236
FXUS63 KDMX 280802
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
302 AM CDT MON APR 28 2025
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 AFTRERNOON 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 /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1102 PM CDT SUN APR 27 2025
LOW STRATUS WILL REMAIN ACROSS THE STATE OVER THE NEXT SEVERAL
HOURS, WITH IFR/LIFR CONDITIONS EXPECTED. RAIN SHOWERS ARE
EXPECTED TO MOVE THROUGH DURING THE MORNING HOURS, WITH A FEW
POSSIBLE STORMS MAINLY OVER THE NORTHERN TERMINALS, THOUGH
LOWER PROBABILITIES OF OCCURRENCE REMAIN. INTO THE LATER
AFTERNOON TO EVENING, SHOWERS AND STORMS ARE STILL POSSIBLE,
WITH THE POTENTIAL REMAINING FOR SEVERE WEATHER ESPECIALLY OVER
NORTHERN IOWA. HOWEVER, UNCERTAINTY REMAINS ON THE HIGHER END ON
OVERALL COVERAGE AND TIMING GIVEN, SO WILL CONTINUE TO KEEP A
CLOSE EYE ON THIS. WINDS WILL INCREASE LATER THIS MORNING INTO
THE AFTERNOON, WITH GUSTS UP TO 30-35 KNOTS WITH SOME ISOLATED
HIGHER VALUES POSSIBLE AT TIMES.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...REV
AVIATION...BURY
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