026
FXUS63 KDMX 020829
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
229 AM CST SUN MAR 2 2025
KEY MESSAGES
- GENERALLY QUIET AND PLEASANT TODAY AND MONDAY, WITH A LOW
(20%) CHANCE OF VERY LIGHT RAIN/SNOW NORTHEAST AROUND SUNRISE
MONDAY.
- INCREASING SHOWERS AND SOME THUNDERSTORMS MONDAY NIGHT INTO
TUESDAY, WITH THE CHANCE OF RAIN NEAR 100% ON TUESDAY. SMALL
HAIL MAY BE POSSIBLE.
- TUESDAY NIGHT AND WEDNESDAY STRONG NORTHWEST WINDS WILL SPREAD
IN, WITH THE POTENTIAL FOR GUSTS TO NEAR 50 MPH, AND RAIN WILL
CHANCE TO SNOW FROM NORTHWEST TO SOUTHEAST BY WEDNESDAY
MORNING. TRAVEL IMPACTS APPEAR INCREASINGLY LIKELY FROM SOME
COMBINATION OF WINDS/SNOW/BLOWING SNOW.
DISCUSSION
ISSUED AT 229 AM CST SUN MAR 2 2025
IT IS QUIET ACROSS IOWA TONIGHT WITH NEARLY CLEAR SKIES AND
VARIABLE/CALM WINDS, BUT AN ACTIVE FORECAST IS IN STORE THIS
WEEK. THE LARGE HIGH PRESSURE AREA DRAPED ACROSS THE MIDWEST
EARLY THIS MORNING WILL DRIFT OFF TO THE EAST TODAY, WITH
SOUTHEASTERLY SURFACE FLOW RETURNING BY THIS AFTERNOON. AS A
DEEP-LAYER RIDGE MOVES OVER THE HIGH PLAINS TOWARD IOWA LATER
TODAY AND TONIGHT, WARM AIR/THETA-E ADVECTION ALOFT WILL
GENERATE INCREASING CLOUDS, AND PERHAPS SOME VERY LIGHT
PRECIPITATION IN OUR NORTHEASTERN COUNTIES AROUND SUNRISE
MONDAY. DURING THE DAY MONDAY INCREASING LOW-LEVEL WINDS AND
DEWPOINTS WILL THEN HELP TO PUSH TEMPERATURES HIGHER, HOWEVER,
SOME MODEL SOLUTIONS ARE SIGNALING STRATUS DEVELOPMENT IN THIS
REGIME SO DID NOT MAKE MUCH ADJUSTMENT TO MONDAY AFTERNOON HIGHS
AND KEPT THEM IN THE MID/UPPER 50S. GENERALLY TODAY AND MONDAY
WILL THUS BE QUIET AND RELATIVELY PLEASANT.
THE MOST IMPACTFUL WEATHER SYSTEM OF THE WEEK, BY FAR, IS SLATED
FOR THE TUESDAY-WEDNESDAY TIME FRAME. BY MONDAY EVENING A 500 MB
LOW WILL BE EMERGING FROM THE ROCKIES OVER EASTERN COLORADO,
INCLUDING LEE CYCLOGENESIS WITH A SURFACE LOW SPINNING UP
QUICKLY ON MONDAY NIGHT. INCREASING THETA-E ADVECTION ALOFT WILL
GENERATE ADDITIONAL RAIN ACROSS OUR FORECAST AREA AT THAT TIME,
WITH LOW BUT SUFFICIENT INSTABILITY TO JUSTIFY SHOWERS AND A
FEW THUNDERSTORMS, MAINLY IN THE SOUTH WHERE MUCAPE OF SEVERAL
HUNDRED J/KG SHOULD BE PRESENT. LATE MONDAY NIGHT INTO TUESDAY
MORNING A SEASONALLY ROBUST LOW-LEVEL JET WILL DEVELOP ALONG THE
LEADING FLANK OF THE APPROACHING CYCLONE, STREAMING MOISTURE
NORTHWARD FROM THE GULF UP TOWARD IOWA. THIS WILL MANIFEST AS A
SWATH OF SHOWERS AND THUNDERSTORMS SPREADING ACROSS MISSOURI AND
INTO PARTS OF IOWA, WITH MODEL CONSENSUS BRINGING THIS SWATH
INTO OUR SOUTH/SOUTHWESTERN COUNTIES TUESDAY MORNING AND
NORTH/NORTHEASTERN COUNTIES TUESDAY AFTERNOON. THERE MAY BE A
BRIEF LULL IN PRECIPITATION BEHIND THE LEADING BAND IF THE DRY
SLOT GETS FAR ENOUGH NORTH, BUT A LARGE PRECIPITATION SHIELD
WILL BE EXPANDING IN THE DEFORMATION ZONE TO THE NORTH OF THE
LOW ON TUESDAY AS WELL, SO IT IS MORE LIKELY THAT MUCH OF OUR
SERVICE AREA WILL SEE PRECIPITATION FOR MOST OF THE DAY, AND
90-100% POPS ARE INCLUDED IN THE FORECAST. FOR NOW ANY SEVERE
WEATHER THREAT APPEARS LIMITED AS INSTABILITY VALUES REMAIN LOW
AND WE SHOULD BE CLOUDY FOR MUCH OF THE DAY, HOWEVER GIVEN
SEASONALLY COOL TEMPS AND FAIRLY STEEP LAPSE RATES IN THE MID-
LEVELS, SMALL HAIL IS A DEFINITE POSSIBILITY.
