textproduct: Wilmington

WHAT HAS CHANGED

Showers and storms are possible in the Wednesday to Thursday timeframe when a strong low pressure moves across the Great Lakes region.

KEY MESSAGES

1) A cold front brings showers and storms chances late tonight and Sunday.

2) Cooler temperatures to start the week.

3) Showers and thunderstorms possible Wednesday and Thursday when a strong low is expected to move through the Great Lakes.

DISCUSSION

KEY MESSAGE 1)

Surface high pressure slowly retreats further southeast of the Ohio Valley this afternoon continuing fair weather through the evening hours. High clouds eventually start to stream in from west later today ahead of an approaching surface low and cold front.

Showers and storms are possible late tonight and into Sunday as the aforementioned low moves across the lower Great Lakes and the trailing cold front moves through the Ohio Valley. The severe risk is fairly low since forecast instability is marginal with skinny CAPE profiles, supporting only weak updrafts. However, there will be increasing shear which could aid in storm strength and organization if enough instability does form later on Sunday.

KEY MESSAGE 2)

High pressure builds in behind a cold front late Sunday and moves across the region on Monday and Tuesday. Dry conditions and below average temperatures accompany the surface high through at least Monday night before winds shift back to the south behind the high on Tuesday.

KEY MESSAGE 3)

Medium range global ensemble guidance is showing increasing probabilities of an anomalously strong surface low moving through the Great Lakes on Wednesday and Thursday. Strong upper level winds accompany this surface low. The impressive kinematic profile over the region may overlap with instability ahead of a cold front on Wednesday/Thursday which could end up supporting a severe storm risk. Heavy rain is also possible as anomalously high PWATs are advected in from the southwest. While it is far too early to know exact details regarding the storm risk, the presence of such a strong low in mid June could lead to active weather later this week.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

VFR conditions to start the TAF, but a transition to more MVFR CIGs is expected by 12Z. Moisture returning to the area supports the potential for showers and elevated thunderstorms starting after 06Z. The best thunderstorm coverage is forecast across the southern TAF sites (CVG/LUK), with lower chances to the north.

After 12Z, scattered showers will continue and a few thunderstorms cannot be ruled out, however, the best coverage of thunderstorms is forecast as the cold front drops through the sites, generally between 17-21Z. A wind shift from southwest/west to northwest will take place, and wind gusts around 25 knots will occur. The passage of the cold front will also assist in breaking up the MVFR CIGs. VFR conditions return after 00Z as winds gradually decrease below 10 knots.

OUTLOOK... Thunderstorms possible Wednesday and Thursday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...None. KY...None. IN...None.