Sunrise 6:17 AM   Sunset 7:44 PM Moonrise 2:51 PM   Moonset 3:34 AM

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FXUS63 KLSX 192311 AFDLSX

Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 611 PM CDT Fri Apr 19 2024

KEY MESSAGES

- Seasonably cool weather is forecast through the weekend, with frost potential both Saturday and Sunday nights.

- Dry weather expected until next Tuesday.



SHORT TERM
THROUGH SATURDAY NIGHT/...
Issued at 309 PM CDT Fri Apr 19 2024

Dry but seasonably cool conditions are expected through the short term. This will come as a surface ridge of high pressure extending from the northern Plains into the Ohio River Valley will dominate the sensible weather through the short term. Lows tonight, with light winds and mostly clear skies, will fall into the mid 30s to lower 40s. Continuing modest cold air advection tomorrow will keep temperatures on the cool side with highs in the mid 50s to mid 60s. Tomorrow night, the area becomes more under the influence of the surface ridge allowing for another night of good radiational cooling. This will drop temperatures into the 30s CWA-wide and as such, a frost advisory will likely be needed for much of the forecast area.

LONG TERM
UNDAY THROUGH THURSDAY/...
Issued at 309 PM CDT Fri Apr 19 2024

The surface ridge of high pressure will continue to be the main feature of interest as we move into the beginning extended period. The surface ridge will continue to dominate the area on Sunday providing weak mixing. As such, temperatures are only expected to rise into the upper 50s to mid 60s. The ridge axis moves directly over the forecast area Sunday night providing another night of good radiational cooling as temperatures again fall into the 30s. A frost advisory will again likely be needed Sunday night. The surface ridge finally will slide south of the area by Monday afternoon allowing WAA to get underway. This will allow temperatures to return to near seasonal normals with highs in the mid 60s to near 70. Monday night into Tuesday, a upper level trough will dig from the northern Plains into the Upper Midwest forcing a cold front into the area. This will bring the next chance for showers and thunderstorms. Severe weather is not anticipated as MUCAPE values of 400J/kg will be a limiting factor. Will the cold frontal passage not expected until later in the day Tuesday, highs should still reach the upper 60s to lower 70s. Conditions will dry out for Wednesday as a surface ridge builds into the area under northwest flow aloft keeping highs in the mid 60s to near 70. Thursday, a upper level trough will dig from the Great Basin into the eastern Rockies lead shortwave ejecting out ahead of this system will move into the area bringing the next chance for thunderstorms. Storm activity will hold highs in the mid 60s to near 70.

AVIATION
(For the 00z TAFs through 00z Saturday Evening)
Issued at 609 PM CDT Fri Apr 19 2024

Dry and VFR conditions are expected through the period with northerly winds increasing over 10 knots with gusts to 20 knots on Saturday afternoon.

Britt

LSX WATCHES/WARNINGS/ADVISORIES
MO...None.
IL...None.

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