609
FXUS63 KDMX 300800
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
300 AM CDT WED APR 30 2025
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS EXPAND ACROSS THE AREA TODAY,
BECOMING WIDESPREAD BY THIS EVENING.
- ADDITIONAL SHOWERS AND THUNDERSTORMS ON THURSDAY AND FRIDAY.
- WARMER AND DRY FOR THE WEEKEND.
DISCUSSION
ISSUED AT 259 AM CDT WED APR 30 2025
THE SOUTHERN STREAM TROUGH HAS PUSHED INTO THE CENTRAL US WITH CLOUD
COVER SPREADING INTO IOWA THROUGH THE EARLY MORNING HOURS.
CONDITIONS AHEAD OF THE PRECIPITATION ARE PRETTY DRY WITH DEWPOINT
DEPRESSIONS OF 10-15 DEG F. MODEL SOUNDINGS ACROSS THE AREA ARE SLOW
TO SATURATE INTO THE LOW LEVELS THROUGH MIDDAY AND EARLY
PRECIPITATION ACROSS SOUTHERN TO CENTRAL IOWA IS EXPECTED TO BE
FAIRLY SPOTTY. BY THIS AFTERNOON PROFILES SATURATE AND CAMS
DEVELOP MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY ACROSS
THE AREA. THIS WILL LAST THROUGH THE OVERNIGHT BEFORE LIFTING
OFF TO THE EAST ON THURSDAY MORNING. THE NORTHERN STREAM
SHORTWAVE DOESN'T QUITE PHASE AND ENDS UP PASSING ACROSS THE
AREA LATER THURSDAY AFTERNOON, PROVIDING ANOTHER WINDOW FOR
SHOWERS AND THUNDERSTORMS. A FINAL LOBE OF VORTICITY ROTATES
ACROSS THE AREA ON FRIDAY WITH ANOTHER WINDOW FOR SHOWERS AND
THUNDERSTORMS ACROSS THE AREA. THIS FINAL EMBEDDED SHORTWAVE IS
FINALLY ENOUGH TO SHIFT THE PARENT TROUGH EAST OF THE AREA IN
TIME FOR THE WEEKEND. THE ENTIRE PERIOD HAS MEAGER INSTABILITY
WITH UNDER 500 J/KG MLCAPE AND LITTLE IN THE WAY OF A WELL
DEFINED FORCING MECHANISM TO FOCUS CONVECTION. AS SUCH, SEVERE
CHANCES ARE QUITE LOW THOUGH RUMBLES OF THUNDER ARE CERTAINLY
ANTICIPATED. A WIDESPREAD 0.25" OF QPF IS FORECAST WITH HREF
LPMM PAINTING MUCH OF THE AREA AS SUCH WITH POCKETS OF LOCALLY
HIGHER AMOUNTS.
THE WESTERN US THERMAL RIDGE WILL BUILD ACROSS THE AREA FOR THE
WEEKEND, KEEPING THE AREA DRY AND SENDING TEMPERATURES BACK INTO THE
70S ACROSS IOWA. A RATHER ROBUST SYSTEM WILL DEVELOP OVER THE
WESTERN US DURING THIS TIME AND SHOULD MOVE INTO THE CENTRAL US
SOMETIME EARLY NEXT WEEK. THERE IS SIGNIFICANT SPREAD IN MODEL
GUIDANCE AT THIS RANGE, ESPECIALLY IN REGARD TO TIMING AND THIS
WILL NEED TO BE FINE TUNED LATER. AS IS OFTEN THE CASE WITH
UPPER LEVEL CUT OFF LOWS, A DELAY IN ARRIVAL NEXT WEEK IS
POSSIBLE.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1048 PM CDT TUE APR 29 2025
VFR CONDITIONS WITH LIGHT, VARIABLE WINDS PREVAIL THIS MORNING.
HIGH CLOUDS HAVE BEGUN TO FILL IN OVER SOUTHERN IOWA, AND WILL
CONTINUE NORTH THROUGH THE MORNING HOURS. THESE CLOUDS WILL
PRECEDE SCATTERED RAIN MOVING INTO THE AREA IMPACTING ALL SITES
AT SOME POINT TODAY/TONIGHT. THAT SAID, WIDESPREAD
PRECIPITATION OCCURRING IN THE MORNING HOURS IS BECOMING MUCH
LESS LIKELY AS THIS RAINFALL MEETS THE DRY AIR OVERHEAD.
THEREFORE, HAVE PUSHED BACK THE START TIME OF RAINFALL IN TAFS,
WITH MOST OF THE RAIN EXPECTED TO FALL IN THE MID TO LATE
AFTERNOON AND BEYOND. AS SATURATION OCCURS AND RAIN FALLS,
CEILINGS WILL ALSO DROP INTO MVFR AND POTENTIALLY IFR
OVERNIGHT. ISOLATED THUNDER WILL BE POSSIBLE THIS AFTERNOON AND
EVENING AS WELL, ESPECIALLY AT KDSM AND KOTM, BUT CONFIDENCE IN
LOCATION AND TIMING IS TOO LOW TO INCLUDE IN TAFS AT THIS TIME.
RAIN AND DRIZZLE PERSISTS THROUGH THE END OF THE PERIOD.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HAGENHOFF
AVIATION...DODSON
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