027
FXUS63 KDMX 071743
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1243 PM CDT TUE APR 7 2026
...UPDATED FOR THE 18Z AVIATION DISCUSSION...
KEY MESSAGES
- BAND OF MODERATE TO HEAVY SNOW WANES INTO THE DAYLIGHT HOURS
TODAY SPUTTERING OUT TO PATCHY LIGHT SNOW AND RAIN THAT LIFTS
NORTHWARD THROUGH THE DAY. ANY NEW ACCUMULATIONS AFTER
SUNRISE ARE MINIMAL.
- WARMER, WINDY WEDNESDAY. WIDELY SCATTERED SHOWERS AND A FEW
NON-SEVERE STORMS POSSIBLE LATE IN THE DAY INTO THURSDAY.
MONITORING FOR POSSIBLE ELEVATED FIRE WEATHER CONDITIONS TOO.
- ADDITIONAL STORMS POSSIBLE LATE THURSDAY INTO FRIDAY WITH A
FEW STRONGER STORMS POSSIBLE.
- WHILE THE FORECAST CONTINUES TO SHOW SEVERAL RAIN EPISODES
THIS WEEKEND INTO NEXT WEEK, RAINFALL TOTAL ARE TRENDING LOWER
AND WILL CONTINUE TO MONITOR THE HEAVY RAINFALL SIGNAL.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 317 AM CDT TUE APR 7 2026
EARLY MORNING RADAR SHOWS A BAND OF HIGH RETURNS UPWARDS OF 45
DBZ FROM THE OMAHA METRO THROUGH SOUTHWEST INTO SOUTHERN IOWA
EARLY THIS MORNING. THIS PRECIPITATION HAS BEEN FORCED BY STRONG
FRONTOGENESIS CENTERED IN THE 850-700MB LAYER PER LATEST SPC
MESOANALYSIS. CROSS SECTIONS SHOW UPWARDS OF 8 HOURS OF STRONG
LIFT IN THE DENDRITIC GROWTH ZONE (DGZ) ATOP THIS FRONTOGENESIS.
WHILE MUCH OF THE EVENING THE PRECIPITATION WAS RAIN, BETWEEN
MIDNIGHT AND 1AM A WEBCAM IN CRESTON AND SURFACE OBSERVATIONS
SHOWED A TRANSITION TO SNOW DUE TO FINALLY WET BULBING
SUFFICIENTLY WITH THE TEMPERATURE FALLING FROM 39 TO 33 DEGREES
AT CRESTON. SOME SNOW OR SLUSHY ACCUMULATIONS ARE OCCURRING ON
ROADWAYS UNDER THE HIGHEST RADAR RETURNS AS OF THIS WRITING
WITH EYEBALLING AN INCH OR SO OFF OF IOWA DOT PLOW CAMS AND THE
CRESTON WEBCAM AS PAVEMENT TEMPERATURES ARE 32 OR 33 DEGREES.
EVENING HREF HAS ABOUT 5 HOURS OF 1 INCH/HOUR SNOW RATE
PROBABILITIES OF AT LEAST 30%, WHICH WOULD BE OCCURRING NOW AND
ALIGNS WITH SPC MESOSCALE DISCUSSION 365. IF THESE RATES ARE
ACHIEVED AND CAN MAINTAIN THEMSELVES TO OVERCOME THE WARM
SURFACE, THEN SEVERAL INCHES OF SNOW ACCUMULATION ARE POSSIBLE
WITH PERHAPS ISOLATED SWEET SPOTS UP TO 5 INCHES. FORECAST
SOUNDINGS OVER THE NEXT FEW HOURS ALSO SHOW THAT THERE IS
WARMING OCCURRING AROUND 850MB, WHICH ALIGNS WITH THE PUSH OF
THETA-E ADVECTION NORTHWARD. IT'S POSSIBLE THERE COULD BE
PARTIAL MELTING OF SNOWFLAKES IN THIS LAYER TO REDUCE THE
DENDRITES FORMED OR TO RESULT IN GRAUPEL/ICE PELLETS, WHICH HAS
OCCURRED IN THE OMAHA METRO PER THEIR NWSCHAT ROOM. WHILE THE
REFLECTIVITY BAND IS IMPRESSIVE, IT IS EQUALLY IMPRESSIVE THE
DRY AIR INTRUDING INTO THE NORTHERN SIDE OF THIS PRECIPITATION
SHIELD CAUSING A SHARP CUTOFF IN THE PRECIPITATION. DEWPOINT
DEPRESSIONS OF 15 TO 20F ARE SHOWN FROM DENISON TO AUDUBON, DES
MOINES, AND KNOXVILLE, AND OTTUMWA. THIS HAS SHOWN UP WELL IN
THE CROSS SECTIONS. BASED ON ALL OBSERVATIONS AVAILABLE, THERE
IS NO DATA POINTING TO A NEED TO UPGRADE TO A WARNING; HOWEVER,
WILL BE MONITORING FOR POSSIBLE CANCELLATION OF A FEW COUNTIES
ON THE NORTH SIDE OF THE CURRENT ADVISORY.
