319
FXUS63 KDMX 291949
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
249 PM CDT SUN MAR 29 2026
KEY MESSAGES
- WARMING INTO MONDAY WITH NEAR RECORDS POSSIBLE. ELEVATED FIRE
WEATHER POSSIBLE SOUTHERN INTO WESTERN IOWA MONDAY.
- STRONG TO A FEW SEVERE STORMS POSSIBLE MONDAY EVENING WITH MAIN
THREAT LARGE HAIL.
- TURNING COOLER TUESDAY WITH GUSTY WINDS BEHIND A FRONT.
SEVERAL PRECIPITATION CHANCES REMAINDER OF THE WEEK.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED AT 249 PM CDT SUN MAR 29 2026
THE NEXT 24 TO 30 HOURS OR SO WILL BE THE MORE TRANQUIL PERIOD OF
THE WEATHER FORECAST AS THE PATTERN TURNS MORE ACTIVE THEREAFTER.
THIS AFTERNOON, BREEZY WINDS FROM THE SOUTH-SOUTHWEST HAVE PREVAILED
AS LOWER PRESSURE OVER THE CENTRAL ROCKIES DEVELOPS WITH THESE WINDS
ALSO HELPING TO USHER IN MORE MOISTURE IN THE BOUNDARY LAYER. THIS
HAS HELPED TO KEEP RELATIVE HUMIDITY VALUES GENERALLY ABOVE 30% AND
CRITICAL FIRE WEATHER CONDITIONS AT BAY WITH THE GRASSLAND FIRE
DANGER INDEX (GFDI) MAINLY IN THE HIGH CATEGORY. IT IS ALSO WARMER
THIS AFTERNOON WITH HIGHS WELL INTO THE 60S TO LOW 70S DUE TO TOP OF
THE BOUNDARY LAYER TEMPERATURES +6C SINCE THIS TIME YESTERDAY. AS WE
HEAD INTO TONIGHT, WINDS WILL DIMINISH AND BE UNDER 10 MPH. A FEW
MODELS TRY TO DEPICT LIGHT FOG DEVELOPMENT OVER PARTS OF NORTH
CENTRAL INTO NORTHEASTERN IOWA. GLAMP PROBABILITIES OF VISIBILITIES
BELOW 5 MILES HAVE BEEN DROPPING IN RUNS THROUGH THE DAY SO HAVE
ONLY INCLUDED A VERY LIMITED AREA OF FOG EAST OF MASON CITY TO NORTH
OF WATERLOO.
A BOUNDARY WILL RESIDE NORTH OF THE STATE ON MONDAY AS LOW PRESSURE
MOVES SLOWLY TOWARDS THE STATE. THERE WILL BE GOOD SOUTHWESTERLY
FLOW AHEAD OF THIS LOW, WHICH WILL PUMP MORE MOISTURE AND BUMP LOW
LEVEL TEMPERATURES UP AGAIN. HIGH TEMPERATURES WILL REACH NEAR
RECORD LEVELS (SEE CLIMATE SECTION BELOW) AS THEY SOAR INTO THE 80S
AND IN MANY CASES WELL INTO THE 80S. WITH BETTER BOUNDARY LAYER
MIXING, HAVE ALSO LOWERED DEWPOINTS BY A FEW DEGREES TO ACCOUNT FOR
ENTRAINMENT FROM ALOFT. THE LOWEST RELATIVE HUMIDITY VALUES WILL BE
OVER WESTERN IOWA IN THE 20 TO 30% RANGE; HOWEVER, THE RELATIVELY
STRONGER WINDS WILL BE OVER SOUTHERN IOWA. WITH THESE FIRE WEATHER
VARIABLES SPATIALLY OUT OF PHASE, THIS WILL RESULT IN ELEVATED FIRE
WEATHER CONCERNS, WHICH WILL BE HIGHEST OVER WESTERN INTO SOUTHERN
IOWA WHERE THE GFDI WILL BE IN THE VERY HIGH CATEGORY.
MONDAY NIGHT WILL SEE THE LOW LEVEL JET RAMP UP TO 40 TO 50 KNOTS
AND THIS WILL PROVIDE FOR STRONG THETA-E ADVECTION SOUTH OF AND INTO
THE BOUNDARY. THIS PHASED LOW LEVEL THERMODYNAMIC AND KINEMATIC
FORCING WILL BE SUFFICIENT TO DEVELOP STRONG TO A FEW SEVERE STORMS
TOWARDS 3Z/10PM MONDAY EVENING PER MANY HIGH RESOLUTION MODELS.
