641
FXUS63 KDMX 301750
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1250 PM CDT WED JUL 30 2025
...UPDATED FOR THE 18Z AVIATION DISCUSSION...
KEY MESSAGES
- SEVERE THUNDERSTORMS EARLY THIS MORNING ARE EXPECTED TO
TRANSITION TO A HEAVY RAIN THREAT. 1-3" RAIN EXPECTED WITH
POCKETS OF 3-5" POSSIBLE.
- SHOWERS AND THUNDERSTORMS LINGER THROUGH THE AFTERNOON. A FEW
STRONGER STORMS MAY REDEVELOP IN SOUTHEAST IOWA LATER THIS
AFTERNOON.
- PLEASANTLY COOLER AND DRY LATE WEEK THROUGH THE WEEKEND.
UPDATE
ISSUED AT 213 AM CDT WED JUL 30 2025
SEVERE STORMS PERSIST ACROSS THE AREA EARLY THIS MORNING AT THE
2 AM TIME OF THIS WRITING. WIND HAS BEEN THE PRIMARY HAZARD
OVERNIGHT WITH GUSTS UP TO 60 MPH COMMONLY REPORTED. WHILE THE
FIRST ROUND HAS EXITED EAST ALREADY, A SECOND ROUND IS ARRIVING
INTO WESTERN AND CENTRAL IOWA WITH CONTINUED STRONG WINDS. EARLY
INDICATIONS THAT THESE WINDS SHOULD BEGIN TO TREND DOWN IN THE
NEXT COUPLE HOURS. A LARGE STRATIFORM RAIN AREA TRAILS THIS
SECOND LINE OF STORMS WHICH WILL BRING AN EXPECTED ADDITIONAL
1-2" ON TOP OF AMOUNTS ALREADY RECEIVED OVERNIGHT. THE GOOD
NEWS OVERNIGHT IS THAT SO FAR THE ORIENTATION OF THE LINE HAS
BEEN MORE NORTH-SOUTH COMPARED TO EXPECTATIONS IN EARLIER CAM
RUNS WHICH HAS A MORE WEST-EAST COMPONENT AND INCREASED
PROPENSITY FOR TRAINING STORMS. THIS SHOULD HELP TO EASE SOME
OF THE FLOOD CONCERNS THROUGH THE MORNING, BUT WE'LL CONTINUE TO
MONITOR CLOSELY FOR ANY PIVOT AND POCKETS OF HEAVIER RAIN
RATES. MOST SUSCEPTIBLE AREAS REMAIN METRO AREAS WITH FLASHIER
BASINS, INCLUDING THE DES MOINES METRO THAT DID SEE A FEW QUICK
RISES WITH THE FIRST ROUND EARLIER TONIGHT. FURTHER RISES REMAIN
POSSIBLE ON OTHER AREA RIVERS AS WATER IS ROUTED. HEFS 30%
EXCEEDANCE PROBABILITIES PLACES SEVERAL SITES ON THE
WINNEBAGO/SHELL ROCK/CEDAR RIVERS IN MINOR TO NEAR MODERATE AS
WATER ROUTES. OTHER LOCATIONS WITHIN THE DES MOINES AND IOWA
BASINS ALSO MAY BE SUSCEPTIBLE DEPENDING ON WHERE HEAVIER RAIN
SETS UP OVERNIGHT.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO PERSIST OFF AND ON
THROUGH THE DAY ACROSS MUCH OF THE AREA, WITH SOME STRENGTHENING
ALONG THE SINKING BOUNDARY AND OTHER SPURIOUS OUTFLOW
BOUNDARIES LATER THIS AFTERNOON. ANY SEVERE THREAT WITH THIS
RESTRENGTHENING LOOKS TO BE CONFINED TO FAR SOUTHERN/SOUTHEAST
IOWA WITH GUSTY WINDS AGAIN THE PRIMARY THREAT.
