827
FXUS63 KLSX 281736
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1236 PM CDT FRI MAR 28 2025
KEY MESSAGES
- WELL ABOVE NORMAL TEMPERATURES (HIGHS IN THE UPPER 70S-LOWER 80S)
ARE EXPECTED TODAY ALONG WITH SOUTHWEST WINDS GUSTING TO 30-35+ MPH.
- SHOWER CHANCES RETURN LATE TONIGHT AND INTO SATURDAY, MAINLY
ACROSS SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS.
- SEVERE THUNDERSTORMS ARE LIKELY ON SUNDAY AFTERNOON AND EARLY
EVENING WITH ALL HAZARDS POSSIBLE INCLUDING LARGE HAIL, DAMAGING
WINDS, AND TORNADOES.
SHORT TERM
(THROUGH LATE SATURDAY AFTERNOON)
ISSUED AT 344 AM CDT FRI MAR 28 2025
SHOWERS HAVE RECENTLY REDEVELOPED FROM SOUTHWEST AND SOUTH-CENTRAL
IL ACROSS SOUTHEAST MO IN RESPONSE TO WAA AND WEAK MOISTURE
CONVERGENCE ASSOCIATED WITH A SOUTHWESTERLY LLJ. THIS ACTIVITY
SHOULD TREK EAST AND I WOULD THINK DISSIPATE NEAR TO SHORTLY AFTER
SUNRISE. A SMALL CHANCE OF SHOWERS AND THUNDERSTORMS WILL
CONTINUE FOR A FEW HOURS PAST SUNRISE ACROSS NE MO/WC IL DUE TO A
MIGRATORY WEAK MID-LEVEL VORT MAX AND ASSOCIATED FORCING.
OTHERWISE WARM AND WINDY ARE WORDS OF THE DAY. A PRONOUNCED LOW-
LEVEL WAA REGIME WILL BE IN PLACE WITH FAVORABLE LOWER TROPOSPHERIC
SOUTHWESTERLY FLOW AND A DEFINED THERMAL RIDGE, AND THIS SHOULD
YIELD HIGHS SOME 15-25 DEGREES ABOVE NORMAL. IF IT WEREN'T FOR
CLOUDS THIS MORNING AND INCREASING CLOUDS AGAIN THIS AFTERNOON, I
WOULD PROBABLY BOOST THE CURRENT HIGHS BY ANOTHER 2-3 DEGREES.
SOUTHWEST WINDS WILL GUST TO 30-35+ MPH.
TONIGHT LOOKS RATHER MILD, WITH LOW-LEVEL SOUTH-SOUTHWEST FLOW
AND CLOUDS KEEPING TEMPS ELEVATED. THE UPPER LOW/TROF OVER TX WILL
BE LIFTING NORTHEAST AND A LEAD IMPULSE WITHIN THE TROF AND
MOISTURE CONVERGENCE WITH THE LLJ SHOULD BRING SHOWERS TO
SOUTHEAST MO AND PARTS OF SOUTHWEST IL OVERNIGHT. THE COVERAGE OF
SHOWERS SHOULD EXPAND ON SATURDAY TO THE SOUTHEAST HALF OF THE
CWA, AS WHAT IS LEFT OF THE DAMPENING TROF LIFTS THROUGH THE LOWER
MS VALLEY. CLOUDS AND PRECIPITATION WILL ALSO SUPPRESS TEMPERATURES
IN THE AFOREMENTIONED REGION WITH THE WARMEST HIGHS ACROSS
CENTRAL AND NORTHEAST MO.
GLASS
LONG TERM
(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 344 AM CDT FRI MAR 28 2025
THE PERIOD FROM SATURDAY NIGHT-LATE WEDNESDAY LOOKS RATHER
ACTIVE.
THE NEXT FORMIDABLE PROGRESSIVE UPPER TROF WILL MOVE INTO THE
CENTRAL/SOUTHERN PLAINS ON SATURDAY NIGHT, AND THEN ADVANCE INTO
THE MIDDLE MS VALLEY ON SUNDAY, AND EXIT TO THE EAST ON SUNDAY
NIGHT. THERE STILL REMAIN DIFFERENCES IN THE MODEL GUIDANCE WITH
THE SPEED/POSITION OF THE TROF AND HENCE THE ATTENDANT ADVANCING
SURFACE COLD FRONT. WE BEGIN TO SEE WEAK HEIGHT FALLS SPREAD INTO
THE REGION LATE SATURDAY NIGHT AND THE SURFACE COLD FRONT
SOMEWHERE ACROSS WESTERN MO BY 12Z SUNDAY. PRESENT INDICATIONS
SUGGEST THAT THUNDERSTORMS COULD MOVE FROM WESTERN MO INTO CENTRAL
MO DURING THE OVERNIGHT PERIOD, ROUGHLY 6-12Z SUNDAY. HOWEVER
VARIATIONS IN THE POSITION OF THE FRONT, DEGREE OF AVAILABLE
INSTABILITY, AND POTENTIAL FOR SOME CAPPING IN THE WARM SECTOR
LOWER CONFIDENCE IN THE SEVERE POTENTIAL (WHICH LOOKS LOW AT THIS
TIME.)
