Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270841 AFDOKX Area Forecast Discussion National Weather Service New York NY 441 AM EDT Tue Sep 27 2016 .SYNOPSIS...
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A weakening cold front moves through this morning and stalls just offshore this afternoon. This boundary remains in the vicinity during Wednesday while weak high pressure builds in from the north. Then, low pressure over the Ohio Valley and Mid Atlantic states will meander about this region into the weekend bringing an extended period of unsettled weather. The low will gradually lift through New England early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... Showers shift east across the CWA this morning with a weakening cold front. Clouds then diminish behind the front west to east. High temperatures will be near normal but perhaps slightly above normal for the western half of the CWA where clouds will diminish earlier. There is a moderate risk of rip current development at the ocean beaches for Today. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Looks like the frontal boundary will remain not too far offshore tonight and may begin to drift back towards the CWA by late. High pressure will also be building in from the northeast late at night into Wednesday. This ridging will limit moisture to the low levels. Isentropic lift pushing in from the east could supply enough lift for light rain or drizzle with the best overall chances appearing to be Wednesday afternoon. Will go with slight chc pops tonight, but only over the twin forks region...and then expand pops westward during Wendesday, but capping them at chance. Temperatures are a blend of Superblend, MAV and MET MOS. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... NWP guidance and ensembles are in good agreement with the overall H5 pattern across North America through the first half of the weekend...then solutions begin to diverge with the next trough/cutoff low entering the PacNW although this should not impact the local area until early next week. The long term period starts with cutoff low pres over the Ohio Valley trapped between ridging to the east and west. This will result in the system meandering about this area into the weekend before the ridge to the east finally begins to break down allowing it to track through the eastern Great Lakes and New England early next week. Confidence decreases in the finer details...although a frontal boundary extending from the sfc low in combination with strengthening isentropic lift will result in much needed overrunning rainfall Wed night into Fri morning. While the periods of heavier rainfall remain uncertain there is a signal that Thu night could be one timeframe where heavier pcpn does occur with mid level vort energy passing through. Unsettled pattern will continue into the weekend with abundant cloud cover and perhaps a transition to more showery pcpn with mid level ridging trying to build in from the east. Moisture transport will still be originating from the Gulf of Mexico under this pattern. Warm front may push through on Sun as the system begins to lift through the Great Lakes. This will also push the heaviest rainfall to the north as well...resulting in decreasing PoPs through Mon. The EC remains the western outlier...hanging tough with this soln for the past 3 runs...although it has moved somewhat closer to consensus. Based on the location of the system...heaviest rainfall is expected to fall west of the area. See hydro section for more information on expected totals locally. Removed thunder as the lower heights associated with the deep low are too far west...thus it remains too warm aloft for any elevated instability. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/...
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A cold front moves east of the terminals this morning, and then lingers just offshore tonight. MVFR with some pockets of IFR continue through day break. SHRA will end at city terminals around 11z, KISP and BDR around 13z, and KGON around 15z. Ceilings gradually improve to VFR from west to east 14z to 18z. Winds veer to the SW early this morning and then the W-WNW behind the cold front in the morning. The flow then backs to the S-SW in the afternoon around 10 kt. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http://www.weather.gov/zny/n90 KJFK TAF Comments: -SHRA may end by 10z. MVFR ceiling could persist an hour or two longer than indicated in TAF. KLGA TAF Comments: -SHRA may end by 10z. MVFR ceiling could persist an hour or two longer than indicated in TAF. KEWR TAF Comments: -SHRA may end shortly after 09z. MVFR ceiling could persist an hour or two longer than indicated in TAF. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: -SHRA may end shortly after 09z. MVFR ceiling could persist an hour or two longer than indicated in TAF. KHPN TAF Comments: IFR should improve to MVFR when -SHRA ends. MVFR could persist an hour or two longer than indicated in TAF. KISP TAF Comments: Brief IFR through around 10z. -SHRA may end closer to 11-12z. MVFR may improve to VFR a few hours earlier than in TAF. .Outlook for 06Z Wednesday through Saturday... .TUE NIGHT-WED...VFR. .THU-SAT...Potential IFR/MVFR in showers. NE winds 15-20 kt with gusts 25-30 kt possible THU-FRI.
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&& .MARINE... Wind gusts on the non-ocean waters have been falling short of advisory criteria and are not expected to strengthen much if any, so have cancelled the SCA for these areas. On the ocean, marginal advisory criteria conditions are expected today. Changes were made east of Fire Island Inlet to shorten the SCA by a few hours based on guidance and trends. Sub-sca conds then prevail tonight, then the pressure gradient tightens on Wednesday with increasing winds. Will probably need another SCA for some of the waters, but with the current headline up, will wait before posting any headlines for that period. SCA conditions all waters Wed night through at least Thu night due to a tight pres gradient across the waters. There still remains a low probability of marginal gale force gusts during this time...thus will continue the mention in the HWO. It may only be confined to the ocean waters however. The GFS is indicating gusts into the 40`s but feel this is overdone. NAM looks more reasonable...but perhaps a tad light. Have used a compromise of the 2 weighted more towards the NAM. Winds subside on Fri as the gradient weakens...although seas on the ocean will remain elevated...possibly into Sat. && .HYDROLOGY... Between 1/4 to 1/2 inch of rain is expected through this morning. No hydrologic impacts are expected at this time other than typical urban ponding. The proximity of a low pressure system late in the week looks to be too far west at the current time for the local area to fall in the axis of heaviest QPF. Currently between 1/2 and 1 1/2 inches of rainfall is forecast between Wed night through Sat. This is not expected to cause any hydrologic impacts. && .TIDES/COASTAL FLOODING... A persistent moderate easterly flow during mid to late week may combine with increasing astronomical high tides associated with the new moon on Friday to cause minor to locally moderate coastal flooding late this week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until noon EDT today for ANZ355. Small Craft Advisory until 8 PM EDT this evening for ANZ350. Small Craft Advisory until 2 PM EDT this afternoon for ANZ353. && $$ SYNOPSIS...JC/24 NEAR TERM...JC SHORT TERM...JC LONG TERM...24 AVIATION...DS MARINE...JC/24 HYDROLOGY...JC/24 TIDES/COASTAL FLOODING...

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