DISCUSSION
ISSUED AT 317 PM CDT TUE JUL 29 2025
HOT AND HUMID CONDITIONS HAVE PREVAILED GENERALLY THROUGH THE DAY,
THOUGH A VERY BRIEF REPRIEVE OCCURRED FOR PORTIONS OF CENTRAL
IOWA AS A LARGE OUTFLOW BOUNDARY FROM DECAYING CONVECTION ACROSS
THE NORTH DOVE SOUTHWARD, LEADING SO SLIGHTLY REDUCED
TEMPERATURES IN THE 80S IN SOME LOCATIONS THIS AFTERNOON.
HOWEVER, TEMPERATURES HAVE INCREASED AS OF 2PM ACROSS THE AREA
WITH VALUES IN THE UPPER 80S NORTH INTO CENTRAL IOWA AND IN THE
LOW 90S SOUTH. THE EXPECTATION REMAINS THAT VALUES WILL INCREASE
FURTHER INTO THE LOW TO MID 90S THROUGH THE REST OF THE
AFTERNOON AND REMAIN INTO THIS EVENING, WITH HEAT INDICES
REACHING IN AROUND 105+ DEGREES IN SOUTHERN IOWA AND EXTENDING
UP TO AROUND THE I-80 CORRIDOR, THUS THE EARLIER EXPANSION OF
THE HEAT ADVISORY FURTHER NORTH THAT WILL REMAIN UNTIL 8PM.
THE ATTENTION THEN PRIMARILY BECOMES VERY FOCUSED ON THE RETURN OF
ACTIVE WEATHER THIS EVENING, WHICH PER CAM GUIDANCE STILL HAS SOME
VARIATION BETWEEN MEMBERS ON WHEN THE ACTIVITY DEVELOPS WITH THE
PASSING BOUNDARY. HRRR AND FV3 MEMBERS SUGGEST THAT STORMS BEGIN TO
FIRE AROUND OR JUST AFTER 7-8PM, WHILE MORE TEND TO FAVOR CONVECTION
DEVELOPING INTO WESTERN IOWA AND BECOME MORE WIDESPREAD BETWEEN 10PM-
12AM. GIVEN AN INCREASE IN FORCING TO LIFT WITH THIS BOUNDARY, ALONG
WITH THE INCREASE OF AT LEAST SOME LOW LEVEL JET FURTHER WEST, AND
PLENTY OF INSTABILITY OVER 3000+ J/KG THOUGH SHEAR IS MORE MARGINAL,
STORMS SHOULD HAVE NO ISSUE DEVELOPING BUT MAY BE MORE MESSY IN
COVERAGE AS UPDRAFTS MAY STRUGGLE TO MAINTAIN THEMSELVES. WITH WARM
AIR NEAR THE SURFACE AS WELL, THIS CONVECTION LOOKS TO BE MORE
ELEVATED IN NATURE, WITH STEEP LAPSE RATES AROUND 7 J/KG SUPPORTING
AT LEAST A SMALL HAIL THREAT, THOUGH DAMAGING WINDS REMAIN THE MAIN
SEVERE HAZARD AS DCAPE VALUES AROUND 1000-1500 J/KG ARE DEPICTED IN
RAP AND NAM SOUNDINGS OVER SOUTHWESTERN IOWA. THE SLIGHT RISK PER
SPC REMAINS REASONABLE, WITH MORE OF AN ISOLATED SEVERE RISK FURTHER
NORTH AND EAST. OF INCREASING CONCERN AS WELL IS THE POTENTIAL FOR
HEAVY RAINFALL, AS HREF GUIDANCE DEPICTS THE SHOWERS AND STORMS
TONIGHT INTO WEDNESDAY MORNING KICKING OUT AMOUNTS OF 1-3+ INCHES OF
RAINFALL , ESPECIALLY OVER SOUTHERN/WESTERN IOWA, WHILE THE GEFS HAS
THESE HIGHER AMOUNTS FURTHER NORTH. WHILE THE VARIABILITY REMAINS ON
THE LOCATION OF THE HEAVIER RAINFALL, THE CERTAINTY IS HIGH THAT
HEAVY RAINFALL WILL FALL SOMEWHERE IN THESE AREAS, WHICH HAS
RESULTED AFTER COORDINATION OF NEIGHBORING OFFICES TO ISSUE A FLOOD
WATCH FOR MUCH OF WESTERN INTO SOUTHERN IOWA TONIGHT THROUGH
WEDNESDAY MORNING. SCATTERED FLASH FLOODING IS POSSIBLE, ALONG WITH
RIVER RISES THAT COULD LEAD TO ADDITIONAL IMPACTS, WHICH IS
HIGHLIGHTED PER THE SLIGHT ERO THAT THE WPC INCLUDED IN THE AREA,
THOUGH MORE BROAD IN COVERAGE TO ACCOUNT FOR LINGERING
UNCERTAINTIES. DETAILS WILL CONTINUE TO BE REFINED OVER THE NEXT
SEVERAL HOURS AS CONDITIONS SET UP.
