Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 131908 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 308 PM EDT Wed Mar 13 2024 .SYNOPSIS...
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More warm weather and gusty winds are likely on Thursday ahead of a low pressure and cold front which will cross the area on Friday. With the gusty winds will come higher moisture, and shower and thunderstorm chances will increase with most areas seeing rain at some point from Thursday into Friday. Behind the front the airmass will cool considerably as high pressure builds into the area. Secondary cold fronts will swing through the Great Lakes during the weekend into early next week, reinforcing the cooler air and continuing the mostly dry weather from the upcoming weekend.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Primary concern tonight will be with shower and thunderstorm chances/coverage. Ample sunshine and warm breezes across the ILN CWA early this afternoon, and dew points have held steady in the lower 40s which is keeping humidities in the 30-40% range, so with the more sporadic wind gusts vs yesterday`s more widespread and stronger winds, did not feel a need to message any fire weather concerns into this evening on a larger scale. After midnight, increasing theta-e advection aloft will drive the potential for an arc of showers and perhaps a few elevated storms from southwest to northeast across mainly the northwest half of the ILN forecast area. This is not a high confidence signal across the suite of convective allowing and global ensemble members, however, thus chances along I-71 are maintained in the 20-40% range. A better /spatial and forcing/ signal exists for showers and thunderstorms to develop tonight in Illinois and cross Indiana on an ENE trajectory toward the northwestern third of the ILN forecast area, arriving in the hours before or just after sunrise in west central Ohio. Likely elevated in nature, these are unlikely to be strong / severe but do warrant the maintenance of higher rain chances that were ongoing in the forecast already across west central Ohio in the 10Z-12Z timeframe.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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Expect the cluster of showers/storms mentioned above entering west central Ohio around sunrise to continue on a east-northeast trajectory toward central Ohio during the morning hours, but it is at this point where the forecast begins to lose some degree of certainty, and how long these hold together downstream over central Ohio (or perhaps moving more into northern Ohio) remains to be seen. In general, as a potent mid level speed max ejects northeast owing to height falls digging into the Rockies and with heights rising downstream over the Ohio Valley, activity should have the propensity to either weaken/diminish over central Ohio or lift more north into northern Ohio as forcing diminishes immediately over the ILN CWA, leaving somewhat of an open-warm- sector lull across much of our forecast area from late morning into early mid afternoon. That being said, as this speed max and embedded shortwave arrives into Indiana/Michigan during the afternoon, expect a renewed storm cluster/MCS to develop across ILN/IN and move rapidly toward MI/OH. There are some convective-allowing solutions which develop a rather robust MCS that rides along the synoptic warm front lying either just north of our area or across our northern tier, taking on linear/bowing characteristics. Some solutions ride this activity well north of our area, but there is a general / overarching trend in most guidance /backed up by machine learning probabilities based on GEFS/HREF/ that our northern half of our forecast area is under a threat for severe storms tomorrow that could - if things come together - exceed current Level 1 /Marginal Risk/ categories from the SPC. But the uncertainty tied to the coverage / track of this cluster of storms, coupled with marginal thermodynamics are likely playing a role here. What we do know is that low level and deep level shear /hodograph curvature/ is rather optimal for storm longevity and organization for any MCS or discrete cells which may form, but there is some concern for the level of moistening that can be maintained in an open warm sector scenario. If dewpoints can`t ascend past the mid 50s - which is being hinted by some of the CAMS which have handled low level moisture more optimally this week - overall convection may struggle to maintain intensity outside a more optimal setup with regards to shear/warm front/synoptic forcing with the jet streak. This situation will need to be watched closely, and if a more robust storm cluster can get going in this kind of shear environment across the northern half of the ILN forecast area, all modes of severe weather including a tornado or two will be in play. After the potential afternoon-early evening storm threats, we are not out of the woods as the passing jet streak will begin to push low pressure and associated cold front southeast toward our area later Thursday night into Friday morning, and another wave of storms /likely focused more to the southwest of the ILN CWA/ may impact areas along the Ohio River and points south later in the night. While severe threats with this activity would be less, there would still be ample low level shear in play,as despite the more reduced instability by coming through at such a late time of night.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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Showers and a chance of thunderstorms will continue into Friday morning, but should be tapering off from the northwest through late morning and into the afternoon as the cold front moves southeast of our area. In the developing CAA behind the front, highs on Friday will range from the mid 50 northwest to the mid 60s in the southeast. Surface high pressure will build briefly into the lower Ohio and Tennessee Valleys Friday night into Saturday. This will provide for drier conditions with highs on Saturday in the mid 50s to lower 60s. Mid level short wave energy, embedded in a broader upper level trough, will drop down across the Great Lakes on Sunday, leading to the potential for a few rain showers across our area. Temperatures will continue to cool with highs on Sunday in the mid 40s to mid 50s. A somewhat stronger secondary short wave will rotate through the base of the trough and across the lower Great Lakes and upper Ohio Valley on Monday. This will bring a chance for mainly snow showers to the region as high on Monday will only be in the upper 30s to lower 40s. The upper level trough will shift off to the east and surface high pressure will build into the region through mid week. This will lead to drier conditions and slowly moderating temperatures. Highs on Tuesday will be mostly in the 40s with highs on Wednesday in the upper 40s to mid 50s.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... VFR conditions expected for the most part across the terminals through the TAF cycle, though shower and thunderstorm chances later tonight and Thursday morning at DAY/CMH could threaten some MVFR visibilities and/or ceilings depending on coverage. For the rest of the daylight hours, plenty of sunshine and southwest winds of 8-12kts. There have been some gusts here and there above 15kts at ILN and LCK, but these are not expected to be persistent or widespread. Winds will decrease and back to the south or even southeast this evening. Later in the night - after about 07Z - increasing warmth/moisture aloft will drive the potential for a few showers and storms from southwest to northeast across the area. Uncertainty on the coverage of these is quite high, but maintained these in the CVG/LUK/ILN TAFs as the signal remains in play enough for mention on a few of the models. The better signal is for a larger cluster of showers and a few storms to move out of central Indiana toward DAY/CMH in the hours around sunrise, so maintained the prevailing mention of SHRA with VCTS at these locations as this arc of activity is expected to cross western/central Ohio during the morning hours. Should be some lull or scattering out of rain chances and clouds a the warm front continues to shift north on Thursday, and there is a growing concern/threat of a second complex of showers and storms /which could be strong or even severe/ that moves out of Indiana in the early-mid afternoon into and across many of the terminals after 18Z, likely staying north of CVG/LUK during the afternoon hours, but confidence is low on the track of these storms, with some solutions just grazing the I-70 corridor and DAY/CMH/LCK, and other solutions hitting these TAFs and also ILN with an impacting round of storms in the mid/late afternoon hours. Gusty southwest winds will also be a concern outside of storms on Thursday afternoon with some 30kt gusts not entirely out of the question. OUTLOOK...MVFR ceilings and visibilities likely Thursday night into Friday night with IFR possible. Thunderstorms also possible Thursday into Friday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau NEAR TERM...Binau SHORT TERM...Binau LONG TERM...JGL AVIATION...Binau

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