Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 181742 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 142 PM EDT Wed Oct 18 2017 .SYNOPSIS... High pressure will keep dry air and mainly clear skies over the region through the week. Temperatures will gradually warm as the high moves slowly east. && .NEAR TERM /THROUGH TONIGHT/... Quiet weather as sprawling 1028mb surface high pressure just southeast of the forecast area continues to drift toward the Atlantic Coast. 18.12Z KILN sounding was anomalously dry with tropospheric PWAT at about a third of an inch...which is about 45% of normal. Very little, if any, clouds are expected today, with abundant sunshine allowing for some locations to push toward a 30-35F diurnal rise, which is typical for a very dry mid-October day. Some southerly breeze on the backside of the high will bring some modest winds to the open areas of eastern IN/western OH, with lightest winds in the Scioto Valley and northeast Kentucky closer to the departing high. Tonight, added some valley fog in the far east/southeast parts of the forecast area /Scioto Valley and associated tribs/ and this may need to be expanded in further updates. Approaching very weak/dry cold front may bring enough pressure gradient to keep things stirred up but fcst soundings still showing a very stable boundary layer after sunset. Expect min temps tonight to be a little warmer thanks to said gradient, though some upper 30s will still be possible in the far east/southeast portions of the area, and much warmer west where winds and perhaps a few clouds will keep temps in the 40s. && .SHORT TERM /THURSDAY/... The surface ridge axis will shift a little east into Thursday as a dry cold front pushes east/southeast into the Great Lakes. Again, only a few cirrus is expected, with perhaps a FEW-SCT cumulus clouds developing along ahead of the frontal boundary in our far northwest late in the day Thursday. Southwest to west winds ahead of the front along with sunshine will boost highs into the lower 70s. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Under an amplifying mid-level ridge over the eastern half of the CONUS, a sprawling area of very dry surface high pressure will be moving slowly east on Thursday night, still maintaining control of the weather situation over the Ohio Valley for another couple days. Aside from a very weak cold front stalling out (and then returning north) in the northern Ohio valley on Thursday night into Friday, there will be little change in the overall pattern through Friday night. Low-level warm advection, with gradually increasing 925mb temps, will allow for Friday to be slightly warmer than Thursday. As confidence has increased in a more amplified pattern on Saturday, with deep-layer flow becoming more southerly over the Ohio Valley, there is greater confidence as well in temperatures being warm for the first day of the weekend. If the forecast for max temps in the middle to upper 70s verifies, it will be about ten degrees above normal. This looks to be the warmest day of the entire forecast period. On Sunday, a sharp but narrow trough will begin its progression eastward across the Mississippi Valley, eventually reaching the Ohio Valley at some point between then and Monday. Model timing agreement remains somewhat sub-par with this system, and the differences are primarily focused around the interaction between the southern end of the trough (which may form a cut-off low) and the strong jet stream pushing east across the northern tier of states. Unfortunately, this time frame remains in an unstable part of the forecast cycle, with GFS/ECMWF run-to-run consistency performing poorly. With the above in mind, PoPs will be kept in the chance range until this really gets locked in a little better. As of now, the greatest precipitation chances appear to be during the Sunday night forecast period, possibly continuing into Monday. Once the trough and its associated cold front pass through the area, there appears to be potential for a larger upper trough to move into the Great Lakes late on Monday and into Tuesday, which should provide two things -- much cooler temperatures and continued chances for rain. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... VFR conditions expected through the period, although some valley fog is likely to plague KLUK as it has in recent mornings. Clear skies this afternoon into tonight as flow begins to drop off with boundary layer cooling. Don`t expect winds to go calm however as increasing gradient will offset radiational component to a degree, so expect light SSWLY flow to maintain in the 3-6kt range at most sites through the night. Given how dry the boundary layer is, this should keep most fog at bay. However sheltered valleys may drop off enough to form a shallow fog layer after 07Z, so included this at KLUK. Expect winds to be a little stronger out of the southwest on Thursday but expect very few clouds aside from a little cirrus. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman NEAR TERM...Binau SHORT TERM...Hickman LONG TERM...Hatzos AVIATION...Binau

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