Area Forecast Discussion
Issued by NWS Upton, NY

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991 FXUS61 KOKX 200535 AFDOKX Area Forecast Discussion National Weather Service New York NY 1235 AM EST Tue Feb 20 2018 .SYNOPSIS... High pressure remains anchored over the western Atlantic through mid week as a slow moving frontal system approaches from the Mississippi Valley. The associated warm front will work north across the area this evening. A cold front moves across Wednesday night. A series of lows will be moving through the Northeast late this week into the weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... A dense fog advisory has been issued for the entire area until 15z Tuesday. Visibilities are deteriorating this evening and the trend is expected to continue into the overnight. The NARRE-TL shows a 90 to 100 percent chance at seeing visibilities less than 1/4 mile across at least the southern portion of the CWA into the overnight. An unseasonably mild and moist air mass is place and will only see dew points gradually climb into the early morning hours. A warm front moving into the region and light winds should also aid in dense fog development. This supports the latest thinking for dense fog development across the region. Much of the light rain from earlier this evening has moved to the east. There may be patchy drizzle at times, but no widespread rain is anticipated for the rest of the night. Temperatures will remain steady if not slowly rise overnight. Lows will be about 15 to 20 degrees above normal, in the 40s. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... Dense fog expected to continue into the morning, but gradual improvement is expected after 15z. There may also be some patchy drizzle. Otherwise, low clouds, and patchy fog should give way to some clearing in the afternoon as some warmer, drier air mixes down from aloft. The high res NAM (3km) maintains a strong low-level inversion across the area and maintains saturated low-levels for all but the far interior. This is likely overdone based on past performance and the preference is to go with some improvement. The most uncertainty is near and along the coast where at least patchy fog and low clouds could hang on into the afternoon. We will be in a near record warm pattern as an anomalously strong upper ridge over the western Atlantic strengthens through mid week. At the same time, a slow moving frontal system associated with an upper trough over the western states work east from the Mississippi Valley. This will place the region in a warm, deep- layered SW flow. Temperatures in this type of airmass will also be tricky with an onshore flow keeping coastal areas much cooler than the interior, where highs will be near record levels. Preference was toward the a MET/MAV MOS along the coast, and the warmer MAV across the interior. Some interior locations will approach 70. Areas of fog and drizzle are likely to develop Tuesday night in the warm, moist airmass, as dew points get into the lower 50s. This will be due to both an advection fog off the cooler marine waters, and radiation fog inland where the SW flow becomes light. Lows Tuesday night will approach 30 degrees above normal, generally in the 50s. These readings will likely break record warmest lows. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... The very active and mild weather pattern will remain in place but will become less mild late this week into the weekend. This is due to a strong Southwest Pacific jet that will remain north of the region through the long term period. It`s quite strong looking at model projections of this jet which convey 190+kt extending from Great Lakes northeast through Canadian Maritimes Wednesday through Thursday. Thereafter, the jet structure remains the same but the magnitude decreases. At the surface, a very busy weather period is in store with several systems moving across. Some notable features include areas of fog going into Wednesday especially along the coast and very warm temperatures continuing Wednesday. Forecast highs Wednesday upper 50s for the Twin Forks of Long Island to lower 70s N/W of NYC. The warmth is not as much for the rest of the forecast period but highs most days looking at Thursday through early next week are forecast to be about 5-10 degrees above normal. The other remarkable feature will be chances of rain which is forecast Wednesday afternoon into Wednesday night as well as Thursday and then again Friday afternoon through the weekend. The periods of rain look to be mostly light to perhaps moderate at times. Early next week, drying conditions are forecast. High pressure moves farther southeast into the Western Atlantic Wednesday. A cold front moves across Wednesday night. The front moves south of Long Island Thursday but stalls with an area of low pressure developing along it. The low and front move farther offshore southeast of Long Island Thursday night with high pressure briefly building in from the north. The high will be moving quickly off the New England coast Friday with another frontal system moving in from the west. Once again, there will be a lingering front behind the system and another low developing along it for the weekend. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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A warm front approaches the area early this morning, then lifts north of the terminals mid/late morning. LIFR/VLIFR conditions likely to continue into the morning push. Gradual improvement to MVFR late in the morning into afternoon for NYC/NJ and NW terminals, possibly VFR in the afternoon. Eastern terminals may remain IFR all day. Improvement time could be forecast 1 to 2 hours too soon. LIFR/VLIFR conditions likely to develop this evening once again. S/SW gusts to 20 kt possible for KEWR/KTEB/KSWF in the afternoon if VFR conditions develop. Late day S15g20kt coastal jet development possible for JFK into LGA. Elsewhere occasional SW gusts of 15 to 20 kt possible. S/SW winds subside to 10 kt or less this evening. LLWS possible for SW winds around 2 kft at 35-40 kt into the morning push. .OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY... .Late Tonight...IFR or lower in stratus/fog likely. .Wed...Gradually improving to VFR. Chance of showers with MVFR in the evening. SW wind G15-20KT possible. Winds shift to the N at night. .Thu...MVFR in rain. NE wind G15 KT possible. .Fri...CHC MVFR in rain. .Sat...CHC MVFR in rain.
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&& .MARINE... Have issued a dense fog advisory for all waters through 15z Tuesday morning. Low level moisture will continue to increase through the night with the anticipation that dew points will rise well above SSTs, aiding in dense fog development A prolonged period of S-SW winds ahead of a slow moving frontal system approaching from the Mississippi Valley will produce marginal SCA conditions later tonight into Wednesday night on the ocean waters east of Fire Island Inlet. However, current SCA only goes out through the day Wednesday as confidence at this time is too low to extend into Wednesday night. Aside from Wednesday into Wednesday evening with some seas of 5 ft on the ocean, sub-SCA conditions are forecast across the waters for the rest of the week into the weekend. It`s a relatively quiet period with the pressure gradient remaining weak. && .HYDROLOGY... Several rounds of rain are possible late this week into the upcoming weekend, but no significant hydrologic impacts are anticipated at this time. && .CLIMATE... Temperatures may approach or break record highs in a few spots Tuesday and Wednesday. Record Highs for Tuesday February 20, 2018 Location........Record/Year Newark..............70/1939 Bridgeport..........54/1991 Central Park........69/1939 LaGuardia...........63/1943 JFK.................61/1949 Islip...............62/2016 Record Highs for Wednesday February 21, 2018 Location........Record/Year Newark..............69/1953 Bridgeport..........59/2002 Central Park........68/1930 LaGuardia...........68/1953 JFK.................63/2002 Islip...............63/2002 && .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...
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CT...Dense Fog Advisory until 10 AM EST this morning for CTZ005>012. NY...Dense Fog Advisory until 10 AM EST this morning for NYZ067>075- 078>081-176>179. NJ...Dense Fog Advisory until 10 AM EST this morning for NJZ002-004- 006-103>108. MARINE...Dense Fog Advisory until 10 AM EST this morning for ANZ330-335- 338-340-345-350-353-355. Small Craft Advisory until 6 PM EST this evening for ANZ350- 353.
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&& $$ SYNOPSIS...JM/DW NEAR TERM...JP/DS/DW SHORT TERM...DW LONG TERM...JM AVIATION...NV MARINE...JM/DS/DW HYDROLOGY...JM/DW CLIMATE... EQUIPMENT...

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