093
FXUS63 KDMX 072343
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
643 PM CDT TUE JUL 7 2026
...UPDATED FOR THE 00Z AVIATION DISCUSSION...
KEY MESSAGES
- QUIET AND SUNNY CONDITIONS CONTINUE TODAY, WITH WARMER
TEMPERATURES NEAR 90 EXPECTED WEDNESDAY.
- THUNDERSTORM CHANCES RETURN WEDNESDAY AFTERNOON THROUGH
THURSDAY MORNING. A FEW STORMS MAY PRODUCING DAMAGING WINDS
AND HEAVY RAINFALL OVER NORTH CENTRAL IOWA.
- ADDITIONAL RAINFALL AROUND 1 TO 2 INCHES WEDNESDAY THROUGH
THURSDAY MAY SLOW OR WORSEN ONGOING IMPROVEMENT ALONG AREA
RIVERS.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 252 PM CDT TUE JUL 7 2026
TODAY'S CONDITIONS OVER IOWA SHOW A SIMILAR PICTURE TO
THIS TIME YESTERDAY, WITH CUMULUS CLOUDS SPECKLING SUNNY SKIES.
WINDS ARE LIGHT AND GENERALLY OUT OF THE SOUTH AND TEMPERATURES HAVE
WARMED INTO THE 80S. HEAT INDEX VALUES ARE A BIT HIGHER IN THE UPPER
80S AND LOW 90S THANKS TO THE MOIST UPPER 60 TO 70 DEWPOINTS AND
LITTLE COOLING FROM THE WIND. SURFACE HIGH PRESSURE IS TO BE THANKED
FOR ANOTHER DAY OF NICE CONDITIONS, BUT WILL BE STEADILY DEPARTING
THE AREA TONIGHT INTO WEDNESDAY. RETURN FLOW ON THE BACKSIDE OF THE
HIGH PRESSURE WILL BRING THE WARM, MOIST LOW TO MID-LEVEL MOISTURE
STREAM BACK INTO IOWA. THIS WILL FIRST RESULT IN WARMER TEMPERATURES
ON WEDNESDAY AS HIGHS CLIMB INTO THE UPPER 80S TO LOW 90S FOR SOME.
THIS MOIST AIR WILL ALSO BRING SOME INCREASED CLOUDINESS AND
RAIN/THUNDERSTORM CHANCES TO IOWA WEDNESDAY THROUGH FRIDAY.
THE FIRST OF THIS RAIN AND CLOUDINESS COULD COME AS EARLY AS MID- TO
LATE WEDNESDAY MORNING, AS CONVECTIVE DEBRIS LINGERS INTO IOWA FROM
OVERNIGHT CONVECTION IN THE DAKOTAS AND MINNESOTA TONIGHT. MOST OF
SHORT-RANGE GUIDANCE HAS THIS ACTIVITY DIMINISHING BY THE TIME IT
ARRIVES IN OUR FORECAST AREA, AS THE AIRMASS OVER IOWA WILL BE MORE
STABLE THAN FARTHER NORTH, AT LEAST IN THE MORNING HOURS. HOWEVER,
WE SAW STORMS PERSIST INTO IOWA THIS MORNING UNDER LESS FAVORABLE
CONDITIONS, SO IT'S CERTAINLY POSSIBLE A FEW SHOWERS OR EVEN A
THUNDERSTORM GRAZES NORTHERN IOWA THIS MORNING. FORTUNATELY, THESE
STORMS WOULD BE ELEVATED WITH LESS THAN 1000 J/KG OF MUCAPE, SO
ANTICIPATE STORMS WILL BE SUB-SEVERE ALBEIT WITH SOME GUSTY WINDS
POSSIBLE GIVEN THE DRY SUB-CLOUD AIR.