THESE SAME MODELS TRY TO FESTER SHOWERS OR PERHAPS A STORM BEFORE
THAT TIME, BUT CAPPING SHOULD KEEP THINGS MOSTLY CONTAINED UNTIL MID-
EVENING. FORECAST SOUNDINGS CONTINUE TO POINT TO THESE STORMS BEING
ELEVATED IN NATURE WITH MUCAPE IN EXCESS OF 1500 J/KG, EFFECTIVE
SHEAR AROUND 30 KNOTS UP TO PERHAPS 40 KNOTS, AND STEEP MID-LEVEL
LAPSE RATES OF 8C/KM. THESE VARIABLES POINT TO A LARGE HAIL THREAT.
WHILE HODOGRAPHS ARE ELONGATED (AND THUS SUPPORTIVE OF THE HAIL
RISK), THEY ARE A BIT GUNKY IN THE CAPE BEARING LAYER ABOVE 3KM SO
WILL BE INTERESTING TO SEE HOW STORMS EVOLVE TOMORROW EVENING.
FORECAST SOUNDINGS ALSO SHOW A GOOD AMOUNT OF SUB-CLOUD DRY AIR FROM
3KM TO THE SURFACE SUCH THAT THIS BALLOONS DOWNDRAFT CAPE VALUES
WITH A GRADIENT IN VALUES UP TO AROUND 1000 J/KG TOWARDS IOWA
FALLS/MASON CITY TO AROUND 700 J/KG TOWARD DES MOINES. THESE LOWER
VALUES TOWARDS THE I-80 CORRIDOR ARE A RESULT OF THE LOW LEVEL
MOISTURE ADVECTION. SO, THE WIND THREAT LOOKS TO BE
ISOLATED/LOCALIZED TO WHERE STORMS DEVELOP AND LOW LEVEL MOISTURE
ADVECTION HAS NOT REACHED TO SATURATE AND MINIMIZE THE EFFECTS OF
ENTRAINMENT TO THE SURFACE. CONVECTIVE ALLOWING MODELS ARE SHOWING
LITTLE IN THE WAY OF GUSTY WINDS AT THIS TIME, BUT THE ISOLATED
POTENTIAL REMAINS GIVEN THE SETUP. MUCH OF THIS STORM ACTIVITY WILL
CLEAR OUR FORECAST AREA INTO EASTERN IOWA AROUND OR SHORTLY AFTER
MIDNIGHT.
LONG TERM /TUESDAY THROUGH SATURDAY/
ISSUED AT 249 PM CDT SUN MAR 29 2026
TUESDAY WILL BE A TRANSITION DAY AS THE BOUNDARY NORTH OF THE STATE
IS FORCED THROUGH THE STATE AS AN UPPER LEVEL SHORTWAVE TROUGH
PUSHES ITS INFLUENCE OVER THE NORTHERN STATES. THE NOW COLD FRONT
WILL ALSO BE THE FOCUS FOR POSSIBLE STORM DEVELOPMENT IN THE
AFTERNOON INTO EARLY EVENING HOURS - ROUGHLY ALONG AND EAST OF
HIGHWAY 63 - THOUGH THE OVERALL RISK WILL BE HIGHER TO THE
EAST/SOUTHEAST. IN THE FRONT'S WAKE, GUSTIER WINDS WILL DEVELOP FROM
THE NORTHWEST AND USHER IN COOLER, MORE SEASONAL AIR WITH HIGHS 25
DEGREES LOWER IN NORTHWESTERN IOWA (COMPARED TO MONDAY) TO A FEW TO
5 DEGREES LOWER IN SOUTHEAST IOWA. THERE SHOULD BE SOME DEGREE OF A
SHORT WINDOW OF DRY CONDITIONS AFTER THE FRONT CLEARS THE AREA
TUESDAY NIGHT, BUT ANOTHER TROUGH WILL BE APPROACHING FROM THE WEST
ON WEDNESDAY. MOISTURE TRIES TO ADVECT AHEAD OF IT, BUT THE FRONT
WILL LIMIT THE DEGREE OF MOISTURE RETURN INTO IOWA. HOWEVER, THERE
WILL BE STRONG THETA-E ADVECTION THAT SHOULD ALLOW FOR PRECIPITATION
TO DEVELOP LATER WEDNESDAY INTO THURSDAY. FORECAST SOUNDING PROFILES
CONTINUE TO LOOK INTERESTING AS THEY HAVE OVER THE LAST DAY WITH
PROFILES JUST BELOW FREEZING AND ISOTHERMAL FOR SOME SORT OF NARROW,
