559
FXUS63 KDMX 102327
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
627 PM CDT SUN MAY 10 2026
...UPDATED FOR THE 00Z AVIATION DISCUSSION...
KEY MESSAGES
- TEMPERATURES COOL NEAR FREEZING OVER NORTHERN IOWA TONIGHT
INTO MONDAY MORNING. A FROST ADVISORY WILL BE IN EFFECT.
- SHOWER AND STORM POTENTIAL RETURNS THROUGH LATE MONDAY NIGHT
INTO TUESDAY. A FEW STRONGER STORMS COULD DEVELOP IN
SOUTHEASTERN IOWA ON TUESDAY AFTERNOON, WITH GUSTY WINDS BEING
THE MAIN CONCERN.
- BREEZY CONDITIONS ALSO EXPECTED THROUGHOUT THE AREA ON
TUESDAY, WITH THE STRONGEST WINDS IN NORTHERN IOWA. SUSTAINED
WINDS OF 25 TO 30 MPH, WITH GUSTS UP TO 40 MPH.
- WARMER TEMPERATURES EXPECTED THROUGH THE WEEK AND INTO NEXT
WEEKEND.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 248 PM CDT SUN MAY 10 2026
THE WEATHER OVER IOWA HAS CERTAINLY SHOWN OUT FOR MOTHER'S DAY
TODAY. DRY CONDITIONS PREVAIL OVER IOWA, WITH SUNNY SKIES AND
TEMPERATURES IN THE MID TO UPPER 60S THIS AFTERNOON. THE EXCEEDINGLY
DRY LOW LEVELS AND STEEP LOW LEVEL LAPSE RATES HAVE LED TO BREEZY
CONDITIONS ACROSS NORTHERN IOWA, WHERE GUSTS ARE ONCE AGAIN
EXCEEDING THE 90TH PERCENTILE OF THE NBM GUIDANCE TODAY. SURFACE
OBSERVATIONS AT MASON CITY AND ESTHERVILLE HAVE SHOWN PEAK GUSTS
AROUND 35 TO 40 MPH THIS AFTERNOON, ALTHOUGH THESE ARE ON THE HIGH
END, WHILE THE BROADER WIND FIELD HAS BEEN GUSTING CLOSER TO 25 TO
30 MPH. WINDS WILL DIMINISH SHORTLY AFTER SUNSET, BECOMING LIGHT TO
CALM OVERNIGHT AS THE SURFACE RIDGING CONTINUES TO MOVE IN.
WITH THE SURFACE HIGH OVERHEAD, EXPECT LIGHT WINDS, CLEAR SKIES AND
TEMPERATURES TO PLUMMET OVER NORTHERN IOWA TONIGHT INTO MONDAY
MORNING. LAST NIGHTS LOWS COOLED 2 TO 4 DEGREES BELOW THE FORECAST
YESTERDAY, WHICH HAD ALREADY BEEN NUDGED A DEGREE OR TWO COOLER THAN
NBM GUIDANCE. TONIGHT, WITH COOLER AIR AND SIMILAR CONDITIONS, HAVE
ELECTED TO PUSH LOWS TOWARD THE 10TH PERCENTILE OF NBM GUIDANCE,
WHICH BRINGS LOW TEMPERATURES NEAR FREEZING BY MONDAY MORNING.
WITH DEWPOINTS IN THE UPPER 20S, WOULD NOT BE SURPRISED IF SOME
AREAS EVEN DIPPED BELOW 30, ESPECIALLY IN VALLEYS OR LOW-LYING
AREAS. GIVEN THE TEMPERATURES NEARING FREEZING AND FROST
POTENTIAL TONIGHT, HAVE ISSUED A FROST ADVISORY FOR TOMORROW
MORNING WHERE THE COLDEST TEMPERATURES ARE ANTICIPATED ACROSS
NORTHERN IOWA. OTHER AREAS OF THE STATE COULD ALSO SEE PATCHY
FROST DEVELOP AS TEMPERATURES DIP INTO THE LOW TO MID 30S,
NAMELY PORTIONS OF THE NISHNABOTNA VALLEY, BUT MID-LEVEL CLOUD
COVER OVER CENTRAL INTO SOUTHWESTERN IOWA SHOULD LIMIT
RADIATIONAL COOLING FOR THESE AREAS THROUGH AT LEAST A PORTION
OF THE NIGHT.
SOUTHWESTERLY WINDS ON MONDAY WILL BRING WARMER RETURN FLOW UP INTO
THE STATE, BOOSTING HIGHS BACK INTO THE 70S DURING THE DAY. DRY
CONDITIONS ARE EXPECTED MONDAY BEFORE ANOTHER SHORTWAVE DIVES
SOUTHEASTWARD THROUGH THE UPPER MIDWEST MONDAY NIGHT INTO TUESDAY.
THE MAIN WAVE, AND COINCIDENT FORCING, LOOKS TO STAY TO OUR
NORTHEAST ACROSS MINNESOTA AND WISCONSIN, BUT THE SYNOPTIC LIFT DOES
CLIP THE FAR NORTHEASTERN PORTIONS OF IOWA. THIS, IN COMBINATION
WITH AN INCREASING GULF MOISTURE STREAM INTO THE STATE, WILL
INTRODUCE THE POTENTIAL FOR SOME SHOWERS AND EVEN A FEW STORMS ON
TUESDAY.
