849
FXUS63 KDMX 080358
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1058 PM CDT THU MAY 7 2026
...UPDATED FOR THE 06Z AVIATION DISCUSSION...
KEY MESSAGES
- 20% CHANCE OF ISOLATED SHOWERS FRIDAY MORNING OVER SOUTHERN
IOWA. FEW SPRINKLES POSSIBLE INTO PORTIONS OF CENTRAL IOWA.
- SEVERAL CHANCES FOR SHOWERS AND/OR THUNDERSTORMS FROM SATURDAY NIGHT
INTO NEXT WEEK. THERE CONTINUES TO BE NO APPARENT SIGNAL FOR
SIGNIFICANT OR WIDESPREAD SEVERE WEATHER OR HEAVY RAINFALL
WITH ANY STORM CHANCES.
SHORT TERM /THROUGH SATURDAY/
ISSUED AT 145 PM CDT THU MAY 7 2026
EARLY AFTERNOON GOES-EAST UPPER LEVEL WATER VAPOR IMAGERY SHOWS A
SUBTLE SHORTWAVE TROUGH PUSHING INTO THE WESTERN GREAT LAKES, WHICH
BROUGHT THE LIGHT SHOWERS TO A SMALL PORTION OF CENTRAL IOWA THIS
MORNING. THERE IS STILL A ZONE OF CLOUDS BACK INTO CENTRAL IOWA WITH
SCATTERED, DIURNALLY DRIVEN CUMULUS DEVELOPING ON EITHER SIDE
AND A WEAK RADAR RETURN NEARING PELLA. FORECAST SOUNDINGS SHOW
A DEEP BOUNDARY LAYER THAT ATTEMPTS TO SATURATE WITHIN THIS
DIURNALLY DRIVEN CUMULUS AREA ABOVE THE MIXED LAYER AND THIS IS
ALSO REFLECTED IN MODEL QPF FROM CONVECTIVE ALLOWING MODELS
(CAMS) AND GLOBAL GUIDANCE. SO, HAVE INCLUDED SOME LOW POPS
THROUGH THE AFTERNOON ALONG AND SOUTH OF I-80 TO NORTH OF US 34
AND AS FAR WEST AS I-35. GIVEN THE DEEP DRY SUBCLOUD LAYER,
WILL BE ON WATCH FOR GUSTY WINDS, BUT DOWNDRAFT CAPE VALUES AND
CAM WIND GUST FIELDS ARE NOT ALARMING. DEWPOINTS WERE ONCE AGAIN
LOWERED THIS AFTERNOON TO ACCOUNT FOR THE BOUNDARY LAYER
MIXING, WHICH LOWERS RELATIVE HUMIDITIES (RHS) OVER WESTERN AND
NORTHERN IOWA TO AROUND OR BELOW 20%. FORTUNATELY, WINDS IN THE
MIXED LAYER ARE NO MORE THAN 25 KNOTS AND COMBINED WITH THE
GREENING FUELS, THERE ARE NO ELEVATED FIRE WEATHER CONCERNS.
WHILE THE NIGHT WILL START MAINLY CLEAR, CLOUDS WILL INCREASE
AHEAD OF THE NEXT PUSH OF FORCING. SIMILAR TO LAST NIGHT,
TEMPERATURES MAY FALL QUICKLY AFTER SUNSET BEFORE STABILIZING AS
CLOUDS ARRIVE. THERE MAY ONCE AGAIN BE SOME PATCHY FROST, BUT
LESS COVERAGE THAN THE PAST TWO NIGHTS BEING CONFINED TO
ISOLATED AREAS OF NORTH CENTRAL INTO NORTHEASTERN IOWA. AS THE
FORCING ARRIVES TOWARD SUNRISE FRIDAY VIA WEAK QG CONVERGENCE
AND THETA-E ADVECTION, A LOW CHANCE OF SHOWERS MAY DEVELOP OVER
SOUTHERN IOWA IN THE MORNING HOURS. SATURATION WILL ONCE AGAIN
BE A CHALLENGE PER FORECAST SOUNDINGS, BUT THERE IS ENOUGH
SUPPORT IN THE MODEL QPF FIELDS TO INCREASE POPS OVER THE
INITIAL NATIONAL BLEND OF MODELS UP TO SLIGHT CHANCE. THIS WILL
SCOOT AWAY BY THE AFTERNOON WITH DECREASING CLOUDS. WITH THE
DEEP BOUNDARY LAYER MIXING AGAIN, HAVE LOWERED DEWPOINTS AS LOW
AS THE 10TH PERCENTILE OF MODEL GUIDANCE IN THE AFTERNOON BASED
