787  
FXUS63 KLSX 021131  
AFDLSX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
631 AM CDT FRI JUN 2 2023  
   
SHORT TERM
 
(THROUGH LATE SATURDAY AFTERNOON)  
ISSUED AT 427 AM CDT FRI JUN 2 2023  
 
THE PRIMARY FOCUS THROUGH SATURDAY WILL THE CHANCES FOR  
DAY TIME SHOWERS AND THUNDERSTORMS AND ABOVE NORMAL TEMPERATURES.  
 
HIGH PRESSURE TO THE NORTHEAST CONTINUES TO PROMOTE LOW LEVEL  
EASTERLY FLOW THROUGH THE SHORT TERM. THIS EASTERLY FLOW WILL  
CONTINUE TO PUSH DRIER AIR THAT AS OF 09Z IS OVER THE OHIO RIVER  
VALLEY INTO THE REGION THROUGHOUT THE DAY TODAY WITH THE HIGHEST  
MOISTURE CONTENT BEING OVER CENTRAL MO. TODAY, AREAS EAST OF THE  
MISSISSIPPI RIVER CAN EXPECT LARGELY CLEAR SKIES WHILE AREAS WEST OF  
THE RIVER CAN EXPECT DIURNAL CU DURING THE DAY. BY SATURDAY, THIS  
DRY AIR WILL ENCOMPASS THE WHOLE AREA LEAVING SKIES MOSTLY CLEAR  
WITH ISOLATED DIURNAL CU.  
 
THE GREATEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE TODAY  
OVER CENTRAL MO WHERE THE MOISTURE CONTENT AND SURFACE INSTABILITY  
IS THE HIGHEST. OVER 50% OF ENSEMBLE MEMBERS SUGGEST SURFACE BASED  
CAPE VALUES IN EXCESS OF 1200 J/KG OVER CENTRAL MO, SUFFICIENT  
ENOUGH TO PROMOTE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS.  
GIVEN THE WEAK SHEAR ENVIRONMENT, PULSE SHOWERS AND THUNDERSTORMS  
ARE EXPECTED. SHOWERS AND THUNDERSTORMS ARE NOT EXPECTED ON  
SATURDAY AS DRY AIR TAKES OVER.  
 
HIGH TEMPERATURES TODAY ARE FORECAST TO BE IN THE UPPER 80S TO LOW  
90S ACROSS THE AREA. THE HIGHEST TEMPERATURES ARE EXPECTED TO BE BE  
IN THE ST. LOUIS METRO AREA AND THE MISSISSIPPI RIVER EASTWARD WHERE  
CLOUD COVER WILL BE THE MOST LIMITED. TEMPERATURES ON SATURDAY WILL  
BE THE WARMEST WITH HIGHS FORECASTED IN THE LOW TO MID 90S. RECORD  
HIGH TEMPERATURES FOR ST. LOUIS ARE LIKELY TO BE CHALLENGED WITH  
TEMPERATURES IN THE MID-90S. THE PREVIOUS RECORD HIGH WAS SET IN  
2011 AT 96 DEGREES.  
 
MMG/GLASS  
   
LONG TERM
 
(SATURDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 427 AM CDT FRI JUN 2 2023  
 
A HIGHER LATITUDE OMEGA BLOCK WILL BE IN PLACE AT THE START OF THE  
PERIOD FEATURING AN ANOMALOUSLY STRONG UPPER HIGH CENTERED NEAR  
LAKE WINNIPEG. RATHER DEEP BUT WEAK LOW-MID LEVEL EASTERLY FLOW  
WILL PERSIST ACROSS THE REGION. WITHIN THIS FLOW REGIME, A VORT  
MAX WILL MIGRATE EASTWARD FROM THE OHIO VALLEY ACCOMPANIED BY A  
SLUG OF "BETTER" MOISTURE AND TRAVERSE THE REGION ON SUNDAY. OTHER  
THAN THE VORT MAX THERE IS A LACK OF FORCING. CUMULATIVELY THE  
VORT MAX/MOISTURE ALONG WITH VERY WEAK DEEP LAYER SHEAR, WOULD  
SUGGEST POTENTIAL FOR ISOLATED-WIDELY SCATTERED DIURNAL PULSE  
THUNDERSTORMS. HIGH TEMPERATURES SUNDAY SHOULD BE A TOUCH COOLER  
THAN SATURDAY, BUT STILL AVERAGING AROUND 10 DEGREES ABOVE NORMAL.  
PERSISTENT LOW-LEVEL EAST-NORTHEAST FLOW WILL BRING SOME DRIER  
AIR INTO THE AREA ON MONDAY. OTHERWISE THERE IS LITTLE IF ANY  
CHANGE TO THE PATTERN AND HIGHS ON MONDAY SHOULD REMAIN ABOVE  
NORMAL AND COMPARABLE TO SUNDAY.  
 
THE OMEGA BLOCK WILL SETTLE EQUATORWARD HEADING INTO TUESDAY AS THE  
LAKE WINNIPEG UPPER HIGH MOVES INTO THE NORTHERN PLAINS AND A LARGE  
DEEP UPPER LOW DIGS SOUTHWARD FROM QUEBEC AND TAKES RESIDENCE OVER  
THE MID-ATLANTIC/NEW ENGLAND REGION. THE EXPANSE OF THE NERN UPPER  
LOW WILL BRING HEIGHT FALLS ALOFT TO OUR REGION AND DRIVE A WEST-  
EAST COLD FRONT ACROSS THE AREA TUESDAY-TUESDAY NIGHT. DEEP MOISTURE  
AND INSTABILITY MAY BE LACKING A BIT WITH THE COLD FROPA, BUT AT  
THIS TIME FRAME THERE IS ENOUGH SUPPORT FOR AT LEAST A LOW CHANCE OF  
SHOWERS AND THUNDERSTORMS.  
 
THE FRONT WILL BRING COOLER AND MUCH DRIER AIR STARTING WITH THE  
FROPA TUESDAY, BUT ESPECIALLY WEDNESDAY AND THURSDAY. THE LATEST  
FORECAST HAS TRENDED COOLER, BUT WE WILL LIKELY SEE ADDITIONAL  
LOWERING OF THE HIGH TEMPS IN UPCOMING FORECASTS THE NEXT FEW DAYS.  
THE 02/00Z ENSEMBLE CLUSTER ANALYSIS SUGGESTS THAT OUR CURRENT  
FORECAST HIGH TEMPERATURES ARE PROBABLY A BIT ON THE HIGH SIDE BY 5  
DEGREES OR SO. ONE CLUSTER WHICH HAS A DEEPER NE TROF AND LOWER  
HEIGHTS INTO THE MID MS VALLEY HAS MEAN HIGH TEMPERATURES AS MUCH AS  
10 DEGREES COOLER WITH HIGHS ONLY IN THE MID-UPPER 70S WEDNESDAY-  
THURSDAY.  
 
GLASS  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)  
ISSUED AT 630 AM CDT FRI JUN 2 2023  
 
LIGHT EASTERLY WINDS WILL CONTINUE THROUGH THE TAF PERIOD WITH  
DIURNAL CUMULUS POSSIBLE IN THE AFTERNOON. THERE IS A CHANCE OF  
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS IN CENTRAL MO  
THROUGH THE AFTERNOON AND EARLY EVENING HOURS. OTHERWISE, VFR FLIGHT  
CONDITIONS WILL PERSIST.  
 
MMG/GLASS  
 

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

 
 

 
 
WFO LSX  
 
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