textproduct: Wilmington

WHAT HAS CHANGED

No major changes to the key messages. Added a mention of fog to the forecast this morning.

KEY MESSAGES

1) Potential for severe thunderstorms today and tonight. Gusty winds occur Friday behind a cold front.

2) Temperatures above normal today. Areas of fog this morning.

3) Below normal temperatures early next week.

DISCUSSION

1) Potential for severe thunderstorms today and tonight. Gusty winds occur Friday behind a cold front.

Strong southwesterly mid level flow with deepening low/trof as 5H jet of 90-100 KTs rotates around the base of the trof thru from the Central Plains and Mid MS Valley today and into the Great Lakes tonight/Friday. In the WAA field ahead of deepening surface low pressure expect elevated convection to pivot thru ILN/s northern counties across west central Ohio this morning. Do not expect this convection to be severe.

As the mid level flow increases across the area surface low pressure is expected to advance east into the Mid Mississippi River Valley this afternoon. This will push a warm front through the area with surface dewpoints expected to increase into the upper 50s and lower 60s. Showers and scattered thunderstorms are expected to develop into southwestern portions of the area (eastern Indiana, north central KY and southwest Ohio ) by mid afternoon and then spread northeast across the entire region thru the afternoon into early evening. Expect a high shear low CAPE environment with effective bulk shear around 60 kts and MUCAPE values between 250-750 J/kg.

Given the environment - some of these storms will be capable of producing severe weather. The threats include large hail, damaging winds, and isolated tornadoes with the primary threat occurring between 5pm and 10pm.

Also, PWAT values increase to 300 percent of normal - especially in the Tri-State region. Although the system is progressive - given the anomalously high moisture and a moist ground, if storms train across an area localized flooding will also be a threat.

The severe weather threat remains very conditional due to limited instability and the indication that the best instability may only exist for a few hours before trends decrease into the evening. Will continue to message the severe weather threat and localized flood threat in HWO and one-pager.

The cold front moves through early on Friday, with the deep surface low pressure (sub 990 mb) to the northwest leading to an opportunity for mixing of stronger winds aloft to the surface. Applying momentum transfer technique to forecast soundings yields wind gusts of 35 to 40 mph Friday afternoon - with the highest gusts across eastern Indiana and west central and central Ohio. NBM solution looks a little low which tends to be observed in CAA cases so increased wind gusts up to 5 kts.

KEY MESSAGE 2) Temperatures above normal today. Areas of fog this morning.

Under the influence of WAA fog and stratus was developing across the southern portions of ILN/s FA (northern KY and southern Ohio) where skies had cleared. These low clouds are advecting north. At the same time a canopy of thick high level clouds was streaming into the northern FA. This may work to inhibit the restriction to visibility. Have allowed the stratus and fog to overspread the entire area from the south and added this mention to the forecast but have held off on the mention of dense fog. Another warm day is in store for the area on the warm side of strong low pressure to the west. Expect highs to be around 20 degrees above normal ranging from the lower 60s north to the upper 60s south. Records for today are rather warm and look safe - CVG 74 set 1939, DAY 70 set 1939, CMH 70 set in 1939 and 2018.

KEY MESSAGE 3) Below normal temperatures early next week.

As the trough digs into the northeast US, a northwesterly flow pattern across the area will offer a period of below normal temperatures early next week. The coldest period will be Monday into Monday night, with highs in the lower and middle 30s, dropping into the teens overnight into Tuesday morning.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Stratus and fog has developed across the area this morning. LIFR ceilings are generally the rule with visibilities varying and bouncing from LIFR to IFR. The widespread fog and stratus will be slow to improve and will continue to affect the TAFs thru mid morning. Conditions should gradually improve trough mid to late morning with VFR conditions developing.

A warm front will lift north across the region through the day ahead of a cold front approaching from the west. This will lead to a developing chance for showers and thunderstorms this afternoon into this evening with the best chances between 23Z to 05Z. Some of the storms may be strong to severe. A period of LLWS is also possible later this evening into the overnight hours as winds aloft increase.

A surface cold front will sweep east thru the TAF sites late in the TAF period. Gusty southwest to west winds will develop in the wake of the front.

OUTLOOK...Surface wind gusts of 30 to 35kt are likely behind a cold frontal passage early Friday.

ILN WATCHES/WARNINGS/ADVISORIES

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