278
FXUS63 KDMX 081144
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
644 AM CDT WED JUL 8 2026
...UPDATED FOR THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- LIMITED PATCHY FOG IN LOW LYING AREAS THIS MORNING.
- THUNDERSTORM CHANCES RETURN INTO THIS AFTERNOON THROUGH
THURSDAY MORNING. A FEW STORMS MAY PRODUCE DAMAGING WINDS AND
HEAVY RAINFALL.
- 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 307 AM CDT WED JUL 8 2026
A LOOK AT OBSERVATIONS ACROSS CENTRAL IOWA EARLY THIS MORNING
INDICATE TEMPERATURES IN THE LOW 70S, WITH DEWPOINTS NEAR THE SAME
VALUES IN SOME ISOLATED LOCATIONS UNDER CLEAR SKIES AND CALM OR VERY
LIGHT WINDS, LEADING TO SOME PATCHY FOG. WHILE PATCHY FOG MAY
CONTINUE TO FORM MAINLY IN LOW LYING AREAS UNTIL SUNRISE OR SO, A
LOOK FURTHER NORTH INTO MINNESOTA SHOWS A LINE OF SHOWERS AND
THUNDERSTORMS NEAR A BOUNDARY THAT ARE MOVING EAST-SOUTHEAST WITH
TIME. THE CONVECTIVE DEBRIS (CLOUD SHIELD) IS EXTENDING SOUTHWARD,
WHICH HAS ALREADY STARTED TO MOVE INTO NORTHERN IOWA AND WILL LIKELY
CONTINUE THE DESCENT SOUTH THROUGH THE MORNING, KEEPING FOG
FORMATION RELATIVELY MINIMAL. THE AFOREMENTIONED BOUNDARY IS
AHEAD OF A MID-LEVEL SHORTWAVE TROUGH THAT IS CURRENTLY OVER THE
DAKOTAS, WHICH WILL CONTINUE TO PUSH EAST THROUGHOUT THE DAY,
WHILE THE BOUNDARY GRADUALLY SHIFTS SLOWLY SOUTHEASTWARD TODAY.
CAM GUIDANCE GENERALLY INDICATES THAT THESE SHOWERS AND STORMS
WILL NOT ARRIVE INTO NORTHERN IOWA UNTIL AROUND 17-18Z, THOUGH
THIS MAY BE TOO SLOW, GIVEN HOW CONVECTION IS AT LEAST SLIGHTLY
FURTHER SOUTH AT THIS TIME AND MAY RESULT IN AN EARLIER ARRIVAL
CLOSER TO MID-MORNING. IF THE CURRENT STORMS IN SOUTHERN IOWA DO
DIE BEFORE REACHING THE NORTHERN PARTS OF THE FORECAST AREA,
ADDITIONAL STORM DEVELOPMENT IS EXPECTED TO OCCUR NEAR/ALONG
THIS SAGGING FRONT, WITH HIGHER CONFIDENCE IN SHOWERS AND STORMS
ENTERING NORTHERN IOWA BY EARLY-MID AFTERNOON.
AHEAD OF THIS FEATURE, CONDITIONS ACROSS IOWA WILL BE ON THE HOT AND
HUMID SIDE, WITH HIGHS IN THE UPPER 80S TO LOW 90S AND DEW POINTS IN
THE MID 60S TO LOW 70S, WHICH WILL ALLOW FOR INSTABILITY TO INCREASE
INTO THE AFTERNOON AND REMAIN THROUGH THE EVENING, WITH VALUES
AROUND 1500-2000 J/KG AND SHEAR VALUES AROUND 30 KNOTS THAT WILL BE
FAVORABLE FOR STORMS TO GROW UPSCALE TO AT LEAST SOME DEGREE. LESS
FAVORABLE LAPSE RATES BELOW 7 C/KM AND HIGH FREEZING LEVEL HEIGHTS
(15 KFT) WILL LIKELY LEAD TO DIFFICULTY IN LARGE HAIL DEVELOPMENT,
THOUGH THE DAMAGING WIND POTENTIAL IS MUCH MORE FAVORABLE AS STORMS
GRADUALLY CONGEAL INTO LINES. THE RISK FOR A FEW ISOLATED TORNADOES
ALSO REMAINS, THOUGH LOW, WITH SRH VALUES BELOW 100 M2S2 AND LIMITED
DIRECTIONAL SHEAR. THE SLIGHT RISK PER SPC WAS EXPANDED FURTHER
SOUTH AND WEST TO HIGHLIGHT THE INCREASING POTENTIAL FOR SEVERE
WEATHER IN THESE AREAS. A LOOK AT THE ENVIRONMENT FOR HEAVY RAIN
POTENTIAL INDICATES HIGH PWAT VALUES NEAR 2 INCHES OVERHEAD TOWARDS
THE EVENING AND OVERNIGHT AS THIS BOUNDARY NEARS THE I-80 CORRIDOR,
PAIRED WITH THE AFOREMENTIONED DEEP WARM CLOUD DEPTHS. THE RISK
WOULD INCREASE FURTHER FOR FLOODING IF ANY PARTICULAR AREAS SEES
MULTIPLE STORMS, WHICH WOULD INCREASE CONCERNS SUBSTANTIALLY
FOR NEW AND RENEWED RISES OF RIVERS AND ALSO THE POTENTIAL FLASH
FLOODING RISK, ESPECIALLY IN AREAS THAT RECEIVED THE SEVERAL
INCHES OF RAIN LATE LAST WEEK.
