Area Forecast Discussion

KEY MESSAGES

- Frost or light freeze conditions are expected across most of eastern Kentucky late tonight into early Tuesday morning.

- Below normal temperature will last through early Tuesday, followed by warmer weather to last into the weekend.

- The next expectation of area wide rain is not until the weekend.

UPDATE

Issued at 1210 AM EDT TUE APR 21 2026

No significant changes were made to the forecast with mainly just the inclusion of the latest obs and trends for the T/Td/Sky grids as clear skies will promote temperatures dropping toward freezing for the eastern valleys and patchy frost elsewhere. These minor adjustments have been sent to the NDFD and web servers along with a freshening of the SAFs and zones.

UPDATE Issued at 735 PM EDT MON APR 20 2026

23Z sfc analysis shows chilly high pressure of to the northeast of the area in control of our weather. This is working to settle the northerly winds of 5 to 10 mph with a few lingering higher gusts and is keeping skies mostly clear. Currently, temperatures are running in the mid 50s north to the low 60s south. Meanwhile, dewpoints are rather dry, varying from the mid 30s near Lake Cumberland to the mid and upper teens northeast. Have updated the forecast mainly to add in the latest obs and trends for the T/Td/Sky grids. These minor adjustments have been sent to the NDFD and web servers along with forthcoming freshenings of the SPS, NPWs, SAFs, and zones.

SHORT TERM

(This evening through Tuesday night) Issued at 432 PM EDT MON APR 20 2026

Sunny, cool and dry weather dominates eastern Kentucky this afternoon as surface high pressure passes over the Great Lakes. Temperatures range from the mid 50s in the northern foothills to the mid 60s near the KY-TN border while dew points range from the mid 10s north to mid 30s south as drier air continues to filter in on a light northerly breeze.

This will set the stage for a cold and mostly clear night with the threat of frost or a light freeze across the area. The coldest temperatures are expected to occur in northeastern Kentucky valleys where dew points are the lowest and temperatures will be coolest heading into the night. Upper 20s could be quite common there. The remainder of the interior Coalfield valleys east of I-75 and the Pottsville Escarpment are favored to dip into the 30 to 32F range. A Freeze Warning has been issued across the counties with the most freeze prone sheltered valleys. The warning is bordered to the west by a Frost Advisory over the Eastern Bluegrass/northern Pottsville Escarpment and across Laurel and Whitley counties where temperatures should still be could enough for substantial frost with temperatures mostly in the mid 30s. The frost is expected to be most sparse from Rockcastle down to the Lake Cumberland area counties where the southerly return flow should begin to develop late in the night and prevent temperatures from fully bottoming out. Even here though, some patchy to perhaps areas of frost cannot be ruled out in sheltered low lying areas. Across ridgetops, temperatures will generally remain warm enough to avoid anything more than patchy frost at most.

The aforementioned high pressure will have shifted to the east side of the Central Appalachians by 12Z Tuesday while a cold front will be dropping southeast into the Ohio Valley from the Upper Midwest. This will result in a strengthening southwesterly return flow and tightening pressure gradient on Tuesday and Tuesday night. This will bring warm air flooding back north across the area, buoying temperatures back into the mid and upper 70s by afternoon but moisture recoveries will lag with dew points only reaching the 30s to near 40F. GFS BUFKIT mixed layer momentum transfer supports gusts up to around 20 mph during the afternoon. Temperatures dip back into the mid 40s to mid 50s on Tuesday night with more cloud cover moving into the north. There is a small chance of a shower north of the Mountain Parkway toward daybreak on Wednesday.

LONG TERM

(Wednesday through Monday) Issued at 332 PM EDT MON APR 20 2026

Upper level ridging will dominate the beginning of the long term period. On Wednesday, a cold front will meander south from the Great Lakes region, but will become diffuse as it is abandoned by its upper level support. Weak moisture return ahead of the front could potentially support isolated showers and perhaps a rumble of thunder in the northernmost portion of the forecast area (generally north of the Mountain Parkway). However, PoPs remain relatively low at this time (20-40%), with better precipitation chances generally expected closer to the front. Elsewhere, warm temperatures and limited moisture return will allow RH values to approach critical levels. This, in combination with breezy conditions, will allow for elevated fire weather concerns. By Thursday, continued high pressure will allow for temperatures to soar into the 80s, once again leaving afternoon RH values near critical levels. However, a weakening pressure gradient will limit afternoon wind gusts (likely reaching a maximum of 10-15 mph), helping to mitigate fire weather concerns somewhat.

This weekend, a series of shortwaves moving through a longwave trough over the western half of the US will gradually break down upper level ridging, allowing for a wetter pattern to set in. By Friday, southwesterly flow ahead of a sharp cold front over the central United States will usher in a period of more earnest moisture return, leading to gradual dewpoint increases. This front will enter Kentucky on Saturday, finally allowing for widespread and appreciable rainfall. As of now, the best chance for showers and thunderstorms seems to be from Friday night through Saturday. However, models diverge with respect to the synoptic pattern this weekend, particularly with respect to the amplitude of pre- existing upper level ridging and when this ridge will breakdown. The structural evolution of these upper level features will be critical for precipitation timing and QPF this weekend. This QPF uncertainty is reflected in LREF guidance, which maintains a ~0.50 discrepancy between 25th and 75th percentile accumulations this weekend. Regardless, confidence is high (80-90%) in receiving at least a quarter of an inch of rain across the forecast area this weekend. Looking ahead, quasi-zonal flow should allow for a more active weather pattern early next week.

AVIATION

(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 139 AM EDT TUE APR 21 2026

VFR conditions will persist through the period. Southwesterly winds will gust near 20 kts west of the foothills on Tuesday afternoon.

JKL WATCHES / WARNINGS / ADVISORIES

Frost Advisory until 9 AM EDT this morning for KYZ044-050-051- 058>060-069-080-085.

Freeze Warning until 9 AM EDT this morning for KYZ052-086>088- 104-106>120.