THE STRONG FORCING WANES FAIRLY QUICKLY AFTER SUNRISE THIS MORNING
AS THE THETA-E ADVECTION TRIES TO PUSH THE PRECIPITATION
NORTHEASTWARD. HOWEVER, IT WILL STILL BE FIGHTING THE DRY
NORTHEASTERLY FLOW FROM THE SURFACE HIGH PRESSURE OVER THE
GREAT LAKES, WHICH SHOULD RESULT IN THIS PRECIPITATION BEING
MORE PATCHY AND LIGHT. PRECIPITATION TYPE FIRST THING THIS
MORNING WILL BE PREDOMINATELY SNOW, BUT WILL BEGIN TO MIX WITH
RAIN WITH THE TYPE FAVORING ALL LIQUID BY LATE IN THE DAY. ANY
SNOW ACCUMULATIONS WILL BE QUITE MINIMAL AT OR UNDER A HALF INCH
AFTER SUNRISE. SPOTTY SHOWERS MAY PERSIST IN SOME PORTIONS OF
CENTRAL IOWA INTO TONIGHT AS THETA-E ADVECTION CONTINUES.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
ISSUED AT 317 AM CDT TUE APR 7 2026
WHILE TONIGHT AND TUESDAY WILL BE MORE WINTRY, MORE SPRING-LIKE
CONDITIONS ARE FORECAST FOR WEDNESDAY AS STRONG WINDS FROM THE
SOUTH AND SOUTHWEST DELIVER MUCH WARMER CONDITIONS AS HIGHS
REACH THE 60S TO AROUND 70 DEGREES. INITIAL SUSTAINED WINDS
FROM THE NATIONAL BLEND OF MODELS LOOKS REASONABLE WHEN COMPARED
TO FORECAST SOUNDINGS FROM THE NAM AND GFS AT 20 TO 30 MPH.
WIND GUSTS MAY NEED TO BE BUMPED UP A FEW KNOTS/MPH AS TOP OF
MIXED LAYER WINDS ARE BETWEEN 40 TO NEAR 50 KNOTS. HOWEVER,
THIS IS A WARM AIR ADVECTION (WAA) REGIME SO THE MOMENTUM
TRANSPORT IS TYPICALLY NOT AS EFFICIENT. PROOF OF THIS IS THE
LIFT SHOWN IN FORECAST SOUNDINGS, WHICH WILL BE WORKING AGAINST
FULL TRANSPORT. WIND GUSTS OF UP TO AROUND 40 TO 45 MPH WILL BE
POSSIBLE AND WILL HAVE TO MONITOR FOR POSSIBLE WIND ADVISORY
CONDITIONS. THESE BREEZY WINDS WILL DRIVE GRASSLAND FIRE DANGER
INDEX INTO THE HIGH TO VERY HIGH CATEGORY AND WILL BE MONITORING
FOR AN ELEVATED FIRE WEATHER DAY. MITIGATING FACTORS TO MORE
CRITICAL CONDITIONS ARE GREEN-UP UNDERWAY IN SOUTHERN PARTS OF
THE STATE AND MINIMUM RELATIVE HUMIDITY VALUES OF 30 TO 40%.
THESE WINDY CONDITIONS WILL BE AHEAD OF A COLD FRONT, WHICH WILL BE
PUSHED INTO THE STATE AS LOW PRESSURE TRACKS OVER SOUTHERN CANADA
PRAIRIES TOWARDS LAKE SUPERIOR ON WEDNESDAY. WIDELY SCATTERED
SHOWERS AND A FEW STORMS WILL DEVELOP ALONG THIS BOUNDARY, BUT
THERE IS NOT A LOT OF TIME TO RECOVER MOISTURE WITH PERHAPS SOME
COMPONENT OF GULF MOISTURE WITH DEWPOINTS MAINLY IN THE 40S.
