507
FXUS63 KDMX 312021
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
321 PM CDT TUE MAR 31 2026
KEY MESSAGES
- SHOWERS AND NON-SEVERE THUNDERSTORM POTENTIAL OVERNIGHT INTO
EARLY WEDNESDAY MORNING, MAINLY OVER FAR SOUTHERN IOWA.
- WIDESPREAD MODERATE TO HEAVY RAINFALL INCREASES FROM THE SOUTH
AND WEST LATER WEDNESDAY THROUGH THURSDAY MORNING.
THUNDERSTORMS ARE POSSIBLE, BUT SEVERE THREAT IS LOW.
- INCREASING POTENTIAL FOR SEVERE THUNDERSTORM MID-DAY THURSDAY
INTO THE AFTERNOON AND EVENING. ALL HAZARDS POSSIBLE.
- ADDITIONAL SEVERE THUNDERSTORM POTENTIAL ON FRIDAY, THEN
DRIER AND MILD THROUGH THE WEEKEND.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 301 PM CDT TUE MAR 31 2026
OUR COLD FRONT TODAY HAS NOW PASSED THROUGH THE ENTIRE AREA, LEAVING
WIDESPREAD NORTHERLY WINDS ACROSS CENTRAL IOWA. WINDS HAVE BEEN
QUITE BREEZY TODAY, SUSTAINED AROUND 15 TO 25 MPH WITH GUSTS UP TO
40 MPH AT TIMES. COLD AIR ADVECTION HAS LEAD TO MILDER TEMPERATURES
AS WELL, DROPPING MANY LOCATIONS ALMOST 10 DEGREES THROUGH THE
MORNING. HOWEVER, SUNSHINE BEHIND THE FRONT HAS STILL LET
TEMPERATURES WARM SOME TODAY, WITH MUCH OF THE AREA IN THE UPPER 40S
AND 50S. THE THREAT FOR SEVERE WEATHER THIS AFTERNOON HAS GENERALLY
DIMINISHED WITH THE DEPARTURE OF THE FRONT, ALTHOUGH SOME ELEVATED
INSTABILITY DOES REMAIN OVER SOUTHEASTERN IOWA. THAT SAID, A STOUT
WARM NOSE AND LACK OF ANY ROBUST FORCING APPEARS TO KEEP ANY
CONVECTIVE INITIATION AT BAY INTO THE EVENING.
THETA-E ADVECTION WILL STEAM BACK NORTHWARD AND OVERRUN THE COLD
FRONT TO OUR SOUTH OVERNIGHT TONIGHT AS ANOTHER SURFACE LOW DEVELOPS
OVER THE TEXAS/OKLAHOMA PAN HANDLES. THIS WILL INTRODUCE THE
POTENTIAL FOR SOME ADDITIONAL ELEVATED SHOWERS AND THUNDERSTORMS
OVER FAR SOUTHERN IOWA EARLY WEDNESDAY MORNING. INSTABILITY WILL
HAVE WANED CONSIDERABLY BY THIS POINT, GENERALLY UNDER 500 J/KG, SO
THE RISK FOR SEVERE WEATHER WITH THIS ACTIVITY APPEARS LOW.
LIKEWISE, PRECIPITATION HAS BEEN TRENDING SOUTHWARD IN RECENT
GUIDANCE, INDICATING IT WILL BE MOSTLY ALONG THE IOWA/MISSOURI
BORDER AND SOUTHWARD.
