Area Forecast Discussion
Issued by NWS Wilmington, OH
Issued by NWS Wilmington, OH
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
529 FXUS61 KILN 131834 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 234 PM EDT Sat Jul 13 2024 .SYNOPSIS... A few isolated showers, with perhaps a rumble of thunder or two, will be possible today. Better chances for periodic showers and storms may evolve Sunday and Monday before widespread storm activity moves through the region Tuesday into Wednesday. Drier and cooler conditions will return toward the end of the workweek. However, very warm and humid conditions are expected through the first part of the workweek. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Partly cloudy skies have evolved area-wide thanks to a fairly healthy Cu field that continues to percolate about the area this afternoon. Along with this will be the development of some very isolated/disorganized SHRA, with perhaps a rumble of thunder or two. Coverage and intensity of storms should be a notch below what parts of the area have experienced over the past few days owing to lack of forcing, lift, and shear. And as such, most areas will stay dry through the near term period. With coverage of clouds and SHRA a bit less widespread than in past few days, temps have nudged a bit warmer -- a degree or two either side of 90 for most spots. This, combined with dewpoints in the mid to upper 60s will push heat index values into the mid 90s by late afternoon. Tranquil, but muggy, conditions are expected overnight underneath mostly clear skies as lows dip into the upper 60s to lower 70s. Some patchy river valley BR/FG may again be possible in vulnerable locales. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... The focus of the short term period is going to be potential for both storms and heat. Although there is some uncertainty regarding both, especially in terms of specific timing and location, there is a slightly stronger signal that has emerged in some of the short-term guidance suggesting that a decaying MCS will work its way into the nrn OH Vly after daybreak Sunday. While the focus of this activity will initially be to the N of the local area where the better forcing/shear will be collocated, the MCS may lay out a thermally-induced boundary in the nrn/wrn OH Vly into early Sunday afternoon. With some good diurnally-driven instby expected to develop, it won`t take much to initiate, or perhaps maintain, some convection stemming from an MCS influence of some sort. While the shear and forcing will be increasingly meager with southward extent, a better pooling of richer LL moisture/instby will be positioned to the SW of the best shear/forcing, suggesting redevelopment in some capacity on the SW flank of a decaying MCS and/or boundary as we progress into Sunday afternoon. With the activity largely cold-pool driven, this suggests that ISO/SCT convection may redevelop (initially off to the W/NW of the ILN FA) before progressing to the E/SE through the local area during the heart of the afternoon/early evening. As with any convection that is largely driven from mesoscale boundary positioning/interactions, there are uncertainties regarding coverage/location/timing with pretty much all of the specifics. But... from an ingredients perspective, there will be the potential for ISO/SCT storms posing a gusty wind threat for many spots near/N of the OH Rvr and especially near/N of I-71 into the afternoon. Some isolated damaging wind will be possible with any of this activity given the 1500-2000 J/kg MLCAPE, steep LL lapse rates, and favorable DCAPE environment. The other aspect of the weather Sunday, one that should not be overlooked, will be the combination of heat and humidity that will lead to the potential for some heat index values around 100 degrees across central and southern portions of the region on Sunday. This may be more widespread if storm activity is more isolated and/or delayed than current forecasts. However, given the prospect of storms/convectively-driven cloud cover, confidence was not yet high enough to issue a Heat Advisory. The setup on Sunday night offers its own set of challenges as well as there are indications for another S/W to move to the ESE through the nrn OH Vly, with westerly midlevel flow developing to its W/SW, suggesting a backbuilding convective setup somewhere near/N of the I-70 corridor. Of course, the convection evolution and environment augmentation that occurs during the daytime period will undoubtedly play a role in exactly where storm activity may redevelop/persist during the nighttime hours. For now, have maintained a chance PoP near/N of I-70 to account for this potential. && .LONG TERM /MONDAY THROUGH SATURDAY/... Summertime pattern continues to start the extended period. Weak mid- level ridging will likely build east into the Ohio Valley Monday into early Tuesday. Can`t rule out an isolated storm or two Monday with low-level moisture and persistent instability, however the primary weather story during this time will be increasing heat under the ridge. Blended guidance shows max heat indices from 100 to 105 degrees Monday and near 100 degrees on Tuesday. By later on Tuesday, digging shortwave energy will cause a cold front to sag southeast into the Ohio Valley late in the day. Showers and storms will increase in coverage ahead of this feature Tuesday afternoon and continue into Wednesday as the front moves through the CWA. Cooler air arrives behind the front Wednesday and continues to provide relief to the heat through the end of the week. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... VFR conditions have evolved area-wide, with SCT/BKN VFR Cu already draped across the region. While a stray brief SHRA cannot be completely ruled out through sunset, coverage of any activity should be limited/disorganized enough that will keep fcsts dry at this point. Skies should trend mostly clear after sunset, with perhaps a few VFR Cu lingering about from time to time. Some VSBY reductions are likely again late tonight at KLUK given light/stagnant flow. After 12z, focus will shift to one or more decaying clusters of storms that will be approaching from the W/NW, likely approaching the local area after 18z. The sites should remain dry through 18z, but there is the expectation for at least ISO SHRA/TSRA to overspread the area between 18z-00z, potentially impacting the latter part of the KCVG 30-hr TAF. Light WNW winds around 6-8kts will be maintained through sunset before going light/VRB/calm overnight. WSW winds around 10-12kts, with gusts 15-20kts, are expected ahead of any ISO/SCT SHRA/TSRA activity Sunday afternoon. OUTLOOK...Thunderstorms possible at times Sunday through Wednesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...KC NEAR TERM...KC SHORT TERM...KC LONG TERM... AVIATION...KC