Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 251954 AFDOKX Area Forecast Discussion National Weather Service New York NY 354 PM EDT Sun Oct 25 2020 .SYNOPSIS... High pressure to the north moves towards the Canadian Maritimes tonight as a wave of low pressure meanders along the Middle Atlantic coast. The low slowly lifts towards the area on Monday before shifting offshore Monday night. High pressure then settles into the Northeast through mid week before shifting offshore. The remnants of Zeta and a larger low pressure system may impact the region at the end of the week. Strong high pressure then builds into the area over the weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... High pressure to our north across southeast Canada continues to advect cool and dry air southward under northerly flow. There is a cold air damming signature in the pressure field from the Middle Atlantic down into North Carolina east of the Appalachians. This surface pattern is setting up an inverted trough along the coast with a weak wave of low pressure developing along the trough. The surface high will slowly move towards the Canadian Maritimes this evening and tonight. Warm advection and overrunning will develop and help lower and thicken clouds through this evening. The warm advection is stronger to our south this afternoon, but light rain returns on Doppler Radar are having trouble moving northward due to dry air and subsidence from the high. The subsidence should weaken this evening from south to the north as the high moves east. Warm advection/overrunning will be the main forcing mechanism for light rain tonight. The light rain will spread from south to north through the night, taking longest to reach the ground across the interior due to the lingering dry air. Light rain will then continue into the early morning hours. Overall rainfall amounts will be light with around a tenth of an inch or less across the interior to around two tenths near the coast. Lows will range from the lower to middle 40s inland to the upper 40s near the coast. Temperatures could rise a few degrees early in the morning as the flow becomes more easterly. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Thermal forcing weakens Monday morning, which will bring an end to the widespread light rain. The low levels will remain saturated through the day however which will support a chance for light rain or drizzle. The low pressure to the south will only slowly lift towards the area in the morning and afternoon. Forecast soundings indicate dry middle levels through the day, but with continued easterly flow between the low pressure and high well to the northeast, low clouds will remain in place. Slightly warmer air pushes closer to the area through the day and with the saturated low levels, patchy fog is possible outside of any light rain or drizzle. Rainfall amounts will continue to be light. Highs on Monday will be near normal in the middle and upper 50s inland to around 60 close to the coast. The low finally weakens and lifts northeast away from the coast Monday night. Forecast soundings continue to indicate saturated low levels. Mostly cloudy to overcast skies are anticipated with just a slight chance of light rain. High pressure begins to build towards the area late Monday night helping to shift the low level flow to northerly. This should help to scour out some of the lingering low level moisture. Lows range from the upper 40s to lower 50s. && .LONG TERM /TUESDAY THROUGH SUNDAY/... At the surface a high pressure system settles into New England Tuesday into Wednesday. In the upper levels southwest flow continues to bring moisture overhead. This moisture will likely manifest as increased cloudiness though isolated light rain can quite be ruled out. Regardless temperatures are mild in the mid to upper 50s both Tuesday and Wednesday with overnight lows in the 40s. Late Wednesday into Thursday as the high shifts offshore attention shifts to the remnants of Tropical Storm Zeta and a deepening mid level trough over the Oklahoma. Though the exact location is uncertain, models show Zeta possibly in the right exit region of a 120 kt jet streak. This southwest to northeast jet transports the system and moisture into the forecast area Thursday. As the low transitions rain is likely to begin Thursday morning initially as warm frontal showers. By the evening, precipitable water values around 1.2 to 1.5 inches promote heavy rainfall throughout the region. The main hazard will be nuisance flooding possible. A second wave of moderate to heavy rain arrives Friday with the main upper level trough. Over the weekend a strong high pressure system builds behind the trough into the Northeast. Dew points drop dramatically into the 20s and 30s particularly for our inland counties. This sets up the possibility of Freezing temperatures Saturday morning. The dry air zeros out the rain chances through the weekend. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... High pressure builds north of the area through this evening while a surface trough along the mid Atlantic coast resides over the region. Low pressure will remain southeast of the area on Monday. MVFR ceilings develop this evening, between 01-05Z. These conditions will last through Monday morning. IFR conditions are likely to develop Monday morning. IFR to MVFR conditions will continue into Monday afternoon with only slight, if any improvement throughout the day. Mainly east winds for this evening as wind speeds will be 10-15 kt for coastal terminals, 5 to 10 kt for terminals away from the coast. For late tonight occasional gusts to 20 kts are expected for coastal terminals. East winds will continue into Monday, but lighter at 5 to 10 kt. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Amendments are possible early this evening as ceilings continue to lower. Further amendments are possible towards early Monday morning with the likely development of IFR conditions. Any improvement from IFR to MVFR into Monday afternoon is low confidence and would be gradual. .OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY... .Monday afternoon...IFR and MVFR conditions are expected with a chance of -SHRA and -DZ. .Tuesday...MVFR possible with a chance of showers. .Wednesday...VFR. .Thursday...MVFR or lower possible in RA. .Friday...MVFR conditions possible in -RA. Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ && .MARINE... Long period swells subside this evening. However, seas will remain elevated and should build to 6 to 7 ft tonight into Monday in response to strengthening easterly flow ahead of the an approaching low pressure system. Seas will slowly diminish Monday afternoon into Monday night as the low moves away from the waters. There will also be a period of wind gusts around 25 kt on the ocean as the low approaches tonight. No changes were made to the Small Craft Advisory, which is in effect until 6 pm Monday. Winds diminish on all waters Monday afternoon into Monday night as the pressure gradient weakens. Waves range 3-4 feet over the ocean with light east to northeast winds through Wednesday. Late Wednesday southwest winds develop and transition into northeast winds as the remnants of Zeta enter the marine zones. Waves of 8-10 feet with wind gusts of 25 kts over the ocean waters are possible Friday. These SCA conditions owing to the system making its closest approach remain in place through Saturday. && .HYDROLOGY... No hydrologic concerns through Wednesday. Heavy rain is possible Thursday and Friday with the arrival of tropical moisture. The main hazard will be from nuisance flooding. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 PM EDT Monday for ANZ350-353-355. && $$ SYNOPSIS...DJ/DS NEAR TERM...DS SHORT TERM...DS LONG TERM...DJ AVIATION...JE MARINE...DJ/DS HYDROLOGY...DJ/DS is the U.S. government's official web portal to all federal, state and local government web resources and services.