Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KOKX 231804 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 204 PM EDT WED JUL 23 2014 .SYNOPSIS... AS HIGH PRESSURE MOVES EAST OF THE AREA...A COLD FRONT WILL MOVE SLOWLY EAST AND PASS EAST OF THE AREA ON THURSDAY. HIGH PRESSURE WILL FOLLOW FRIDAY THROUGH SATURDAY. WAVES OF LOW PRESSURE THEN PASS NEAR THE REGION SUNDAY INTO MONDAY FOLLOWED BY A COLD FRONT MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FORECAST REMAINS ON TRACK WITH JUST MINOR ADJUSTMENTS TO REFLECT LATEST OBSERVATIONS. SOUTHWEST WINDS BETWEEN A DEPARTING OFFSHORE HIGH PRESSURE SYSTEM AND AN APPROACHING COLD FRONT WILL CONTINUE TO ADVECT WARM MOIST UNSTABLE MARITIME TROPICAL AIR ACROSS THE AREA. HIGH TEMPS IN THE LOWER 90S COMBINED WITH DEW POINTS APPROACHING 70 DEGREES WILL PRODUCE HEAT INDEX VALUES IN THE MID 90S ACROSS URBAN AREAS OF NYC AND NORTHEAST NJ THIS AFTERNOON. BECAUSE A COLD FRONT IS FORECAST TO MOVE SOUTH OF THE AREA THU PRODUCING COOLER TEMPS...WE WILL NOT MEET THE 2 DAY HEAT CRITERIA OF 95 DEGREES AND THEREFORE WILL NOT ISSUE A HEAT ADVISORY FOR NYC. BECAUSE BOTH SFC AND LOW LEVEL BASED INSTABILITY WILL BE INCREASING ALONG AND AHEAD OF A DEVELOPING PRE FRONTAL TROUGH...THERE WILL BE AN INCREASING POTENTIAL FOR SEVERE TSTMS...MAINLY WEST AND NORTH OF NY AFT 19Z. WITH A FCST MEAN STORM MOTION OF 230 DEGREES AT 15 KTS...CAN NOT RULE OUT TRAINING OF STORMS ACROSS THE SAME AREA WITH AN ADDED POTENTIAL FOR ISOLATED FLASH FLOODING. THERE IS A MODERATE RISK OF RIP CURRENTS...MAINLY THIS AFTERNOON THROUGH EVENING WITH ENHANCED SEA BREEZE DEVELOPMENT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... TONIGHT...SHOWERS AND TSTMS WILL GRADUALLY WEAKEN AS THEY MOVE INTO A MORE STABLE MARINE ENVIRONMENT IN PLACE ACROSS LONG ISLAND AND SOUTHERN CT. THURSDAY...WITH MOST MODELS FORMING A WAVE OF LOW PRESSURE ALONG THE SAGGING BOUNDARY...LOOK FOR THE REDEVELOPMENT OF A STRATIFORM RAIN SHIELD WITH EMBEDDED CONVECTION FOCUSED ACROSS THE COASTAL AREA THROUGH AT LEAST THE EARLY AFTERNOON HOURS. THE LATEST RAINFALL AMOUNTS MIGHT BE UNDER ESTIMATED. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... THE PERIOD BEGINS WITH THE COLD FRONT SLOWLY MAKING ITS WAY FARTHER TO OUR E/SE. AS SUCH...POPS WILL CONTINUE DIMINISHING WITH ALL AREAS DRY BY LATE THURSDAY NIGHT. HIGH PRESSURE BUILDS ACROSS THE AREA FOR FRIDAY...YIELDING DRY WEATHER AND TEMPS NEAR TO A COUPLE DEGREES BELOW SEASONAL NORMS. SATURDAY WILL SEE SIMILAR TEMPERATURES WITH MOISTURE STARTING TO INCREASE ACROSS THE AREA ONCE AGAIN. ZONAL FLOW WILL BE PRESENT ALOFT...AND WITH A SUBTLE/WEAK SHORTWAVE PASSING NEAR THE AREA...CONTINUED WITH SLIGHT CHANCE POPS ACROSS WESTERN PORTIONS OF THE CWA. WEAK FORCING WILL LEAD TO MOST SPOTS STAYING DRY THOUGH. THE UPPER-LEVEL PATTERN ACROSS THE CONUS REALLY STARTS TO AMPLIFY SATURDAY NIGHT INTO SUNDAY...AS A STOUT SHORTWAVE DROPS OUT OF THE SOUTHERN CANADIAN PRAIRIES AND INTO THE MIDWEST. AS IT PROPAGATES AROUND THE UPPER LOW CENTERED ACROSS NORTHERN QUEBEC...A DEEP TROUGH WILL BE CARVED OUT ACROSS THE EASTERN US. THIS WILL SET THE STAGE FOR A PERIOD OF UNSETTLED WEATHER SUNDAY INTO MONDAY...AS STRENGTHENING JET DYNAMICS ALOFT ALLOW FOR A COUPLE WAVES OF LOW PRESSURE TO PASS NW OF THE AREA. WITH INCREASING SOUTHERLY FLOW/MOISTURE ACROSS THE AREA...SHOWERS AND STORMS WILL BECOME MORE LIKELY. STILL...SIGNIFICANT TIMING DIFFERENCES EXIST IN THE PASSAGE OF SHORTWAVES/BETTER DYNAMICS ALOFT...WHICH LEADS TO CONTINUED UNCERTAINTY IN THE TIMING OF MORE WIDESPREAD PRECIPITATION. WILL GO WITH HIGHER-END CHANCE POPS SUNDAY THROUGH MONDAY AS A RESULT. THE ATTENDANT SURFACE COLD FRONT THEN LOOKS TO PUSH THROUGH MONDAY NIGHT INTO TUESDAY...WITH CONDITIONS SLOWLY DRYING OUT. THERE IS A GOOD AMOUNT OF UNCERTAINTY WITH THE FRONTAL TIMING AS WELL...AS THE 23/00Z ECMWF SHOWS IT STALLING ACROSS THE AREA WITH PRECIP LINGERING ACROSS EASTERN AREAS INTO TUESDAY NIGHT. