Area Forecast Discussion
Issued by NWS Wilmington, OH
Issued by NWS Wilmington, OH
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012 FXUS61 KILN 101029 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 629 AM EDT Thu Oct 10 2024 .SYNOPSIS... High pressure will continue to dominate the weather pattern across the Ohio Valley through the end of the work week with several more sunny, mild days and clear, crisp nights. A weak cold front will sag into the Ohio Valley on Saturday morning where it will stall temporarily, awaiting a ripple of low pressure to move along it Saturday night into Sunday morning, and then swinging a cold front across the area as the low departs. This series of events will allow for a few showers or thunderstorms across the Ohio Valley later in the weekend as temperatures remain mild. Behind the cold front, much cooler air with frost potential will sweep into the Ohio Valley for the early part of next week, with another week of mainly dry weather on tap. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Any river valley fog that forms here in the next few hours before sunrise will mix out and dissipate by mid morning, with yet another day of blue skies and brilliant sunshine expected as surface high pressure remains in control of the area. There is a little more concerted push of low level cooling on northeast flow today vs. yesterday, with 925mb temperatures dropping by 2-3C from yesterday. That should result in high temperatures being a few degrees below yesterday`s values, and with some 5-7kt easterly winds and plenty of sunshine, have allowed surface dewpoints to mix out a little more than most model 2m dewpoint forecasts. All in all, a spectacular autumn afternoon with the warm sunshine and light winds, that may feel a bit chilly in the shade given the very dry low level airmass. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... With -1 sigma PWAT anomalies continuing over the ILN CWA tonight (focus on Scioto Valley), and the surface high pressure consolidating somewhat and sagging across the heart of the forecast area around 06Z with light winds, tonight offers a higher chance of frost where the combination of the coolest low level temps combines with the deeper dry air and driest soils (central Ohio). Am right on the fence with issuing a Frost Advisory for areas north/east of Columbus, and perhaps down the Scioto Valley into Pike/Ross counties, as this area per HREF ensemble probabilities has the highest potential to see lows in the mid 30s. While patchy frost is certainly going to be likely in sheltered and low lying areas, just am not confident enough on this forecast cycle for a widespread frost event to hoist an advisory on this shift, though one may certainly be warranted as newer data filters in. Valley fog will also likely develop in the fog prone areas. Shortwave trough on Friday afternoon will be shifting across central Canada on fast/progressive northern stream flow. This system shears/deamplifies as it spreads quickly eastward into southeast Canada on Friday night, with height falls and any meaningful kinematic forcing remaining well north of the area, for the bulk of the night. A low end / outside chance that as the decaying frontal zone sags toward areas north of I-70 toward sunrise Saturday, a few showers may approach this area, but forcing/moisture advection is quite weak, and overall moisture associated with this feature will be weakening with time, so am keeping Friday night dry in its entirety. Low level warm advection ahead of the decaying frontal zone will focus mainly west/north of the forecast area on Friday, but there will be enough push to send temperatures well into the 70s under plentiful sunshine. Minimum humidity will fall back into the 30-35% range as dewpoints again mix back a little in the afternoon into the lower 40s, so getting close enough to begin to have a little concern for elevated fire weather concerns, but winds should remain < 10kts the bulk of the day which mitigates a good deal of the concern for a larger scale fire weather threat. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Frontal zone discussed above will sag into the ILN forecast area on Saturday and come to a halt on southward progression, in response to much stronger height falls/shortwave trough/potent upper jet digging into the Upper Mississippi River Valley. Warm advection on increasing southwesterly flow into and atop this frontal zone may promote the development of a few showers on Saturday morning north of I-70, but with advection magnitudes and ambient moisture being quite anemic, these chances are quite low. As the strong shortwave trough digs further into the Great Lakes, weak low pressure will develop and begin rippling along the front as the front begins to lift northward as a warm front. This should continue/increase the chances of showers and a few thunderstorms on Saturday afternoon across central and northern Ohio as it will likely take rather dry parcels to be lifted isentropically atop the front to get something going. Further deepening of the mid and upper level trough as it spreads southeast into Michigan on Saturday night will allow the surface wave to deepen as well, and there is a more notable 925-850mb layered moisture transport axis that develops and points into the northern 1/2 of the ILN forecast area. Will likely see a better chance/higher coverage of showers and a few storms (elevated instability) Saturday night into Sunday morning as the deepening surface wave runs from Chicago to Buffalo. Cold front attendant to this wave will sweep through on Sunday from west to east, and there may be enough gathering of lower level instability along/ahead of this front to continue chances of showers and storms areawide. Given the deepening wave, winds will respond both ahead and behind the cold front, and some gusts to 30 mph will be likely making for a breezy / warm afternoon ahead of the front, and a rapidly cooling/gusty Sunday night behind the front. Monday-Wednesday - coldest air of the autumn season sets up shop as the upper trough continues to mature over the Great Lakes. Good agreement in ensemble probabilities / anomalies that this will bring the first areas or widespread frost potential on one or multiple mornings, depending on coverage of any stratocumulus clouds that will likely exist in the strong cold advection regime, and how quickly winds can abate. Probably looking at Tuesday/Wednesday mornings as providing the highest frost potential. Once any cold advection sprinkle/shower threat subsides on Monday, much of next week again looks dry as the dry October continues. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... VFR conditions expected across the TAF sites through the next 24 hours, with the exception of valley fog potential at KLUK through about 13Z this morning, and again tonight after about 06Z. Of the two potential valley fog episodes affecting LUK, have a little higher confidence that tonight`s fog will impact KLUK with a higher degree of coverage and intensity. Early this morning, satellite imagery does show a great deal of valley fog in the Ohio River channel east of KLUK, and there is still potential that this fog will develop into the KLUK airfield between 7A and 9A. Low confidence of this occurring, so have maintained an hour of TEMPO MVFR fog at KLUK this morning between 12Z and 13Z. Light winds /easterly to northeasterly/ today under clear skies. Winds should go light/variable this evening and with cooler temperatures, think the river channels will fog in a little heavier tonight, so given guidance signals and consistency went ahead and dropped visibility at KLUK via TEMPO to 1/2SM. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau NEAR TERM...Binau SHORT TERM...Binau LONG TERM...Binau AVIATION...Binau