Area Forecast Discussion
Issued by NWS Upton, NY

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192 FXUS61 KOKX 190140 AFDOKX Area Forecast Discussion National Weather Service New York NY 940 PM EDT Wed Oct 18 2017 .SYNOPSIS... High pressure will remain in control through the end of the week before gradually shifting offshore through the weekend. Meanwhile, a dry cold front will approach from the north on Thursday and move through the local area on Friday. Another cold front will then slowly approach and pass through during the middle of next 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 dewpoints 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. Forecast is generally on track. Minor adjustments made to T/Td/winds based on latest obs and trends. Also added some patchy fog to the forecast overnight with minimal dewpoint depressions and light to calm winds. && .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 /02Z THURSDAY THROUGH MONDAY/... VFR through the TAF period with high pressure remaining southeast of the region through Thursday evening. SW winds 10-12 kt will continue for next few hours at city terminals. Winds will diminish overnight to around 5 kt at city terminals and light and variable elsewhere. SW flow increases on Thursday and becomes gusty in the afternoon. Start time of the gusts 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: A few gusts in the upper teens possible through 01-02z. KLGA TAF Comments: No unscheduled amendments expected through tonight. KEWR TAF Comments: No unscheduled amendments expected through tonight. KTEB TAF Comments: No unscheduled amendments expected through tonight. KHPN TAF Comments: No unscheduled amendments expected through tonight. KISP TAF Comments: No unscheduled amendments expected through tonight. .OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY... .Thursday night...VFR. .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. && .MARINE... Minor adjustments made to winds/seas based on latest obs/trends. 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. && $$

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