Area Forecast Discussion
Issued by NWS Wilmington, OH
Issued by NWS Wilmington, OH
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127 FXUS61 KILN 211835 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 235 PM EDT Sat Sep 21 2024 .SYNOPSIS... Warm conditions will continue through Sunday. A cold front will move through the region Sunday night into Monday, bringing more seasonable temperatures for the start of the work week. This will also result in episodic chances for showers and thunderstorms through Tuesday, with a great deal of uncertainty in the forecast for the latter half of the upcoming week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... The earlier SHRA/TSRA has departed the local area to the SE, leaving abundant sunshine with a narrow corridor of Cu in its immediate wake near/S of the I-71 corridor. Expect that skies will become increasingly clear as we progress later into the day as the remnant moisture mixes out from N to S. In fact, what has occurred thus far today across central/nrn parts of the ILN FA is reminiscent of a "dewpoint bomb" wherein dewpoints have plummeted about 15-20 degrees from AM values with good diurnal mixing. This has allowed for dewpoint depressions on the order of 40-45+ degrees and RH values below 20% stretching from EC IN through central OH, with much higher dewpoints near/S of the OH Rvr. Luckily, the wind is light, so pronounced fire weather concerns are not anticipated. Highs today will top out in the lower 90s for many spots. Further to the S, where cloud cover is more widespread and dewpoints are much higher (lower/mid 60s), highs may top out only in the upper 80s in parts of N/NE KY. Temps will drop quickly/abruptly this evening/overnight with very dry air, mainly clear skies, and light/calm winds. Went above temp guidance for this afternoon, but below guidance for temps tonight, with lows in the upper 50s to lower 60s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... The drier air entrenched across the region tonight into Sunday morning will be shunted to the E into the afternoon, with a fairly pronounced dewpoint gradient expected to go along with it as some richer LL moisture advects in from the W during the afternoon. But it will take some effort to truly moisten the profile, with an expectation that an approaching band of SHRA, with embedded TS, will erode with eastward extent. The SHRA may initially be falling from a deck at about 8-10kft, with quite a bit of dry air to overcome in the LL. This is shown well even on the typically more moisture-robust guidance, with a rather deep layer of dry air in the bottom 8-10kft to overcome, especially during the onset. So while there will most certainly be some virga and perhaps some sprinkles, the prospect of appreciable measurable rainfall drops off rather abruptly near/E of I-75 Sunday afternoon. With some more expansive cloud cover moving in during the afternoon from the W, temps on Sunday will be warmest in the E (lower 90s), with mid 80s favored near/W of I-75. An additional S/W will move into the region Sunday evening through early Sunday night, but will again encounter an increasingly-unfavorable environment locally (after sunset) with eastward extent. So more of the same is on tap Sunday evening/night, wherein approaching SHRA/TSRA from the W should decrease in coverage with eastward extent, providing little more than perhaps a brief period of RA (and generally less than a tenth of any inch) for any one location. While there still should be /some/ precip Sunday evening/night for many locales, the SCT nature of the activity lends itself to PoPs being trimmed rather significantly from previous fcst cycles, generally topping out at only 50-60%. && .LONG TERM /MONDAY THROUGH SATURDAY/... A more active pattern will be in place for the long term. Models continue to be in general agreement through Wednesday with more variability beyond that time. While there is at least some rainfall potential throughout the long term, the greatest likelihood of precipitation is Monday and especially Tuesday. Breezy conditions are also expected on Tuesday. Kept the model blend low end pops for beyond Wednesday with greater uncertainty in place. With precipitation chances and increased cloud cover during the extended, temperatures will be lower than what has been in place. High temperatures in many locations will be in the 70s with some 80s also possible southeast of Interstate 71 on Monday. Lows will be in the 50s and 60s. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... The earlier SHRA/TSRA activity has shifted well to the SE of the local terminals, with SCT VFR Cu lingering about for KILN and points S as some remnant LL moisture gradually mixes out. This VFR Cu should wane in coverage for KILN/KCVG/KLUK by late afternoon into early evening before skies go mostly clear for the overnight period. Aside from a few cirrus from time-to-time, skies should be mainly clear from 00z until about 15z when some additional mid/high level moisture moves in from the W. This will be accompanied by a decaying band of SHRA, which will attempt to work eastward into the afternoon, but will encounter dry air with eastward extent. So there is some uncertainty in just how far E the activity makes it, but have included a VCSH at the 30-hr KCVG for now to indicate potential for some brief SHRA. There could be some brief MVFR VSBY restrictions at KLUK in the several hours around daybreak, but confidence in this occurring is still somewhat low. Calm/light/VRB winds overnight will go more out of the S at 5-10kts after 15z Sunday. OUTLOOK...Thunderstorms possible Tuesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...KC NEAR TERM...KC SHORT TERM...KC LONG TERM... AVIATION...KC