Sunrise 6:33 AM   Sunset 8:35 PM Moonrise 3:40 AM   Moonset 3:43 PM

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FXUS61 KILN 050140 AFDILN

AREA FORECAST DISCUSSION National Weather Service Wilmington OH 940 PM EDT Sat May 4 2024

SYNOPSIS
A warm and moist airmass will remain in place across the region into the middle part of next week, leading to occasional periods of showers and thunderstorms into Thursday. Slightly cooler and drier air will return by the end of the week, although rain chances may persist at times into next weekend.

NEAR TERM /UNTIL 6 AM THIS MORNING/
In a very moist air mass, a broad and nebulous region of ascent ahead of a shortwave has led to continuous shower and thunderstorm development this evening. As the atmosphere is now a bit more worked over, and diurnal heating has diminished, there has been a gradual downward trend in both coverage and intensity of storms. These storms earlier this evening were in a regime of weak flow, with propagative effects contributing significantly to their motion, and some storms seemingly anchoring to previous outflow boundaries or other small-scale features. Though isolated, some areas received as much as 3-4 inches of rainfall, with very close to 5 inches in southern Highland County OH.

With PoPs diminishing overnight, one additional concern is fog potential. Conditions remain moist and stagnant, and fog is likely to form, especially in areas that received rainfall. Have added patchy fog to the grids for all locations, but definitely see some possibility of a few spots having more significant reductions in visibility.

Previous discussion > A very weak/broad LL low center (perhaps a remnant MCV)
continues to drift to the NNE through the ILN FA, providing a focus for renewed convective development this afternoon amidst an uncapped environment. This feature remains evident on both radar and satellite loops, with the center migrating NNE through the Miami Valley as of early this afternoon. SHRA/TSRA continue to develop and move about this "circulation," moving in various directions in response to the weak cyclonic flow.

Activity remains incredibly disorganized, owing to an anomalously- meager flow regime that remains entrenched across the region, with little more than 10kts through the lowest 15kft of the profile as sampled on the 04.12z KILN RAOB. This being said, SBCAPE on the order of about 1000J/kg has developed (with no cap) in parts of the area, according to the latest mesoanalysis, allowing for the development of numerous updrafts.
But with the incredibly weak shear in place, there are questions about just how strong the updrafts will be able to get, suggesting that the severe potential still remains quite low. In fact, the greatest concern (albeit still relatively low), seems to be the potential for brief heavy downpours leading to ponding of water in isolated instances. But such an occurrence should remain relatively spotty in nature (despite the widespread coverage of activity), owing to lack of clustering/backbuilding. The activity may attempt to organize more into clusters as we progress into early evening, especially for central/south-central OH, but the severe and flooding potential should still be minimal.

It is not out of the realm of possibilities to see a few funnels develop this afternoon given the setup of an incredibly moist BL (low LCLs) amidst very subtle stretching along the boundary and directional shear in the lowest part of the profile (augmented somewhat by the MCV). Similar to Friday, this is not an environment that supports severe weather or tornadoes/damage, but the prospect of a few funnels developing beneath the strongest updrafts is non- zero this afternoon/evening, so it is mentioned here for awareness purposes.

As we progress later into the evening, coverage of SHRA/TSRA should decrease from W to E past sunset, perhaps lingering for several hours closer to midnight in parts of central OH.
Although a few spotty SHRA courtesy of a decaying cluster moving in from the W will be possible in SE/EC IN between about 04z-08z, do think that most spots locally remain dry for the overnight.

With a few peeks of sunshine emerging this afternoon, temps are responding in the wake of early day convection for parts of the area. In fact, temps have rebounded into the mid 70s for many spots, with slightly cooler temps residing in the Tri- State where clouds have persisted the longest. The environment, however, remains incredibly humid, especially by early May standards, with sfc DPs generally in the lower/mid 60s. This will remain the case through tonight, inhibiting lows from dipping too much.

Past midnight, there are some indications for fog development if skies can remain sufficiently clear. But the prospect of the development of some stratus may hinder fog development beyond just patchy in nature (particularly in areas that receive(d)
appreciable rainfall today). Nevertheless, brief/patchy VSBY reductions may be an item to contend with if traveling late this evening/tonight, especially if brief clearing is able to develop.

SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/
More unsettled weather is on tap for Sunday, although not as much so as has been the case yesterday or today. In fact, guidance has trended slightly drier with the FROPA during the afternoon, with the greatest chance for a few ISO/SCT storms in the afternoon residing E of I-71 in parts of central/south- central OH. Coverage should remain SCT at best locally, with indications for a /slightly/ faster progression of the front into/through the local area. In fact, the front should be near I-71 into early afternoon, with locales further N/W in the post-frontal environment during peak diurnal heating. This should translate to /mainly/ dry conditions N/W of I-71 on Sunday, with some much-welcome drier air /briefly/ building into the area from the NW Sunday evening/night.

It will be an unseasonably warm day Sunday ahead of the front, with highs topping out in the lower 80s in the lower Scioto Valley, N KY, and central and SW OH, with mid 70s back to the W in WC OH and EC IN. Winds will shift to out of the WNW behind the front, allowing for sfc DPs in the mid 60s to slowly dip into the mid 50s by the evening. Guidance has trended slightly more aggressive with the infiltration of drier air Sunday evening/night, moreso than is being currently depicted by the blend. Would not be surprised at all to see DPs in the lower 50s reach near the OH Rvr by late Sunday night as midlevel S/W approaches from the SW toward daybreak Monday. This will allow for renewed pcpn chances very early Monday morning in SE IN and N KY as lows dip into the mid 50s near/N of I-70 to lower 60s near/S of the OH Rvr.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
This period will feature unsettled weather thanks to disturbances containing plentiful moisture on a persistent southwest flow aloft.

The first mid level short wave due to arrive on Monday will interact with a warm front, producing the likelihood for showers and thunderstorms, mainly over the southern half of the ILN area. Two potent surface lows will bring the categorical threat for showers and thunderstorms Tuesday and Wednesday, with stronger winds enhancing storm strength and structure, resulting in a chance for severe thunderstorms each day. A few additional disturbances will provide chances for showers and thunderstorms Thursday through Saturday. Heavy rain will be possible through the period as well, thanks in part to precipitable water values remaining above an inch.

Temperatures will stay above normal through most of the period, before falling below normal next weekend under an decreasing geopotential heights and a northwesterly low level flow.
Highs are forecast to range from the upper 60s to mid 70s Monday, rising to the low 80s by Wednesday, before falling to the mid 60s to low 70s on Friday. All locations may be limited to the 60s on Saturday.

AVIATION /02Z SUNDAY THROUGH THURSDAY/
A few showers and thunderstorms will continue to impact the TAF sites for the next hour or two, with occasional MVFR conditions.
Dry conditions are then expected for the majority of the overnight hours, with light winds. MVFR to possibly IFR visibilities are expected to develop, along with MVFR ceilings, by morning.

A few showers could occur during the early morning, but the chances are too low to include in the TAFs. Similarly, some additional showers may develop in the early afternoon. A VCSH has been included for KCMH/KLCK, but the chances appear too low to include elsewhere. MVFR ceilings are expected to lift to VFR by late morning / early afternoon.

Westerly winds are expected tomorrow, shifting to the north tomorrow evening. Magnitudes should remain 10 knots or less.

OUTLOOK...Thunderstorms are possible at times each day from Monday through Thursday. MVFR conditions are possible Monday morning and Tuesday morning.

ILN WATCHES/WARNINGS/ADVISORIES
OH...None.
KY...None.
IN...None.

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