THE AFOREMENTIONED WEAK SURFACE LOW TO OUR SOUTHWEST AND FRONT
TO OUR SOUTH WILL RETREAT BACK NORTH TOWARD IOWA ON WEDNESDAY,
BEING HELPED ALONG BY A MORE ROBUST UPPER LEVEL WAVE AND
DEEPENING SURFACE LOW OVER THE PLANES. THIS PROGRESSION THROUGH
WEDNESDAY WILL BRING A HEALTHY STREAM OF MOISTURE TRANSPORT UP
TOWARD IOWA AND RESULT IN A PROLONGED PERIOD OF RAINFALL
OVERNIGHT WEDNESDAY AND INTO THE DAY THURSDAY. THIS MOISTURE
PLUME WILL BOAST ANOMALOUSLY HIGH MOISTURE TRANSPORT FOR THIS
TIME OF YEAR AND PWAT VALUES PUSHING 1.5”. FOR CONTEXT, THE
CLIMATOLOGICAL DAILY MAX FOR THIS TIME OF YEAR IS RIGHT AROUND
1.2 TO 1.3”. WHILE THESE VALUES ARENT ANOMALOUS FOR WARM SEASON
PRECIPITATION, THEY ARE QUITE HIGH FOR AN EVENT THIS EARLY IN
THE YEAR. THE NET RESULT WILL BE WIDESPREAD PRECIPITATION
STARTING AS SOON AS WEDNESDAY AFTERNOON IN THE SOUTH AND WEST
AND LASTING THROUGH AT LEAST THURSDAY MORNING. QPF OUTPUT
INDICATES A WIDESPREAD 1 TO 2” OF RAIN, WITH A FEW LOCATIONS
POTENTIALLY EXCEEDING 2” THROUGH CENTRAL IOWA. THIS WILL
GENERALLY BE A BENEFICIAL RAINFALL FOR THE AREA, GIVEN DRY
ANTECEDENT CONDITIONS BUT WIDESPREAD RAIN OF THIS MAGNITUDE MAY
VERY WELL PRIME THE AREA FOR FUTURE RAINFALL ISSUES. MORE ON
POTENTIAL HYDROLOGICAL IMPACTS IN THE HYDRO SECTION BELOW. WITH
THE SATURATED PROFILES AND POOR MID-LEVEL LAPSE RATES,
INSTABILITY WILL BE MARGINAL OVERNIGHT WEDNESDAY INTO THURSDAY,
LIMITING SEVERE POTENTIAL UNTIL THE MAIN LOW APPROACHES ON
THURSDAY. LIKEWISE, WARMER TEMPERATURES IN NORTHERN IOWA
OVERNIGHT WILL HELP TO MITIGATE CONCERNS WITH FROZEN
PRECIPITATION, ALTHOUGH A BRIEF WINTRY MIX COULD STILL SCRAPE
FAR NORTHERN IOWA THROUGH THIS PERIOD. MINIMAL IMPACTS ARE
EXPECTED GIVEN THE WARM AIR ADVECTION.
AS WE GET INTO THE DAY ON THURSDAY, A NEGATIVELY TILTED UPPER TROUGH
AND SURFACE LOW PRESSURE WILL LIFT DIRECTLY OVERHEAD, BRINGING
BETTER INSTABILITY, 60+ DEWPOINTS AND STRONG KINEMATICS FROM A 50+
KT LOW LEVEL JET INTO CENTRAL IOWA. TIME OF DAY AND PRECEDING
CONVECTION FROM THE MORNING WILL PLAY A FACTOR IN THE SEVERE WEATHER
ENVIRONMENT ON THURSDAY, AS WILL THE AMOUNT OF SHEAR PRESENT, BUT
THE SYNOPTIC SET UP DOES RAISE SOME CONCERNS. SHOULD THE ATMOSPHERE
RECOVER, SEVERE THUNDERSTORMS WOULD CERTAINLY BE ON THE TABLE
THROUGH MID-DAY THURSDAY AS THE SURFACE LOW PUSHES THROUGH, WITH ALL
SEVERE HAZARDS POSSIBLE. THE STORM PREDICTION CENTER CURRENTLY HAS A
MARGINAL RISK (LEVEL 1 OF 5) FOR SEVERE WEATHER ON THURSDAY AND A
BROAD SLIGHT RISK (LEVEL 2 OF 5) JUST TO OUR EAST. THIS SEEMS
REASONABLE GIVEN THE UNCERTAINTY WITH THE MORNING CONVECTION IN THE
WARM SECTOR, BUT THE SEVERE THREAT THURSDAY WILL CERTAINLY WARRANT
WATCHING CLOSELY. IN ADDITION TO SEVERE WEATHER POTENTIAL, STRONG
WINDS ARE POSSIBLE IN THE WARM SECTOR WHERE THE STOUT LOW LEVEL JET
EXISTS.
