Area Forecast Discussion

KEY MESSAGES

- Hot, muggy, and mostly dry weather takes hold for today. Afternoon highs around 90 degrees combined with high humidity will push peak heat indices between 95 and 100 degrees.

- A progressive cold front brings showers and numerous thunderstorms on Friday, with a threat for strong storms with gusty winds and locally heavy rainfall.

- High pressure ushers in a brief break of cooler and drier air for Saturday, before unsettled weather and rain chances return Sunday through early next week.

SHORT TERM

(This evening through Friday night) Issued at 331 PM EDT THU JUN 11 2026

The latest surface analysis shows much of the eastern CONUS is under the influence of the Bermuda High. However, to the west, a potent surface low is moving across the Upper Mississippi Valley and western Great Lakes. The primary low is located in south-central Canada with a cold front trailing south through the Great Lakes, while another surface wave rides along the tail end of the front in the Upper Mississippi Valley. Although most of the synoptic forcing is located well to the northwest of the area, remnant outflow from an MCS that moved toward the region this morning is providing a differential heating boundary. Showers and storms are developing along this boundary this afternoon, but mainly in the Upper Ohio River Valley of eastern Ohio, western Pennsylvania, and West Virginia. Locally, the forecast area is staying dry with temperatures climbing into the upper 80s to lower 90s. Along with these hot temperatures, heat indices are reaching into the low to mid-90s.

Through the rest of the afternoon and overnight, it will continue to feel hot and humid across the area due to temperatures in the upper 80s and dew points in the upper 60s to lower 70s. As mentioned above, a decaying MCS moved across the northern portions of the area this morning and is the focal point for convective development this afternoon. However, the best chances remain north and east of the area, though there is a stray chance of a shower or storm developing this afternoon, mainly north of the Mountain Parkway to the far northeastern portions of the area. Once daytime heating wanes and sunset arrives, any shower or storm that develops, along with the widespread cumulus deck, will dissipate, and clearing skies are expected overnight. Clear skies will allow for fog development in the deepest river valleys of eastern Kentucky. Toward morning, increasing clouds are expected as a cold front dives southeast out of the Ohio Valley and Great Lakes. Like today, the remnants of the morning MCS are forecast to dissipate, with redevelopment occurring on the outflow boundary Friday afternoon.

Friday brings the cold front and remnant MCS to the doorstep of the CWA, providing increased chances for showers and thunderstorms. CAMs are consistent in keeping much of the northwestern portions of the area dry, as the decaying morning MCS is forecast to stabilize that airmass. However, with daytime heating and subsequent destabilization, showers and storms are forecast to redevelop in the afternoon, mainly along and east-southeast of the KY-40/KY-30/I-75 corridor. Forecast soundings ahead of Fridays frontal passage show that a potent thermodynamic environment is expected to develop across the region. Stout moisture advection will be underway ahead of the boundary, but a disconnect remains between the thermodynamic and kinematic profiles. Forecast wind shear values remain meager, with bulk shear values staying less than 20 knots across the entire CWA through FROPA. Even with weak kinematics, steep lapse rates combined with both MUCAPE and MLCAPE ranging from 2,000 to 3,000 J/kg will provide ample instability. Additionally, DCAPE values ranging from 1,200 to 1,400 J/kg point toward a wet microburst environment where damaging outflow winds, some of which could reach severe limits, will be possible. Precipitable water values have started to trend downward but still range from 1.50 to 1.70 inches, lending credit to a heavy rainfall potential. Fortunately, the front is forecast to be progressive, limiting the overall flash flooding threat. Nonetheless, this combination of convective ingredients has prompted a Day 2 SPC Slight Risk for the southeastern portions of the CWA, and a Day 2 Marginal Risk for a tier of counties to the northwest of the Slight Risk contour. A Day 2 WPC Marginal Risk for excessive rainfall is also in effect for the heavy rainfall potential tied to the front. Once frontal passage occurs, skies will clear and weak surface high pressure will build into the area by early Saturday morning. Pre-frontal daytime temperatures on Friday are expected to reach the upper 80s to lower 90s, but weak CAA behind the front will allow overnight lows to drop into the low to mid-60s Friday night.

In short, the forecast transitions from a hot, mostly dry regime dominated by the surface high pressure into a more active, convective period on Friday as a cold front/decaying MCS moves through the region. High moisture and high atmospheric instability will overcome weak wind shear on Friday afternoon, bringing a risk of heavy rainfall and severe wet microbursts, particularly to the southeastern portions of the CWA. This threat will be short-lived, however, as the progressive front clears the area by late Friday night, giving way to high pressure and a noticeably less humid airmass for the start of the weekend.

LONG TERM

(Saturday through Thursday) Issued at 155 PM EDT THU JUN 11 2026

An upper low spinning over Ontario during the short term period will persist there through most of the long term period. Short wave troughs rotating around it will be the main influence on our weather. One of these will be passing over the Great Lakes region on Sunday, working to deepen overall troughing over the eastern CONUS and supporting a cold front which will move through the JKL forecast area from northwest to southeast on Sunday afternoon and evening. Due to the deepening trough, there will be a bit stronger flow aloft and more shear (although nothing phenomenal) than during preceding recent rounds of thunderstorms. Should there be enough instability, some strong storms won't be ruled out on Sunday, but the degree of instability remains uncertain. Once the front and its inclement weather move through, noticeably less humid air will arrive Sunday night and carry into the workweek.

Multiple additional waves will rotate through the eastern CONUS trough Tuesday through Thursday. However, there is much less model agreement on their timing and strength. That being the case, forecast confidence for precipitation drops off considerably after Monday. There is a general consensus that some semblance of an eastern CONUS trough will persist, though, which would prevent any return to oppressive heat and humidity.

AVIATION

(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 143 PM EDT THU JUN 11 2026

Weak surface high pressure will keep the area dry through much of the TAF window. Widespread fair weather cumulus clouds have developed around the 3,500 to 4,500 foot level this afternoon, along with remnant low clouds from a decaying MCS but these clouds should stay VFR before dissipating overnight. Clear skies overnight will give way to increasing and lowering clouds ahead of a cold front that's forecast to dive southeast after 12Z/Friday. PROB30s are in place to account for pulse thunderstorm development ahead of the front through the end of the TAF. Any thunderstorm that develops at or near a TAF could bring brief reduction in category; as well as, gusty and erratic outflow winds. Southwesterly winds are expected throughout the afternoon with gusts upwards of 15 knots, those winds will decrease overnight before picking up again Friday morning ahead of the approaching cold front. Friday winds will be out of the southwest sustained around 10 knots with gusts to 15 knots.

JKL WATCHES / WARNINGS / ADVISORIES

None.