Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 170522 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 122 AM EDT WED SEP 17 2014 .SYNOPSIS... HIGH PRESSURE BUILDS IN FROM THE WEST AND GETS REINFORCED WEDNESDAY NIGHT AND THURSDAY...STAYING ACROSS THE REGION THROUGH FRIDAY NIGHT. HIGH PRESSURE MOVES OFFSHORE FOR THE WEEKEND WITH A COLD FRONT APPROACHING THE BEGINNING OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPDATES MADE TO INCLUDE PATCHY FOG ACROSS EASTERN LONG ISLAND AND LOWERING THE LOW TEMPS A LITTLE OVER THE PINE BARRENS REGION. SOME OF THIS FOG MAY DISSIPATE OR AT LEAST THIN OUT AT TIMES AS SOME MID LEVEL CLOUDS PASS THROUGH. REST OF THE FORECAST PRETTY MUCH ON TRACK. HIGH PRESSURE AT THE SURFACE BUILDS IN FROM THE WEST TONIGHT... GIVING THE REGION MORE OF A NORTHERLY FLOW. THIS WILL ADVECT IN COOLER...DRIER AIR. RADIATIONAL COOLING WILL BE SOMEWHAT EFFICIENT AS WELL. THEREFORE...PREFERRED LOWER MAV GUIDANCE COMPARED TO MET GUIDANCE FOR LOWS...WHICH ARE FORECAST TO RANGE FROM THE LOWER 40S TO UPPER 50S...LOWEST FOR RURAL INTERIOR SECTIONS AND HIGHEST NEAR NYC. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... OVERALL...SUBTROPICAL JET WILL STILL BE SOUTH OF THE AREA. THE OVERALL TROUGH IN THE MID TO UPPER LEVEL WILL BECOME ONE OF DECREASED WAVELENGTH...INDICATING A SHARPENING OF THE TROUGH AND THIS WILL HELP USHER IN A STRONGER HIGH PRESSURE AREA BY WEDNESDAY NIGHT FROM SOUTH CENTRAL CANADA. ONE SURFACE HIGH PRESSURE WEAKENS AS IT CENTERS OVER THE REGION WEDNESDAY. THE FLOW ALOFT WILL BECOME LIGHTER WITH THE GEOPOTENTIAL HEIGHT GRADIENT DECREASE AND SURFACE PRESSURE GRADIENT DECREASING AS WELL. LIGHT WINDS AT THE SURFACE SHOULD EASILY GIVE WAY TO SEA BREEZE CIRCULATIONS AS LAND TEMPERATURES EXCEED SEA SURFACE TEMPERATURES. NOT EXPECTING SUBSIDENCE TO BE THAT STRONG...SO THINKING THAT SOME DIURNAL CU WILL DEVELOP AGAIN LATER IN THE AFTERNOON. MAX TEMPS WERE A BLEND OF NAM12 AND GMOS...WITH SLIGHTLY COOLER READING ALONG THE COAST BUT OVERALL MOSTLY LOWER 70S. DRY CONDITIONS WITH CLEARING SKIES EXPECTED AGAIN WEDNESDAY NIGHT AS A STRONGER CANADIAN HIGH PRESSURE AREA STARTS TO BUILD SOUTHEAST CLOSER TO OUR REGION. THIS WILL ESSENTIALLY REINFORCE HIGH PRESSURE ACROSS THE LOCAL REGION. USED A BLEND OF 3/4 MET AND 1/4 MAV GUIDANCE FOR LOWS. AGAIN EXPECTING COLD AIR ADVECTION AND RADIATIONAL COOLING TO CONTRIBUTE. THERE IS A MODERATE RISK OF RIP CURRENT DEVELOPMENT AT THE ATLANTIC BEACHES ON WED. THIS MAY INCREASE TO A HIGH RISK LATE IN THE DAY DUE TO SWELLS FROM TROPICAL CYCLONE EDOUARD...SITUATED WELL OUT TO SEA. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... GENERALLY DECENT AGREEMENT AMONG THE 12Z MODEL SUITE WITH SYNOPTIC FEATURES HEADING INTO THIS WEEKEND...WITH DIVERGING SOLUTIONS ON THE HANDLING OF THE APPROACHING COLD FRONT. WEAK SFC LOW TREKS THROUGH SOUTHERN CANADA EARLY THURS...WITH ASSOCIATED COLD FRONT TRAILING ACROSS NEW ENGLAND. BUILDING SURFACE HIGH TRAVERSES THE REGION FROM THE GREAT LAKES REGION THROUGH THE NORTHEAST THURS INTO THE COMING WEEKEND. ALOFT...MID LEVEL TROUGH SWINGS THROUGH THURS/FRI...WITH ZONAL FLOW TAKING HOLD THROUGH THE REMAINDER OF THE WEEKEND. MULTIPLE WEAK SHORTWAVES EMBEDDED WITH THE FLOW ALOFT WILL