LONG TERM /FRIDAY THROUGH TUESDAY/
ISSUED AT 301 PM CDT TUE MAR 31 2026
THE THURSDAY SURFACE LOW AND COINCIDENT UPPER LEVEL WAVE PUSHES
THROUGH THE AREA BY THURSDAY EVENING, BUT ANOTHER PROMINENT UPPER
LEVEL TROUGH WILL FOLLOW QUICKLY ON IT’S HEELS. THIS SYSTEM ARRIVES
IN IOWA ON FRIDAY, BRINGING SURFACE LOW PRESSURE WITH 60 DEWPOINTS
AND A HEALTHY AMOUNT OF INSTABILITY AND DEEP LAYER SHEAR THROUGH THE
AREA. THIS WILL INTRODUCE YET ANOTHER DAY OF SEVERE WEATHER
POTENTIAL ON FRIDAY. THE STORM PREDICTION CENTER HAS ISSUED A 15%
RISK FOR SEVERE WEATHER AS A DAY 4 OUTLOOK, WHICH AGAIN SEEMS
WARRANTED GIVEN SYNOPTIC SETUP AND PARAMETER SPACE. WE WILL CONTINUE
TO EVALUATE THIS SYSTEM AS IT DRAWS NEARER. AFTER THE STORM
POTENTIAL ON FRIDAY, CONDITIONS DRY OUT A BIT THROUGH THE WEEKEND
WITH MILDER TEMPERATURES IN THE 40S AND 50S BOTH SATURDAY AND
SUNDAY.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1223 PM CDT TUE MAR 31 2026
A COLD FRONT THAT PASSED THROUGH THIS MORNING HAS LED TO BREEZY
NORTHERLY FLOW EARLY THIS AFTERNOON. WINDS OF 15 TO 20 KTS WITH
OCCASIONALLY GUSTS NEAR 30 KTS WILL BE COMMON THROUGH THE
AFTERNOON. WIND GUSTS WILL DIMINISH SOME THIS EVENING, BUT
REMAIN BREEZY OVERNIGHT. A THIN STRIP OF STRATUS HAS RESULTED IN
BRIEF MVFR CONDITIONS TODAY, AND IS EXPECTED TO MOVE THROUGH
KOTM WITHIN THE NEXT FEW HOURS. OTHERWISE, VFR CONDITIONS
PREVAIL THROUGH THE EVENING, WITH MORE MVFR TO POTENTIALLY IFR
STRATUS DEVELOPING OVER SOUTHERN AND CENTRAL IOWA (KDSM AND
KOTM) EARLY WEDNESDAY MORNING. IN ADDITION TO STRATUS, SCATTERED
SHOWERS AND A FEW THUNDERSTORMS WILL DRIFT OVER SOUTHERN IOWA
EARLY TOMORROW MORNING, LIKELY ONLY IMPACTING KOTM.
HYDROLOGY
ISSUED AT 301 PM CDT TUE MAR 31 2026
MULTI-DAY MODERATE TO HEAVY RAINFALL EVENT OVER THE NEXT
FEW DAYS WILL RESULT IN SHORT AND LONG TERM FLOODING CONSIDERATIONS
MAINLY ACROSS THE SOUTHEAST HALF OF THE CWA. SHORT TERM
CONSIDERATIONS INCLUDE POTENTIAL PONDING AND LOW-END FLASH FLOODING.
SOIL MOISTURE VALUES ARE GENERALLY RUNNING NEAR TO BELOW NORMAL.
THAT DATA COMBINED WITH THE QPF SUGGESTS PONDING AND FLASH FLOOD
CONCERNS WILL BE MAINLY RATE DRIVEN VS. AMOUNT DRIVEN, WITH THE
GREATEST RISK IN URBAN AREAS.
LONGER TERM CONSIDERATIONS INCLUDE POTENTIAL RIVER FLOODING.
NATIONAL WATER MODEL, HEFS AND QPF ENSEMBLE HYDROGRAPHS INDICATE THE
MOST LIKELY SCENARIO ON AREA RIVERS WILL BE MODERATE TO SIGNIFICANT
WITHIN-BANK RISES. A COUPLE LOCATIONS REACHING FLOOD STAGE ARE
POSSIBLE AS WELL. THE PEAKS ON MOST RIVERS WOULD OCCUR THIS WEEKEND
INTO EARLY NEXT WEEK. GREATER CONCERN IS THE NEXT SEVERAL DAYS OF
RAINFALL MAY SET THE STAGE FOR MORE SIGNIFICANT IMPACTS GOING
FORWARD SINCE THE CPC OUTLOOK FOR APRIL INCLUDES ABOVE NORMAL
PRECIP. ELEVATED SOIL MOISTURE AND STREAMS WILL NOT REQUIRE AS MUCH
RUNOFF TO BECOME IMPACTFUL IF THE WET PATTERN CONTINUES.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...DODSON
LONG TERM...DODSON
AVIATION...DODSON
HYDROLOGY...ZOGG
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