A BOUNDARY IS THEN EXPECTED TO SET UP OVER WESTERN INTO NORTHERN
IOWA THROUGH THE DAY WEDNESDAY, AS A VERY SUBTLE 500 MB SHORTWAVE
PASSES FROM WEST TO EAST ACROSS NORTHERN IOWA. THE COMBINATION OF
THIS WEAK WAVE AND BOUNDARY WILL RESULT IN THUNDERSTORM CHANCES OVER
NORTHERN IOWA WEDNESDAY AFTERNOON THROUGH THE EVENING. THE
THUNDERSTORM ENVIRONMENT THROUGH THIS PERIOD ISN'T NECESSARILY
JUMPING OFF THE PAGE, DEPICTING MODEST INSTABILITY (1500 TO 2000
J/KG OF MLCAPE) AND MARGINAL DEEP LAYER SHEAR (25 TO 35 KTS OF 0-6
KM SHEAR). THIS IS SUFFICIENT FOR A FEW ORGANIZED UPDRAFTS AND
STRONG TO SEVERE STORMS. THE MAIN RISK WITH STORMS WILL BE THE
DAMAGING WIND POTENTIAL, AS A WELL-MIXED BOUNDARY LAYER AHEAD OF THE
BOUNDARY WILL PROMOTE EVAPORATIVE COOLING AND ENHANCED WINDS DOWN TO
THE SURFACE. HAIL WILL ALSO BE A POSSIBILITY, ALTHOUGH LARGE HAIL
MAY BE DIFFICULT TO COME BY, BARRING AN INCREASE IN WIND SHEAR
ALLOWING FOR SUPERCELL DEVELOPMENT. FINALLY, THE TORNADO RISK ALSO
APPEARS LOW WITH RELATIVELY HIGH LCLS AND MARGINAL LOW LEVEL SRH (50
TO 100 M2/S2) BUT CAN'T RULE IT OUT WITH ANY STORMS TIED INTO A
SURFACE BOUNDARY. WITH 1.7" TO 2.0" PRECIPITABLE WATER VALUES ALONG
THE BOUNDARY, EFFICIENT RAINFALL MAY OCCUR WITH THESE STORMS.
RAINFALL AMOUNTS AROUND AN INCH ARE EXPECTED, WITH LOCALIZED POCKETS
OF 2 TO 3 INCHES POSSIBLE, MAINLY OVER NORTH CENTRAL IOWA.
THE SEVERE THUNDERSTORM POTENTIAL GENERALLY WANES LATE WEDNESDAY
EVENING AND OVERNIGHT, BUT ISOLATED TO SCATTERED ELEVATED STORM
ACTIVITY MAY STILL LINGER ALONG THE BOUNDARY AS IT SAGS SOUTHWARD
INTO THE OVERNIGHT HOURS. THAT SAID, A LULL IN ACTIVITY IS POSSIBLE
OVERNIGHT BEFORE MORE STORMS BEGIN TO MOVE IN FROM THE WEST EARLY
THURSDAY MORNING, BEING FED BY THE LLJ NOSED UP INTO THE PLAINS.
MODEL GUIDANCE ISN'T IN COMPLETE AGREEMENT FOR HOW THIS SECOND ROUND
OF STORMS WILL LOOK, AS THE NORTHWARD EXTENT OF THE JET VARIES AMONG
SOLUTIONS. THIS COMES IN THE FORM OF A MESOSCALE CONVECTIVE SYSTEM,
BUT TRACK WILL BE DEPENDENT ON THE JET AND THE FINAL POSITION OF THE
BOUNDARY. DAMAGING WINDS COULD BE POSSIBLE SHOULD THIS MCS HOLD ON
INTO CENTRAL IOWA, ALTHOUGH GUIDANCE IS TRYING TO DISSIPATE THE
SYSTEM AS IT ENTERS THE STATE EARLY THURSDAY. OF SIMILAR CONCERN
WOULD BE MORE HEAVY RAINFALL ASSOCIATED WITH THIS SYSTEM AS IT MOVES
THROUGH, AS WELL AS REDEVELOPMENT ASSOCIATED WITH ANY MCVS AS IT
MOVES THROUGH THE STATE THURSDAY. IT'S TOUGH TO PUT TOO MUCH STOCK
IN REDEVELOPMENT ON LEFTOVER MESOSCALE FEATURES AT THIS RANGE, BUT
WILL WANT TO WATCH HIGH RESOLUTION MODELS AS ADDITIONAL THUNDERSTORM
DEVELOPMENT IS POSSIBLE AGAIN THURSDAY AFTERNOON OVER FAR SOUTHERN
IOWA AND INTO MISSOURI.
