368
FXUS63 KDMX 070800
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
300 AM CDT TUE JUL 7 2026
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 /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1046 PM CDT MON JUL 6 2026
TRENDED MORE AGGRESSIVE FOR FOG THIS ISSUANCE AS CLOUD COVER
WILL BE DELAYED IN REACHING MOST TAF SITES. CONFIDENCE HAS
INCREASED IN RIVER VALLEY FOG AT KFOD DUE TO LESS CLOUDS AND
HAVE REFLECTED TRANSIENT LIFR CONDITIONS TYPICALLY SEEN THERE.
KDSM WILL HAVE A SHORT WINDOW OF MVFR VSBYS FROM FOG. HIGHEST
CONFIDENCE IN FOG WILL BE AT KALO AND KOTM WITH IFR VSBYS
POSSIBLE WITHIN 2 HOURS OF SUNRISE.
HYDROLOGY
ISSUED AT 245 PM CDT MON JUL 6 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. TWO RIVERS IN
CENTRAL IOWA MAINTAIN FLOOD WARNINGS AT THIS TIME. THE FIRST IS
THE SOUTH SKUNK RIVER NEAR COLFAX (CFXI4) WHICH IS ACTIVELY
CRESTING AT MODERATE FLOOD STAGE AND EXPECTED TO FALL BELOW
FLOOD STAGE TOMORROW. THIS PORTION OF THE SOUTH SKUNK RIVER
FLOWS INTO THE OSKALOOSA (OOAI4) AREA, BUT THIS POINT SHOULD
REMAIN BELOW IT'S MINOR FLOOD STAGE. THE IOWA RIVER NEAR TAMA
(TMAI4) ALSO MAINTAINS A FLOOD WARNING AS IT CONTINUES TO
SLOWLY RISE, WITH AN EXPECTED TO CREST AT OR JUST BELOW MINOR
FLOOD STAGE TODAY. 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...JIMENEZ
HYDROLOGY...DODSON
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