778
FXUS63 KDMX 270839
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
339 AM CDT SUN APR 27 2025
KEY MESSAGES
- WARM AIR ADVECTION SHOWERS NORTH TODAY AND SCATTERED MORNING
SHOWER/DRIZZLE SOUTH (30% SOUTH TO 50% NORTH)
- WARM AIR ADVECTION STORMS NORTHWEST TONIGHT WITH SMALL RISK OF
SCATTERED SEVERE STORMS FAR NORTHWEST/NORTH 06 TO 12Z.
- POTENT SYSTEM MONDAY - STILL SOME UNCERTAINTIES. COVERAGE 60
TO 80% NORTH OF US20; 30 TO 50% SOUTH OF US20/30 FROM
AFTERNOON INTO EVENING.
- POST EVENT COOL DOWN BACK TO THE SEASONAL 60S
DISCUSSION
ISSUED AT 340 AM CDT SUN APR 27 2025
SHORT TERM /TODAY THROUGH MONDAY/
CONFIDENCE: HIGH TO MEDIUM
CHALLENGING FORECAST FOR MONDAY BUT PRETTY CLEAR CUT TODAY AND
TONIGHT WITH GENERALLY HIGH CONFIDENCE TODAY BUT SLIGHTLY LOWER
CONFIDENCE FOR MONDAY. DETAILS TO FOLLOW. EARLY MORNING TODAY
SURFACE HIGH PRESSURE OVER THE GREAT LAKES CONTINUES TO KEEP EAST
WINDS ACROSS THE REGION. WARM AIR ADVECTION ALOFT WITH A HEALTHY
RETURN OF GULF MOISTURE INTO THE WESTERN/SOUTHERN PLAINS HAS
RESULTED IN AN AREA OF SHOWERS/WEAK CONVECTION ACROSS NORTHERN IOWA
AND MINNESOTA NORTH OF A WARM FRONT AT H850 THAT STRETCHES FROM A
LOW OVER IDAHO EAST INTO SOUTHWEST IOWA AT 00Z. THIS AREA WILL
CONTINUE TO LIFT EAST THIS MORNING WHILE ANOTHER IMPULSE OVER THE
SOUTHERN PLAINS COMBINED WITH THE LIFT ALOFT FROM THE WARM FRONT
JUST ENTERING IOWA WILL CAUSE A WEAKER AREA OF LIGHT SHOWERS TO
DEVELOP AND DRIFT OVER SOUTHERN AREAS THIS MORNING; DISSIPATING BY
NOON. OTHERWISE, TODAY WILL BE PARTLY TO MOSTLY CLOUDY WITH
INCREASING SOUTHEAST WINDS BY AFTERNOON AND TEMPERATURES WARMING
INTO THE LOWER 60S. TONIGHT, INCREASING SOUTH SOUTHEAST FLOW WILL
BECOME PREDOMINANT OVER THE AREA WITH NEARLY STEADY TEMPERATURES AND
INCREASING DEWPOINTS OVERNIGHT. AN AREA OF ELEVATED CONVECTION WITH
SEVERE POTENTIAL WILL FORM OVER THE NORTHWEST PORTION OF OUR
FORECAST AREA WEST OF US71 AND GENERALLY NORTH OF US20 FROM 06Z TO
12Z MONDAY. MOST, IF NOT ALL OF THAT CONVECTION WILL LIFT NORTH INTO
MINNESOTA BY 12Z AS THE WARM FRONT AND WARM AIR ADVECTION LIFT NORTH
AS WELL.
STILL EXPECTING A POTENTIAL OUTBREAK OF SEVERE STORMS MONDAY BUT
QUESTIONS REMAIN AS TO THE EXTENT OVER OUR AREA.
