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
474 FXUS61 KILN 030610 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 210 AM EDT Wed Jul 3 2024 .SYNOPSIS... Hot and humid conditions are expected on Wednesday along with increasing chances for showers and thunderstorms as a cold front approaches from the northwest. This boundary will then remain in the area on the Fourth of July. Embedded mid level disturbances will interact with this boundary, resulting in multiple rounds of showers and thunderstorms. A stronger weather system is expected to move into the Great Lakes and Ohio region Friday into Friday night, continuing the threat for showers and thunderstorms. && .NEAR TERM /THROUGH TONIGHT/... Ongoing fcst remains on track this evening as /mainly/ clear skies, aside from a few 4-5kft clouds from time-to-time, evolve through the near term period. Temps are running about 10-12 degrees above 24 hours ago and this pattern will maintain itself through the night as better LL moisture works its way into the local area. Expect conditions will remain dry locally through sunrise, with southerly winds increasing subtly toward daybreak. PREVIOUS DISCUSSION... Weather remains quiet across the area this afternoon with temperatures topping out in the upper 80s to lower 90s. A weak, low-level trough is moving northward on the western periphery of the surface high pressure to the east, pumping better boundary layer moisture northward through central/northern Kentucky. Most dewpoints in the area are in the 50s, but mesonet stations across Kentucky are already indicating mid to upper 60s dewpoints entering the local area. Light southerly flow will continue to usher in this better moisture over the next few hours before flow becomes more southeasterly this evening. This tongue of moisture will be directed northwestward, combining with the better surface moisture ahead of the approaching front. This moisture will be critical for humidity and thunderstorm development tomorrow afternoon. Even with the better moisture entering the area this evening, no rainfall is expected with forcing remaining quite weak. After the afternoon cumulus dissipates, a few scattered upper level cloud linger into the early evening. Eventually, skies will clear with temperatures dropping into the upper 60s and lower 70s. && .SHORT TERM /THURSDAY/... There is some potential for showers and thunderstorms to be ongoing early Wednesday morning across central Indiana. Whatever remnant activity moves into central Indiana will struggle to survive into the local area due to the corridor of lower dewpoint values across eastern Indiana and western Ohio. Even if the thunderstorms weaken, outflow boundaries and cloud debris will play a role in temperature and rainfall forecasts later in the day. At the same time, low level moisture will continue to improve (low 70s and perhaps mid 70s) as the convergence increases along the boundary. The increasing moisture and forcing along the front/other boundaries will ultimately lead to thunderstorm development during the afternoon and through the evening. All three of the below impacts remain noted in the HWO... Heat: Confidence is fairly high that cloud debris will enter the area through mid-morning. Depending on how quickly this clears, some disruption to heating will be possible. Additionally, low- level moisture will be increasing during the day. Given this uncertainty, local heat conditions may rapidly change from the mid-morning hours into the early afternoon. Then, developing thunderstorms may quickly erode heat advisory conditions that have ultimately developed. The most likely area for a short- fused heat advisory would be across northern Kentucky, southwest Ohio, and southeast Indiana. Severe: Day 2 Slight Risk (Level 2 of 5). With the heating and increasing boundary layer moisture, clusters of strong to severe storms are possible Wednesday afternoon and evening. Damaging wind gusts are the main threat with some hail possible if an updraft split is able to change mean storm motion. At this time, downburst winds appear to be the more likely storm mode with limited ability for organization into bowing segments. Heavy Rain/Flooding: While much of the area remains quite dry, stalled boundaries situated in a very moist atmosphere, in July, should always be viewed as potential heavy rain producers. Ultimately, storm mode and boundary orientation remain the key factors. The latest 18Z HRRR shows how some back-building activity could provide isolated corridors of 2-3"+ into the evening hours. This would be beneficial rain for the abnormally dry conditions, but a few flood advisories may be possible in the heavier/more flood prone areas. Thunderstorm coverage is expected to decrease a little during the overnight activity, but continue mid-level forcing and remnant instability will keep the threat lingering into Thursday morning. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... East-west oriented front will extend across the area at the beginning of the period. High precipitable water and deep warm cloud depths will extend along this same corridor. As a short wave moves across the area, showers and thunderstorms will occur with heavy rain potential and perhaps some damaging winds being the concern. Exactly where that boundary sets up, which latest data suggests will be near I-70, will have a greatest threat of heavy rain with the possibility of training and backbuilding. As that impulse moves off to the east, there will be a relative lull in showers and any storms through late Thursday night. During this time the boundary will lift north. More showers and storms will occur Friday, especially in the afternoon in part due to a pre- frontal trough pushing through the area. Airmass will be the same as on Thursday, so locally heavy rainfall will remain possible although convective elements will be progressive and less prone to training. Damaging wind threat will also persist. The cold front will not move through until Friday evening with the chance of showers and thunderstorms lingering until that passes. High pressure will build in for the weekend and still be influencing the region into Monday. The next cold front will approach and move through the area Monday night into Tuesday bringing the next chance of showers and thunderstorms. Warm, muggy airmass ahead of the first cold front will get replaced by something more seasonal for the weekend. But temperatures and dew points will be rising again early next week ahead of the next system. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... VFR conditions are expected overnight as a mixture of a FEW-SCT cumliform clouds mix with high level convective debris blow off from storms upstream in the middle Mississippi River Valley. Southerly winds will increase some overnight to 10 to 12 knots with gusts up to 20 knots possible by 12Z. There will be a brief period of LLWS at KDAY/KILN/KCVG/KLUK where south/southwest winds of 40 knots at 2000 feet will be possible by a transient low level jet. For today, LLWS threat will end around 12Z. Otherwise, focus will be on the potential for showers and thunderstorms. A cold front will approach our region from the northwest late in the day. It will become hot and humid ahead of this front, leading to moderate instability. Convection allowing models show varying convective initiation timing and coverage, so a blended approach will have to be used at this time. It appears that showers/storms will become induced by either a remnant outflow boundary/mid level weak disturbance or subtle prefrontal trof convergence. Have showers/storms developing in the 18Z to 00Z time frame. Given very moist airmass, MVFR ceilings and IFR or less visibilities will be possible in the stronger storms. For now, will put some MVFR visibilities in the terminals with predominant showers with a VCTS/CB until timing can be better pinpointed. Gusty south/southwest winds between 20 and 25 knots will continue into the afternoon, then diminish between 22Z and 00Z. For tonight, showers/storms should gradually decrease in coverage overnight as the cold front pushing into our northern forecast area weakens and becomes more diffuse. The recent rainfall, if it comes to pass, may help to develop some MVFR ceilings and visibilities late tonight. OUTLOOK...MVFR conditions possible Thursday morning. Thunderstorms possible Thursday through Friday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman NEAR TERM...KC/McGinnis SHORT TERM...McGinnis LONG TERM... AVIATION...Hickman