070
FXUS63 KSGF 281956
AFDSGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
256 PM CDT MON APR 28 2025
KEY MESSAGES
- SLIGHT RISK (2 OUT OF 5) FOR STRONG TO SEVERE THUNDERSTORMS
LATE TONIGHT THROUGH TUESDAY EVENING. PRIMARY HAZARDS ARE
DAMAGING WIND GUSTS AND LARGE HAIL, THOUGH A TORNADO CANNOT BE
RULED OUT.
- FLOOD WATCH IN EFFECT FROM 7 AM TUESDAY THROUGH 7 AM THURSDAY
WITH A SLIGHT (2 OF 4) TO MODERATE (3 OF 4) RISK FOR EXCESSIVE
RAINFALL. MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS WILL
RESULT IN WIDESPREAD EXPECTED AMOUNTS OF 2 TO 4 INCHES, WITH
LOCALIZED AMOUNTS UP TO 4 TO 7 INCHES.
- SHOWER AND THUNDERSTORM CHANCES CONTINUE DURING THE DAY
THURSDAY. THEREFORE, ANY LINGERING FLOOD IMPACTS MAY CONTINUE
FOR AREAS RECEIVING MORE HEAVY RAINFALL.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 300 PM CDT MON APR 28 2025
MID-LEVEL WATER VAPOR IMAGERY SHOWS A DEEP AND ELONGATED
POSITIVELY-TILTED TROUGH EXTENDING FROM SW CALIFORNIA UP THROUGH
NORTHERN ND. AN UPPER-LEVEL JET ON THE EAST SIDE OF THE AXIS
STRETCHES FROM NM TO MN. JET DYNAMICS IS THEN FORCING A DEEP 996
MB LOW-PRESSURE SYSTEM OVER MN WITH A DRYLINE STRETCHED SOUTH
ACROSS THE PLAINS AND A COLD FRONT STRETCHED WEST INTO THE
NORTHERN ROCKIES. WINDS HAVE INCREASED WITH THE DEEPENING LOW
PRESSURE SYSTEM. 15-25 MPH SOUTHERLY WINDS WITH GUSTS UP TO
25-35 (AND INFREQUENT GUSTS UP TO 40 MPH) HAVE BEEN OBSERVED.
THESE WILL CONTINUE UNTIL SUNSET TODAY.
ADDITIONALLY, AN ASSOCIATED WARM FRONT HAS LIFTED THROUGH THE
AREA BRINGING HIGH TEMPERATURES IN THE 80S AND DEWPOINTS IN THE
LOWER TO MIDDLE 60S. MUGGY AND UNSTABLE!
SLIGHT RISK FOR SEVERE STORMS LATE TONIGHT THROUGH TUESDAY:
OUR 12Z BALLOON SOUNDING NOTED OVER 1000 J/KG MUCAPE ABOVE A
VERY STOUT CAPPING INVERSION OF -350 TO -500 J/KG CIN. WITH A
CONVECTIVE TEMPERATURE OF 91 F (WE SHOULDN'T GET ANYWHERE NEAR
THERE TODAY), AND A FORECAST SBCIN OF -95, CAPPING SHOULD KEEP
ANY STORMS FROM DEVELOPING THIS AFTERNOON AND EVENING. SOME
ELEVATED ECHOES HAVE BEEN NOTED ON RADAR AS SYNOPTIC ASCENT
OVERLAPS THE MOISTURE. SOME OF THESE LIGHT SHOWERS COULD MAKE IT
INTO OUR AREA THIS AFTERNOON/EVENING, BUT ARE NOT EXPECTED TO BE
SURFACE-BASED. THAT BEING SAID, IF A STORM WERE TO SOMEHOW BREAK
THROUGH THE CAP, THE ENVIRONMENT WILL BE SUPPORTIVE OF
SUPERCELLS WITH ALL HAZARDS. THIS WOULD MAINLY BE ALONG AND WEST
OF I-49 IF IT OCCURRED, BUT THIS IS A VERY LOW CONFIDENCE
SCENARIO (5-10%).