INSTABILITY HAS AND NOW EVEN DEEP LAYER SHEAR LOOKS RATHER
MARGINAL SO SEVERE WEATHER CONTINUES TO LOOK UNLIKELY, WHICH IS
SUPPORTED BY THE DAY 2 GENERAL THUNDER AREA FROM SPC. THE FRONT
WILL PUSH TO NEAR THE IOWA MISSOURI BORDER BY THURSDAY MORNING
AND STALL. AS A PULSE OF THETA-E ADVECTION INTERACTS WITH THIS
STALLED BOUNDARY, SCATTERED SHOWERS AND STORMS ARE LIKELY TO
RESULT LATE THURSDAY INTO FRIDAY MORNING. INSTABILITY WILL BE A
BIT HIGHER WITH MORE DEEP LAYER SHEAR ALONG AND SOUTH OF THE
BOUNDARY, THOUGH THE STEEPER LAPSE RATES LOOK TO BE OVER WESTERN
IOWA AND POINTS SOUTHWEST. THIS COULD RESULT IN A FEW STRONGER
STORMS WITH RAIN TOTALS IN SPOTS UP TO AROUND 1 TO 1.5 INCHES.
SURFACE HIGH PRESSURE AND ITS DRIER AIR WILL NUDGE THE BOUNDARY
SOUTH OF THE STATE ON FRIDAY, WHICH SHOULD OFFER A 24 TO 36 HOUR
PERIOD OF DRY CONDITIONS LATER FRIDAY INTO A PART OF SATURDAY.
AS HAS BEEN DISCUSSED OVER THE LAST SEVERAL DAYS, A MORE ACTIVE,
APRIL PATTERN LOOKS TO SET UP THIS WEEKEND INTO NEXT WEEK. TRENDS
OVER RECENT NIGHTS HAS BEEN FOR THIS TO SET UP LATER INTO THE PERIOD
JUST OUTLINED DUE TO DOWNSTREAM HIGH PRESSURE TRENDING WESTWARD,
WHICH IS HOLDING UP THE SOUTHWESTERLY FLOW FROM ARRIVING. QPF HAS
ALSO BEEN TRENDING LOWER OVER THE LAST SEVERAL NIGHTS AND WILL HAVE
TO SEE IF THIS CONTINUES TO HOLD, THOUGH SEVERAL RAIN EPISODES ARE
STILL EXPECTED. THE FIRST ROUND WILL BE SPURRED BY A LEAD SHORTWAVE
KICKING OUT INTO THE REGION LATER SATURDAY WITH A CALIFORNIA
SHORTWAVE TROUGH FOLLOWING IT ON SUNDAY. THESE FEATURES WILL PROMOTE
INTERVALS OF SHOWERS AND STORMS FROM LATER SATURDAY INTO SUNDAY
NIGHT. THERE WILL BE A GOOD PLUME OF MOISTURE AHEAD OF THESE WAVES
WITH ABOVE NORMAL PRECIPITABLE WATER VALUES NEAR 1.5 INCHES AND
SEASONALLY HIGH WARM CLOUD DEPTHS. THERE COULD BE A WINDOW FOR
SEVERE WEATHER ON SUNDAY WITH NSSL GEFS SEVERE PROBABILITIES AT 15 TO
30%. A CHANGE FROM PREVIOUS FORECASTS IS THAT ANOTHER TROUGH WILL
DIG OVER THE WESTERN US LATE THIS WEEKEND AND MOVE INTO THE CENTRAL
US TOWARDS TUESDAY OR WEDNESDAY AND BRING ANOTHER ROUND OF STORMS TO
THE REGION. WHILE DETAILS WILL CONTINUE TO EVOLVE, WILL HAVE TO
CONTINUE TO MONITOR FOR POTENTIAL HEAVY RAINFALL WITH ADDITIONAL
DETAILS IN THE HYDRO SECTION BELOW.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1243 PM CDT TUE APR 7 2026
SCATTERED LIGHT RAIN AND SNOW ACROSS THE SOUTHERN HALF OF IOWA
THIS AFTERNOON IS BEING UNDERCUT BY DRY AIR AND NOT MAKING IT
TO THE GROUND IN MANY PLACES. THE LOW LEVEL DRY AIR HAS ALLOWED
FOR WIDESPREAD, EXPANDING VFR CLOUD COVER. IN FAR SOUTHERN IOWA
THERE ARE A FEW MVFR OBSERVATIONS. AS THE ATMOSPHERE CONTINUES
TO SATURATE THIS AFTERNOON CLOUD BASES WILL ALSO COME DOWN.
