Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 152004 CCA AFDOKX Area Forecast Discussion...CORRECTED National Weather Service New York NY 404 PM EDT Thu Mar 15 2018 .SYNOPSIS... A few surface troughs moves across the area through Friday night. A cold front approaches Saturday morning, then moves through the region Saturday afternoon. High pressure then builds down from southern Canada into early next week. A complex low pressure system then affects the region from Tuesday through the middle of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A 700-500 hPa shortwave crosses the area through around 3z with its associated vorticity maxima passing to the S of the area. As a result expect any measurable precipitation to be limited mainly to NE NJ and NYC with this feature. Should see a mix of rain and snow showers transition to snow showers after the sunsets. Could see up to a few tenths of an inch of accumulation in spots across NE NJ and mainly S portions of NYC. Elsewhere it should be mainly dry through early evening, however cannot rule out a stray sprinkle or flurry early mainly over the SW 1/2 of the CWA. Otherwise, with no other shortwaves progged to move through on NW flow aloft, it should be dry tonight with decreasing cloud cover, as the area remains at the base of a large cutoff low centered over the western Canadian Maritime Provinces. Lows tonight should be from a few to up to around 5 degrees below normal. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Another 700-500 hPa shortwave trough passes tomorrow, but with the low-mid levels progged to be a bit drier than today, it should remain dry. It will be blustery tomorrow with highs only in the 30s (maybe reaching 40 in urban NE NJ) - this is around 10 degrees below normal. With the winds (NW gusting 25-35 mph) afternoon wind chills will be in the 20s across the area. Winds slacken Friday evening as 700-500 hPa shortwave ridging builds over the area. Should have a mainly clear to clear sky. If winds decouple overnight, could see decent radiational cooling outside of urban areas. For now, just shaded the forecast towards the coldest guidance at any given location, so forecasting lows around 5-10 degrees below normal. && .LONG TERM /SATURDAY THROUGH THURSDAY/... A cold front passes through Saturday afternoon with limited moisture, so expecting a dry and breezy day. High temperatures are expected to be a few degrees below normal with the help of cyclonic flow aloft. The upper flow then becomes a little more zonal on Sunday and surface high pressure will build in from the NW. The mixing depth will be more shallow versus Saturday along with a fresh cold airmass, so high temperatures once again will end up below normal. The ridge axis of this high pressure system then shifts over us Sunday night and then moves slowly offshore through Monday. Dry weather with below-normal temperatures should continue through this period. There`s uncertainty regarding the evolution and track of the next storm system that would potentially have some impacts on our weather during the mid-week period. The uncertainty stems from how 3 or 4 pieces of energy aloft interact as they approach the east coast and how they will ultimately influence the surface low(s). Although global models are at least beginning to converge on a time period when this may affect us, the other details probably won`t come into better focus for at least another few days when these pieces of energy are better sampled for model input. Will therefore cap PoPs at 50% at this point for this potential which is still 5-6 days away. So far it appears the most likely time for PCPN is Tuesday night through Wednesday. Looks like the PCPN type forecast will be a challenge once again. Favoring accumulating snow will nighttime hours and high pressure in a position to our NW suppling cold air. Working against it among others are daytime hours with the sun angle this time of the year and potential extended periods of E to ENE winds. Will keep things simple for now with snow, rain and a mix of the two types. Other potential impacts are coastal flooding and strong winds. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... An upper level trough moves across the area this evening as low pressure continues to spins over the Canadian Maritimes and high pressure builds to the west. Gusty westerly flow will continue through much of today, with gusts 20-25 kt. Winds will be just south of west today, especially for KEWR and KTEB. Winds subside into the early evening with approaching trough/disturbance, however gusts may not completely come to an end. Scattered rain/snow showers are expected to move across the area late this afternoon/early evening across the NYC terminals. Winds will increase Friday morning with tightening pressure gradient on WNW flow. Winds on Friday will be from the W-NW with gusts between 25-30kt. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: Wind gusts will continue through the evening, but may become occasional at times. KLGA TAF Comments: Wind gusts will continue through the evening, but may become occasional at times. KEWR TAF Comments: Wind gusts will continue through the evening, but may become occasional at times. KTEB TAF Comments: Wind gusts will continue through the evening, but may become occasional at times. KHPN TAF Comments: Wind gusts will continue through the evening, but may become occasional at times. KISP TAF Comments: Wind gusts will continue through the evening, but may become occasional at times. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .Friday afternoon/night...VFR with NW gusts 25-30KT. .Saturday...VFR with NW gusts around 20-25KT early. .Saturday night-Monday night...VFR. .Tue...Sub-VFR possible in rain/snow. Gusty E-NE flow. && .MARINE...
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Frequent wind gusts are no longer reaching Small Craft Advisory (SCA) levels across NY Harbor, W Long Island Sound and the S Shore Bays of Long Island, so have cancelled the remainder of the SCA there. On the remainder of the waters expect SCA conditions to continue tonight. Winds increase on Friday, with gale gusts probable on the coastal ocean waters (continuing through Friday evening) and gusts to SCA levels on the non- ocean waters, with these gusts continuing through Friday night. As a result have issued a Gale Watch for Friday and Friday evening for the coastal ocean waters. Also a SCA was issued for NY Harbor, W Long Island Sound and the S Shore Bays of Long Island for Friday and Friday night, and the existing SCA was extended on the remainder of the waters through Friday night as well. These gusty NW-W winds will also create negative tidal departures through Friday night. While it appears that water levels will stay above the -1.8 ft below MLLW benchmark, it appears they will fall off to around -1 to -1.5 ft below MLLW during low tide tonight and Friday morning. There`s a good chance that SCA conds continue into Saturday for most of the waters during Saturday with gusty W winds. Winds and seas then subside Saturday night with SCA conds still possible for a time on the ocean waters east of Fire Island Inlet. A period of tranquil conditions then follows for Sunday and Monday with a ridge of high pressure approaching and passing through. Winds and seas then increase on Tuesday with the approach of low pressure.
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&& .HYDROLOGY... With less than a tenth of an inch of precipitation expected through Monday night, no significant hydrologic impacts are anticipated through then. There is the potential for a period or periods of moderate to heavy precipitation from Tuesday through Thursday. Predictability of any hydrologic impacts is low at this time. && .TIDES/COASTAL FLOODING... There is the potential for a prolonged period of E-NE flow from Monday Night into Wednesday Night. Tidal departures of generally only 1 to 1 1/2 ft are needed for minor flooding for many locations during this time, and 2 to 3 ft for moderate. Depending on the exact track/strength of a coastal low or lows during this time frame, there is the potential for at least minor coastal impacts, but predictability on any details is low at timeframe. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 6 AM Friday to 6 AM EDT Saturday for ANZ335-338-345. Small Craft Advisory until 6 AM EDT Saturday for ANZ330-340. Gale Watch from Friday morning through late Friday night for ANZ350-353-355. Small Craft Advisory until 6 AM EDT Friday for ANZ350-353-355. && $$ SYNOPSIS...JC/Maloit NEAR TERM...Maloit SHORT TERM...Maloit LONG TERM...JC AVIATION...BC MARINE...JC/Maloit HYDROLOGY...JC/Maloit TIDES/COASTAL FLOODING... EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.