Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 230653 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 253 AM EDT Sun Apr 23 2017 .SYNOPSIS... An area of upper level low pressure will move slowly eastward across the southeastern states on Sunday. Dry high pressure will remain in place across the southern Great Lakes and northern Ohio Valley. A gradual warming trend will begin going into the new week, before a cold front moves into the region Wednesday night into Thursday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The ILN CWA remains well on the north side of a complex low pressure system south of the region, with the upper low currently centered somewhere near Cairo IL, and the surface low centered in the Huntsville AL vicinity. There remains a sharp boundary separating a warm and moist air mass over the southeastern states from the cool and dry air mass in the Ohio Valley -- characterized by dewpoints in the 30s and mostly clear to clear skies. Entrenched in a cool flow pattern (NE near the surface and ENE slightly aloft) there will be little change to the overall air mass today, but a fair degree of warming is expected compared to yesterday, thanks to a significant increase in insolation. It should be noted that the theta-e boundary further aloft (850mb/700mb) remains further north than the surface boundary, and as the day progresses and the low shifts eastward, some of the moisture aloft will make an attempt at advecting NW into the southeastern sections of the ILN CWA. This will probably keep a few more clouds in these areas (and thus keep temperatures down by a couple degrees) but chances for precipitation are much less clear. A 20-percent PoP has been kept in the far southeast this afternoon, but if current model trends continue to suggest a dry solution (as the 00Z runs have done) this may be able to be removed. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Outside of the off chance of a light shower in the southeastern CWA this evening, a dry forecast is expected through the rest of the short term forecast period. Clear skies overnight will allow for another round of cool temperatures by Monday morning, though the warmer starting point and continued wind (5-10 knots) will keep the risk of frost very marginal. By Monday morning, an expansive area of dry surface high pressure will stretch from northern Ontario/Quebec through the Great Lakes, extending SSW through the northwestern Ohio Valley and into eastern Texas. As this high gradually weakens, wind flow will begin a clockwise shift in the Ohio Valley, especially aloft. On the northern periphery of the upper low moving into the Carolinas, 850mb-700mb theta-e advection will become pronounced by Monday afternoon, allowing for an increase in mid-level moisture and clouds during the day. With little change to the boundary layer air mass, temperatures are unlikely to gain significantly from Sunday to Monday, but another day of sun (especially early in the day) will allow for slightly warmer conditions (particularly in the western CWA). && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... With the upper level low now slower and inland than previously forecast, systems have slowed down for the immediate long term. For Monday night into Tuesday, some clouds will rotate westward into the region from slow moving upper level low to our east. A modifying airmass will still boost temperatures into the mid and upper 70s on Tuesday. Next piece of s/wv energy to eject out of a long wave trough (from the Pacific NW to the southern Plains to the western Great Lakes) is now expected to affect the region Wednesday night into Thursday. With a dry Wednesday and southerly flow, highs on Wednesday should warm into the lower perhaps mid 80s. The threat for showers and storms is now forecast for Wednesday night into Thursday as aforementioned s/wv moves through our region along with a surface cold front. Have been waiting for the models to come into better agreement by weeks end and into next weekend. Unfortunately, there continues to be considerable disagreement on how far east/south mid weeks cold front will get and how fast it will return as a warm front. The uncertainty calls for a very broad brushed forecast, keeping a chance of showers and thunderstorms going through this period. Temperatures will remain warm with mainly 70s and perhaps a few lower 80s in our southeast CWFA. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... Skies have generally cleared out over the region tonight, and mostly clear skies are expected through the rest of the TAF period, with just some cirrus at times. Winds will remain out of the NE through the TAF period as well, with sustained winds of 5-10 knots, gusting to 15-20 knots during the afternoon on Sunday. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Hatzos SHORT TERM...Hatzos LONG TERM...Hickman AVIATION...Hatzos

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