THROUGH THURSDAY MORNING, THE EXPECTATION PER VARIOUS MODELS
SUGGESTS THAT STORMS SHOULD GENERALLY HAVE DESCENDED INTO SOUTH
CENTRAL TO SOUTHERN IOWA, WITH THE LINGERING POTENTIAL FOR SEVERE
WEATHER AS FORCING FOR LIFT INCREASES WITH SOME PRESENCE OF THE LOW
LEVEL JET INTO WEST/SOUTHWEST IOWA. TOTAL RAINFALL AMOUNTS BY
THURSDAY MORNING ARE INDICATED AROUND 1-2 INCHES, WITH ISOLATED 3
INCHES POSSIBLE OVER WESTERN INTO WEST CENTRAL IOWA AND LOWER VALUES
ELSEWHERE ACROSS THE STATE. AS THE BOUNDARY MOVES ACROSS SOUTHERN
IOWA, THERE REMAINS A SIGNAL OF A DEVELOPING MCV THAT TRACKS
EASTWARD, WHICH WOULD BRING A RENEWED POTENTIAL FOR DAMAGING WINDS
AND HEAVY RAINFALL. RECENT GUIDANCE THOUGH HAS THIS FEATURE FURTHER
SOUTH INTO MISSOURI BUT STILL NEAR SOUTHERN IOWA, SO WILL NEED TO
KEEP AN EYE ON THIS. AS THIS SYSTEM DEPARTS LATER IN THE DAY,
ADDITIONAL CONVECTION MAY FIRE OFF AGAIN OVER SOUTHERN IOWA WHERE
THE FRONT MAY LINGER YET, THOUGH SEVERE WEATHER POTENTIAL BY THIS
POINT LOOKS MORE LIMITED. THE OVERALL EVOLUTION OF STORM PLACEMENT
AND TRACK INTO THURSDAY WILL BE HEAVILY DEPENDENT ON HOW THE
ACTIVITY PLAYS OUT LATER TODAY INTO TONIGHT, SO TRENDS WILL BE VERY
IMPORTANT TO MONITOR.
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 /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 643 AM CDT WED JUL 8 2026
CLOUDS WILL GRADUALLY INCREASE FROM NORTHWEST TO SOUTHEAST
TODAY, AHEAD OF SHOWERS AND THUNDERSTORMS THAT ARE EXPECTED TO
MOVE WITH A PASSING BOUNDARY ACROSS THE STATE THIS AFTERNOON TO
EVENING. CANNOT RULE OUT A STORM THIS MORNING NEAR KMCW GIVEN
CURRENT RADAR TRENDS, BUT CONFIDENCE IS NOT HIGH THAT THESE
STORMS WILL HOLD TOGETHER, SO HAVE LEFT OUT AT THIS TIME AND
WILL MONITOR. WHILE VFR CONDITIONS ARE GENERALLY EXPECTED, THERE
COULD BE BRIEF PERIODS OF MVFR CONDITIONS AS STORMS PASS THROUGH
DUE TO VISIBILITY AND CEILING RESTRICTIONS. WINDS WILL INCREASE
OUT OF THE SOUTHWEST DURING THE DAYTIME HOURS, THEN TURN
VARIABLE TONIGHT INTO THURSDAY, THOUGH STORMS COULD PRODUCE
BRIEF GUSTY WINDS.
HYDROLOGY
ISSUED AT 638 AM CDT WED JUL 8 2026
RIVERS AND STREAMS IN CENTRAL IOWA CONTINUE TO SEE INCREASED FLOWS
AS WATER CONTINUES TO ROUTE THROUGH THE SYSTEM. RIVERS WITHIN
THE DES MOINES AND CEDAR RIVER BASINS ARE 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 THIS 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...BURY
LONG TERM...DODSON
AVIATION...BURY
HYDROLOGY...DODSON/BURY
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