Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201451 AFDOKX Area Forecast Discussion National Weather Service New York NY 1051 AM EDT Sun May 20 2018 .SYNOPSIS... A cold front slowly crosses the area today. High pressure will briefly build into the region tonight and Monday, before a weak frontal system affects the area from late Monday night into Wednesday. High pressure returns to close out the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Visibilities have improved across the coastal waters, therefore the dense fog adv has been cancelled. Forecast continues to be on track late this morning. Weak shortwave approaches the region late in the day. Meanwhile a stronger northern stream shortwave passes through Quebec today. At the surface, a weak cold front slowly passes through the region this aft/eve. Areas of fog, locally dense, should gradually improve through the morning hours as SW winds begin to pick up. The fog will likely linger longest across coastal SE CT and Eastern LI. A few showers expected as the vort axis moves through this morning, then subsidence in wake of the morning vort axis should allow for some breaks of sun from w to e late this morning into the afternoon. Sct showers and iso tstms are expected to develop along the cold front, to the NW of the NYC metro, in a marginally unstable airmass early this afternoon. This activity should traverse eastward through through the afternoon. Some uncertainty on extent of convective coverage with subsidence in wake of morning convection and late approach of next piece of shortwave energy. With marginally strong deep layer shear, a conditional isolated strong thunderstorm with strong wind gust is possible with if pockets of higher instability develop. Expectation is for convection to weaken as it moves eastward towards the coast in the late aft/eve due to maritime influence. Temperatures today will be above seasonable, well into the 70s, except lower 80s for NYC/NJ metro. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... A couple of shortwaves move east through Quebec tonight, with zonal upper flow developing across the region into Monday. At the surface, high pressure builds into the region through Monday. Clearing conditions expected tonight, with mostly sunny conditions on Sunday. Temps tonight will be near seasonable, with highs on Monday a few degrees above seasonable levels. Highs generally in the mid to upper 70s, except lower 70s across south coasts with afternoon seabreeze development. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The upcoming week looks to be relatively benign with a weak frontal system impacting the area late Monday night into early Wednesday. There are some small timing differences with the global models with both the onset of warm advection rain Monday night and the possibility of scattered convection lingering into Wednesday as the airmass change behind a cold front is subtle. This does not look to be a significant rainfall event. Additionally, while the westerlies and an upper trough will remain across the area through midweek, the instability at this time looks to be only marginal. The second half of the week will feature building heights aloft as the trough works offshore, resulting in dry weather and above normal temperatures. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... A cold front passes late this aftn. MVFR cigs improve to VFR this aftn. Iso/sct shower or TSTM this afternoon mainly after 19/20z. TSTM probability too low to include in TAFs at this time. Will go with VCSH for now. SW winds around 10 kt with gusts up to 20 kt bcmg W this aftn, then finally NW early evening. Winds diminish tonight. .OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY... .Monday...Vfr with light s winds. .Tuesday-Wednesday...Most likely VFR with low chance of MVFR in any shower. S winds G15-20kt possible Tuesday afternoon. .Wednesday night-Thursday...VFR. N-NW winds G15-20KT possible. && .MARINE... Marginal SCA conditions are expected across the coastal ocean waters into tonight, with sub small craft conditions expected elsewhere. A weak gradient is expected Monday through Wednesday, keeping all waters below Small Craft Advisory levels. && .HYDROLOGY... No widespread significant hydrologic issues are anticipated through early next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ350- 353-355. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.