ON THE RAP AND HRRR, WHICH TEND TO PERFORM WELL IN THESE
ENVIRONMENTS. THIS RESULTS IN RHS BELOW 25% FROM A SIMILAR LINE
OF ATLANTIC TO AMES TO WATERLOO. WINDS WILL INCREASE IN THE
AFTERNOON OVER NORTHERN IOWA, BUT NOTHING OF CONCERN FOR
ELEVATED FIRE WEATHER CONDITIONS GIVEN THE GREEN UP.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
ISSUED AT 145 PM CDT THU MAY 7 2026
BROAD CYCLONIC FLOW WILL CONTINUE OVER THE REGION THIS WEEKEND INTO
EARLY NEXT WEEK AS THE CLOSED, UPPER LOW GYRE CONTINUES OVER
HUDSON BAY AND EVENTUALLY MOVES AWAY FROM IT. THIS WILL KEEP
TEMPERATURES AROUND SEASONAL LEVELS IF NOT GENERALLY ABOVE
NORMAL. IN ADDITION, THERE WILL BE SHOWER AND/OR STORM CHANCES
IN AT LEAST SOME PORTION OF IOWA EVERY 36 TO 48 HOURS STARTING
SATURDAY NIGHT THROUGH ABOUT THE MIDDLE OF NEXT WEEK. AS
INDICATED BY THE PREVIOUS DISCUSSION, THE NEXT SHORTWAVE TROUGH
IS STAYING THE COURSE THIS MODEL CYCLE BEING MORE FOCUSED OVER
MISSOURI SATURDAY NIGHT. COMPARED TO THIS TIME YESTERDAY, QG
CONVERGENCE AND THETA-E ADVECTION IS NOW MAXIMIZED SOUTH OF
IOWA, THOUGH MAY STILL SEE A FEW SHOWERS SNEAK INTO FAR SOUTHERN
IOWA WITH THOSE CHANCES UP TO AROUND 30% - ABOUT 30 TO 40%
LOWER THAN THIS TIME YESTERDAY. THE NEXT CHANCE FOR SHOWERS AND
STORMS ARRIVES LATE MONDAY INTO TUESDAY MORNING. KINEMATICS ARE
IMPRESSIVE WITH A STRONG LOW LEVEL JET, BUT INSTABILITY IS
MARGINAL OWING TO THE NIGHTTIME PASSAGE OF THE SYSTEM POINTING
TO PERHAPS STRONG TO A FEW SEVERE STORMS. THIS IS IN LINE AND
CONTINUES TO BE SUPPORTED BY THE GFS/EC FORCED ML/AI SEVERE
PROBABILITY TOOLS WITH NO WIDESPREAD SEVERE WEATHER THREAT
APPARENT. WEDNESDAY AND BEYOND, PATTERN AGREEMENT DETERIORATES
LEADING TO LOWER CONFIDENCE IN ADDITIONAL STORM CHANCES.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1054 PM CDT THU MAY 7 2026
FEW CHANGES FROM PREVIOUS. VFR CONDITIONS ONGOING AND EXPECTED
TO CONTINUE THROUGH THE TAF PERIOD. LIGHT AND VARIABLE WINDS ARE
EXPECTED OVERNIGHT BUT WILL SETTLE OUT OF THE WEST AND INCREASE
INTO FRIDAY AFTERNOON, THE STRONGEST WINDS IN THE NORTH. CLOUDS
WILL INCREASE AGAIN THROUGH THE OVERNIGHT INTO EARLY FRIDAY
MORNING ESPECIALLY OVER SOUTHERN IOWA WITH SOME LOW CHANCES FOR
LIGHT RAIN NEAR KOTM DURING THE MORNING HOURS, AND SPRINKLES
INTO PORTIONS OF CENTRAL IOWA WHICH MAY REACH KDSM. CONFIDENCE
IN IMPACTS REMAINS LESS THAN 30% SO CONTINUED WITH NO EXPLICIT
MENTIONS, THOUGH SHOULD SPRINKLES/AN ISOLATED SHOWER OCCUR NEAR
A TERMINAL, IMPACTS WOULD REMAIN MINIMAL.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...ANSORGE
LONG TERM...ANSORGE
AVIATION...05
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