063
FXUS63 KLSX 131736
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1236 PM CDT FRI JUN 13 2025
KEY MESSAGES
- NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS MUCH OF
THE AREA TODAY. LOCALLY HEAVY RAINFALL COULD RESULT IN AN
ISOLATED INSTANCE OF FLASH FLOODING. COVERAGE OF SHOWERS AND
THUNDERSTORMS WILL BE LOWER OVER THE WEEKEND.
- A WARMING TREND INTO NEXT WEEK WILL SUPPORT SOME HIGH
TEMPERATURES REACHING THE 90S F, THREATENING THE LONG RUN OF
SUB-90 F TEMPERATURES.
SHORT TERM
(THROUGH LATE SATURDAY AFTERNOON)
ISSUED AT 310 AM CDT FRI JUN 13 2025
AN UPPER-LEVEL CLOSED LOW IS EVIDENT ON EARLY MORNING MID-LEVEL
WATER VAPOR IMAGERY ACROSS NORTHEASTERN OK/SOUTHWESTERN MO. A BROAD
AREA OF WEAK LOW TO MID-LEVEL MOISTURE TRANSPORT AND WAA AT THE
FORWARD FLANK OF THE LOW HAS RESULTED IN A BLOSSOMING OF SHOWERS AND
STRATIFORM RAIN ACROSS MOST OF THE CWA EARLY THIS MORNING.
SHOWERS/RAIN SHOULD DECREASE IN COVERAGE AFTER SUNRISE AS THEIR
PARENT FORCINGS WEAKEN, ALLOWING FOR 500 TO 1000 J/KG OF MUCAPE TO
BECOME AVAILABLE BY AFTERNOON WITH DEEP TROPOSPHERIC MOISTURE
DESPITE POOR LAPSE RATES AND MODEST INSOLATION. THIS INSTABILITY AND
BROAD ASCENT ASSOCIATED WITH THE LOW MOVING OVERHEAD IS ANTICIPATED
TO YIELD NUMEROUS SHOWERS AND SOME THUNDERSTORMS AGAIN THIS
AFTERNOON. WEAK DEEP-LAYER WIND SHEAR (20 KT OR LESS) AND POOR LAPSE
RATES WILL LIMIT THE POTENTIAL FOR ANY SEVERE THUNDERSTORMS, BUT
DEEP WARM CLOUD DEPTHS, ANOMALOUS PW APPROACHING 2", AND SLOW CELL
MOVEMENT BENEATH THE LOW WILL SUPPORT LOCALLY HEAVY RAINFALL THAT
COULD RESULT IN ISOLATED FLASH FLOODING. ADDITIONALLY, THE LATEST
HREF LPMM HAS VERY LOCALIZED RAINFALL AMOUNTS OF 2 TO 4" THAT MAY BE
ENOUGH TO EXCEED FLASH FLOOD GUIDANCE. CLOUDS AND PRECIPITATION WILL
LIMIT HIGH TEMPERATURES TODAY TO THE MID-70S TO NEAR 80 F.
AS THE UPPER-LEVEL CLOSED LOW ADVANCES FURTHER EASTWARD AND
INSTABILITY ALSO DECREASES, CAMS INDICATE THAT MOST SHOWERS AND
THUNDERSTORMS WILL DISSIPATE AND EXIT THIS EVENING BUT ISOLATED
SHOWERS AND PERHAPS A THUNDERSTORM WILL LINGER OVERNIGHT ALONG/SOUTH
OF I-44 (MO) AND I-55 (IL). CLOUDS WILL ALSO PERSIST THROUGH THE
NIGHT ACROSS MUCH OF THE CWA, BUT THE WESTERN BACK EDGE OF EXTENSIVE
STRATUS COULD REACH CENTRAL AND NORTHEASTERN MO AND PROMOTE PATCHY
FOG WITH ABUNDANT BL MOISTURE AND LIGHT WINDS.
IN THE WAKE OF THE LOW, MID-LEVEL HEIGHT RISES WILL RESULT IN LOWER
COVERAGE OF MORE DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS ON
SATURDAY. HREF PROBABILITIES OF MEASURABLE RAINFALL ARE HIGHEST EAST
OF THE MISSISSIPPI RIVER AND AROUND 40 TO 60 PERCENT, CLOSEST TO THE
DEPARTING LOW WITHIN THE WEAKEST CONVECTIVE INHIBITION. DRIER BL AIR
WILL BE SLOW TO FILTER INTO THE CWA, BUT A TRANSITION IN MORNING
STRATUS TO MORE CUMULIFORM CLOUDS BY AFTERNOON SUPPORTS GREATER
INSOLATION THAN TODAY AND WARMER HIGH TEMPERATURES AROUND 80 TO 85 F
PFAHLER
LONG TERM
(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 310 AM CDT FRI JUN 13 2025
SATURDAY NIGHT INTO SUNDAY MORNING, MODEL GUIDANCE SIGNALS
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS EASTERN KS AND
SOUTHWESTERN MO AT THE NOSE OF A NOCTURNAL LLJ IN CONJUNCTION WITH A
PASSING MID-LEVEL PERTURBATION/SHORTWAVE TROUGH. THIS EVOLUTION
COULD SEND AN MCV INTO THE CWA LEADING TO A CONDITIONAL CHANCE OF
SHOWERS AND THUNDERSTORMS BUT IT IS ONLY CAPTURED BY 20 TO 30
PERCENT OF ENSEMBLE MODEL GUIDANCE AT THIS POINT. WITH OVERALL LESS
CLOUDS THAN PREVIOUS DAYS, A WARMING TREND WILL PERSIST THROUGH
SUNDAY.