MONDAY IS CERTAINLY A CHALLENGE AS FOR THE FORECAST WITH SOME
PREFERRED AREAS OF HIGHER LIKELIHOOD OF CONVECTION AND SOME THAT ARE
MORE UNCERTAIN. AS THE SFC LOW OVER NORTH CENTRAL NEBRASKA DEEPENS
FROM 06Z MONDAY TO FAR NORTHEAST SOUTH DAKOTA THROUGH 18Z, STRONG
SOUTH SOUTHWEST FLOW AT H850 WILL DRIVE MOISTURE INTO IOWA AND
STATES NORTH. AT THIS TIME, THERE IS LITTLE SFC CONVERGENCE OVER OUR
AREA. A PRE-FRONTAL TROUGH/DRYLINE IN EASTERN NEBRASKA LAGS THE MAIN
H850 MOISTURE SURGE AT THIS TIME, BUT EVENTUALLY MOVES EAST INTO
WESTERN IOWA AROUND 00Z MONDAY. MEANWHILE, A SEPARATE PREFRONTAL
TROUGH DEVELOPS AROUND I35 AROUND 18Z AND MOVES TO NEAR/EAST OF US63
BY 00Z. IT APPEARS THAT SCATTERED, VERY STRONG CONVECTION MAY
DEVELOP ALONG THIS TROUGH DURING THE MID TO LATE AFTERNOON WITH
ANOTHER AREA OF CONVECTION NEAR THE INTERSECTION OF THE MAIN DRYLINE
AND THE APPROACHING COLD FRONT IN FAR NORTHWESTERN IOWA BY MID TO
LATE AFTERNOON. THIS AREA ESPECIALLY IN THE NORTH, SEEMS TO BE AN
AREA OF CONCERN THROUGHOUT THE AFTERNOON AS THE INSTABILITY/SHEAR
PARAMETER SPACE AND THE MOST CONVERGENCE SHOULD BE SUPPORTIVE OF
MORE WIDESPREAD, STRONG TO INTENSE CONVECTION. THIS SOUTHERN EDGE OF
THIS AREA IS DEBATABLE, BUT APPEARS TO BE BOUND BY A POSITION NEAR
US20/US30 OR SOMEWHERE IN BETWEEN. THERE SHOULD BE RAPID STORM
MOTION AND POTENTIAL FOR ALL MODES OF SEVERE STORMS IN THIS AREA. IF
THE SOUTHERN PORTION OF THE DRYLINE HAS ENOUGH SURFACE CONVERGENCE
TO EVENTUALLY FIRE CONVECTION, IT IS MORE LIKELY TO OCCUR FROM 21Z
THROUGH 06Z AS BETTER SFC CONVERGENCE, HIGHER SHEAR ALOFT AND
INCREASING LOW LEVEL JET CAN HELP TO KEEP THE SOUTHERN PORTION OF
THE LINE GOING INTO THE MID TO LATE EVENING HOURS OVER SOUTHERN
IOWA/NORTHERN MISSOURI AND PORTIONS OF FAR EASTERN IOWA. SOUNDINGS
INDICATE THAT THE BOUNDARY LAYER IN THE SOUTH ALONG THE TRAILING
DRYLINE WILL COOL ENOUGH AFTER 8 PM THAT MOST STORMS WILL BE
ELEVATED WITH INSTABILITY LESSENING THE REMAINDER OF THE EVENING.
MODEL FORECASTS SUGGEST THAT MOST OF THE STORMS WILL BE OUT OF THE
AREA AROUND MIDNIGHT TO 1 AM. THE GREATEST COVERAGE OF STORMS LOOKS
MORE LIKELY IN THE NORTH WITH MORE SCATTERED NATURE IN THE SOUTH.
THERE MAY BE A GAP OF SORTS IN SOUTH CENTRAL IOWA, BUT THIS REMAINS
UNCERTAIN DEPENDING ON HOW MUCH OF THIS AREA CAN REALIZE SURFACE
CONVERGENCE ONCE THE STORMS GET GOING. THE CONVECTIVE OUTLOOK FOR
DAY2 IS QUITE BROAD AND ENCOMPASSING FOR THESE REASONS AND MAY STILL
SEE SOME ADJUSTMENTS IN THE NEXT 24 HOURS REGARDING COVERAGE/RISK.
