798
FXUS63 KDMX 110716
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
ISSUED BY NATIONAL WEATHER SERVICE DULUTH MN
216 AM CDT FRI JUL 11 2025
KEY MESSAGES
- FLOOD WATCH FOR FLASH FLOODING BETWEEN US HIGHWAYS 34 AND 20
THROUGH 7AM CDT THIS MORNING. WIDESPREAD RAINFALL TOTALS
BETWEEN 2 AND 3 INCHES WITH LOCALLY HIGHER AMOUNTS.
- FLOOD WATCH FOR FLASH FLOODING FOR THE REMAINDER OF THE DAY
FRIDAY FROM THE WATERLOO THROUGH CORYDON AREAS AND POINTS EAST
FOR ANOTHER ROUND OF HEAVY RAINFALL THIS AFTERNOON AND
EVENING.
- SCATTERED SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING
ACROSS PORTIONS OF CENTRAL IOWA (RISK LEVEL 2 OUT OF 5).
DAMAGING WINDS AND A TORNADO OR TWO ARE THE PRIMARY THREATS IN
ADDITION TO HEAVY RAIN.
DISCUSSION
ISSUED AT 104 AM CDT FRI JUL 11 2025
A LONG LIVED MCS WITH DAMAGING WINDS WILL CONTINUE TO PROPAGATE
EAST ACROSS THE I-80 CORRIDOR EARLY THIS MORNING, SUSTAINED BY
A LOW LEVEL JET AND ALONG A GRADIENT OF STEEP MID LEVEL LAPSE
RATES AND DOWNDRAFT CAPE. IN THIS WAKE OF THIS LEADING MCS,
TRAINING CONVECTION ALONG A STATIONARY FRONT SUSTAINED BY THE
LOW LEVEL JET WITH A PRECIPITABLE WATER AXIS AROUND 2.00 INCHES
WILL YIELD HEAVY RAINFALL AND A FLASH FLOOD THREAT BETWEEN US
HIGHWAYS 34 AND 20. RAINFALL TOTALS BETWEEN 2.00 AND 3.00 INCHES
ARE LIKELY FOR MANY LOCATIONS, WITH LOCALLY HIGHER AMOUNTS IN
EXCESS OF 4.00 INCHES. A FLOOD WATCH REMAINS IN EFFECT FOR THESE
AREAS UNTIL 7 AM CDT THIS MORNING.
FOR THIS AFTERNOON AND EVENING, ANOTHER ROUND OF STRONG TO
SEVERE STORMS WITH HEAVY RAINFALL IS EXPECTED. ISSUED A SECOND
FLOOD WATCH FOR THE WATERLOO THROUGH CORYDON AREAS AND POINTS
EAST FOR ANOTHER ROUND OF HEAVY RAINFALL WITH PRECIPITABLE WATER
VALUES REMAINING NEAR 2.00 INCHES WITH TRAINING CONVECTION
LIKELY ALONG THE SLOW MOVING FRONTAL BOUNDARY. ADDITIONAL RAINFALL
AMOUNTS OF ONE AND A HALF TO THREE INCHES ARE POSSIBLE FOR
THESE AREAS, SUPPORTED BY THE HREF LPMM QPF, MPAS CAMS AND RRFS.
THIS ALSO ALIGNS WELL WITH THE WPC SLIGHT RISK IN THE EXCESSIVE
RAINFALL OUTLOOK FOR TODAY (LEVEL 2 OUT OF 4).
REGARDING THE SEVERE RISK FOR TODAY, SPC HAS MUCH OF SOUTH
CENTRAL INTO EASTERN IOWA IN A SLIGHT RISK FOR SEVERE
THUNDERSTORMS (LEVEL 2 OUT OF 5). PLENTIFUL MOISTURE AND
BUOYANCY WITH MLCAPE ON THE ORDER OF 2000-3000 J/KG WITH
DAYTIME HEATING WILL BE IN PLACE ALONG AND AHEAD OF A SLOW
MOVING FRONTAL BOUNDARY. DEEP LAYER SHEAR AROUND 30-40KTS
AUGMENTED BY AN APPROACHING SHORTWAVE THIS AFTERNOON WILL
PROMOTE ANOTHER ROUND OF SEVERE THUNDERSTORMS. OUTFLOW
BOUNDARIES FROM MORNING CONVECTION WILL HAVE TO BE SORTED OUT
FOR THEIR MESOSCALE IMPACTS ON THE THERMODYNAMIC AND KINEMATIC
SETUP. STILL, INITIAL SUPERCELL STRUCTURES ARE FAVORED WITH A
TORNADO OR TWO POSSIBLE WITH LARGE LOW LEVEL CURVATURE IN THE
FORECAST HODOGRAPHS AND LOW CLOUD BASES. AS STORMS BECOME MORE
NUMEROUS IN THE LATE AFTERNOON AND EVENING, UPSCALE GROWTH IS
EXPECTED WITH DAMAGING WINDS BECOMING THE PRIMARY THREAT.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 203 AM CDT FRI JUL 11 2025
THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS THE TERMINALS FOR THE
NEXT FEW HOURS. DSM AND OTM TO BE MOST STRONGLY AFFECTED FOR THE
NEXT FEW HOURS, WITH STRONG WIND GUSTS AND IFR VISIBILITIES AND MVFR
CEILINGS. THE OTHER TERMINALS TO GET MVFR TO POTENTIALLY IFR
CONDITIONS IN THUNDERSTORMS WITH HEAVY RAIN. A PERIOD OF MVFR
CEILINGS ARE POSSIBLE, A 50 TO 70 PERCENT CHANCE, FRIDAY MORNING,
MAINLY FOR KALO AND KMCW. RAIN SHOWER AND THUNDERSTORM TO
TEMPORARILY DECREASE FRIDAY MORNING IN THE 12-17Z TIMEFRAME, BEFORE
INCREASING ONCE AGAIN WITH DAYTIME HEATING. FRIDAY AFTERNOON STORMS
TO MOST LIKELY AFFECT KDSM, KOTM AND KALO, WITH LOWER PROBABILITIES
FOR KFOD AND KMCW.
DMX WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR IAZ033>037-044>048-
057>060-070>073.
FLOOD WATCH THROUGH LATE TONIGHT FOR IAZ038-039-049-050-061-
062-074-075.
FLOOD WATCH FROM 7 AM CDT THIS MORNING THROUGH LATE TONIGHT
FOR IAZ084>086-095>097.
DISCUSSION...DLH
AVIATION...DLH
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