279
FXUS63 KDMX 010342
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1042 PM CDT FRI JUL 31 2026
...UPDATED FOR THE 06Z AVIATION DISCUSSION...
KEY MESSAGES
- SHOWERS ARE EXPECTED TODAY INTO SATURDAY MORNING. A FEW STORMS
REMAIN POSSIBLE IN SOUTHEAST IOWA EARLY THIS AFTERNOON BUT THE
WINDOW IS QUITE SMALL IN SPACE AND TIME FOR ANY STRONGER
STORMS (TORNADO POTENTIAL), THOUGH AN ISOLATED STORM WIND GUST
IS POSSIBLE AS ARE A FEW FUNNEL CLOUDS. LOCALLY HEAVY
RAINFALL IS ALSO POSSIBLE, ESPECIALLY NORTH AND EAST, THOUGH
THE OVERALL RISK IS LOWER WITH LESS RAIN OVERNIGHT/THIS
MORNING, BUT COULD STILL OCCUR IN MAINLY AN URBAN AREA.
- INCREASING WINDS WITH GUSTS OF AROUND 35 TO 45 MPH SPREAD
FROM NORTHWEST IOWA TO EASTERN IOWA BY AROUND SUNSET.
- RELATIVELY COOLER AND QUIET WEATHER IS THEN FORECAST SATURDAY
THROUGH AT LEAST MONDAY.
SHORT TERM /THROUGH SUNDAY/
ISSUED AT 254 PM CDT FRI JUL 31 2026
SURFACE LOW HAS MOVED INTO NORTHERN IOWA EARLY THIS AFTERNOON WITH A
COLD FRONT EXTENDING TO THE SOUTH OF THE LOW WHICH EVENTUALLY ARCS
BACK INTO THE SOUTHERN PLAINS. WIDESPREAD CLOUD COVER REMAINS IN
PLACE AROUND THE LOW WITH A FEW BREAKS SHOWING UP ON SATELLITE TO
THE EAST OF THE COLD FRONT. THE SMALL AREA OF A WARM SECTOR AHEAD OF
THE FRONT (GENERALLY EAST OF I-35) IS THE MAIN AREA TO WATCH FOR ANY
THUNDERSTORM DEVELOPMENT THIS AFTERNOON. SHOWERS HAVE BEEN ONGOING
MUCH OF THE DAY IN THE NORTH, WITH MORE RECENT SHOWER DEVELOPMENT
FURTHER SOUTH THROUGH PORTIONS OF CENTRAL AND EVEN
SOUTHERN/SOUTHEAST IOWA. ALTHOUGH DEW POINTS ARE IN THE 70S IN
PORTIONS OF CENTRAL AND SOUTHERN IOWA, TEMPERATURES ARE ALSO STILL
IN THE 70S TO TOUCHING 80. WITH THE SCATTERED SHOWERS ALREADY
INCOMING, OUR WINDOW FOR STRONGER STORMS IS SMALL IN BOTH SPACE AND
TIME. THE MAIN FAVORABLE LOCATION IS IN SOUTHEAST IOWA, EAST OF I-35
AND SOUTH OF I-80 WHICH IS WHERE THE SPC DAY 1 MARGINAL IS ROUGHLY
LOCATED. THE CHALLENGE IS 0-1 SRH QUICKLY DWINDLES WITH TIME IN THE
NEXT FEW HOURS AND WHERE SURFACE-BASED CAPE OVER 1000 J/KG EXISTS,
SOUNDINGS DO NOT SUPPORT MUCH IN TERMS OF A TORNADO THREAT, AS
DISCUSSED IN THE PREVIOUS DISCUSSION. DCAPES DO REACH TOWARDS,
THOUGH STILL BELOW, 1000 J/KG AT TIMES SO AN ISOLATED STRONG TO
MARGINALLY SEVERE GUST CANNOT BE RULED OUT WITH THE DRIER AIR
WORKING INTO THE STORMS FROM ALOFT, BUT THE OVERALL PROBABILITIES
FOR SEVERE STORMS REMAINS LOW WITH HIGHER PROBABILITIES TO THE EAST
AND SOUTH OF OUR AREA. THERE MAY STILL BE SOME POTENTIAL FOR SOME
FUNNEL CLOUDS AS 0-3 CAPES OVERLAP WITH THE SURFACE VORTICITY,
ESPECIALLY NEAR THE LOW, WITH THE NAM/GFS/RAP ALL HIGHLIGHTING AREAS
OF MAINLY NORTH CENTRAL INITIALLY (AROUND 19Z, AS ALSO NOTED IN SPC
MESOANALYSIS DATA) AND THEN EAST CENTRAL TO EASTERN IOWA WITH THE
NON-SUPERCELL TORNADO PARAMETER. THESE CONDITIONS WILL CERTAINLY BE
WATCHED CLOSELY, ESPECIALLY WITH WHERE CLOUD BREAKS ARE OCCURRING.
OUTSIDE OF THE STRONGER STORM POTENTIAL JUST DISCUSSED, MAIN
WEATHER FOR THE NEXT 12-18 HOURS WILL BE THE SCATTERED SHOWERS
AND THE INCREASING WIND GUSTS. THESE GUSTY WINDS OUT OF THE
NORTH HAVE STARTED TO ENTER NORTHWEST IOWA EARLY THIS AFTERNOON
AND ARE EXPECTED TO MOVE IN NORTHWEST TO SOUTHEAST THROUGH THE
NIGHT. PEAK GRADIENT GUSTS TOP OUT AROUND 35-45 MPH, ISOLATED
HIGHER, WITH BREEZY CONDITIONS REMAINING BEHIND THE STRONGEST
GUSTS INTO SATURDAY AFTERNOON BEFORE WINDS DIMINISH INTO
SATURDAY NIGHT. THESE GUSTS MAY TOUCH WIND ADVISORY CRITERIA AT
TIMES, BUT EXPECTATION WAS NOT WIDESPREAD ENOUGH TO ISSUE A
HEADLINE.
