780
FXUS63 KDMX 281748
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1248 PM CDT MON APR 28 2025
...UPDATED FOR THE 18Z AVIATION DISCUSSION...
KEY MESSAGES
- POTENT SYSTEM TODAY WITH HIGHER END SEVERE STILL POSSIBLE
NORTH; CONDITIONAL SOUTH AND CENTRAL. COVERAGE 50 TO 60% NORTH
OF US20; 20 TO 50% SOUTH OF US20/30 FROM AFTERNOON INTO
EVENING.
- STRONGER SOUTH TO SOUTHEAST WINDS TODAY...GUSTS TO NEAR 45 MPH
- POST EVENT COOL DOWN BACK TO THE SEASONAL 60S
- WEAKER SYSTEM WEDNESDAY WITH MORE RAIN/ISO STORMS
DISCUSSION
ISSUED AT 300 AM CDT MON APR 28 2025
SHORT TERM /TODAY THROUGH TUESDAY/
CONFIDENCE: MEDIUM
MAIN CONCERNS REMAIN THE SAME. SEVERE WEATHER IS STILL LIKELY OVER
PORTIONS OF THE FORECAST AREA THIS AFTERNOON AND EVENING WITH
SCATTERED STORMS THIS MORNING AND AGAIN EARLY THIS AFTERNOON. OUR
DAY1 OUTLOOK IS THE SAME AS YESTERDAY, WITH THE NORTH THIRD IN A
MODERATE RISK, THE REMAINDER OF THE AREA IN AN ENHANCED RISK. FOR
NOW, WE HAVE A WEAK LINE OF SHOWERS ALONG AND EAST OF US63 AT 0630Z
HEADING EAST NORTHEAST. A LARGE MCS IS TRACKING ACROSS NORTH CENTRAL
NEBRASKA CLOSER TO A COMPLEX AREA OF LOW PRESSURE AND STRONG WARM
ADVECTION. THIS WILL CONTINUE TRACKING EAST NORTHEAST, EVENTUALLY
CLIPPING OUR NORTHWEST, FAR WEST AND NORTH WITH A LINE OF
SHOWERS/STORMS THROUGH MID MORNING. AS THE LOW TRACKS NORTHEAST,
GRADIENT WINDS AND MIXING WILL INCREASE DRAMATICALLY INTO THE LATE
MORNING AND AFTERNOON HOURS. SOUNDINGS SUGGEST RELATIVELY
RELATIVELY STRONG WINDS OFF THE DECK WITH POTENTIAL GUSTS OF 45
MPH OR HIGHER INTO THE AFTERNOON HOURS. DUE THE TRANSIENT NATURE
OF THE STRONGER GUSTS MOVING OVER THE REGION WITH TIME, WILL
OPT TO LET THE DAY SHIFT KNOW AND HIT WITH EITHER HEADLINES OR
SPS, DEPENDING ON THE DURATION, SPEED AND COVERAGE. TIMING OF
THE BETTER MIXING WILL BE BETWEEN 15Z AND 00Z THIS EVENING. THE
CURRENT SYSTEM TO OUR WEST IS AN ELONGATED TROUGH WITH SEVERAL
WEAK CENTERS OF LOW PRESSURE, TWO IN WESTERN NEBRASKA AND ONE IN
WESTERN SOUTH DAKOTA. THE LOW IS EXPECTED TO STRENGTHEN AND
CONSOLIDATE BY 18Z TO A 994 LOW NEAR HURON SOUTH DAKOTA. THOUGH
INSTABILITY WILL BE REALLY RAMPING UP IN THE LATE MORNING TO
EARLY AFTERNOON, THE BULK OF ANY CONVECTION WILL BE FARTHER
NORTH INTO MN/SD CLOSER TO THE LOW AND WARM FRONT. BY 00Z, THE
SURFACE LOW WILL LIKELY CHANGE LITTLE IN STRENGTH AS IT MOVES
TOWARD DULUTH, MN, WEAKENING THEREAFTER. IN OUR AREA, WE WILL
STILL SEE SOME SHOWER OR WEAK STORM DEVELOPMENT ALONG A PRE-
FRONTAL NORTH-SOUTH TROUGH FROM AROUND 18Z TO 21Z AND AT THIS
TIME, THIS DOES NOT LOOK SEVERE. WITH THE LOW TRACKING
NORTHEAST, THE DRYLINE WILL BE PULLED INTO NORTHWEST IOWA AROUND
20Z AND STORM INITIATION THERE NORTH OF US20, CLOSER TO US18 IS
LIKELY TO OCCUR. THIS APPEARS TO THE FIRST REAL START TIME OF
SEVERE CONVECTION IN OUR FORECAST AREA. ALL MODES OF SEVERE
WEATHER WILL BE POSSIBLE IN THIS LIMITED CORRIDOR. ADDITIONAL
STORMS ARE EXPECTED TO FIRE OVER NORTHWEST IOWA DURING THE
EVENING HOURS FROM 00 TO 02Z WITH A FEW STRONG TO SEVERE STORMS
AGAIN NORTH OF US20. AS THE MAIN COLD FRONT TRACKS SOUTH INTO
SOUTHERN IOWA AFTER 04 TO 05Z, THE LOW LEVEL JET WILL BEGIN TO
IMPINGE ON THE BOUNDARY AND RESULT IN FURTHER DEVELOPMENT OVER
