Area Forecast Discussion
Issued by NWS Wilmington, OH

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931 FXUS61 KILN 200754 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 354 AM EDT Sun Aug 20 2017 .SYNOPSIS... Light to calm winds have taken hold across the area this morning as high pressure slowly builds in. Above normal temperatures will persist through Monday ahead of the next cold front which is currently forecast to push through the area Tuesday night. Showers and thunderstorms are likely ahead and along the front, before a much cooler and drier airmass moves in for the later half of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Weak surface high pressure has slowly moved into the area this morning allowing winds to go light and calm. Dewpoint depressions are sitting near zero this morning with fog already having formed in Licking county. There is some cloud debris across our southwestern zones this morning from earlier convection which might delay river valley fog formation by a bit. During the afternoon today temperatures will quickly warm as mid-level heights rapidly rise towards 590 dm. Some high res models also indicate weak isolated convection trying to form this afternoon along and ahead of some PVA. Looking at GFS and NAM forecast soundings though reveals dry air in the mid-levels with a capping inversion around 700 mb. Even if the cap is not as strong as forecast dry air entrainment should easily cause most updrafts to fail. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Tonight into Monday morning surface high pressure will pull southeast of the area allowing a return of southwest winds to the region. During the day Monday the area should remain mostly dry with forecast soundings remaining capped. The main concern for Monday will be whether or not there will be any clouds for the eclipse. The issue looks to be that there will likely be ongoing convection out towards Iowa which means some convective cloud debris (cirrus) will possibly spread over the area. For now have nudged cloud cover up, but there always exists uncertainty on how opaque this cirrus will be when and if it arrives. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... A seasonably strong mid level short wave will rotate down across the southern Great Lakes through the day on Tuesday. As it does, an associated cold front will push southeast across the Upper Ohio Valley Tuesday into Tuesday night. Good forcing along and ahead of the front will combine with increasing instabilities through the day to produce fairly widespread shower and thunderstorm activity across our area. the thunderstorm chances should then taper off from the northwest heading into Tuesday night as the cold front moves through. Increasing dynamics and strengthening wind fields aloft will lead to developing deep and mid layer shear along and ahead of the front through the mid afternoon hours. This will lead to the possibility of severe storms with damaging wind being the primary threat. Surface high pressure will build down across the Great Lakes behind the front on Wednesday and then remain in place across the region into the weekend. Both the GFS and ECMWF are showing a secondary mid level short wave dropping down across the western Great Lakes and into our area through the day on Thursday. Moisture is pretty limited so will maintain a dry forecast at the moment, but some lower chance pops may eventually be needed with this feature. Otherwise, expect mainly dry and cooler conditions through the remainder of the long term period with highs mainly in the mid to upper 70s each day. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... Weak surface high pressure will slowly build into the region this morning with winds mostly light to calm. Dewpoint depressions are already nearing zero degrees in many locations with river valleys all but certain to fog in. As the sunrises this morning fog will slowly burn off allowing conditions to return to VFR. This afternoon slightly drier air will build in with only daytime CU possible. Some high res guidance is trying to get some very isolated coverage going this afternoon, but think this is way overdone given the GFS and NAM forecast soundings (updraft failure from dry air entrainment). Sunday evening, surface high pressure will be off to our southeast with winds veering towards the southwest. Besides restrictions from fog this morning VFR conditions expected. OUTLOOK...Thunderstorms are likely Tuesday into Tuesday evening. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines NEAR TERM...Haines SHORT TERM...Haines LONG TERM...JGL AVIATION...Haines

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