Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 261406 AFDOKX Area Forecast Discussion National Weather Service New York NY 1006 AM EDT THU MAY 26 2016 .SYNOPSIS... The region will be under the influence of a westward extension of the Bermuda High through the weekend. A cold front approaches from the west Monday, then pushes through the area Monday night. This front then stalls out near or just to the south of the area through Wednesday as high pressure builds to the north. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Under full sun early this morning, and light winds, temperatures have risen a little more quickly than expected. Have updated sky cover and temperatures. With deep-layered ridging area will remain mostly clear. One weak shortwave moving through northeastern Pennsylvania and into the lower Hudson Valley was producing some cloudiness to the west and will bring increased clouds, mainly to the north, through the morning and into the afternoon. Another shortwave embedded within ridge approaches late in the day, and with increasing mid- level moisture there could be a shower or thunderstorm by late, primarily over the NW zones where CAPES will be higher. Limiting factors however will be some capping aloft with relatively stable mid-level lapse rates. Thinking is that most spots will be a little cooler than yesterday, more so at the coastal areas as sea breezes will begin earlier this time around and affect more areas. Additionally, 850 mb temps are forecast to be about a degree Celsius cooler. There is a moderate risk of rip current development at the Atlantic beaches today into this evening. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... 500 mb shortwave enters tonight, but weakens as it moves across the region. Loss of instability will help keep any showers/storms isolated to scattered in nature. 850-700 mb shortwave slowly moves through the CWA during Friday. Moisture depth and lift will be greater during the morning, but CAPES will be higher in the afternoon. Will therefore go no higher than chance pops for now. High temps still well above normal with 850 mb temps climbing back up to 15-16C. Amount of cloud cover and sea breezes should offset the max temp potential somewhat, but in general, going with highs a little cooler than today in most spots, primarily due to more cloud cover. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A westward extension of the Mid-Atlantic Ocean based sub-tropical ridge builds in Friday night-Saturday, then retreats back to the southeast Saturday night and Sunday. The result will be continued very warm and humid conditions across the region. There will also be some mainly diurnal isolated-scattered showers and thunderstorms from Friday evening through Sunday as well. Temperatures during this time frame were based on a blend of all available guidance, with NAM 2-meter temperatures blended in Friday night-Saturday night, and a mix down from 975-850 hPa, per BUFKIT soundings, blended in for highs on Saturday. Lows will run around 10 degrees above normal both Friday and Saturday night. Highs Saturday and Sunday should run around 10-15 degrees above normal. The forecast for Sunday night-Wednesday is very much dependent on the interaction between a northern stream shortwave that is forecast to move across the Great Lakes and a possible closed low near the mid-Atlantic Coast. There is quite a spread in model solutions, with the GFS showing the most interaction between these two systems and the ECMWF the least. The CMC-Global is somewhat in between these two solutions, but trends closer to the ECMWF with time. It should be noted that the ECMWF and GFS basically flipped solutions from the 12z to the 00z runs. The result is a low confidence forecast from Sunday night-Wednesday. For now will run with pops increasing to chance throughout Sunday night for showers and thunderstorms, continuing on Monday, then tapering off Monday night. Given uncertainties in how quickly the airmass changes on Tuesday, have included some diurnal convection then, however, if the ECMWF/CMC are correct, Tuesday could end up dry. Given the overall uncertainty then maintain mainly slight chance pops for Tuesday night and Wednesday. For temperatures Sunday night-Wednesday, the Superblend was used, with above normal temperatures forecast, but not quite as warm as this weekend. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... VFR forecast. High pressure builds east of the area today. Light and variable winds this morning will quickly be replaced by by a a S/SW flow with local seabreeze enhancements. KLGA will see its typical NE flow off the East River this morning before switching around to the S by late morning/early aft. Wind speeds should max to just above 10 kt. A shower or thunderstorm is possible across the terminals late tonight into Friday morning. However, chances are too low to mention in the TAFs. Better chances for showers and thunderstorms for northwest terminals such as KSWF and KHPN. 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. KLGA TAF Comments: Sound breeze off East River may persist 1-2 hours longer. KEWR TAF Comments: No unscheduled amendments expected. The afternoon KEWR haze potential forecast is green...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: No unscheduled amendments expected. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 12Z Friday through Monday... .Friday through Friday night...Mainly VFR, but sub-VFR possible in isolated showers and evening thunderstorms. .Saturday...Mainly VFR. Isolated showers and thunderstorms north of NYC/Long Island. .Sunday...Sub-VFR possible in afternoon showers and thunderstorms. .Monday...Sub-VFR possible in showers and thunderstorms. && .MARINE... No changes at this time. A weak to moderate pressure gradient over the region through Monday will keep winds to 15 kt or less over the waters around Long Island. With no significant swells forecast during this time frame, seas will remain below Small Craft levels as well. && .HYDROLOGY... No significant widespread precipitation expected through Thursday night. Local minor flood impacts from heavier showers/tstms are possible on Friday. There is the potential for locally heavy rainfall, for areas mainly N/W of NYC Saturday and Sunday, with a higher chance of a more widespread moderate to heavy rainfall from Sunday night into Monday, and possibly lingering farther into next week. For this weekend, the main threat is ponding of water on roadways, with a low risk of minor flooding of urban and poor drainage areas (once again the main threat this weekend will be to the N/W of NYC). At this time, there is too much uncertainty to specify any threat for early next week, other than to note the situation bears watching. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$

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