THE POTENTIAL FOR A SCATTERED INTENSE STORMS IN THE SOUTH STILL
EXISTS IN THE LATE AFTERNOON AND EARLY EVENING, BUT IS MORE
CONDITIONAL AS IT LOOKS RIGHT NOW. THUS THE GREATER UNCERTAINTY, BUT
LOOKING AT SOUNDINGS, IT'S HARD TO NOT INCLUDE THE POTENTIAL FOR
SOME HIGHER END, STRONG TO INTENSE STORMS INTO SOUTH OF THE
US20/US30 CORRIDOR IN IOWA AS WELL.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
CONFIDENCE: MEDIUM TO HIGH
BY LATE IN THE OVERNIGHT, WE WILL SEE INCREASING WEST TO NORTHWEST
WINDS AND COOLER TEMPERATURES MOVING INTO THE REGION. LOWS WITH THE
COOLER AIR SETTLING INTO THE REGION WILL FALL TO THE LOWER 40S
NORTHWEST TO THE MID 50S SOUTHEAST. HIGH PRESSURE WILL MOVE INTO THE
REGION TUESDAY WITH A PLEASANT DAY EXPECTED. HIGHS WILL RANGE FROM
THE LOWER 60S NORTH TO THE LOWER 70S SOUTHEAST. ANOTHER AREA OF LOW
PRESSURE WILL BRING RETURN FLOW INTO IOWA BY WEDNESDAY MORNING.
SHOWERS AND SOME THUNDERSTORMS WILL DRIFT NORTH INTO THE REGION BY
18Z, INCREASING INTO THE OVERNIGHT HOURS TO THURSDAY MORNING. THE
RISK OF SEVERE STORMS APPEARS TO BE LOW, BUT A FEW STRONGER STORMS
COULD PRODUCE SOME SMALL HAIL WEDNESDAY AFTERNOON/EVENING OVER
SOUTHERN IOWA. HIGHS WEDNESDAY WILL BE IN THE MID 60S WITH A FEW
HIGHER VALUES IN THE SOUTH. THE STORM WILL EXIT THURSDAY MORNING
WITH A STRETCH OF DRY AND MILD WEATHER THROUGH MOST OF SATURDAY.
HIGHS THURSDAY, FRIDAY AND SATURDAY WILL WARM TO THE UPPER 60S TO
LOWER 70S. WE ARE LIKELY TO END THE WEEKEND WITH ANOTHER ROUND OF
SHOWERS AND STORMS WHICH MAY PERSIST IN THE LONGER TERM PATTERN.
LOOKING ALOFT AT THE HEMISPHERIC H500, A BLOCKING RIDGE OF HIGH
PRESSURE IS SETTING UP IN THE SOUTHEAST CONUS, WHILE A LARGE GYRE
WITH SOME ENERGY PEELING INTO THE CENTRAL PLAINS MAY KEEP THE
MISSISSIPPI RIVER VALLEY IN A WARM AND WET PATTERN WELL INTO THE
FOLLOWING WEEK.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1055 PM CDT SAT APR 26 2025
CEILINGS ARE EXPECTED TO GRADUALLY LOWER THROUGH THE MORNING,
WITH MVFR CONDITIONS EXPECTED AFTER MID-MORNING FROM WEST TO
EAST AS LOW CLOUDS MOVE INTO THE STATE. LIGHT RAIN SHOWERS ARE
POSSIBLE EARLY THIS MORNING AT KMCW, BUT SHOULD OTHERWISE REMAIN
DRY FOR MOST TERMINALS UNTIL SUNDAY EVENING WHEN ADDITIONAL
CHANCES FOR SHOWERS AND A FEW POSSIBLE STORMS MOVE INTO THE
AREA. BREEZY WINDS ARE EXPECTED FROM MID-MORNING THROUGH THE
AFTERNOON WITH GUSTS UP TO 20-25 KNOTS.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...REV
AVIATION...BURY
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