IN TERMS OF RAINFALL, HEAVY RAIN REMAINS POSSIBLE WITH PWATS LESS
THAN THE WERE THIS MORNING, BUT STILL OVER 1", AND WARM CLOUD
DEPTHS. SHOWERS IN NORTHERN IOWA ARE ALSO EXPECTED TO MOVE SLOWER
THAN IN SOUTHERN IOWA AND THESE SLOW MOVING SHOWERS WITH SOME
BACKBUILDING/TRAINING POTENTIAL COULD LEAD TO QPF ADDING UP. WITH
LESS RAIN INTO THIS MORNING, CAPACITY REMAINS HIGHER FOR HEAVIER
RAINFALL AMOUNTS INTO THIS EVENING AND ANY FLOODING CONCERNS REMAIN
MAINLY IN URBAN AREAS IN FAR NORTH TO EASTERN IOWA. SEE THE
HYDROLOGY SECTION BELOW FOR MORE DETAILS.
SHOWERS WILL BE SLOW TO DEPART INTO SATURDAY MORNING IN THE
EAST/SOUTHEAST, BUT DRY CONDITIONS LOOK TO RETURN BY SATURDAY
AFTERNOON. HAZY SKIES MAY REMAIN BEYOND CLOUDS CLEARING WEST TO EAST
AS WILDFIRE SMOKE ALOFT LOOKS TO RETURN TO THE STATE. TEMPERATURES
SATURDAY REMAIN PLEASANT AND IN THE 70S TO LOW 80S.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
ISSUED AT 254 PM CDT FRI JUL 31 2026
PLEASANT AND DRY CONDITIONS CONTINUE ON SUNDAY AND MONDAY AS THE
UPPER RIDGE BUILDS EASTWARD WITH TEMPERATURES IN THE UPPER 70S TO
LOW 80S. ACTIVE WEATHER THEN RETURNS THROUGH MID NEXT WEEK AS A
LONGWAVE TROUGH APPROACHES WITH SEVERAL WAVES MOVING THROUGH THE
OVERARCHING UPPER LEVEL FLOW. THIS WILL RETURN PRECIPITATION CHANCES
TO OUR AREA FROM TUESDAY NIGHT TO AROUND THURSDAY WITH THE PATTERN
LOOKING TO REMAIN ACTIVE INTO NEXT WEEKEND. TEMPERATURES DON'T
REALLY REBOUND KEEPING CONDITIONS FOR EARLY AUGUST LARGELY NICE AND
IN THE 80S.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1042 PM CDT FRI JUL 31 2026
SHOWERS WILL CONTINUE TO IMPACT SITES KDSM/KALO/KOTM THROUGH THE
OVERNIGHT WITH DECREASED VISIBILITY AND CEILINGS. AT THE SAME
TIME MVFR TO IFR STRATUS WILL IMPACT ALL SITES THROUGH SATURDAY
MORNING WITH IMPROVEMENT FROM WEST TO EAST THROUGH THE MORNING.
WINDS WILL REMAIN BREEZY OUT OF THE NORTH WITH GUSTS OF 25-35
KTS OVERNIGHT AND OVER 20KTS THROUGH SATURDAY. WINDS DIMINISH
AFTER 00Z.
HYDROLOGY
ISSUED AT 1144 AM CDT FRI JUL 31 2026
RAINFALL FOR THIS EVENT HAS GENERALLY UNDERACHIEVED VS. EARLIER
FORECASTS THUS FAR, THUS HYDROLOGIC RESPONSES ON AREA RIVERS AND
STREAMS HAS BEEN LESS THAN ANTICIPATED. THE CEDAR BASIN FROM
SOUTHEAST MN INTO NORTHEAST IA RECEIVED THE HEAVIEST RAINFALL, AND
THE CEDAR RIVER ITSELF IS EXPECTED TO CREST AROUND ACTION STAGE
EARLY NEXT WEEK IN THE WATERLOO-CEDAR FALLS AREA. THE UPPER-MOST
PORTIONS OF THE DES MOINES BASIN IN SOUTHWEST MN RECEIVED SOME
LOCALLY HEAVY RAINFALL WHICH MAY LEAD TO MINOR RISES DOWNSTREAM INTO
NORTHWEST IA NEXT WEEK, BUT IS EXPECTED TO REMAIN BELOW ACTION STAGE.
ADDITIONAL MODERATE TO LOCALLY HEAVY RAIN IS EXPECTED THIS AFTERNOON
AND EVENING, MAINLY ACROSS THE EASTERN THIRD OF IA. GREATEST FLOOD
RISK IS PONDING OR POSSIBLE LOW-END FLASH FLOODING MAINLY IN TOWNS
AND CITIES, MAINLY EAST OF US 63, WHICH WOULD BE PRIMARILY WITHIN
THE CEDAR-IOWA BASIN. GOING CEDAR RIVER FORECASTS FOR THE WATERLOO-
CEDAR FALLS AREA INCORPORATE THE MOST LIKELY QPF SCENARIO THROUGH
12Z SATURDAY.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...05
LONG TERM...05
AVIATION...HAGENHOFF
HYDROLOGY...ZOGG
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