862
FXUS63 KDMX 071140
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
640 AM CDT TUE JUL 7 2026
...UPDATED FOR THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- PATCHY FOG EXPECTED TO INCREASE THIS MORNING OVER PORTIONS OF
SOUTHERN TO CENTRAL IOWA. WEAKENING STORMS ARE ALSO POSSIBLE
NEAR SUNRISE IN NORTHERN IOWA.
- WARMER TEMPERATURES IN THE UPPER 80S AND 90S ON WEDNESDAY,
WITH THUNDERSTORM AND HEAVY RAIN CHANCES RETURNING WEDNESDAY
NIGHT INTO THURSDAY AND POTENTIALLY FRIDAY.
- WARMER AND DRIER CONDITIONS DEVELOP LATE THIS WEEKEND INTO
EARLY NEXT WEEK.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 300 AM CDT TUE JUL 7 2026
CONDITIONS ACROSS IOWA EARLY THIS MORNING REMAIN DRY, THOUGH FURTHER
NORTH, A SURFACE BOUNDARY CURRENTLY DRAPED ACROSS SOUTHERN MINNESOTA
HAS A WEAKENING LINE OF SHOWERS AND THUNDERSTORMS THAT ARE SLOWLY
TRACKING SOUTHEAST THROUGH THE STATE. WHILE MOST OF THIS ACTIVITY IS
WEAKENING, ONE CLUSTER ON THE WESTERN FRINGE OF THIS BOUNDARY IS
STILL CARRYING ALOT OF LIGHTNING, WITH OTHER STORMS FURTHER EAST ARE
QUITE WEAK IN NATURE. THE OVERALL EXPECTATION REMAINS THE SAME THAT
THESE STORMS WILL CONTINUE TO WEAKEN AND EVENTUALLY DISSIPATE AS
THEY TRACK FURTHER SOUTHEAST, GIVEN WEAK HIGH PRESSURE OVERHEAD AND
DRIER AIR. MOST GUIDANCE HAS THIS ACTIVITY DYING OFF BEFORE REACHING
IOWA, THOUGH GIVEN SLOWER WEAKENING TRENDS, THE POTENTIAL HAS
INCREASED FOR AT LEAST PORTIONS OF FAR NORTHERN IOWA TO SEE AT LEAST
LIGHT RAIN AND WEAK STORMS NEAR SUNRISE BEFORE DRYING OUT CLOSER TO
MID-MORNING, IF NOT SOONER. THEREFORE HAVE ADDED LOW POP MENTIONS
(10-20%) IN THESE AREAS TO REFLECT CURRENT TRENDS. OTHERWISE,
STARTING TO SEE A FEW SITES EXPERIENCE SLIGHTLY LOWERED VISIBILITIES
BETWEEN 3-7 MILES OVER PORTIONS OF CENTRAL TO SOUTH CENTRAL IOWA DUE
TO PATCHY FOG DEVELOPMENT. GIVEN CLEAR SKIES ACROSS THESE AREAS AND
VERY LIGHT TO CALM WINDS AT THE TIME OF THIS WRITING, THE
EXPECTATION REMAINS FOR PATCHY AND LOCALIZED DENSE FOG TO INCREASE
IN COVERAGE OVER THE NEXT 3-4 HOURS, BEFORE DISSIPATING. THE CLOUD
SHIELD JUST STARTING TO REACH INTO NORTHERN IOWA THOUGH WILL LIKELY
EXPAND FURTHER SOUTH WITH TIME THIS MORNING, WHICH COULD PUT A
DAMPER ON FOG POTENTIAL. THERE IS SOME UNCERTAINTY IN HOW FAR SOUTH
EXACTLY THESE CLOUDS WILL EXTEND, BUT HAVE AT LEAST INCREASED CLOUD
COVER OVER NORTHERN INTO PORTIONS OF CENTRAL IOWA INTO MID MORNING.