FAR SOUTHERN IOWA AND MISSOURI. ANY SIGNIFICANT DEVELOPMENT THAT
OCCURS APPEARS TO BE WELL OUT OF OUR AREA AFTER 06Z. ALL THIS
BEING SAID, ANY SUBTLE CHANGES TO INITIATION TIME EARLIER IN THE
DAY, OUTFLOW BOUNDARY PRODUCTION OR GREATER CONVERGENCE OVER A
GIVEN LOCATION DURING THE AFTERNOON TO EARLY EVENING IN THE
CENTRAL TO SOUTH COULD VERY WELL QUICKLY CHANGE THE SCENARIO
FROM MEDIOCRE TO VERY SIGNIFICANT IN SHORT ORDER, GIVEN THE
ENVIRONMENT WE ARE GOING TO SEE TODAY. THUS THE DAY1 IS STILL
OUTLOOKED FOR A WORSE CASE SCENARIO - PERHAPS A LOWER CHANCE,
BUT STILL NOT ZERO IN A HIGHLY VOLATILE ENVIRONMENT. GETTING OUT
OF THIS WITH NO SIGNIFICANT STORMS WILL NOT BE A BUST, BUT A
BLESSING. THE REMAINDER OF TONIGHT AND TUESDAY WILL BE COOLER
WITH NORTHWEST GUSTY WINDS. LOWS TONIGHT WILL DROP TO THE UPPER
30S NORTHWEST TO THE LOWER 50S SOUTHEAST. HIGHS TUESDAY WILL
REACH THE LOWER TO MID 60S. HIGH PRESSURE WILL BRING SUNSHINE
BACK INTO THE AREA FOR THE BULK OF THE DAY.
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
CONFIDENCE: MEDIUM
AS THE HIGH SLIDES EAST TUESDAY NIGHT AND WEDNESDAY, LOW PRESSURE
WILL BRING RETURN SOUTHERLY FLOW BACK ACROSS THE REGION WITH SHOWERS
AND A FEW THUNDERSTORMS WEDNESDAY AFTERNOON THROUGH WEDNESDAY NIGHT;
MAINLY IN THE SOUTHEAST HALF OF THE STATE. WITH CLOUDS COVERING MUCH
OF THE AREA WEDNESDAY, HIGHS WILL BE HELD BACK TO THE LOWER TO MID
60S WHILE OVERNIGHT MINS WEDNESDAY NIGHT WILL BE MILD IN THE MID 40S
TO THE MID 50S SOUTHEAST. THE MIDWEEK SYSTEM IS EXPECTED TO BRING,
ON AVERAGE, A COUPLE OF TENTHS OF SHOWERS ON THE NORTHWEST EDGE TO
OVER THREE QUARTERS OF AN INCH IN THE FAR SOUTHEAST NEAR DAVIS
COUNTY. THE EC IS MOST ROBUST WITH THE DETERMINISTIC MODEL SHOWING
UP TO ONE HALF INCH ON THE NORTHWEST EDGE TO NEARLY 1.5 INCHES IN
THE SOUTHEAST. THE REMAINDER OF THE WEEK/EARLY WEEKEND WILL BE DRY
WITH A RETURN OF SOME SHOWERS/STORMS BY LATE WEEKEND OR EARLY NEXT
WEEK. THE GFS IS SLOWER WITH MOISTURE RETURN COMPARED TO THE EC,
MAINLY DUE TO A CANADIAN/GREAT LAKES HIGH MAINTAINING A BLOCK OVER
OUR AREA SUNDAY INTO MONDAY. CONFIDENCE IN THE EXTENDED DROPS LATE
IN THE WEEKEND AND EARLY NEXT WEEK. CONDITIONS WILL REMAIN
COMFORTABLE THURSDAY AND FRIDAY WITH HIGHS IN THE 60S TO LOWER 70S.
BY SATURDAY AND SUNDAY, WE DRIFT BACK INTO THE 70S ALONG WITH THE
POTENTIAL SHOWERS/STORMS DEPENDING ON MODEL CORRECTNESS. OUR CURRENT
BLENDED APPROACH DOES INCLUDE THE LATTER WEEKEND SHOWERS.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1241 PM CDT MON APR 28 2025
HAVE ADDED PROB30 FOR KDSM FOR INCOMING SHOWERS AND STORMS FROM
THE SOUTHWEST. MAIN CHANGE OF NOTE WAS REMOVING PROB30 GROUPS
FOR KFOD AND KDSM FOR THUNDERSTORMS THIS AFTERNOON DURING PEAK
SEVERE WEATHER HOURS. CONFIDENCE NOT THERE FOR STORMS TO MOVE
THROUGH THE CENTER OF THE STATE. KMCW AND KALO HAVE THE HIGHEST
CHANCES FOR SEEING THUNDERSTORMS THIS EVENING, FOLLOWED BY KOTM
AFTER SUNSET. ALL MODES OF SEVERE WEATHER TO ACCOMPANY THE
STORMS. A FRONT PASSES AFTERWARD WITH GUSTY WINDS CONTINUING
OVERNIGHT. IFR STRATUS TO LINGER OVER THE NORTHEAST.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...REV
AVIATION...JIMENEZ
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