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
443 FXUS61 KILN 092348 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 748 PM EDT Tue Jul 9 2024 .SYNOPSIS... The remnants of Tropical System Beryl will migrate northeast through the Ohio Valley through Wednesday, bringing rain and storms through early tonight, followed by breezy and seasonably cool conditions during the day Wednesday. Warmer and more humid air will quickly return to the region by the end of the week into the upcoming weekend, with more pronounced rain chances returning by early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Skies have trended partly to mostly sunny for many spots SE of I-71, with the better cloud cover hanging on near/NW of I-71 this afternoon. A few small clusters of SHRA and ISO TSRA will continue to develop and move through srn portions of the ILN FA through late afternoon, with a slow uptick in coverage expected into the evening hours - however the degree of coverage still remains somewhat uncertain. Needless to say, the setup this afternoon through early tonight is atypical of what a "normal" mid-July day/night would feature. The remnants of Beryl will approach and move through the region, with the extratropical low center migrating from the bootheel of MO into nrn IN from late afternoon through late tonight. This, of course, will put us squarely in the "warm sector" of this system, with stronger-than-normal LL and deep- layer flow to work with. The main item of concern as we progress into late afternoon, but more specifically mid/late evening with the arrival of the stronger wind fields, will be discrete/semi- discrete supercells given the elongated/increasingly-curved hodographs, supporting rotating updrafts in just about any sustained activity. The dynamics and kinematics, of course, are quite impressive (H8 LLJ of 40+kts), especially considering the time of the year, but what remains somewhat lacking is a consistent signal for a more favorable LL thermodynamic environment/setup, especially with northeast extent. LL lapse rates are expected to remain rather meager (even in the Tri- State). In fact, there are some indications for an elevated warm layer developing/persisting just above the sfc (within the H9-H8 layer) late into the evening, the presence of which lends itself to considerable uncertainty regarding whether rotation within any of the storms will become surface-based, or rooted near the surface. This will offer a unique challenge to message into the evening as the storms will likely appear on radar aloft (3-5kft) to be rotating quite nicely, but whether that will also be reflected on the lowest 1500ft remains to be seen, especially with NE extent. This appears to very much be a scenario where storms will have the potential to produce brief/weak tornadoes, but likely not much else. The meager LL and thermodynamic environment will likely limit the wind and hail potential, respectively, so the brief transient areas of rotation are going to be the primary focus. Although tornado potential will exist just about anywhere to some extent, especially considering the relatively low LCLs, the primary focus will be near I-71 in the Tri- State/nrn KY extending to near the I-75 corridor, particularly with an arcing line of storms (with embedded mesovortices) between about 02z-06z. The arcing line should weaken with NE extent as it moves into the Miami Valley/central OH after 06z and encounters an increasingly thermodynamically- unfavorable environment with even less instability. The one item that shouldn`t be overlooked will be the torrential rainfall rates with any of the activity through early tonight. PWATs in excess of 2" will overspread parts of the area by this evening, with extremely efficient rainfall rates expected in the heaviest activity. Luckily, the storms should be moving fairly quickly to the northeast, but any brief training or backbuilding will undoubtedly cause localized issues if it occurs in vulnerable/flood-prone locales. The forward motion of the activity should preclude a more widespread flash flood threat, but certainly 1-2" seems very likely in a few spots, especially near/W of the I-75 corridor through this evening. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... As the sfc low migrates into NW OH Wednesday during the daytime, an unseasonably-strong pressure gradient will set up on the ern/srn/wrn flank of the low center, promoting a very unusual breezy and "cool" July day for the local area. There are some indications for ample cloud cover to linger through most of the afternoon, which admittedly could keep deeper mixing in-check just a bit. This being said, there is high confidence in SW/W gusts on the order of 30-35kts Wednesday afternoon especially near/W of I-75 on the backside of the low center late in the day. As the winds go more out of the WNW by 20z, the best potential for a brief window of gusts close to 40kts may evolve in EC IN and WC OH and the Miami Valley between about 20z-22z before the low begins to pull E and the gradient relaxes into the mid/late evening and beyond. Temperatures on Wednesday will be considerably cooler - ranging from the lower/mid 70s northwest to the upper 70s in the southeast. Lows in the lower to mid 60s are expected Wednesday night as skies very slowly clear from W to E toward Thursday morning. && .LONG TERM /THURSDAY THROUGH TUESDAY/... A large area of high pressure building in behind the remnants of Beryl will bring dry weather from Thursday through Saturday. Increasing instability combined with a mid-level disturbance may allow a few showers and thunderstorms on Sunday afternoon. Mainly afternoon showers and storms will be possible on Monday and Tuesday under continued instability and mid-level short wave support. A westerly flow aloft may support MCS development so this will bear watching. Expect temperatures a few degrees below normal to start the period, with highs in the low and mid 80s on Thursday. A warming trend is indicated for the rest of the long term under insolation and warm advection, with highs reaching the 90s in many locations, while isolated spots could see apparent temps around 100. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... The unsettled TAF period really begins after 00Z this evening as remnants of Post-Tropical Cyclone Beryl begin to move into the forecast area. Recent radar reflectivity indicates storms firing south of I-70 and pushing northeast. Anticipate that all TAF sites will have periods of VCTS this evening after 00z. Any storms that move over the TAF sites will likely produce frequent cloud to ground lightning, torrential rain/ reduced VSBYs and brief lowering in CIGs. The heaviest precipitation moves out of the region after midnight and then the widespread lowered CIGs move in. Have widespread low end MVFR in the TAFs, but IFR CIGs might be needed, particularly Wednesday morning after sunrise. These will linger through much of Thursday, before scattering out Thursday late afternoon/evening hours. As the remainder of the post-tropical cyclone moves through the region, winds will pick up substantially on Thursday, as early as 10Z, starting out of the south, before turning southwesterly, then, ultimately, westerly. Sustained winds will be anywhere from 10-20 knots, with gusts up to 30 knots possible through the afternoon hours. Winds decrease around sunset Thursday and shift to out of the north. OUTLOOK...No Significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...KC NEAR TERM...KC SHORT TERM...KC LONG TERM...Coniglio AVIATION...CA