Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 180259 AFDOKX Area Forecast Discussion National Weather Service New York NY 1059 PM EDT Mon Jul 17 2017 .SYNOPSIS... A weak trough remains nearly stationary over the region through Thursday. A cold front passes Friday, followed briefly by high pressure Saturday. A warm front approaches Sunday, and low pressure impacts the area early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Convection has dissipated across the region. However, both the upper and surface troughs move into the area overnight. Some of the high res models, in particular the 3km NAM, fires up convection across the Lower Hudson Valley and southern CT. The HRRR on the other hand is quiet, but has also done poorly with over forecasting convection over NE PA. Have decided to keep low chances overnight with moderate to high instability in place. The other forecast challenge will be any fog/stratus development overnight. Typically, in the warm season, dense fog is not a problem. The greatest chance for fog development will be across eastern CT and far eastern Long Island, with patchy fog possible everywhere outside of the city. Low temperatures will be several degrees above normal.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Although the short wave will move east of the area by Tuesday, a secondary upper low to the southwest and the stalled frontal boundary will likely provide focus for at least isolated showers and thunderstorms through Tuesday night, with the greatest potential north and west of the city. High temperatures will be close to normal, while lows will once again be near to slightly above climatological normals with humid conditions lingering. The potential for fog to redevelop will need to be monitored. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Unsettled weather expected through much of this time frame. Lingering weak trough aloft, along with sfc trough should result in a few showers or thunderstorms Wednesday. Thereafter, the weak upper trough just to our south makes slow progress east Wednesday night and Thursday, with gradually lowering heights over the northeast late in the week and through the weekend as larger upstream trough tracks east. A surface cold front ahead of these lowering heights slowly moves through Friday. Cannot rule out an isolated shower or thunderstorm during this time frame, although drier air in NW flow Friday should result in predominately dry conditions. Thereafter, the weekend forecast remains in question due to differences in handling potential MCS riding along a warm front. At this time, feel Saturday remains dry, although latest ECMWF and Canadian solutions suggest otherwise. Hard to pinpoint these complexes this far out, and will maintain higher probabilities for the latter portion of the weekend as the main low, and front approach. Unsettled weather continues into Monday as a cold front slowly pushes through. Temperatures Wednesday and Thursday look warm, with above normal readings anticipated. By the weekend, the lowering heights should result in closer to normal temps. Potential showers/tstms will also impact temps if they do indeed occur this weekend across the area. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/...
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A weak front remains nearly stationary over the region through Thursday. VFR through the period at the city terminals. However, there is a possibility that fog does develop overnight, bringing vsby down to MVFR conditions. Confidence is not high enough to mention in the TAFS. Outside of the city, expecting MVFR ceilings and visibilities to develop from east to west, beginning around 06Z. The lowest conditions are expected to be at KGON overnight, where IFR cigs and visibilities are possible. VFR conditions then return Tuesday morning as any fog and/or low clouds lift. Southerly flow will become light and variable outside of the city overnight. Winds then return out of the south Tuesday afternoon at 10 kt or less. .OUTLOOK FOR 00Z TUESDAY THROUGH SATURDAY... .Tuesday-Thursday...Chance of showers and thunderstorms, primarily in the late afternoon and from NYC north and west. .Friday-Saturday...VFR.
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&& .MARINE... A very weak pressure gradient over the region will limit winds to 10 kt or less, and keep seas well below SCA levels through Saturday. Any thunderstorms that move across the area waters may produce brief SCA to possibly gale conditions. && .HYDROLOGY...
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There is a low chance for heavy rain/flooding this weekend ahead of a frontal system.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...MD/PW NEAR TERM...MD/DW SHORT TERM...MD LONG TERM...PW AVIATION...CB MARINE...MD/PW HYDROLOGY...MD/PW

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