FOLLOWING THE ACTIVE WEATHER EXPECTED TONIGHT THROUGH WEDNESDAY
MORNING, WILL SEE MID-LEVEL FLOW GRADUALLY SHIFT NORTHWESTERLY AND
SURFACE FLOW SHIFT NORTHEASTERLY, WHICH WILL USHER IN COOLER AND
COMFORTABLE TEMPERATURES AS HIGHS ARE ONLY EXPECTED TO REACH THE 70S
ACROSS MUCH OF IOWA. HOWEVER, FURTHER SOUTH/SOUTHEAST, A BOUNDARY
OVERHEAD WITH THE AREA REMAINING IN THE WARM AND HUMID AIR WILL LEAD
TO AT LEAST THE POTENTIAL FOR ADDITIONAL SHOWERS AND STORMS TO
DEVELOP LATE WEDNESDAY AFTERNOON THROUGH THE EVENING. WILL HAVE TO
CLOSELY MONITOR HOW CONDITIONS EVOLVE THROUGH THE DAY WEDNESDAY. ANY
REDEVELOPMENT OF SHOWERS AND STORMS WOULD POSE PRIMARILY DAMAGING
WINDS AND HEAVY RAIN AS THE MAIN THREATS AGAIN.
THURSDAY AND BEYOND WILL BE COME WITH MUCH QUIETER AND COOLER
WEATHER OVER SEVERAL DAYS AS HIGH PRESSURE SINKS DOWN, THOUGH SOME
LOW END CHANCES FOR AT LEAST SHOWER ACTIVITY IS NOT COMPLETELY OUT
OF THE QUESTION. THESE DETAILS WILL BE ASSESSED IN THE COMING
DAYS.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1250 PM CDT WED JUL 30 2025
ISOLATED SHOWERS CONTINUE TO SLOWLY DESCEND ACROSS NORTHERN IOWA
THIS AFTERNOON, WHICH IS EXPECTED TO REMAIN THROUGH THE
AFTERNOON. CANNOT RULE OUT A FUNNEL CLOUD IN THIS AREA, AND A
FEW LIGHTNING STRIKES THOUGH THE OVERALL POTENTIAL SHOULD REMAIN
FAIRLY LOW. OTHERWISE ADDITIONAL SHOWERS AND A POSSIBLE WEAK
STORM COULD IMPACT KOTM THIS AFTERNOON AS THE FRONT EXITS THE
STATE. MVFR/IFR CEILING MAY LARGELY REMAIN, ESPECIALLY FURTHER
SOUTH/SOUTHEAST INTO THURSDAY BEFORE GRADUALLY IMPROVING.
NORTHEASTERLY WINDS WILL GENERALLY OCCUR THROUGH THE PERIOD,
WITH OCCASIONAL 15KT GUSTS.
DMX WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 4 PM CDT THIS AFTERNOON FOR IAZ050-061-062-
074-075-084>086-095>097.
UPDATE...HAGENHOFF
DISCUSSION...BURY
AVIATION...BURY
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