172
FXUS63 KLSX 191838
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
138 PM CDT SUN APR 19 2026
KEY MESSAGES
- WARMER AND MOSTLY DRY WEATHER IS EXPECTED FOR THE FIRST HALF OF THIS
WEEK.
- THE POTENTIAL FOR WIDESPREAD SHOWERS AND THUNDERSTORMS RETURNS
TO THE FORECAST LATE THIS WEEK.
SHORT TERM
(THROUGH LATE MONDAY NIGHT)
ISSUED AT 138 PM CDT SUN APR 19 2026
A WEAK COLD FRONT IS PUSHING THROUGH THE NORTHERN FORECAST AREA THIS
AFTERNOON, ALLOWING A COOL AIRMASS TO GRAZE NORTHEAST MISSOURI
THROUGH SOUTH-CENTRAL ILLINOIS TONIGHT AND RESULTING IN SIMILAR
TEMPERATURES TO LAST NIGHT. SEEING AS LITTLE TO NO FROST DEVELOPED
THIS MORNING, CONFIDENCE IS LOW IN WIDESPREAD FROST BUILDING
TONIGHT. HOWEVER, RADIATIONAL COOLING WILL BE AT PLAY, SO THE
POTENTIAL FOR PATCHY FROST TO DEVELOP ON ELEVATED SURFACES IS HIGHER
THAN YESTERDAY. THE COOL AIRMASS WILL PUSH EAST ON MONDAY, OPENING
THE REGION BACK UP TO LOW-LEVEL SOUTHWESTERLY FLOW BY THE AFTERNOON.
WEAK WAA WILL WORK IN TANDEM WITH A SECOND DAY OF CLEAR SKIES TO
LIFT AFTERNOON HIGHS INTO THE LOW 60S TO LOW 70S - JUST A TOUCH
WARMER THAN TODAY.
JAJA
LONG TERM
(TUESDAY THROUGH NEXT SUNDAY)
ISSUED AT 138 PM CDT SUN APR 19 2026
THE PRESSURE GRADIENT IN THE LOW-LEVELS WILL TIGHTEN OVER THE MID-
MISSISSIPPI VALLEY ON TUESDAY AS LOW PRESSURE TO OUR NORTH PUSHES
INTO HIGH PRESSURE TO OUR SOUTHEAST. THE STRONGER FLOW WILL ADVECT
MUCH WARMER AIR INTO THE REGION WITH WIDESPREAD MID TO UPPER 70S
FORECAST FOR HIGHS TUESDAY AFTERNOON. AFTER A SIMILARLY WARM
WEDNESDAY, TEMPERATURES WILL ROCKET INTO THE LOW-80S THURSDAY
AFTERNOON AHEAD OF OUR NEXT NOTABLE SYSTEM. DETERMINISTIC MODELS
MATCH EACH OTHER WELL, ALL PLACING A SOUTHWEST-NORTHEAST ORIENTED
COLD FRONT IN NORTHWESTERN MISSOURI AT 06Z FRIDAY. THE SET-UP LOOKS
SIMILAR TO WHAT WE'VE BEEN SEEING THESE PAST COUPLE OF WEEKS: A COLD
FRONT IN THE EASTERN PLAINS INITIATES CONVECTION THAT'S WEAKENING BY
THE TIME IT REACHES THE EASTERN HALF MISSOURI AFTER SUNSET. HOW
QUICKLY IT DOES OR DOESN'T WEAKEN WILL DETERMINE OUR POTENTIAL FOR
STRONGER THUNDERSTORMS. THE COLD FRONT IS FORECAST TO CLEAR THE CWA
TO THE SOUTH LATE FRIDAY BEFORE BUCKLING BACK NORTHWARD AS A WARM
FRONT AND USHERING ANOTHER CHANCE OF RAIN THIS WEEKEND.
JAJA
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1149 AM CDT SUN APR 19 2026
DRY AND VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. A WEAK
FRONT IS SHIFTING WINDS TO NORTHERLY AS IT PASSES THROUGH THE
AREA. BETWEEN THIS AFTERNOON AND TOMORROW AFTERNOON, WINDS WILL
VEER TO SOUTHEASTERLY. GUSTY WINDS WILL BECOME LIGHT THIS EVENING
BEFORE INCREASING TO NEAR 10 KTS TOMORROW MORNING.
JAJA
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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