THE BETTER CHANCE FOR STRONG TO SEVERE THUNDERSTORMS EXISTS AS
THE COLD FRONT MOVES IN FROM THE NW AFTER 3 AM TONIGHT. OUR
ENVIRONMENT WILL BE CHARACTERIZED BY 1000-2000 J/KG MUCAPE
WITHIN 35-45 KTS OF EFFECTIVE BULK SHEAR WHICH IS SUPPORTIVE FOR
SEVERE THUNDERSTORMS. THEREFORE, SOME STRONG TO SEVERE
THUNDERSTORMS WILL BE POSSIBLE ALONG THE FRONT IN OUR
NORTHWESTERN COUNTIES EARLY TUESDAY MORNING. GIVEN MUCH OF THE
INSTABILITY EXPECTED TO BE ELEVATED HAIL UP TO QUARTERS WILL BE
THE MAIN HAZARD WITH THESE. THEN, GIVEN THE STRONGER FORCING
ALONG THE COLD FRONT, WITH MAINLY BOUNDARY-PARALLEL SHEAR, WIND
GUSTS UP TO 60 MPH WILL ALSO BE POSSIBLE IF A MORE LINEAR MODE
DEVELOPS. TORNADO RISK SHOULD BE VERY LOW AS LONG AS INSTABILITY
REMAINS ELEVATED, THOUGH WE CANNOT RULE OUT ONE OR TWO IF A
SURFACE-BASED STORM EVOLVES ALONG THE FRONT.
THE ABOVE SCENARIO IS IF STORMS FORM ALONG THE FRONT. AN
ADDITIONAL SCENARIO IS A COMPLEX OF STORMS THAT MOVES IN FROM OK
DURING THE SAME TIMEFRAME. IN THIS SCENARIO, POTENTIAL HAZARDS
AND TIMING ARE THE SAME, BUT THE LOCATION MAY BE CLOSER TO I-44.
THE COLD FRONT IS THEN EXPECTED TO STALL SOMEWHERE ALONG THE
I-44 CORRIDOR DURING THE DAY TUESDAY AS THE UPPER-LEVEL JET'S
PROGRESSION SLOWS AND HEIGHT FALLS CEASE. THIS WILL KEEP THE
MOIST AND UNSTABLE AIRMASS ALONG AND SOUTH OF I-44, BRINGING A
SLIGHT (2 OF 5) RISK FOR SEVERE THUNDERSTORMS IN THIS AREA. THIS
THREAT WILL MAINLY BE CONDITIONAL FOR THE POSITION OF THE COLD
FRONT, ESPECIALLY AS INSTABILITY QUICKLY DECREASES BEHIND THE
FRONT ACCORDING TO RAP FORECASTS. THE COOLER HREF MEMBERS HAVE
THE FRONT CLEARED THROUGH THE SOUTHERN BORDER. THE WARMER HREF
MEMBERS HAVE THE FRONT OVER I-44. NO MATTER THE SCENARIO,
EFFECTIVE SHEAR OF 35-50 KTS OVERTOP HREF MEAN MUCAPE UPWARDS OF
1000 J/KG WILL BE ENOUGH FOR SUPERCELLS. THESE CAN STILL
DEVELOP BEHIND THE FRONT AND BE ELEVATED. THEREFORE, LARGE HAIL
UP TO GOLF BALLS WILL BE THE MAIN HAZARDS. HOWEVER, IF THE
FRONT HANGS OUT FURTHER NORTH, SURFACE-BASED STORMS COULD
PRODUCE WIND GUSTS UP TO 60 MPH AND A LOW-END TORNADO THREAT
GIVEN AROUND 100 M2/S2 OF 0-1 KM SRH AND MODEST LOW-LEVEL SHEAR
SOUTH OF THE FRONT (15-25 KTS VIA RAP FORECAST HODOGRAPHS).
THESE STORMS WOULD HAVE THE BEST CHANCE OF OCCURRING DURING THE
AFTERNOON AND EVENING HOURS. THAT BEING SAID, THE ENVIRONMENT
WILL BE CONDUCIVE FOR FOR ANY DEVELOP STORM FROM 3 AM TUESDAY
ALL THE WAY THROUGH WEDNESDAY NIGHT.
