Area Forecast Discussion
Issued by NWS Upton, NY

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367 FXUS61 KOKX 301617 AFDOKX Area Forecast Discussion National Weather Service New York NY 1217 PM EDT MON MAY 30 2016 .SYNOPSIS...
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A cold front approaches from the eastern Great Lakes this afternoon, then crosses the Tri-State tonight. High pressure then builds down from southeastern Canada from Tuesday through Thursday, then retreats to the northeast Thursday night. A cold front approaches from the west on Friday, then moves across the region this weekend.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Dry conditions initially, with main area of showers offshore. Updated probabilities based on latest radar trends, and latest mesoscale model solutions. Slight chance to chance coverage for showers/possible thunderstorms expected early this afternoon. Then convection should fire upstream along the front per hrrr/arw and nmm. Noting expected gap in precipitation and breaks in the clouds, could see CAPES of 1000-1500 J/kg across interior portions of the Lower Hudson Valley/SW CT/NE NJ mid to late afternoon. If these CAPES are achieved, then isolated strong storms would be possible with 30-35 kt of Bulk Shear. However the main issue likely would be locally heavy rainfall. With some sunshine, highs should exceed 80 degrees, with 70s east of NYC due to clouds/onshore flow. There is a moderate risk for the meteorological enhancement of rip current formation at Atlantic beaches through this evening.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... A 700-500 hPa shortwave crosses the area tonight...bringing with it mainly scattered showers mainly this evening...except over far se CT/Twin Forks of Long Island where they should be more numerous and linger into the overnight hours. Might see showers linger over the Twin Forks into Tuesday morning, otherwise the day should be dry as the low levels dry out with a NW boundary layer flow. This should be enough to overcome forcing from the passing of a flattening 700-500 hPa trough axis. For lows tonight, a blend of MAV/ECS/MET guidance and NAM 2-meter temperatures was used, with values around 10 degrees above normal. On Tuesday, a blend of ECS/MET/MAV guidance, NAM 2-meter temperatures and a mix down from 850-825 hPa, per BUFKIT soundings, was used for highs. Readings should be around 10 degrees above normal. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Upper level ridging will build over the region Wednesday and then shift eastward towards eastern New England and then the Canadian Maritimes on Thursday. At the surface, high pressure will traverse across New England on Wednesday and then situate itself over the Canadian Maritimes on Thursday. While the core of the high moves east, it will ridge down across the area. The 00z models and ensembles are in good agreement on this pattern. A northern stream shortwave trough is progged to moved across SE Canada on Thursday which will help push the upper ridge to the east. NHC`s 11pm advisory show the remnant circulation of Bonnie moving off the Carolina coast Wednesday night and then passing around 100 miles south and east of the 40/70 Benchmark. Most of the tropical moisture with the remnants are expected to remain well offshore. This is because of the approaching shortwave and increasing westerlies aloft associated with it. Will continue to advertise a slight chance of a shower for the far SE portion of the area, but think subsidence from the high to the NE will keep conditions mostly dry. Models diverge on the timing and amplitude of the passing shortwave trough Friday into Saturday. Differences continue to grow with the h5 pattern into the weekend. The cold front will slowly approach from the west Thursday night into Friday and then should move through on Saturday. Have kept pops in the low chance category this time frame. It will not be raining the whole time, but cannot rule out a few showers with the front in the vicinity. Instability is lacking, but have left mention of thunder Friday into Saturday with the front. Another shortwave establishes itself late Saturday into Sunday across the Great Lakes region and this is likely to approach late in the weekend. However, there is a lot of spread on how amplified the shortwave gets and how strong the downstream ridge ends up which will ultimately determine the timing of any precipitation. Since this a day 7 forecast, do not want to go to far from a model consensus at this time. Temperatures on Wednesday will be near to slightly above normal. Onshore flow Thursday and Friday should keep temperatures a few degrees below normal. Seasonable temperatures forecast this weekend. && .AVIATION /16Z MONDAY THROUGH FRIDAY/...
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A cold front will approach, moving across late tonight. Conditions now vary from VFR to LIFR across the region. Drier air moving in will allow cigs to lift to MVFR and eventually VFR throughout today from west to east. There will be a chance of showers and thunderstorms this afternoon...especially late...with the greatest chances NW of the city terminals. However, confidence is too low to include in TAFs. Low confidence forecast tonight. Onshore flow plus low level moisture may result in patchy fog with IFR conditions, but drier air aloft may limit this potential until after midnight tonight. Winds dependent on cloud cover. If flight cat improves earlier than expected NYC metro and coastal terminals could see stronger sustained S-SW winds and also gusts close to 20 kt this afternoon. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component fcsts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: MVFR possible before 18Z. There could be occasional gusts up to 20 kt late this afternoon. KLGA TAF Comments: MVFR possible before 18Z. Winds could be 3-5 kt higher than forecast mid to late this afternoon. KEWR TAF Comments: Winds could be 3-5 kt higher than forecast mid to late this afternoon. The afternoon KEWR haze potential forecast is green...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: MVFR will be temporary into early this afternoon. Winds could be 3-5 kt higher than forecast mid to late this afternoon. KHPN TAF Comments: MVFR may last 1-2 hours later than indicated in the TAF. Late day tstm possible after 21Z. KISP TAF Comments: End time of IFR uncertain and could vary 1-3 hours compared to forecast. Winds could be stronger than fcst mid to late this afternoon with ocnl gusts 20-25 kt. .OUTLOOK FOR 12Z Tuesday through Friday... .Tuesday-Wednesday night...VFR. .Thursday...Mainly VFR. E winds G15-20kt. .Thursday night...Chance of showers with brief MVFR conditions. .Friday...Chance of showers with brief MVFR conditions, and possibly an afternoon tstm.
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&& .MARINE...
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Extended the dense fog advisory for eastern waters per obs and latest forecast guidance. Will monitor to see if dense fog adv needs to extend into tonight for these eastern waters. A light to moderate pressure gradient over the region will limit sustained winds to 15 kt or less through Tuesday. For now, it appears that there will not be a significant enough swell to bring seas to SCA levels through Tuesday. It should be noted though, that there is still some uncertainty with how much significant swell, if any, the coastal ocean waters will experience early this week from Tropical Depression Bonnie. Sub-sca conditions are expected Tuesday Night and Wednesday with winds less than 20 kt and ocean seas 3 to 4 ft. Uncertainty remains on how much residual swell will exist Thursday into Friday as remnants of Bonnie pass south and east of the waters. It is possible seas approach 5 ft during this time on the ocean. Winds could also approach sca levels on the ocean on Friday.
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&& .HYDROLOGY...
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Other than possible scattered showers and thunderstorms, no additional significant rainfall is expected through the afternoon. Any thunderstorm could result in minor urban and small stream flooding.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Dense Fog Advisory until 5 PM EDT this afternoon for ANZ330- 340-345-350-353.
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&& $$ SYNOPSIS...Maloit/DS NEAR TERM...Maloit/DS/PW SHORT TERM...Maloit LONG TERM...DS AVIATION...Goodman/JM MARINE...Maloit/DS/PW HYDROLOGY...Maloit/DS

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