Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 202349 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 749 PM EDT Wed Sep 20 2017 .SYNOPSIS... A weak mid level trough will move east of the area today. Over the next several days, a stagnant weather pattern will set up, with mid-level ridging and high pressure near the surface. Temperatures will remain above normal through the weekend. && .NEAR TERM /THROUGH THURSDAY/... A stray shower or two may still pop up over the CWA for the next few hours as a high moisture content airmass continues to interact with a departing upper level shortwave. Any cells that might pop will not be deep enough to support thunderstorm activity and thunder has been removed from the forecast with a weak 20% coverage added to mainly the southeastern quarter of the CWA. Did not change the fog forecast tonight given the unusually moist air over the region. Fog potential is the greatest concern for tonight, with a favorable setup in the wind and pressure pattern (overall light flow with the main axis of the boundary-layer ridging just to the east). Where skies clear out, conditions will be favorable for fog to become locally dense, especially in river valleys or more broadly in the eastern half of the forecast area. && .SHORT TERM /THURSDAY NIGHT/... The stagnant weather pattern will essentially remain in place on Thursday, with broad mid-level ridging extending from the Great Lakes into the middle Mississippi Valley, and an elongated surface high centered well northeast of the Ohio Valley region. Thursday appears to set up as another day with light wind flow and some chance of afternoon instability, which has resulted in some inconsistent/weak QPF output across the suite of models. Looking at soundings, there will be some warming of temperatures in the 800mb-750mb layer between Wednesday and Thursday, which will make it less likely for any precipitation to develop. The chance certainly isn`t zero percent, but appears small or isolated enough to not include in the main forecast. Temperatures should be able to rise by a few degrees for both Thursday and Thursday night. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Strong H5 ridge will be the dominant feature for much of the forecast period. The ridge will keep Jose off the East Coast and away from the Ohio Valley, and later on Maria. Meanwhile at the surface, a surface high centered over the St. Lawrence Valley will extend southwest into the fa. The combination of these two features will bring dry condition and above normal temperatures through the weekend and into early next week. High temperatures will be about 10 degrees above normal values through Tuesday as they push into the mid and upper 80s. Morning lows be around 60. By Wednesday a cold front will be moving east up the Ohio Valley. It will bring some scattered convection. The GFS is a little quicker than the ECMWF and Canadian with the front. Have included 20 PoPs in the wrn half of the fa for Wednesday. Highs Wednesday will still be around 80 degrees. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... Generally clear skies are expected tonight with some lower stratocu associated with the showers possible through the evening, and some higher blowoff cloud cover that will be thinning through the next several hours. Wind field will be light and variable, and this will combine with the generally clear skies and moist lower atmosphere to create another night of fog development, possibly dense in river valleys. Expect IFR conditions to be present, with KLUK dropping right to VLIFR in more dense valley fog. Moisture will lift to help form some scattered cu in the morning and early afternoon, which should mix out early in the afternoon. A brief bkn deck is possible just about anywhere, but should be the exception and not the rule. OUTLOOK...No significant weather is expected at this time. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Franks SHORT TERM...Hatzos LONG TERM...Sites AVIATION...Franks

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