Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181958 AFDOKX Area Forecast Discussion National Weather Service New York NY 358 PM EDT Wed Oct 18 2017 .SYNOPSIS... Dominant high pressure is briefly shunted southward on Thursday as a cold front passes to the north. The high then rebuilds through late week before gradually shifting offshore through the weekend ahead of an approaching cold front. The front slowly moves towards the area through mid week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Seasonable weather continues as high pressure remains across the area. Although clear skies and light winds will create favorable radiational cooling conditions tonight, subtle return flow has allowed dew points to increase into the mid 40s to lower 50s. As such, low temperatures tonight will be closer to normal climatological values rather than the below normal we have experienced the past few nights. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Southwesterly flow will strengthen into Thursday ahead of a weak cold front. Temperatures will be 5 to 10 degrees above normal in warm advection, particularly to the west of NYC where marine influence will be minimal. Have trended a few degrees above guidance in these areas, primarily for northern NJ. A few gusts will be possible by evening ahead of the front and with its passage late. The mixing associated with the front will keep temperatures above normal into the overnight. Given the antecedent dry air mass, no precipitation is expected with the frontal passage. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Large ridge remains in place Friday and Saturday, ahead of downstream trough that will makes its way east, deepening as it does so. The global models prog a southern stream cutoff low over the southeast states Monday, and this shortwave energy quickly moves northeast Tuesday ahead of the main longwave trough that remains to the west, slowing down as it deepens Tuesday and Wednesday. Surface high pressure builds behind a weak front during the Friday through Sunday period. By Monday, a wave of low pressure likely develops over the southeast states along a cold front. The front will make slow eastward progress, approaching Tuesday and passing Tuesday night as low pressure rides along it. Still, there is much uncertainty though on all these features and forecast details this far out as the front could move east or stall nearby. As for sensible weather, dry conditions are expected until Monday, or Monday night. Increasing chances for showers Monday night/ Tuesday can be expected ahead of shortwave/trough/front. In fact, increasing moisture sweeps northward as the Gulf of Mexico is tapped which could lead to some heavier showers Tuesday or Tuesday night. These showers could very well linger into Wednesday depending on speed of front and trough, a conveyor belt of moisture advecting south to north. Have a feeling the slower solutions will pan out due to strength of the trough. Either way, showers will be possible as upper cold pool approaches from the west if the front passes quicker. Temperatures through the period will remain several degrees above normal. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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High pressure builds southeast of the region through the TAF period with a high confidence of VFR continuing for most terminals. Only exception would be KSWF where there is a low chance of some MVFR patchy fog overnight into daybreak Thursday. The wind forecast is moderate confidence due to some terminals remaining uncertain with exact wind direction. Wind speeds stay 10 kt or less through tonight with winds picking up Thursday afternoon to 10kt or just a few kts higher, gusting to 15-20 kt. Gust timing could vary a few hours from forecast. 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: No unscheduled amendments expected through tonight. KLGA TAF Comments: No unscheduled amendments expected through tonight. KEWR TAF Comments: No unscheduled amendments expected through tonight. KTEB TAF Comments: Winds could stay variable in direction before 22Z instead of SW. KHPN TAF Comments: Winds could stay variable in direction before 23Z instead of SW. KISP TAF Comments: No unscheduled amendments expected through tonight. .OUTLOOK FOR 20Z THURSDAY THROUGH MONDAY... .Thursday afternoon-Thursday night...VFR. SW-W winds G15-25kt afternoon-evening. .Friday-Friday night...VFR. NW-N winds G15-20kt possible Friday afternoon and evening. .Saturday-Sunday night...VFR. .Monday...MVFR possible with chances of showers in the afternoon. SW wind gusts near 15kt.
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&& .MARINE... Winds and seas will remain tranquil into tonight before gradually building into tomorrow in strengthening southwesterly flow. A SCA has been hoisted for the ocean areas east of Fire Island as gusts near 25 kt and seas briefly building to 5 ft will be possible by tomorrow evening. Conditions gradually subside into Friday as the front passes to the east and high pressure begins to build into the area once again. The high pressure then builds this weekend, with sub SCA conditions forecast. As the high moves east Sunday and Monday, southerly flow will increase as the waters sit between the high to the east and an approaching cold front to the west. && .HYDROLOGY... No hydrologic issues expected through the weekend. Locally heavy rain is possible during the beginning of next week. Urban/poor drainage flooding would be the main threat if heavy rain does indeed occur. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 4 PM Thursday to 6 AM EDT Friday for ANZ350-353. && $$ SYNOPSIS...MD/PW NEAR TERM...MD SHORT TERM...MD LONG TERM...PW AVIATION...JM MARINE...MD/PW HYDROLOGY...PW

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