Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 212029 CCA AFDOKX Area Forecast Discussion...CORRECTED National Weather Service New York NY 329 PM EST Sun Jan 21 2018 .SYNOPSIS...
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A warm front will approach the region tonight, slowly working north through the region late Monday night into Tuesday morning . A cold front then follows later on Tuesday. High pressure returns for Wednesday through Friday. The high moves east to start the weekend ahead of the next cold front.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A warm front approaches from the south tonight and likely remains just offshore. Ahead of this front, increasing moisture and lift bring chances of PCPN across the area. The moisture is somewhat shallow, so a light rain or drizzle would be expected. The majority of the area will have temperatures above freezing coinciding with the rain/drizzle chances, however portions of interior CT and the Lower Hudson Valley could have freezing temperatures. Temps aloft are too warm for snow and likely too warm for any chance of sleet, so freezing rain/drizzle could happen for these northern areas. Coverage and likelihood for freezing rain is not high enough for any advisory at this time, and will continue to address this threat with the HWO and SPSs as needed. Cloud cover and weak warm advection will result in a non-diurnal temperature trend for tonight. Rising dewpoints should also produce at least patchy fog across most of the area. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... The warm front remains just offshore or potentially shifts into some of the southern zones during Monday. The moisture profile doesn`t change all that much, so PCPN chances remain through the day. Model consensus has higher PoPs towards the north and east and with SW zones potentially dry during the afternoon. Still a threat early on for freezing rain/drizzle across some northern zones, otherwise temps warm into the 40s with even some 50s across parts of the city and NE NJ. Low pressure heads into the Great Lakes Region with a cold front advancing into central PA by late Monday night. The warm front probably remains just south of us or across some of the southern zones. It will have a better chance of advancing north when a 60-70 kt low level jet pushes in from the south Tuesday morning. The cold front then passes through during the afternoon. Moisture deepens as a theta-e ridge shifts in late at night into Tuesday morning. Strong lift will be available as well with the llj, cold front, and synoptic lift from a 200-300 mb jet streak. Rain becomes likely late at night into Tuesday morning and ends for all but perhaps eastern LI and SE CT by sunset. Can`t completely rule out a rumble or two of thunder with strong lift and a little CAPE right ahead of the cold front, but will leave a mention of it out of the forecast for now. Rain however may still by heavy at times on Tuesday with the cold front passage. No flooding headlines anticipated based on guidance and expected rainfall totals. Despite a low level inversion, a period of 30 to 40 mph gusts appears likely for LI/SE CT Tue late morning into afternoon ahead of the cold front as the llj passes through. There`s a low chance for a few gusts of 40 to 50 mph being mixed down should there be any convection/heavy rain. No wind headlines at this time given the low likelihood of a widespread event and it being a 4th period event. Another day of above-normal temperatures expected for Tuesday, with near-record warmth for KJFK, KISP and KBDR. Highs generally in the 50s across the region. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Relatively quiet and dry long term period is anticipated as mean upper trough Wednesday into Thursday gives way to upper ridging Friday into the first half of the weekend. The flow pattern remains progressive across the CONUS with the next upper trough and shortwave approaching for next weekend. Deterministic and ensemble means are in overall good agreement in the above scenario, with diverging solutions regarding the trough/cold front next weekend. Initial shortwave moves offshore Tuesday night which quickly takes the cold front impacting the region on Tuesday with it as well. This should help carve out a large upper trough over the eastern Seaboard later Wednesday into Thursday. The temperatures behind the front will only fall to near/slightly above seasonable levels Tuesday night and Wednesday. As the mean upper trough takes shape Wednesday night into Thursday, a resurgence of colder air is advected southward with Canadian High pressure building towards the Tri- State. Temperatures on Wednesday night fall into the teens inland to the lower 20s closer to the coast. Below normal temperatures in the lower 30s are forecast for Thursday. Breezy conditions should also prevail both Wednesday and Thursday as the region will lie between low pressure to our NE and building high pressure to the west. The high pressure briefly settles over the region on Friday as upper ridging builds overhead. Below normal temperatures continue with highs only a few degrees warmer than Thursday. Much milder conditions quickly return for next weekend. Temperatures should warm well into the 40s for Saturday and possibly the 50s on Sunday ahead of the next cold front. Model guidance is slowly converging on the timing of the front, but this is seven days out so have elected to hold PoPs in the chance category with a PTYPE of rain. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... High pressure remains south of the region through tonight. Meanwhile, a warm front approaches from the south. Clouds gradually increase across the region through 05Z and VFR conditions will gradually lower to MVFR with the approach of the front. IFR conditions will likely develop Monday morning as the warm front stalls across the area. Conditions are expected to remain IFR or less through the day Monday. There may be some improvement very late in the 30 hours TAFs. Light W-SW winds this evening. Winds will then become light and variable tonight as the warm front approaches, remaining light and at times variable through Monday afternoon. .OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY... .Monday...MVFR/IFR likely. Chance of -RA. .Tuesday...IFR/LIFR in -RA. LLWS. S winds G25KT morning, WSW winds G30-35KT possible near the coast in the afternoon. .Wednesday...VFR. WNW G20-25KT. .Thursday...VFR. NW winds G20KT. .Friday...VFR. && .MARINE... A warm front then approaches tonight and slowly moves through some of the waters on Monday, keeping winds light and seas tranquil. As the warm front heads farther north Monday night into Tuesday, southerly flow will rapidly strengthen, with at least SCA-level winds on the waters. A strong low-level jet will lead to the possibility of at least isolated gale-force winds on Tuesday, despite an inversion that may hinder the strongest winds from reaching the waters. Seas will rapidly build in response to the strengthened flow. A gale watch is therefore in effect for the ocean waters, eastern LI Sound and the LI Bays. A small craft advisory would probably be needed elsewhere, but with this a 4th period event, will wait for new guidance to finalize where SCAs and other gale headlines will be issued. There may be a brief drop off in winds on the waters Tuesday evening as the cold front moves through. SCA gusts will return quickly into Wednesday morning and then continue into Thursday as the waters will be situated between low pressure to the north and high pressure to the west. Winds on the LI Bays, LI Sound, and NY Harbor may be a bit lower than on the ocean, especially on Thursday, but could still gust close to 25 kt. Winds diminish Thursday night into Friday as high pressure builds over the waters. Highest ocean seas should occur Tuesday night into Wednesday, before subsiding below 5 ft Wednesday night. && .HYDROLOGY... Total rain Monday night through Tuesday is expected to range mostly 1/2 to 1 inch, with locally 1 to 2 inches possible. No significant hydrologic issues are anticipated at this time. No hydrologic impacts are anticipated Wednesday through early next weekend. && .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...Gale Watch from Tuesday morning through Tuesday afternoon for ANZ330-340-345-350-353-355. && $$ SYNOPSIS...JC/DS NEAR TERM...JC SHORT TERM...JC LONG TERM...DS AVIATION...BC MARINE...JC/DS HYDROLOGY...JC/DS EQUIPMENT...

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