Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 280247 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1047 PM EDT WED APR 27 2016 .SYNOPSIS... HIGH PRESSURE WILL BUILD FROM THE NORTH THROUGH EARLY THURSDAY...THEN RETREAT NORTHEAST LATER THURSDAY AS LOW PRESSURE APPROACHES FROM THE OHIO VALLEY. THE LOW WILL PASS TO THE SOUTH AND EAST THURSDAY NIGHT INTO FRIDAY. HIGH PRESSURE WILL BRIEFLY BUILD IN ON SATURDAY BEFORE MOVING OFF THE COAST ON SUNDAY. LOW PRESSURE MAY IMPACT THE AREA ON MONDAY...AND UNSETTLED WEATHER COULD CONTINUE INTO THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... HIGH PRESSURE BUILDS IN FROM THE NORTH...PUSHING A COLD FRONT THROUGH LATE AT NIGHT AND GIVING US A A SHOT OF COLD/DRY AIR ADVECTION. HAD TO MAKE SOME UPWARD ADJUSTMENTS TO TEMPS AND DEWPOINTS FOR MANY LOCATIONS AS WINDS FROM THE SW PRECEDE THE COLD FRONT/TROUGH PASSAGE FROM THE NORTH OVERNIGHT. WITH A SHORT PERIOD OF CAA ALONG WITH CIRRUS STREAMING IN FROM THE WEST...NOT SO SURE IF WE WILL MEET CRITERIA FOR SOME OF THE ZONES THAT CURRENTLY ARE UNDER FROST AND FREEZE HEADLINES. WITH UNCERTAINTY...WILL NOT CHANGE HEADLINES OR LOW TEMP FCST...BUT MIGHT EVENTUALLY NEED TO ADJUST LOW TEMPS UPWARD. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THE CANADIAN CLOSED LOW SHOULD MOVE SLOWLY EAST...ALLOWING A FLATTENING UPPER RIDGE ALOFT TO APPROACH BUT NOT QUITE MAKE IT THIS FAR EAST. AFTER A MOSTLY SUNNY START...CLOUDS SHOULD INCREASE THROUGH THE DAY AS LEADING SHORTWAVE ENERGY WELL AHEAD OF A WEAKENING CLOSED LOW IN THE MISSISSIPPI VALLEY ARRIVES ALOFT AND OVERTAKES THE FLATTENING RIDGE...WITH CHANCE OF LATE DAY SHOWERS FROM NYC SOUTH/WEST...AND EXPANDING TO WRN LONG ISLAND IN THE EVENING. ANOTHER LOBE OF THE CANADIAN HIGH BUILDING INTO NEW ENGLAND MAY PREVENT MUCH IF ANY PRECIP FORM EXPENDING FARTHER NORTH/EAST...BUT THIS IS UNCERTAIN...SO REST OF THE CWA CARRIES SLIGHT CHANCE POP. HIGHS ON THU SHOULD BE A LITTLE MILDER THAN THOSE OF TODAY AND ONLY A COUPLE OF DEG BELOW AVG...UPPER 50S AND LOWER 60S. LOWS THU NIGHT SHOULD BE IN THE MID 40S IN/NEAR NYC...UPPER 30S/LOWER 40S MOST ELSEWHERE. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... UNSETTLED WEATHER PATTERN THROUGH THE LONG TERM AS MUCH OF THE LATEST ENSEMBLE GUIDANCE AGREE IN A NEGATIVE NAO/AO COMBINE WITH A SPLIT FLOW REGIME ACROSS THE CONUS. THE NAO/AO ARE FORECAST TO BECOME NEUTRAL LATE THIS WEEKEND AND EARLY NEXT WEEK. WHATS LEFT OF THE STRONG SOUTHERN STREAM TROUGH AND VORT ENERGY CURRENTLY ACROSS THE PLAINS WILL OPEN UP AND SLOWLY INTERACT WITH THE NORTHERN STREAM INTO FRIDAY AS DEEP UPPER LOW OVER SE CANADA MOVES INTO THE N. ATLANTIC. THIS VORT ENERGY AT 500 HPA APPROACHES ON FRIDAY WITH GOOD PVA AND MOVES SOUTH AND OFFSHORE FRIDAY NIGHT. MOISTURE DOES NOT LOOK OVERLY IMPRESSIVE AND THERE IS SOME UNCERTAINTY IN HOW MUCH SUBSIDENCE WILL REMAIN FROM SURFACE HIGH PRESSURE PRESSING DOWN FROM THE NORTH. HAVE INCREASED POPS FRIDAY AFTERNOON/EVENING BUT LIMITED THEM TO CHANCE...HIGHEST ACROSS SOUTH AND WESTERN PARTS OF THE AREA. THE DISTURBANCE IS QUITE PROGRESSIVE SO DRY CONDITIONS RETURN QUICKLY OVERNIGHT FRIDAY. A BRIEF RESPITE IN THE UNSETTLED PATTERN OCCURS ON SATURDAY WITH