Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250251 AFDOKX Area Forecast Discussion National Weather Service New York NY 951 PM EST Fri Feb 24 2017 .SYNOPSIS... As high pressure moves out to sea, a cold front will approach late Saturday, then sweep east across the area Saturday evening. High pressure will then build in through Sunday, and pass east Sunday night into Monday. A warm front will move through Tuesday into Tuesday night, followed by an approaching cold front on Wednesday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... South winds continue to transport unusually mild and moist air north across the area as high pressure moves out to sea. The latest loop of 11-3.9 micron sat imagery shows multiple areas of BKN low level stratus clouds advecting north and rapidly expanding north and east mainly east of the Hudson River through 0230z. Dense fog developed at KGON with a vsby of 1/4 mile and KJFK was reporting 1/2 mile in fog. Look for this trend to continue with expansion occurring west of the Hudson River by midnight. We continue to monitor for the development of widespread dense fog. Confidence is not high enough for widespread dense fog at this time. Stay tuned. Otherwise, lows tonight should be fairly uniform in the upper 40s and lower 50s, unusually mild for late February. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Expect the fog to hang on into at least Sat morning, then lift, except perhaps along the immediate coast Sat afternoon. Once the fog and clouds break expect another mild day, with highs in the upper 50s and 60s. Chances for showers and a few tstms will increase in the afternoon and evening as the cold front approaches and passes through, mainly from NYC north and west. Any storms could produce a brief downpour and gusty winds mainly in this area, where instability, while marginal would be more likely to be surface- based. Highs on Sat could be a few degrees cooler than fcst if fog and low clouds continue into Sat afternoon. This would make most of the instability elevated in nature except perhaps right with cold frontal passage itself. With some model guidance showing a good push of westerly winds right behind the front and low level thermal profiles going quickly dry adiabatic, this could be a situation where convection right along the front could produce strong winds even out over the more stable marine layer to the east. Gusty NW flow and cold/dry air advection later Sat night, with precip chances waning and lows in the 30s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Zonal flow aloft Sunday, with the center of high pressure over the Tennessee Valley. Northwest flow will usher in a colder air mass, allowing temperatures to come down to near normal levels for this time of year. The high quickly pushes off the Mid-Atlantic Coast Sunday night, allowing for weak warm air advection to begin and continue into Monday. Highs will once again be above normal, in the upper 40s to lower 50s across the entire area. A warm front approaches the area Monday night into Tuesday. Overrunning moisture out ahead of the front will give the area increasing chances for precipitation beginning late Monday night for western portions, then for the entire area Tuesday morning as the front continues its approach. Temperature profiles look to warm for any frozen or freezing precipitation, except may be a brief period of mixed rain and snow showers for northern Orange County. Models differ on placement and timing of the warm front, this also leads to differences in where the axis of heavier precipitation will be. Both the 12Z ECMWF and the 12Z GFS develop a low along this frontal boundary, however, the ECMWF is quicker to develop this low, and thus has an axis of heavier precipitation over the tri-state, while the GFS is slower and shunts the heaviest precipitation to the north. The area will be warm sectored Tuesday, allowing the warm advection to continue. Highs will continue to be above normal, upper 40s to middle 50s. Cooler conditions along the shore with southerly winds off the relatively cool ocean waters. There may be a brief respite in precipitation for the area late Tuesday night as any forcing associated with the warm front lifts north with the front, though there remains a slight chance for a shower. Another round of showers is expected with a cold front approaching Wednesday and moving through Wednesday night. Temperatures continue to warm out ahead of the approaching cold front. Highs on Wednesday will be in the 50s for much of the region. Some upper 50s for the New York City metro area, while coastal sections will once again remain in the upper 40s to near 50. GFS is too progressive as usual, moving the front through during the day Wednesday. Cooling trend then expected as cooler air moves in behind the front through at the end of the week. By next Friday, temperatures will be below normal. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Weak high pressure remains over the terminals tonight, then a cold front moves through late day/early evening Saturday. Stratus development and advection so far is affecting KJFK/KHPN and points east, bypassing KLGA. Still anticipating an eventual westward expansion. Expecting all terminals to eventually lower to IFR. Timing of when this occurs at KLGA and points west is uncertain, and TAFs could be off probably in the order of 1-3 hours. Stratus and some fog then remain likely for Saturday morning with IFR, then IFR cigs in the afternoon with late-day early evening showers with possible thunderstorms. .OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY... .SAT NGT...Improving to VFR with a COLD Frontal Passage around 00Z that will included at least SCT Convection. WNW Wind G25 KT after the front. .SUN...VFR. NW WND G25KT .MON...VFR. .TUE...MVFR with areas of IFR in showers. .WED...Improving to VFR. W WND G20KT. && .MARINE... A Dense Fog Advisory remains in effect for all coastal waters until Noon Saturday for VSBY 1 NM or less. A low pressure system off the southeast coast will produce SE swells across the Atlantic Ocean coastal waters with seas above 5 ft. Sat into Sat evening before a strong cold frontal passage. Winds after fropa likely to gust up to 35 kt, therefore a Gale Watch has been issued for Sat night for the ocean waters. This may need to be expanded in area and in time to the remaining waters and into Sunday as well. Winds will diminish Sunday night as low pressure tracks away from the area. Winds then generally remain below 25 kt through Wednesday night. SCA gusts then possible over all waters on Thursday, and then just the ocean waters Thursday night as a low pressure system over the Gulf of Maine intensifies then moves away from the area. Ocean seas will also diminish late Sunday into Sunday night, coming below 5 ft everywhere around sunrise Monday. Thereafter, waves should remain generally below 5 ft through the day Tuesday. Waves build Tuesday night in response to increased southerly flow as a warm front lifts north of the region. Ocean seas up to 5 ft are possible on Wednesday, and could continue to build to 5-7 ft by Thursday morning. Waves diminish in the afternoon as a cold front pushes offshore late Wednesday night, allowing winds to shift to more of an offshore flow. && .HYDROLOGY... Basin avg rainfall of 1/4 to 1/2 inch is likely on Saturday, with local amounts up to double that which could cause associated isolated nuisance ponding. Higher amts NW of NYC. && .CLIMATE... The following are record high minimum temperatures for Saturday February 25, 2017 along with the forecast minimum temperature. Record High Min Temperature Forecast Min ------------------------------ ------------ Central Park........51 (1930) 56 LaGuardia...........49 (1996) 53 Kennedy.............46 (1996) 50 Islip...............47 (1996) 50 Newark..............47 (1996) 53 Bridgeport..........44 (1996) 50 && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Dense Fog Advisory until noon EST Saturday for ANZ330-335-338- 340-345-350-353-355. Small Craft Advisory from 6 PM Saturday to 6 AM EST Sunday for ANZ330-335-338-340-345. Gale Watch from Saturday evening through late Saturday night for ANZ350-353-355. Small Craft Advisory from 6 AM to 6 PM EST Saturday for ANZ353- 355. Small Craft Advisory from noon to 6 PM EST Saturday for ANZ350. && $$ SYNOPSIS...GC/Goodman/JP NEAR TERM...GC SHORT TERM...Goodman LONG TERM...JP AVIATION...JC MARINE...GC/Goodman/JP HYDROLOGY...GC/Goodman/JP CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.