ALTERNATIVELY, DESPITE THE DIFFERENCES IN THE SPEED/POSITION OF
THE UPPER TROF AND ADVANCING COLD FRONT ON SUNDAY, CUMULATIVELY
THE GUIDANCE IS SHOWING AN INCREASINGLY FAVORABLE SET-UP FOR
SEVERE THUNDERSTORMS, ESPECIALLY DURING THE AFTERNOON AND EARLY
EVENING. IN THE WAKE OF THE MORNING SHOWERS AND STORMS, AMPLE
HEATING COMBINED WITH SURFACE DEW POINTS OF 60+, AND STEEP MID-
LEVEL LAPSE RATES SHOULD YIELD SEASONABLY ROBUST SBCAPE OF
1500-2000+ J/KG. THE COMBO OF LARGE SCALE FORCING WITH THE TROF
AND FRONTAL CONVERGENCE SHOULD SUPPORT DEVELOPMENT OF A BROKEN
LINE OF THUNDERSTORMS BETWEEN 19-21Z NEAR OR JUST EAST OF
COLUMBIA. SOUTHWESTERLY DEEP LAYER SHEAR VECTORS OF 40-60 KNOTS
AND THE MORE ORTHOGONAL ORIENTATION WITH RESPECT TO THE FRONT
WOULD SUGGEST SEMI-DISCRETE SUPERCELLS WOULD BE THE FAVORED MODE.
ALL SEVERE HAZARDS ARE POSSIBLE. THE AFOREMENTIONED THERMODYNAMIC
CHARACTERISTICS AND STRONG WIND SPEEDS ALOFT FAVOR LARGE HAIL AND
DAMAGING WINDS, AND FORECAST HODOGRAPHS EXHIBIT NOTABLE LOW-LEVEL
CURVATURE AND LENGTH YIELDING 0-1 KM SRH OF 250+ J/KG SUPPORTING
POTENTIAL FOR TORNADOES.
DRY AND TRANQUIL WEATHER IS EXPECTED MONDAY IN THE WAKE OF THE UPPER
TROF/COLD FRONT AS SURFACE HIGH PRESSURE MOVES INTO THE MS VALLEY.
HIGH TEMPERATURES WILL BE QUITE A BIT COOLER, LARGELY IN THE 50S.
ANOTHER STRONG UPPER TROF IS FORECAST TO IMPACT THE REGION AROUND
THE MIDDLE OF NEXT WEEK, HOWEVER THERE IS CONSIDERABLE SPREAD IN THE
POSITION AND STRENGTH OF THE UPPER TROF. THE LREF CLUSTER ANALYSIS
HAS A CLUSTER WITH A TROF POSITION AS FAR WEST AS INTERMOUNTAIN
REGION AND AS FAR EAST AS THE WESTERN FRINGES OF THE MISSISSIPPI
VALLEY AS AN EXAMPLE. GIVEN THIS DIFFERENCE, THERE IS LOW CONFIDENCE
IN THE TIMING OF THE TROF/COLD FRONT AND DEGREE OF INSTABILITY THAT
WILL BE PRESENT BUT IT COULD END UP BEING NOTEWORTHY.
GLASS
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1233 PM CDT FRI MAR 28 2025
DRY AND VFR CONDITIONS WILL CONTINUE INTO TONIGHT BEFORE SHOWERS
ENTER THE FORECAST AREA FROM THE SOUTH. THESE SHOWERS WILL
INCREASE IN COVERAGE TOMORROW MORNING AND CEILINGS WILL DROP TO
MVFR AREAWIDE. IFR CEILINGS ARE POSSIBLE WHERE RAIN IS EXPECTED
(SOUTHEAST MISSOURI/SOUTHERN ILLINOIS). CONFIDENCE IN IFR
CONDITIONS IMPACTING THE ST. LOUIS METROPOLITAN TERMINALS IS TOO
LOW TO INCLUDE IN THE TAFS AT THIS JUNCTURE. OTHERWISE, TODAY'S
WIND GUSTS WILL DIMINISH TONIGHT BEFORE INCREASING AGAIN TOMORROW
AFTERNOON.
JAJA
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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