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG A PRE-FRONTAL TROUGH AHEAD OF A COLD FRONT APPROACHING FROM THE WEST THIS AFTERNOON. THE BULK OF THE SHOWERS/TSTMS WILL HOLD OFF UNTIL AFTER 00Z...WHEN THE COLD FRONT BEGINS TO MOVE ACROSS THE TERMINALS FROM WEST TO EAST. WILL TEMPO TSRA FROM 00-04Z AND CARRY A PROB30 GROUP FOR TSRA FROM 04-08Z. WILL EXPECT BRIEF PERIODS OF MVFR...POSSIBLY LOWER...IN HEAVY RAIN REDUCING VSBY. CAN ALSO EXPECT BRIEF GUSTS TO 30 KT IN TSRA. THE BULK OF THE ACTIVITY WILL END BY 08Z...AND CONDS WILL LIFT TO VFR. SOUTH WINDS GENERALLY 10-20 KT FOR THE REST OF THE AFTERNOON. WINDS THEN VEER TO THE WSW IMMEDIATELY BEHIND THE COLD FRONT...AND THEN WINDS SHIFT TO THE NORTH AT 8-12 KT LATE TONIGHT AND INTO THURSDAY MORNING. ...NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: MODERATE CHANCE OF OCCASIONAL GUSTS OF 20-25 KT WITH SEABREEZE THIS AFTERNOON. ISOLD SHRA/TSTM POSSIBLE 19-23Z. KLGA FCSTER COMMENTS: MODERATE CHANCE OF OCCASIONAL GUSTS OF 20-25 KT WITH SEABREEZE THIS AFTERNOON. SCT SHRA/TSTM POSSIBLE 19-23Z. KEWR FCSTER COMMENTS: MODERATE CHANCE OF OCCASIONAL GUSTS OF 15-20 KT WITH SEABREEZE THIS AFTERNOON. SCT SHRA/TSTM POSSIBLE 19-23Z. KTEB FCSTER COMMENTS: SCT SHRA/TSTM POSSIBLE 19-23Z. KHPN FCSTER COMMENTS: SCT SHRA/TSTM POSSIBLE 19-23Z. KISP FCSTER COMMENTS: MODERATE CHANCE OF OCCASIONAL GUSTS OF 20-25 KT WITH SEABREEZE THIS AFTERNOON. ISOLD SHRA/TSTM POSSIBLE 23-03Z. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .THURSDAY AFTERNOON....VFR WITH NORTH WINDS 8-12 KT. .THURSDAY NIGHT-SATURDAY MORNING...VFR. .SATURDAY AFTERNOON...MVFR OR LOWER POSSIBLE IN ISOLD SHRA/TSTM MAINLY NW OF NYC. .SATURDAY NIGHT-MONDAY...CHANCE OF SHRA/TSTMS WITH MVFR OR LOWER POSSIBLE. && .MARINE... THIS AFTERNOON THROUGH THIS EVENING...WINDS AND SEAS WILL APPROACH SMALL CRAFT ADVISORY LEVELS OF 25 KNOTS AND 5 FEET AS A COLD FRONT MOVES EAST TOWARD THE AREA. SOUTHWEST WINDS WILL INCREASE TO 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS DURING THIS TIME. ISOLATED WIND GUSTS UP TO 25 KNOTS CAN NOT BE RULED OUT. GUSTY WINDS ARE ALSO POSSIBLE IN AND AROUND TSTMS MAINLY FROM SANDY HOOK NJ EAST ACROSS THE COASTAL WATERS DURING THIS TIME. SATURDAY NIGHT THROUGH SUNDAY...INCREASING SOUTH WINDS AND BUILDING SEAS WILL ONCE AGAIN APPROACH SMALL CRAFT ADVISORY LEVELS WITH THE APPROACH OF LOW PRESSURE. OTHERWISE...WINDS AND SEAS WILL REMAIN TRANQUIL. && .HYDROLOGY... THIS AFTERNOON THROUGH THURSDAY...1/4 TO 1/2 INCH OF RAIN IS FORECAST WITH THE APPROACH OF A COLD FRONT. AS THE PRECIPITABLE WATER CONTENT INCREASES TO AROUND 2 INCHES...BASED ON A SLOW MEAN FLOW OF AROUND 15 KNOTS...A FEW STORMS MIGHT MOVE ACROSS TH SAME AREA AND PRODUCE FLASH FLOODING WITH ISOLATED AMOUNTS OF 1.0 TO 1.5 INCHES. WAVES OF LOW PRESSURE PASSING NEAR THE AREA SUNDAY INTO MONDAY HAVE THE POTENTIAL TO PRODUCE SHOWERS AND STORMS CAPABLE OF HEAVY RAIN. BECAUSE SIGNIFICANT UNCERTAINTY STILL EXISTS WITH THE TIMING AND AMOUNTS...THIS HEAVY RAIN POTENTIAL WILL NOT BE INCLUDED IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GC/PICCA NEAR TERM...BC/GC/PICCA SHORT TERM...GC LONG TERM...PICCA AVIATION...MPS MARINE...GC/PICCA HYDROLOGY...GC/PICCA

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.