LONG TERM /FRIDAY THROUGH TUESDAY/
ISSUED AT 252 PM CDT TUE JUL 7 2026
ONE MORE SHORTWAVE PASSES THROUGH THE 500 MB PATTERN ON FRIDAY,
BRINGING MORE SHOWER AND STORM CHANCES TO THE STATE, ALBEIT TO A
LOWER CONFIDENCE GIVEN A LOT OF THE MOISTURE TRANSPORT WILL BE
FOCUSED TO THE SOUTH OF IOWA. AFTER THIS FRIDAY WAVE, 500 MB RIDGING
FILLS IN ALOFT, KEEPING CONDITIONS DRY AND WARM FOR MOST OF THE
STATE THROUGH THE WEEKEND. HIGHS BY NEXT WEEK CLIMB BACK INTO THE
UPPER 80S AND POTENTIALLY THE LOW 90S. THIS HIGH PRESSURE LOOKS TO
STICK AROUND FOR A FEW DAYS, BEFORE EVENTUALLY BREAKING DOWN LATE
NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 631 PM CDT TUE JUL 7 2026
VFR CONDITIONS TO PREVAIL THROUGH THE END OF THIS TAF PERIOD.
THE REST OF THE NIGHT WILL FEATURE LIGHT WINDS WITH MOSTLY CLEAR
SKIES. AS WE NEAR THE END OF THIS TAF PERIOD SHOWERS AND STORMS
WILL START TO PUSH INTO NORTHERN IOWA. CONFIDENCE IS MEDIUM
(30-50%) THAT STORMS WILL BE IMPACTING KMCW AT THE END OF THIS
TAF PERIOD THAT A PROB30 GROUP HAS BEEN INTRODUCED. CONFIDENCE
IS TOO LOW TO INCLUDE PROB30 GROUPS AT ANY OTHER TERMINALS AT
THIS TIME.
HYDROLOGY
ISSUED AT 252 PM CDT TUE JUL 7 2026
RIVERS AND STREAMS IN CENTRAL IOWA CONTINUE TO SEE INCREASED FLOWS
AS WATER CONTINUES TO ROUTE THROUGH THE SYSTEM. ONE RIVER IN CENTRAL
IOWA MAINTAINS A FLOOD WARNING, WHICH IS THE SOUTH SKUNK RIVER NEAR
COLFAX (CFXI4) THAT HAS ACTIVELY CRESTED AT MODERATE FLOOD STAGE AND
WILL BE FALLING BELOW FLOOD STAGE THIS AFTERNOON. THIS PORTION OF
THE SOUTH SKUNK RIVER FLOWS INTO THE OSKALOOSA (OOAI4) AREA, BUT AT
THIS POINT SHOULD REMAIN BELOW IT'S MINOR FLOOD STAGE. OTHER RIVERS
WITHIN THE DES MOINES AND CEDAR RIVER BASINS ARE ALSO AT INCREASED
LEVELS AS WATER WORKS IT'S WAY DOWN STREAM, ALBEIT ALL BELOW FLOOD
STAGE AND CONTINUING TO RECEDE.
ADDITIONAL RAINFALL LATER THIS WEEK, ESPECIALLY WEDNESDAY EVENING
THROUGH FRIDAY, COULD LEAD TO SLOWER IMPROVEMENT AND/OR ADDITIONAL
RISES ON AREA RIVERS, DEPENDING ON WHAT BASINS THIS RAIN AFFECTS.
THE HEAVIEST RAIN LOOKS LIKE IT WILL FALL OVER NORTH CENTRAL IOWA,
AND SHOULD BE IN ISOLATED POCKETS. HOWEVER, SHOULD ONE OF THESE
ISOLATED POCKETS FALL IN THE WRONG SPOTS, CONDITIONS MAY BE
EXACERBATED.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...DODSON
LONG TERM...DODSON
AVIATION...TDR
HYDROLOGY...DODSON
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