FLOOD WATCH IN EFFECT BEGINNING 7 AM TUESDAY:
IN ADDITION TO SEVERE WEATHER, EXCESSIVE RAINFALL AND FLOODING
WILL ALSO BE A CONCERN AS THE FRONT STALLS OVER THE AREA, MEAN
LAYER FLOW BECOMES STATIC PARALLEL TO THE FRONT, AND 90TH
PERCENTILE PWATS OF 1.25-1.5 INCHES REMAIN IN THE AREA. HREF AND
EXPERIMENTAL REFS/MPAS HIGH RESOLUTION ENSEMBLES ARE IN PRETTY
GOOD AGREEMENT WITH THE FIRST ROUND OF WIDESPREAD RAINFALL
OCCURRING ALONG THE THE I-44 CORRIDOR DURING THE DAY TUESDAY.
WITH 90TH PERCENTILE PWATS FOR THIS TIME OF YEAR, ACCORDING TO
NAEFS, THUNDERSTORMS SHOULD BE QUITE PRODUCTIVE. HREF SUGGESTS
WIDESPREAD RAIN RATES OF 0.25-0.5 IN/HR RATES UNDER HEAVIER
RAIN, WITH ANY THUNDERSTORM CAPABLE OF PRODUCING 0.75-1 IN/HR
RAIN RATES. BEING SO SATURATED FROM RECENT RAIN EVENTS, EVEN
THESE COULD PRODUCE SOME FLOODING. BY THE END OF THE DAY
TUESDAY, WE COULD SEE WIDESPREAD AMOUNTS OF 0.5-1.25 INCHES,
WITH HREF AND REFS LPMMS HINTING AT LOCALIZED SWATHS UP TO 2-3
INCHES.
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
ISSUED AT 300 PM CDT MON APR 28 2025
SLIGHT TO MODERATE RISK FOR EXCESSIVE RAINFALL WEDNESDAY:
THE SURFACE FRONT WILL GO THROUGH SOME SPATIAL WIGGLES THROUGH
WEDNESDAY AS ANOTHER SHORTWAVE TROUGH SLOWLY APPROACHES FROM THE
WEST. THIS BRINGS A LITTLE UNCERTAINTY IN THE EXACT AREA OF
HEAVIEST RAINFALL. IN FACT, IT MAY SHIFT A BIT FROM NORTH TO
SOUTH AND BACK TO NORTH THROUGH THE PERIOD, EFFECTIVELY
SMOOTHING OUT THE HEAVIER RAIN ACROSS MUCH OF THE AREA.
NEVERTHELESS, THE WARM FRONT IS EXPECTED TO SLOWLY LIFT NORTH
THROUGH THE AREA LATE TUESDAY NIGHT AND THROUGH WEDNESDAY.
DURING THIS PERIOD, HREF/REFS/MPAS CAM ENSEMBLES ARE ALL IN
AGREEMENT WITH A LULL IN SHOWERS AND STORMS EARLY WEDNESDAY
MORNING BEFORE ANOTHER ROUND ENTERS FROM THE SW AS HEIGHT FALLS
BEGIN AGAIN AHEAD OF THE NEXT TROUGH EJECTION. THIS WILL BRING
MORE HEAVY RAINFALL AND THE POTENTIAL FOR SOME ISOLATED STRONG
TO SEVERE THUNDERSTORMS AS THE MOIST AND UNSTABLE ENVIRONMENT
REMAINS IN PLACE (OUR WHOLE AREA IS IN A MARGINAL (1 OF 5) RISK
FOR SEVERE THUNDERSTORMS). HAIL UP TO QUARTERS AND WIND GUSTS UP
TO 60 MPH LOOK TO BE THE MAIN HAZARDS.