PUSH THROUGH DURING THIS TIME...BUT OVERALL WEAK DYNAMICS COMBINED WITH MINIMAL MOISTURE SHOULD RESULT IN A PREDOMINATELY DRY FORECAST. NAM AND GFS HINT AT AFTN DEVELOPMENT THURS CORRESPONDING WITH THE PASSAGE OF THE STRONGEST WAVE...BUT CONFIDENCE IS TOO LOW TO INCLUDE POP MENTION AT THIS TIME. SUBSIDENCE BUILDING IN ALOFT SHOULD AID IN KEEPING MOSTLY SUNNY CONDITIONS FRIDAY. FOR THE WEEKEND...ZONAL FLOW BEGINS TO WEAKEN BY SAT WITH THE NEXT TROUGH DIPPING SOUTH ACROSS THE NORTH PLAINS. SURFACE HIGH PUSHES OFFSHORE AS THE LOW PRESSURE SYSTEM LIFTS INTO THE GREAT LAKES REGION...PLACING THE NORTHEAST INTO THE WARM SECTOR BY SUNDAY. TIMING AND STRENGTH DIFFERENCES...WITH THE 12Z GFS SOLUTION A MORE POTENT SOLUTION SUN/MON...THEN ALIGNING ONCE AGAIN WITH THE ECMWF BY TUES. CMC LOOKS TO DEEPEN TOO MUCH/TOO QUICKLY SO SIDED MORE TO A COMPROMISE OF THE GFS/ECMWF FOR NOW. AS SUCH...SWING THE COLD FRONT THROUGH SOMETIME MONDAY-MONDAY NIGHT WITH HIGH PRESSURE BUILDING IN BY TUESDAY. CHC POPS IN FOR MONDAY WITH STILL UNCERTAINTY ON WHEN EXACTLY THE PCPN WILL OCCUR...THOUGH ANTICIPATING IT RIDING THE FRONTAL PASSAGE...WITH THINGS QUICKLY DRYING IN THE WAKE WITH THE HIGH. THURSDAY TEMPS REMAIN NEAR NORMAL. FRIDAY TEMPS BELOW NORMAL WITH A SHOT OF CAA AS THE HIGH BUILDS INTO THE REGION. ALONG WITH THE DIPPING TEMPS...SHOULD SEE DEW PTS DROPPING...WITH SOME INTERIOR REGIONS EVEN DROPPING INTO THE 30S. AT THE MOMENT...FROST DEVELOPMENT LOOKS TO REMAIN NORTH OF THE FORECAST AREA...BUT WILL BE WATCHFUL. TEMPS REBOUND QUICKLY BACK TO NORMAL FOR THE WEEKEND...WITH RISING HEIGHTS ALOFT AND DECENT WAA RIDING THE SOUTHERLY WINDS AS THE HIGH PUSHES OFFSHORE. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE BUILDS INTO THE REGION TODAY. VFR THROUGH THE TAF PERIOD. N/NW WINDS AT 5 KT OR LESS THROUGH MORNING. WINDS WILL BE LIGHT ENOUGH TO CARRY VRB IN THE TAF. NORTH WINDS INCREASE TO 5-7 KT AFTER 12-14Z. SEA BREEZES WILL SHIFT WINDS TO THE SOUTH AROUND 5 TO 10 KT IN THE AFTERNOON. THEN WINDS LIGHTEN ONCE AGAIN BY EVENING. .OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY... .THURSDAY-SUNDAY...VFR. && .MARINE... LOWERED OCEAN SEA HEIGHTS FOR THE OVERNIGHT PERIOD BASED ON OBS AND TRENDS. OTHERWISE...A CONTINUANCE OF SUB SCA CONDITIONS ARE EXPECTED WITH A WEAK PRESSURE GRADIENT IN PLACE. HOWEVER...SWELLS FROM EDOUARD WILL BUILD OCEAN SEAS THROUGH WEDNESDAY NIGHT. LEANED CLOSER TO THE NORTH ATLANTIC HURRICANE MODEL GUIDANCE AND NOT WAVEWATCH...SO NOT GOING WITH SCA AT THIS TIME AND LIMITED OCEAN SEAS TO 4 FT. SUB-SCA CONDITIONS THURSDAY WITH WEAK OFFSHORE FLOW AND ANY SWELLS FROM EDOUARD DECREASING. INCREASING NE FLOW FRIDAY SHOULD AID IN PUSHING SEAS TO 5-6 FT ON THE OCEAN INTO THE WEEKEND. OCNL GUSTS TO 25 KT PSBL AS WELL DURING THIS TIME ON THE OCEAN. CONDITIONS DIMINISH BACK DOWN TO SUB-SCA EVERYWHERE BY SAT AND REMAIN AS SUCH HEADING INTO NEXT WEEK. && .HYDROLOGY... NO SIGNIFICANT PRECIPITATION RESULTING IN HYDROLOGIC ISSUES IS EXPECTED THROUGH THIS WEEKEND. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JM/SEARS NEAR TERM...JC/JM/DW SHORT TERM...JM/DW LONG TERM...SEARS AVIATION...PW MARINE...JC/JM/SEARS HYDROLOGY...JM/SEARS

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