THAT SAID, THERE ARE STILL A FEW QUESTION MARKS WITH THIS
SYSTEM'S PASSAGE. THE RATE OF MOISTURE RETURN SEEMS QUESTIONABLE
AMONG GUIDANCE, WITH SOME MODELS STRUGGLING TO SATURATE THE LAYER
AND PRODUCING LITTLE TO NO QPF, EVEN IN THE NORTHEASTERN PORTIONS OF
THE FORECAST AREA WHERE FORCING IS BEST. MOISTURE AVAILABILITY IS
SLIGHTLY BETTER FARTHER SOUTH AND WEST INTO CENTRAL AND SOUTHERN
IOWA, BUT FORCING IS WEAKER IN THESE AREAS. THERE WILL BE A WEAK
BOUNDARY/TROUGH MOVING THROUGH THE STATE, BUT CONVERGENCE ALONG IT
LOOKS MEAGER, LIMITING THE AMOUNT OF FORCED ASCENT OUTSIDE OF WHAT'S
TIED TO THE MAIN WAVE. THESE FACTORS ARE LEADING TO VERY LOW
PROBABILITIES BEING OUTPUT BY NBM, BOTH IN NORTHEASTERN IOWA WHERE
FORCING IS BEST AND IN AREAS FARTHER SOUTH AND WEST IN CENTRAL AND
SOUTHERN IOWA ALONG THE BOUNDARY. HOWEVER, LOOKING AT GRAND ENSEMBLE
OUTPUT (GEFS, ENS, & GEPS), THE PROBABILITY OF 0.01" OR MORE OF
PRECIPITATION IS 60 TO 80% OVER NORTHEAST IOWA, MUCH HIGHER THAN THE
20 TO 30% IN NBM. ALL THIS TO SAY, GUIDANCE IS CLEARLY STRUGGLING
WITH THIS SETUP, BUT THE SIGNAL IS THERE FOR AT LEAST SCATTERED
SHOWERS IN THE AREA TUESDAY MORNING, WITH EVEN A FEW STORMS POSSIBLE
IN SOUTHEASTERN IOWA BEFORE THE SURFACE FRONT PUSHES THROUGH. THE
TIMING ISN'T IDEAL FOR SEVERE THUNDERSTORMS IN MOST OF OUR AREA, BUT
SOME DESTABILIZATION AHEAD OF THE FRONT MAY LEAD TO A FEW STRONGER
STORMS. WINDS WILL BE THE PRIMARY CONCERN, ESPECIALLY WITH THE DRY
LOW LEVELS. OF COURSE, THIS WILL BE CONTINGENT ON ENOUGH CONVERGENCE
TO DISPLACE PARCELS AND OVERCOME ANY CAPPING IN PLACE TUESDAY
AFTERNOON.
GREATER CERTAINTY RESIDES IN THE WIND POTENTIAL ON TUESDAY, AS
INCREASED WIND FIELDS AROUND THIS SYSTEM RESULT IN GUSTY WINDS ON
TUESDAY. NBM SEEMS TO HAVE A PRETTY GOOD HANDLE ON WINDS BASED ON
MODEL SOUNDINGS, DEPICTING SUSTAINED WINDS OVER NORTHERN IOWA AROUND
25 TO 30 MPH, WHICH WOULD BE APPROACHING WIND ADVISORY CRITERIA.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ISSUED AT 248 PM CDT SUN MAY 10 2026
TEMPERATURES COOL SLIGHTLY ON WEDNESDAY, ALBEIT STILL IN THE 70S.
THE BROAD UPPER LEVEL RIDGING THEN FILLS IN BEHIND THE DEPARTING
SHORTWAVE, WARMING TEMPERATURES INTO THE 80S THROUGH THE SECOND HALF
OF THE WORK WEEK. AS MENTIONED IN YESTERDAY'S LONG TERM DISCUSSION,
DESPITE THE BRIEF RIDGE MOVING IN, THE PATTERN QUICKLY BECOMES
AGITATED THROUGH THE END OF THE WEEK AND INTO NEXT WEEKEND WITH
MULTIPLE SHORTWAVES AND INCREASING SHOWER AND THUNDERSTORM
POTENTIAL, THE FIRST OF WHICH LOOKS TO BE ON THURSDAY NIGHT INTO
FRIDAY AS A HEALTHY GULF MOISTURE STREAM RETURNS TO THE STATE.
ADDITIONAL CHANCES CONTINUE INTO THE WEEKEND. THIS WILL LIKELY PUT A
DAMPER ON THE HIGHS IN THE 90S THAT NBM GUIDANCE HAD BEEN
FORECASTING FOR NEXT WEEKEND AND TODAY'S EXTENDED FORECAST NOW
REFLECTS THIS A BIT BETTER. THAT SAID, WITH THE SOUTHWESTERLY TO
WESTERLY FLOW PATTERN, TEMPERATURES SHOULD STAY SEASONABLY WARM
IN THE 80S THROUGH THE WEEKEND.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 619 PM CDT SUN MAY 10 2026
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THIS TAF PERIOD.
PATCHY VFR CUMULUS IS EXPECTED TO DISSIPATE SHORTLY AFTER
SUNSET, LEADING TO CLEAR SKIES THROUGH THE NIGHT. WINDS ARE
CURRENTLY FROM THE NORTHWEST AT 10-15KT, GUSTING FROM 20-25KT,
BUT WILL BECOME LIGHT AND VARIABLE AFTER SUNSET AND WILL REMAIN
LIGHT THROUGH THE TAF PERIOD. A SURFACE HIGH WILL MOVE ACROSS
IOWA, LEADING TO A GRADUAL WIND SHIFT THROUGHOUT THE PERIOD.
SHORTLY AFTER THIS TAF PERIOD, WINDS WILL BE LIGHT AND BECOME
FROM THE SOUTH AS THE HIGH CLEARS THE REGION.
DMX WATCHES/WARNINGS/ADVISORIES
FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM CDT MONDAY FOR
IAZ004>007-015>017-025>028-039.
SHORT TERM...DODSON
LONG TERM...DODSON
AVIATION...HAGENHOFF/ROTTER
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