TO THE FORECAST BY WEDNESDAY AND POSSIBLY ON THURSDAY. THURSDAY AND BEYOND... MODELS BEGIN TO DRIVE THE WESTERN TROUGH TOWARDS THE EAST COAST BY THURSDAY. APPEARS THAT THIS LOW PRESSURE SYSTEM WILL BRING HEAVY RAIN AS WELL AS STRONG WINDS TO THE REGION BY THURSDAY MORNING LASTING INTO FRIDAY MORNING. BECAUSE THIS SYSTEM IS SEVERAL DAYS AWAY...A LOT CAN CHANGE SO STAY TUNED TO THE LATEST FORECAST. && .AVIATION /13Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. 9 AM UPDATE... LINE OF LOW TOP SHOWERS ACROSS EASTERN NY AND WESTERN NJ WILL WEAKEN AS IT ENTERS NEW ENGLAND. SOUTHERN PORTION OF THE LINE WILL BE STRONGER ACROSS NYC/LONG ISLAND AND THE NEW ENGLAND COASTAL WATERS. SSW WINDS GUSTS TO 45 KT INTO THROUGH THIS MORNING...THEN SHIFT TO WSW THIS AFTERNOON WITH G45KT ESPECIALLY NORTHERN MA INTO NH. EARLIER DISCUSSION BELOW. ------------------------------------------------------------------- TODAY...IFR-MVFR WITH A BAND OF LOCALLY HEAVY SHOWERS MOVING ACROSS THE REGION...EXITING 18-21Z FROM WEST TO EAST WITH IMPROVING CONDITIONS TO VFR. STRONG S/SW WINDS GUSTING UP TO 40-45 KT RI AND EASTERN MA IN THE MORNING...THEN SHIFTING TO WSW IN THE AFTERNOON WITH GUSTS 30-40 KT. HIGH CONFIDENCE ON TRENDS. TONIGHT...LINGERING MVFR/IFR IN OCCASIONAL SHOWERS AT ACK...POSSIBLY AS FAR N AS CAPE COD. OTHERWISE VFR WITH DIMINISHING WIND. MODERATE CONFIDENCE. KBOS TAF...HIGH CONFIDENCE IN TRENDS...LOWER IN EXACT TIMING. KBDL TAF...HIGH CONFIDENCE IN TRENDS...LOWER IN EXACT TIMING. OUTLOOK...SATURDAY THROUGH TUESDAY... SATURDAY...MVFR/IFR CONDITIONS TO START WILL IMPROVE TO VFR FROM WEST TO EAST. SUNDAY...VFR. NNW WINDS COULD GUST TO 25 KTS. MONDAY AND TUESDAY...VFR. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY...SW GALE FORCE WINDS TO 35-40 KT. SCATTERED HEAVY SHOWERS EXIT OFFSHORE DURING THE AFTERNOON...HOWEVER MAY LINGER OVER SOUTHEAST WATERS. HIGH CONFIDENCE. TONIGHT...DIMINISHING WIND AND SEAS. OCCASIONAL SHOWERS WILL CONTINUE ACROSS SE WATERS...OTHERWISE MAINLY DRY. MODERATE CONFIDENCE ON NW EXTENT OF SHOWERS. OUTLOOK...SATURDAY THROUGH TUESDAY...HIGH CONFIDENCE. SATURDAY AND SUNDAY...SMALL CRAFT ADVISORIES WILL LIKELY BE NECESSARY FOR SEAS OVER 5 FEET AND NORTHWESTERLY WINDS GUSTING TO 30 KTS. THERE IS A LOW PROBABILITY THAT NORTH GALES WILL OCCUR ACROSS THE EASTERN OUTER WATERS ON SUNDAY. VISIBILITIES MAY BE LIMITED IN INTERMITTENT SHOWERS. MONDAY AND TUESDAY...WINDS AND SEAS DIMINISH AS HIGH PRESSURE MOVES OVER SOUTHERN NEW ENGLAND AND OVER THE WATERS. LIGHT NORTHERLY WINDS SHIFT TO THE EAST AND THEN SOUTH THROUGH THIS TIME PERIOD. ONCE AGAIN HAPPY BIRTHDAY PETER CREEDON. && .TIDES/COASTAL FLOODING... COASTAL FLOODING CONCERNS ALONG THE SOUTH COAST ARE MINIMAL. NOT MUCH OF A SURGE GIVEN SURFACE LOW AND PRESSURE FALLS ARE TRACKING SO FAR NORTHWEST OF NEW ENGLAND. WILL HAVE MODEST TO LARGE WAVE ACTION ON THE SOUTH COAST BUT TIDES WILL NOT BE HIGH ENOUGH TO WARRANT ANY FLOODING. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...WIND ADVISORY UNTIL 6 PM EDT THIS EVENING FOR CTZ002>004. MA...WIND ADVISORY UNTIL 6 PM EDT THIS EVENING FOR MAZ002>024-026. NH...WIND ADVISORY UNTIL 6 PM EDT THIS EVENING FOR NHZ011-012-015. RI...WIND ADVISORY UNTIL 6 PM EDT THIS EVENING FOR RIZ001>008. MARINE...GALE WARNING UNTIL 6 PM EDT THIS EVENING FOR ANZ230>237-250- 251-254>256. && $$ SYNOPSIS...KJC/DUNTEN NEAR TERM...NOCERA SHORT TERM...KJC/DUNTEN LONG TERM...DUNTEN AVIATION...KJC/DUNTEN MARINE...KJC/DUNTEN TIDES/COASTAL FLOODING...
Posted on: Fri, 01 Nov 2013 14:00:19 +0000
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