THE MOST SIGNIFICANT IMPACTS OF THIS SYSTEM IN IOWA WILL LIKELY
COME AS THE AFOREMENTIONED DEFORMATION ZONE PRECIPITATION
INCREASES LATE TUESDAY, IN THE NORTHWEST, THEN FILLS IN
SOUTHEASTWARD BEHIND THE PASSING CYCLONE CENTER TUESDAY NIGHT
INTO WEDNESDAY. A VERY STRONG PRESSURE GRADIENT AND COLD AIR
ADVECTION ON THE BACK SIDE OF THE DEEPENING LOW WILL SUPPORT
VERY STRONG WINDS DURING THIS TIME, WITH FORECAST SOUNDINGS
INDICATING TOP OF THE MIXED LAYER WIND GUSTS POTENTIAL NEAR 50
KT ON WEDNESDAY. IN ADDITION, WITH FALLING TEMPERATURES AND THE
SOUNDING PROFILES ABOVE THE SURFACE WELL BELOW FREEZING IN THIS
PHASE OF THE EVENT, THE RAIN WILL CHANGE OVER TO SNOW FROM
NORTHWEST TO SOUTHEAST AS NEAR-SURFACE TEMPERATURES FALL TUESDAY
NIGHT/WEDNESDAY MORNING. SIGNIFICANT UNCERTAINTIES REMAIN IN THE
TIMING OF THIS TRANSITION, THE TIMING OF THE END OF THE SNOW ON
WEDNESDAY AND RESULTANT ACCUMULATION AMOUNTS, HOWEVER, WHILE
SNOW IS FALLING AND THE WINDS ARE GUSTING TO 40 KT OR GREATER,
BLOWING SNOW EFFECTS COULD PRODUCE HAZARDOUS TRAVEL IMPACTS
WHICH WOULD BE EXACERBATED BY ANY MODERATE SNOW ACCUMULATIONS.
WE ARE CLOSELY MONITORING THIS POTENTIAL AND IT APPEARS WIND
HEADLINES ARE A NEAR CERTAINTY AT SOME POINT, WITH A WINTER
WEATHER HEADLINE FOR COMBINED WIND/SNOW/BLOWING SNOW A DISTINCT
POSSIBILITY. AGAIN, HOWEVER, WHILE CONFIDENCE IN STRONG WINDS IS
VERY HIGH AND CONFIDENCE IN SOME AMOUNT OF SNOW IS HIGH,
CONFIDENCE IN THE DURATION AND AMOUNT OF SNOW REMAINS FAIRLY
LOW. STAY TUNED FOR UPDATES ON THIS SYSTEM OVER THE NEXT COUPLE
OF DAYS.
THE MID-WEEK STORM SHOULD CLEAR QUICKLY TO THE EAST LATER
WEDNESDAY AND WEDNESDAY NIGHT, WITH A BRIEF PERIOD OF RIDGING
AROUND THURSDAY BRINGING QUIET WEATHER. ANOTHER TROUGH WILL THEN
MOVE THROUGH THE CENTRAL U.S. LATER IN THE WEEK, BUT CONTINUES
TO BE DEPICTED AS MORE DISCOMBOBULATED AND NOT AS STRONG AS THE
TUESDAY/WEDNESDAY SYSTEM. THIS BRINGS A RETURN OF 30-50%
PRECIPITATION CHANCES TO THE FORECAST FROM THURSDAY NIGHT
THROUGH FRIDAY, HOWEVER TYPE AND AMOUNTS OF PRECIPITATION ARE
INSCRUTABLE AT THIS RANGE.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1134 PM CST SAT MAR 1 2025
MINOR CHANGES TO WINDS FOR THE DAYTIME TOMORROW, PRIMARILY
DECREASING SPEEDS. VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...LEE
AVIATION...JIMENEZ
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