HIGH PRESSURE BUILDING AT THE SURFACE AND WEAK RIDGING ALOFT. FRONTAL BOUNDARY WILL LIE WELL SOUTH OF THE AREA ON SATURDAY. THIS WILL BE SHORT-LIVED AS FAIRLY POTENT SHORTWAVE ENERGY MOVES OUT OF THE PLAINS ON SUNDAY. SW FLOW ALOFT SHOULD HELP WITH INCREASING MOISTURE AS HIGH PRESSURE MOVES OFFSHORE. THE AMOUNT OF INTERACTION FROM THE SOUTHERN STREAM SHORTWAVE AND THE NORTHERN STREAM LEADS TO UNCERTAINTIES IN TIMING OF TRACK OF LOW PRESSURE DEVELOPING ALONG THE FRONTAL BOUNDARY. THE 12Z GFS AND CMC KEEP THE ENERGY SHEARED OUT AND BROAD WHILE THE 12Z ECMWF KEEPS A MORE COMPACT PIECE OF ENERGY ROUNDING THE BASE OF THE LARGER TROUGH. AT BASED ON THE LATEST MODEL CONSENSUS...LOW PRESSURE MOVES ACROSS THE AREA LATE SUNDAY NIGHT INTO MONDAY...WITH UNCERTAINTY ON WHETHER IT TRACKS SOUTH OF LONG ISLAND OR FURTHER TO THE NORTH. HAVE INCREASED POPS TO HIGH CHANCE SUNDAY NIGHT INTO MONDAY WITH THIS PACKAGE. CONFIDENCE IN THIS SYSTEM OCCURRING HAS INCREASED...BUT UNCERTAINTIES ARE QUITE HIGH IN TIMING OF SMALLER SCALE FEATURES. THE SYSTEM MOVES OFFSHORE MONDAY NIGHT INTO TUESDAY. TROUGHING OVER THE EASTERN STATES IS DEPICTED ON LATEST GFS/EPS ENSEMBLE MEANS AFTER THIS SYSTEM PASSES...SO THE PATTERN COULD REMAIN UNSETTLED INTO THE MIDDLE OF THE WEEK. BELOW AVG TEMPERATURES ARE FORECAST THROUGH THE PERIOD. DEPENDING ON WHERE THE LOW ON MONDAY TRACKS...TEMPERATURES COULD STRUGGLE TO RISE OUT OF THE 40S. DID NOT GO THIS LOW RIGHT NOW...BUT IT IS WORTH NOTING THIS POTENTIAL WITH IT BEING EARLY MAY. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... HIGH PRES BUILDS INTO THE REGION TONIGHT AND THEN OFF THE NEW ENGLAND COAST THU MORNING. LOW PRES THEN APPROACHES FROM THE OHIO VALLEY WITH A CHC OF RAIN LATE. VFR THROUGH THE TAF PERIOD. SW FLOW WILL DIMINISH BELOW 10 KT THIS EVE AND VEERS AROUND TO THE NE BY MORNING. SOUTHEASTERLY PSEUDO SEABREEZES ARE LIKELY THU AFTN. MOST OF THE GUIDANCE EXCEPT THE GFS KEEPS THE AREA DRY UNTIL AFT 18Z AND EVEN THEN LIGHT RAIN ONLY IMPACTS WESTERN TERMINALS. DUE TO THE UNCERTAINTY...HAVE INCLUDED PROB30 AT ALL TERMINALS EXCEPT KISP/KBDR/KHPN/KGON FOR THE TIME BEING. .OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY... .THU NIGHT THROUGH FRI NIGHT...LOW CHC OF MVFR IN LIGHT RAIN. .SAT...VFR. .SUN THROUGH MON...MVFR OR LOWER POSSIBLE IN RAIN. && .MARINE... WITH INCREASING NE FLOW ON FRIDAY...WINDS AND SEAS ON THE OCEAN MAY APPROACH MINIMAL SCA LEVELS. SCA CONDITIONS ARE ALSO POSSIBLE LATE SUNDAY INTO MONDAY AS LOW PRESSURE MAY IMPACT THE WATERS. && .HYDROLOGY... THERE IS POTENTIAL FOR AN AVERAGE OF AN INCH OF RAINFALL LATE SUNDAY INTO MONDAY. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...FROST ADVISORY UNTIL 8 AM EDT THURSDAY FOR CTZ009. FREEZE WARNING UNTIL 8 AM EDT THURSDAY FOR CTZ005>008-010>012. NY...FROST ADVISORY UNTIL 8 AM EDT THURSDAY FOR NYZ069-070-079-081. FREEZE WARNING UNTIL 8 AM EDT THURSDAY FOR NYZ067-068. NJ...FROST ADVISORY UNTIL 8 AM EDT THURSDAY FOR NJZ002-103. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/DS NEAR TERM...JC/GOODMAN SHORT TERM...GOODMAN LONG TERM...DS AVIATION...24 MARINE...GOODMAN/DS HYDROLOGY...GOODMAN/DS

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