EXPECT WIDESPREAD MVFR CONDITIONS ACROSS MOST SITES THIS EVENING
AND OVERNIGHT, WITH SOUTHERN/WESTERN SITES KFOD/KDSM REACHING
IFR CONDITIONS INTO WEDNESDAY MORNING. OVERNIGHT INTO WEDNESDAY
MORNING DEVELOPING LLWS UNTIL CONDITIONS MIX OUT LATER WEDNESDAY
MORNING. BY WEDNESDAY AFTERNOON EXPECT SOUTHERLY WINDS GUSTING
25-35+ KTS ACROSS ALL SITES.
HYDROLOGY
ISSUED AT 250 PM CDT MON APR 6 2026
MANY STREAMS ARE CRESTING NOW OR WILL CREST OVER THE NEXT ~24 HRS
WITH AROUND 15 RIVER FORECAST POINTS REACHING ACTION STAGE. THE
CEDAR RIVER AT CEDAR FALLS HAS REACHED MINOR FLOOD STAGE AND THE
IOWA RIVER NEAR TAMA THAT IS EXPECTED TO CREST AROUND FLOOD STAGE
TUESDAY MORNING.
THE PRECIPITATION TODAY INTO TONIGHT, INCLUDING THE SNOW BAND,
WILL LARGELY FALL OVER AREAS THAT HAVE NOT SEEN THE HIGHER RAINFALL
THAT OCCURRED LAST WEEK. NASA SPORT GFS FORCED 0-10 CM AND 0-40 CM
SOIL MOISTURE PERCENTILES ARE FORECAST TO RECOVER TO BETWEEN THE
30TH AND 70TH PERCENTILES BY LATE THIS WEEK. WHILE OFFICIAL RIVER
FORECASTS ACCOUNT FOR ONLY 24 HOURS OF QPF, BOTH THE OFFICIAL
FORECASTS AND THE 120-HR CONTINGENCY FORECASTS SHOW ALL CURRENT
LOCATIONS IN ACTION OR MINOR FLOOD STAGE TO FALL BELOW ACTION STAGE
BY LATE THIS WEEK. THEY ARE UNLIKELY TO RETURN TO THEIR BASE FLOWS
OF EARLY LAST WEEK THOUGH.
RAINFALL UP TO 1-2 IN WILL FALL WITH A COLD FRONT WEDNESDAY INTO
THURSDAY, WHICH MAY TAKE AWAY SOME SOIL CAPACITY AS THE ACTIVE, WET
PATTERN SETS UP LATE THIS WEEKEND INTO EARLY NEXT WEEK. UP TO A FEW
ADDITIONAL INCHES ARE POSSIBLE OVER PORTIONS OF THE STATE, BUT
UNCERTAINTY ON AMOUNTS AND PLACEMENT WITHIN ANY GIVEN BASIN AT THIS
TIME RANGE REMAINS HIGH. THE GFS AND NBM FORCED NATIONAL WATER MODEL
HIGH MAGNITUDE FLOW ANNUAL EXCEEDANCE PROBABILITIES ARE GENERALLY
~50% ON LARGER STREAMS. THIS DATA SUGGESTS RENEWED GENERALLY WITHIN-
BANK RISES ESPECIALLY SHOWN OVER SOUTHERN INTO EASTERN IOWA, WITH
SOME ISOLATED MINOR FLOODING POSSIBLE. THE EXPERIMENTAL FLOOD HAZARD
OUTLOOK (FHO) CONTINUES HIGHLIGHTING MUCH OF IOWA FOR LIMITED
POTENTIAL FLOOD IMPACTS WITH THE EXPERIMENTAL HYDROLOGIC ENSEMBLE
FORECASTING SERVICE (HEFS) AT THE 30% CHANCE OF EXCEEDANCE WITH
STAGES SIMILAR TO CURRENT, BUT AT THE 10% CHANCE OF EXCEEDANCE WITH
SEVERAL MORE POINTS REACHING MINOR STAGE AND A FEW TO MODERATE
STAGE. TRENDS IN THE HEAVY RAINFALL SIGNAL WILL CONTINUE TO NEED TO
BE MONITORED.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...ANSORGE
LONG TERM...ANSORGE
AVIATION...HAGENHOFF
HYDROLOGY...ZOGG
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