UPPER LEVEL RIDGING OVER THE UPPER MIDWEST, PAIRED WITH WEAK HIGH
PRESSURE EXTENDING WESTWARD INTO IOWA YET WILL KEEP CONDITIONS ON
THE DRY SIDE ACROSS MUCH OF THE AREA TODAY, WITH SURFACE WINDS
SHIFTING SOUTH/SOUTHWESTERLY, BRINGING IN SLIGHTLY WARMER AIR AS
TEMPERATURES REACH INTO THE MID TO UPPER 80S. SURFACE CYCLOGENESIS
ON THE LEE SIDE OF THE ROCKIES LATE THIS AFTERNOON TO EVENING PER
GUIDANCE IS EXPECTED TO OCCUR, WITH A WARM FRONTAL BOUNDARY OVER
SOUTH DAKOTA INTO MINNESOTA, PLACING IOWA IN THE WARM SECTOR. GIVEN
THE OVERALL SETUP, ANY SHOWER AND STORM DEVELOPMENT IS EXPECTED TO
BE IN CLOSE PROXIMITY TO THE BOUNDARY NORTH/NORTHWEST OF IOWA, WHICH
WILL BE THE FOCUS FOR THE NEXT CHANCE OF SHOWERS AND STORMS INTO THE
STATE BY WEDNESDAY AFTERNOON TO EVENING AS THIS BOUNDARY IS SHUNTED
SOUTH AND EAST. A SLIGHT RISK PER SPC NOW EXISTS FOR POTENTIAL
SEVERE WEATHER INTO NORTHEAST IOWA DURING THIS TIME FRAME. MORE
DETAILS REGARDING THIS ACTIVITY IS IN THE LONG TERM DISCUSSION
BELOW.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
ISSUED AT 245 PM CDT MON JUL 6 2026
THE UPPER LEVEL WAVE TO OUR SOUTH AND SURFACE HIGH OVERHEAD WILL
BEGIN TO DEPART EASTWARD ON TUESDAY, BRINGING SOUTHERLY RETURN FLOW
BACK UP INTO IOWA TUESDAY NIGHT THROUGH WEDNESDAY. THE RESULT WILL
FIRST BE WARMER TEMPERATURES WITH HIGHS IN THE UPPER 80S TO LOW 90S
ON WEDNESDAY. THE UPPER LEVEL PATTERN WILL BEGIN TO TRANSITION TO
MORE ZONAL FLOW THROUGH THIS SAME PERIOD AND THE BOUNDARY TO OUR
NORTHWEST WILL BEGIN TO SINK SOUTH AND EAST TOWARDS THE STATE. WEAK
ENERGY WORKING THROUGH THE ZONAL FLOW WILL DEVELOP SHOWER AND
THUNDERSTORM CHANCES ALONG SAID BOUNDARY STARTING LATE WEDNESDAY AND
LASTING INTERMITTENTLY OVER IOWA INTO THURSDAY MORNING. PLENTY
OF MOISTURE (2"+ PRECIPITABLE WATER VALUES) AND INSTABILITY
(~1500 TO 2500+ J/KG OF MUCAPE) WILL BE PRESENT OVER IOWA DURING
THIS SAME TIME, ALTHOUGH SHEAR WILL BE MINIMAL (20 TO 30 KTS OF
0-6 KM SHEAR), SUGGESTING UPDRAFTS MAY STRUGGLE TO BECOME
ORGANIZED. LIKEWISE, WHILE THERE DOES APPEAR TO BE WEAK ENERGY
MOVING THROUGH THE ZONAL FLOW, THE FORCING IS UNIMPRESSIVE FOR
MOST OF THE AREA, BARRING SOUTHWEST IOWA WHERE THE LOW LEVEL JET
IS EXPECTED TO NOSE INTO OVERNIGHT. THIS JET COULD PROVIDE SOME
EXTRA LIFT FOR STORMS THROUGH CENTRAL AND SOUTHERN IOWA
WEDNESDAY NIGHT INTO THURSDAY, BUT OTHER AREAS MAY NEED A BIT
MORE JUICE TO KICK THINGS OFF. THEREFORE, THE MAIN CONCERN AT
THIS TIME IS THE POTENTIAL FOR HEAVY RAINFALL FUELED BY THIS LOW
LEVEL JET. SEE HYDRO DISCUSSION BELOW.
THE PATTERN REMAINS ACTIVE THROUGH THE END OF THE WEEK, WITH ANOTHER
SHORTWAVE SLATED TO MOVE THROUGH THE MIDWEST FRIDAY, ALBEIT WITH
MORE UNCERTAINTY ON EXACT TRACK AND EVOLUTION. HOWEVER, BY THIS
WEEKEND MODELS SHOW GOOD CONSENSUS OF A BROAD UPPER LEVEL RIDGE
SPANNING MUCH OF THE WESTERN AND CENTRAL US. THIS REGIME WOULD LEND
ITSELF TO WARMER TEMPERATURES AND DRIER CONDITIONS FOR IOWA LATE
THIS WEEKEND AND INTO EARLY NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 639 AM CDT TUE JUL 7 2026
PATCHY FOG WILL REMAIN AT KFOD AND KOTM OVER THE NEXT HOUR OR SO
BEFORE DISSIPATING. HAVE ADDED A PROB30 MENTION AT KMCW DUE TO
WEAKENING SHOWER ACTIVITY THAT IS NEAR THE SITE, WHICH IS ONLY
EXPECTED OVER THE NEXT HOUR BEFORE DRY CONDITIONS RETURN.
OTHERWISE, VFR CONDITIONS WILL PREVAIL, THOUGH DIURNAL CUMULUS
IS EXPECTED LATER THIS MORNING AND INTO THE AFTERNOON THAT WILL
LOWER CEILINGS AT TIMES. WINDS WILL REMAIN LIGHT THROUGH THE
PERIOD.
HYDROLOGY
ISSUED AT 634 AM CDT TUE JUL 7 2026
RIVERS AND STREAMS IN CENTRAL IOWA CONTINUE TO SEE INCREASED
FLOW AS WATER FROM THE HEAVY RAINS LATE LAST WEEK AND THIS
WEEKEND 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 IS EXPECTED TO FALL BELOW FLOOD STAGE
LATER TODAY. THIS PORTION OF THE SOUTH SKUNK RIVER FLOWS INTO
THE OSKALOOSA (OOAI4) AREA, BUT 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 EXACT CORRIDOR OF THE HEAVIEST RAIN IS STILL UNCERTAIN, BUT WILL
BE MONITORING CLOSELY THROUGH THE COMING DAYS.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...BURY
LONG TERM...DODSON
AVIATION...BURY
HYDROLOGY...DODSON/BURY
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