FLOODING WEDNESDAY INTO THURSDAY WILL BECOME THE MAIN CONCERN AS
CONTINUED HEAVY RAIN IS EXPECTED. AGAIN, WITH THE SMALL
DEVIATIONS IN FRONTAL POSITION, WHEN ALL IS SAID AND DONE, NBM
25TH-75TH PERCENTILE SUGGESTS ALL AREAS SHOULD EXPECT AT LEAST A
HALF INCH OF RAIN (10TH PERCENTILE), WITH MANY AREAS SEEING
1.5-4 INCHES OF RAIN (25TH-75TH) PERCENTILE. AS OF RIGHT NOW,
THE HEAVIEST AXIS OF RAIN LOOKS TO BE IN THE SW CORNER OF MO
ALONG THE I-44 CORRIDOR WHERE A MODERATE (3 OF 4) RISK FOR
EXCESSIVE RAINFALL EXISTS. HREF AND EXPERIMENTAL REFS LPMMS
SUGGEST THAT LOCALIZED AREAS COULD SEE UP TO 4-7 INCHES IF UNDER
MULTIPLE THUNDERSTORMS. THEREFORE, A FLOOD WATCH HAS BEEN
ISSUED FOR ALL OF OUR AREA THROUGH THURSDAY MORNING.
SHOWER AND THUNDERSTORM CHANCES CONTINUE THURSDAY:
THE SYSTEM WILL FINALLY BECOME PROGRESSIVE THURSDAY WITH A COLD
FRONT MOVING THROUGH. THIS WILL BRING ADDITIONAL CHANCES OF
SHOWERS AND THUNDERSTORMS (60-80% CHANCE), THOUGH THE SYNOPTIC
SETUP AND EARLY SIGNALS FROM MPAS MEMBERS SUGGEST THESE WILL BE
MORE SCATTERED IN NATURE. THEREFORE, THE WIDESPREAD FLOODING
RISK SHOULD DIMINISH THROUGH THE DAY THURSDAY, THOUGH ANY
LINGERING FLOODING COULD BE EXACERBATED IF THOSE AREAS SEE SOME
OF THESE SCATTERED STORMS SINCE 1.00-1.25 IN PWATS WILL STILL
BE IN PLACE ACCORDING TO THE GEFS.
WARMING TREND OVER THE WEEKEND WITH LOW RAIN CHANCES:
AFTER 80S TODAY, HIGHS IN THE 70S AND LOWS IN THE 50S WILL BE
PERSISTENT THROUGH THE WEEK. AFTER THE SYSTEM CLEARS THE AREA,
NBM DETERMINISTIC BRINGS A WARMING TREND AS GLOBAL ENSEMBLES ARE
SHOWING LARGE-SCALE RIDGING MOVING INTO THE REGION.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1240 PM CDT MON APR 28 2025
A 3-5 KFT CU FIELD IS DEVELOPING AND MOVING IN FROM WEST TO EAST
AND WILL BE IN PLACE DURING THE 18-01Z TIMEFRAME. ADDITIONALLY,
SOUTHERLY WINDS WILL BE BREEZY IN THE 15-25 KT RANGE WITH GUSTS
UP TO 25-35 KTS THROUGH THE SAME TIMEFRAME, SLIGHTLY
DIMINISHING AFTER 01Z.
AFTER 06Z, THE FORECAST BECOMES A BIT UNCERTAIN. SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE THE LATER THE
PERIOD GOES ON, HOWEVER, START TIME AND DURATION IS STILL AN
UNCERTAINTY WITH LOTS OF DIFFERENCES IN MODELS. A DECAYING
COMPLEX MAY MOVE IN FROM THE SW DURING THE 07-14Z TIMEFRAME
(PROB30 FOR THIS TIMEFRAME). AFTER 14Z, MODELS CONVERGE ON
GREATER COVERAGE OF SHOWERS AND THUNDERSTORMS ALONG A COLD
FRONT THAT WILL BE ACROSS THE AREA BRINGING VARIABLE WINDS (HAVE
INCLUDED A TEMPO HERE).
LASTLY, LLWS WILL BE BORDERLINE 40 KTS DURING THE 06-12Z
TIMEFRAME. HIGHER CONFIDENCE IN SEEING VALUES BETWEEN 30-35 FOR
MOST OF THE PERIOD.
SGF WATCHES/WARNINGS/ADVISORIES
KS...FLOOD WATCH FROM TUESDAY MORNING THROUGH THURSDAY MORNING FOR
KSZ073-097-101.
MO...FLOOD WATCH FROM TUESDAY MORNING THROUGH THURSDAY MORNING FOR
MOZ055>058-066>071-077>083-088>098-101>106.
SHORT TERM...PRICE
LONG TERM...PRICE
AVIATION...PRICE
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