GLOBAL MODEL GUIDANCE ARE IN GENERAL AGREEMENT THAT THE UPPER-LEVEL
FLOW PATTERN WILL TRANSITION FROM NORTHWESTERLY EARLY NEXT WEEK TO
SOUTHWESTERLY BY MID-WEEK WITH FREQUENT SHORTWAVE TROUGHS OR MID-
LEVEL PERTURBATIONS. THIS PATTERN WILL FAVOR A GRADUAL WARMING TREND
TO ABOVE AVERAGE AS WELL AS MULTIPLE OPPORTUNITIES FOR SHOWERS AND
THUNDERSTORMS, POSSIBLY ORGANIZED INTO MCSS. THE DETAILS OF THIS
PATTERN AND THE PREFERRED TIMEFRAMES OF SHOWERS AND THUNDERSTORMS
ARE DIFFICULT TO DETERMINE AT THIS LEAD TIME, BUT MOST ENSEMBLE
MODEL GUIDANCE ARE AT LEAST IN SOME AGREEMENT ON SHOWERS AND
THUNDERSTORMS ACCOMPANYING A WEAK COLD FRONT SOMETIME LATE WEDNESDAY
INTO THURSDAY AS A LONGER WAVELENGTH UPPER-LEVEL TROUGH ARRIVES. THE
NBM IS IN RELATIVELY GOOD AGREEMENT ON TEMPERATURES NEXT WEEK (3 TO
5 F INTERQUARTILE RANGE) AND ADVERTISE SOME HIGH TEMPERATURES
REACHING THE 90S F THAT THREATEN THE GOING STREAK OF SUB-90 F
TEMPERATURES AT KCOU AND KSTL. THE HIGHEST PROBABILITIES OF 90+ F
HIGH TEMPERATURES ARE TUESDAY AND WEDNESDAY BENEATH A LOW-LEVEL
THERMAL RIDGE ALONG AND SOUTH OF THE MISSOURI RIVER THAT ARE
GENERALLY 60 TO 80 PERCENT. WITH DEWPOINTS IN THE 70S F, THESE DAYS
WILL HAVE SOME OF THE HIGHEST AFTERNOON HEAT INDEX VALUES WE HAVE
SEEN SO FAR THIS SEASON, REACHING THE MID-90S TO NEAR 100 F IN THE
WARMEST LOCATIONS. IT IS ALSO IMPORTANT TO NOTE THAT SHOWERS AND
THUNDERSTORMS HAVE THE POTENTIAL TO IMPACT THESE TEMPERATURES.
PFAHLER
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1227 PM CDT FRI JUN 13 2025
A CUTOFF LOW PRESSURE SYSTEM HAS MADE FOR A DIFFICULT AVIATION
FORECAST THIS AFTERNOON. CIGS HAVE BEEN GRADUALLY TRENDING UPWARD
THROUGH THE LATE MORNING, BUT ARE STILL BOUNCING BETWEEN IFR AND
MVFR AT MOST LOCATIONS. GUIDANCE CONSENSUS DEPICTS CIGS FINALLY
GETTING ABOVE 1000 FT AT ALL TERMINALS BY THE EARLY AFTERNOON.
MEANWHILE, A WING OF LIGHT TO MODERATE RAIN HAS BEEN SLOWLY
PIVOTING NORTH THROUGH THE REGION. THE MOST WIDESPREAD RAIN HAS
DEPARTED THE ST. LOUIS METRO TERMINALS, BUT IT'S PIVOT POINT IS
ATOP CENTRAL MISSOURI, KEEPING COU AND JEF IN MORE PERSISTENT
PRECIPITATION.
AS WE MOVE THROUGH THE AFTERNOON, SCATTERED SHOWERS AND PERHAPS A
FEW THUNDERSTORMS WILL DEVELOP ACROSS SE MO AND SOUTHERN IL,
PUSHING NORTH TOWARD THE TERMINALS. I'VE JUST GONE WITH PROB30S
FOR NOW AT THE METRO TERMINALS, BUT THIS MAY NEED TO BE ADJUSTED
TO A TEMPO GROUP SHOULD IT BECOME APPARENT THAT THOSE TERMINALS
WILL BE IMPACTED BY A SHOWER.
PRECIP CHANCES WILL TAPER OFF THIS EVENING, BUT GUIDANCE IS IN
STRONG AGREEMENT THAT CIGS WILL TANK TO NEAR OR BELOW AIRPORT
MINIMUMS OVERNIGHT.
BSH
CLIMATE
ISSUED AT 620 PM CDT WED JUN 11 2025
ST LOUIS STILL HASN'T REACHED 90 YET IN 2025. THIS PUTS 2025 IN
THE TOP 20 ALL TIME LATEST DATES OF THE FIRST 90 DEGREE
TEMPERATURE, AND THE LATEST IN AT LEAST 30 YEARS (JUN 19, 1995).
THE ALL TIME LATEST FIRST 90 DEGREES WAS JULY 4 IN BOTH 1961 AND
1912. RECORDS BEGAN IN ST LOUIS IN 1874.
COLUMBIA HAS ALSO NOT YET SEEN A 90 DEGREE READING IN 2025. THE
LATEST DATE OF FIRST 90 DEGREES ON RECORD WAS JULY 14, 1904.
RECORDS BEGAN IN COLUMBIA IN 1890.
QUINCY REACHED 90 DEGREES ON MAY 15 OF THIS YEAR.
BASED ON THE CURRENT FORECAST, OUR NEXT BEST CHANCE TO SEE 90
DEGREES IS AROUND JUNE 17.
KIMBLE
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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