Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 260750 AFDOKX Area Forecast Discussion National Weather Service New York NY 350 AM EDT THU MAY 26 2016 .SYNOPSIS... High pressure will be in place through Friday, and the region will be under the influence of a westward extension of the Bermuda High for 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/... Dry weather expected this morning with deep-layered ridging. A 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. High temperatures will be well above normal as they were yesterday. 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 iso to sct. 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 chc 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 /07Z THURSDAY THROUGH MONDAY/... VFR forecast. High pressure builds to the south overnight and Thursday. Light west/southwest expected overnight. Light winds in the morning become south around 10 kt. Sea breezes are expected by afternoon, sooner across CT terminals. KLGA may be affected by a sound breeze which may make winds turn to an east or southeast direction between 12Z and 15Z. However, there is a low chance of this happening. .OUTLOOK FOR 00Z Friday through Monday... .Thursday night through Friday morning...Mainly VFR but sub-VFR possible in showers/evening thunderstorms. .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... With the pressure gradient overall remaining rather weak...seas and wind gusts will stay below SCA criteria through Friday. A weak to moderate pressure gradient over the region Friday Night 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. && $$ SYNOPSIS...JC/Maloit NEAR TERM...JC SHORT TERM...JC LONG TERM...Maloit AVIATION...JP MARINE...JC/Maloit HYDROLOGY...JC/Maloit is the U.S. government's official web portal to all federal, state and local government web resources and services.