WET SNOW AREA POTENTIAL ON THE NORTHERN EDGE OF THE PRECIPITATION
SHIELD. AS THIS SYSTEM SLIPS AWAY ON THURSDAY, A MORE ROBUST TROUGH
WILL BE ENTERING FROM THE PACIFIC NORTHWEST TOWARDS IOWA. ONCE
AGAIN, MOISTURE TRANSPORT WILL PRECEDE ITS ARRIVAL LATER FRIDAY INTO
SATURDAY. FROM A PATTERN RECOGNITION PERSPECTIVE, THIS SETUP LOOKS
GOOD FOR SEVERE WEATHER POTENTIAL LATER FRIDAY. AI/ML SOLUTIONS
YESTERDAY WERE RATHER MUTED OR SHUNTED AWAY FROM IOWA, PERHAPS DUE
TO MEAGER DEWPOINTS PEAKING IN THE LOW 50S, BUT TODAY'S NSSL GEFS ML
SEVERE PROBABILITY DOES HAVE AN AREA FROM TEXAS INTO IOWA AHEAD OF
THE TROUGH ALONG WITH LOW PROBABILITIES FROM SOME OTHER ML SEVERE
PROBABILITY MODELS. AS THIS MOVES THROUGH ON SATURDAY, MOISTURE MAY
TRY TO WRAP AROUND INTO THE COLDER AIR SATURDAY NIGHT FOR SOME
ADDITIONAL WET SNOWFLAKES IN NORTHERN IOWA, BUT THAT WILL DEPEND ON
THE PLACEMENT OF THE DRY SLOT PUNCH AND TRACK OF THE SYSTEM.
REGARDLESS OF SEVERE AND SNOWFLAKE POTENTIAL, LOOKS TO BE A GOOD
AMOUNT OF MOISTURE. GLOBAL DETERMINISTIC, ENSEMBLE, AND AI SOLUTIONS
SHOW PARTS OF IOWA RECEIVING AT LEAST 1 TO 1.5 INCHES OF RAINFALL
FOR THE 48 HOUR PERIOD ENDING LATE SATURDAY EVENING. WHILE MUCH
REMAINS TO BE SEEN WITH WHERE, HOW, AND HOW MUCH RAIN FALLS, WILL BE
MONITORING TRENDS IN THE EXPERIMENTAL HEFS (HYDROLOGIC ENSEMBLE
FORECASTING SERVICE) AND THE NBM AND GFS FORCED NATIONAL WATER MODEL
WITH THESE SHOWING MOSTLY WITHIN BANK STREAM RESPONSES AT THIS
TIME.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1226 PM CDT SUN MAR 29 2026
VFR CONDITIONS WILL LARGELY PREVAIL THOUGH THE TAF PERIOD.
BREEZY WINDS FROM THE SW ARE EXPECTED THROUGH THE AFTERNOON WITH
GUSTS FROM 20-25 KTS BEFORE DYING DOWN AFTER 23Z. WHILE NOT
INCLUDED IN THE TAFS, SIGNAL EXISTS FOR PATCHY MVFR OR IFR FOG
(~30% CHANCE) FOR KMCW AND KALO SITES. ADDITIONALLY, MARGINAL
SHEAR ~30KTS BEING MONITORED FOR KOTM MONDAY MORNING, THOUGH
CERTAINTY IS LOW. TRENDS IN FOG AND SHEAR LIKELIHOOD WILL BE
MONITORED FOR FUTURE TAF UPDATES.
CLIMATE
ISSUED AT 249 PM CDT SUN MAR 29 2026
...FORECAST AND RECORD HIGH TEMPERATURES FOR SELECT CENTRAL IOWA
CITIES...
=============================================
| MONDAY | PERIOD
| FORECAST RECORD/ | OF
CITY | HIGH YEAR | RECORD
=============================================
DES MOINES 85 83/1968 1878-
MASON CITY 79 78/1967 1903-
OTTUMWA 84 83/1967 1923-
WATERLOO 81 84/1967 1895-
=============================================
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...ANSORGE
LONG TERM...ANSORGE
AVIATION...ANSORGE/DE BRUIN
CLIMATE...ANSORGE
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