Area Forecast Discussion
Issued by NWS Upton, NY

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530 FXUS61 KOKX 291954 AFDOKX Area Forecast Discussion National Weather Service New York NY 354 PM EDT Sat Apr 29 2017 .SYNOPSIS... A weak cold front will move south of the area this evening as high pressure builds to the north. The high moves east Sunday into Sunday night as the front returns north as a warm front. A cold front will slowly approach from the west on Monday, and pass by Tuesday morning. High pressure builds in briefly for the middle of the week, then low pressure brings rain for the end of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Mid and upper level ridging will remain across the region through tonight as a weak surface cold front moves south of the area. The front was just north of the CWA, across the lower Hudson Valley and into northwestern Connecticut at mid Saturday afternoon. With little lift, moisture, or instability with the front, will bring through dry. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Weak cold advection will continue through the day Sunday as the ridge shifts to the east. Winds will back to the east and southeast keeping the area cool. Low level moisture increases and a low level inversion develops and strengthens through the day. Low level clouds are expected to develop during Sunday afternoon. High temperatures Sunday will be close to the lows that occur Sunday morning, maybe rising a couple of degrees early, then holding nearly steady. Did not use a diurnal trace for temperatures for Sunday. Stratus and fog develop Sunday night as the east flow remains. Initially weak cold advection continues then becomes weak warm advection after 06Z as the frontal boundary to the south begins to return as a warm front. Forcing will remain weak until toward 12Z Monday. So removed probabilities of precipitation, and mentioned drizzle. There is a chance that showers do develop ahead of the warm front, however, that would be more into Monday, and across the far southern sections of the CWA. If the front move quicker, which is unlikely as the surface and upper lows remain well to the west. Sunday night lows may occur during the evening, then hold steady or slowly rise toward morning. Again did not use the usual diurnal trace for hourly temperatures Sunday night. && .LONG TERM /MONDAY THROUGH SATURDAY/... The models were in good agreement through the extended, so the Superblend was generally used. After some residual fog and drizzle Monday morning, a warm front is progged to lift just north of the forecast area before stalling. It is possible that the front does not get as far north as the models depict, but for now the model consensus has been followed. This should allow the drizzle to cut off across the southwestern portion of the area, with some lingering light stuff still possible in the vicinity of the front. Chances for showers will increase through the day as the cold front and upper support draw closer, but the main window for rain looks to be Monday night closer to the frontal passage. Isolated thunderstorms have been included for this period with the enhanced lift with the system acting on some elevated instability. Lapse rates increase on Tuesday as cooler temperatures aloft move in. The best chance for a stray shower will be on the northern fringe of the forecast area per the model consensus at this time. A dry day is progged for Wednesday with high pressure building in from the west. Chances for overrunning light rain then increase Wednesday night ahead of developing low pressure over the Ohio Valley. The low then tracks through the area Thursday night and Friday, bringing moderate rain to the Tri-State Region. The temperature forecast for Monday is complicated, as the combination of southerly flow, the exact location of the warm front, and the influence of onshore flow will all play a part. It is possible a 20 degree difference will set up from southwest to northeast. Temperatures will be uniformly mild on Tuesday due to good mixing on southwesterly flow behind the cold front. Readings will then cool on Wednesday with the colder airmass in place. Cooler and damp thereafter with the rain and clouds, although nighttime temperatures will likely be above normal due to these same elements. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... A series of cold fronts will move through the area, one late this afternoon, and another early this evening. These are forecast to be dry frontal passages. Gusty W/SW winds this afternoon will veer to the W/NW, and then NW to NE overnight. Gusts 20-25 kt this afternoon with the potential for up to 30 kt. Gusts may linger into early this evening. VFR with SCT-BKN 4-5 kft this afternoon, and then again Sunday morning. .OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY... .Sunday afternoon-Monday....MVFR development late afternoon/early evening, then widespread IFR conditions in fog/drizzle overnight into Monday. Possible improvement to VFR Monday afternoon. .Monday night...IFR or lower conditions, LLWS and scattered thunderstorms are possible. .Tuesday-Wednesday...VFR. SW-WSW winds G15-20KT possible Tuesday. W-NW winds G20-25KT possible Wednesday. .Thursday...MVFR or possible in late day rain. && .MARINE... Winds and seas are expected to remain below small craft advisory levels tonight through Sunday night. There may be a brief period of seas near 5 feet, especially west of Fire Island Inlet, Sunday evening as easterly winds increase. A strong westerly flow late Saturday afternoon into the evening may build ocean seas briefly to near 5 feet. However, seas on the ocean waters were ranging from 3 to near 4 feet through Saturday afternoon, below previous forecast thinking. Therefore, the small craft advisory for hazardous seas was cancelled. Southerly winds will increase on Monday, with the ocean reaching Small Craft Advisory criteria. The protected waters will be close to criteria by Monday night, but all areas will reach 25 kt on Tuesday behind a cold front. Seas will then linger above 5 ft on the ocean through Wednesday. Winds and seas are progged to remain below Small Craft Advisory levels on Thursday. && .HYDROLOGY... No hydrologic impacts are expected through the forecast period. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...12/GS NEAR TERM...MET SHORT TERM...MET LONG TERM...12 AVIATION...DW MARINE...12/MET HYDROLOGY...MET is the U.S. government's official web portal to all federal, state and local government web resources and services.