478
FXUS63 KDMX 300356
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1056 PM CDT TUE APR 29 2025
...UPDATED FOR THE 06Z AVIATION DISCUSSION...
KEY MESSAGES
- LOWS WILL DROP INTO THE MID 30S NORTH TONIGHT.
- RAIN AND A FEW THUNDERSTORMS POSSIBLE WEDNESDAY. NO SEVERE
WEATHER EXPECTED, AT THIS TIME.
- LIGHT RAIN AND SOME RUMBLES OF THUNDER THROUGH FRIDAY, WARMING
BACK UP OVER THE WEEKEND.
DISCUSSION
ISSUED AT 246 PM CDT TUE APR 29 2025
HEIGHT RISES AND A SURFACE HIGH KEPT WEATHER FAIR TODAY. WINDS
WILL CONTINUE TO SLOW THROUGH THE AFTERNOON AS THE HIGH'S
INFLUENCE INCREASES. HIGHS WILL BE IN THE LOW TO MID 60S WITH
SOME PLACES IN THE NORTH REMAINING IN THE UPPER 50S. MAIN CHANGE
THIS FORECAST WAS LEANING ON THE LOWER END OF GUIDANCE
SOLUTIONS FOR TEMPERATURES ACROSS THE NORTH TONIGHT. A MIXTURE
OF SUBSIDENCE, CALM WINDS AND MOSTLY CLEAR SKIES WILL ALREADY
ALLOW LOWS TO UNDERPERFORM, BUT ADD TO IT THE DRY LOW-LEVELS
(SURFACE DEW POINT DEPRESSIONS ARE ON AVERAGE AROUND 15
DEGREES) FROM THE HIGH PRESSURE AND TEMPERATURES WILL BE ABLE TO
SINK INTO THE MID 30S. HAVE LOWERED TEMPERATURES ONLY AS FAR
SOUTH AS THE HIGHWAY 20 CORRIDOR AS MIDLEVEL CLOUDS WILL BEGIN
THEIR SNOW NORTHWARD PROGRESSION AFTER MIDNIGHT, KEEPING
SOUTHERN IOWA WARMER, IN COMPARISON.
SOME NOTABLE CHANGES IN THE SYNOPTIC PATTERN FOR THE REST OF THE
WORK WEEK. THE CLOSED LOW IN THE SW US WILL NOW ARRIVE IN THE REGION
BEFORE THE NORTHERN STREAM TROUGH DOES, DEEPENING AS IT DOES. THIS
FEATURE WILL LOCK IN MOST OF THE LOW-LEVEL MOISTURE FETCH AND
REDIRECT IT INTO THE OHIO RIVER VALLEY. THE MORE SOUTHERLY TREND OF
THE SYSTEM HAS TAKEN THE INSTABILITY GRADIENT WITH IT, WITH MUCAPE
VALUES REMAINING UNDER 500 J/KG IN THE FAR SOUTH. THERE WILL BE SOME
POSSIBLE THUNDERSTORMS WITH THIS MUCH INSTABILITY, BUT ACTIVITY
WON'T BE SEVERE. RAINFALL AMOUNTS WILL BE LARGELY UNDER AN INCH, BUT
CONVECTION IN THE FAR SOUTHEAST COULD LEAD TO LOCALLY HIGHER
AMOUNTS. HAVE LOWERED TEMPERATURES TO REFLECT THE CLOUDY, WET
CONDITIONS. THE NORTHERN STREAM SYSTEM DIVES IN FOR THURSDAY,
BRINGING WITH IT AN REINFORCING SHOT OF PACIFIC MOISTURE TO KEEP
PRECIPITATION GOING. FINALLY, ANOTHER SHORTWAVE PIVOTS FROM THE
NORTHWEST FOR ADDITIONAL LIGHT RAIN CHANCES ON FRIDAY.
AN OMEGA BLOCK PATTERN TAKES SHAPE OVER THE WEEKEND WITH IOWA BEING
IN PROXIMITY OF THE INFLUENCE OF THE RIDGE. TEMPERATURES WILL
RESPOND BY RETURNING INTO THE 70S. ACTIVE SPRING WEATHER WON'T BE
FAR AWAY AS THE INFLUENCE FROM THE CLOSED LOW IN THE SW US WILL
CHURN IN PVA AND GULF MOISTURE, HENCE THE RAIN CHANCES IN THE WEST
TOWARDS THE END OF THE PERIOD.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1048 PM CDT TUE APR 29 2025
VFR CONDITIONS WITH LIGHT, VARIABLE WINDS PREVAIL THIS MORNING.
HIGH CLOUDS HAVE BEGUN TO FILL IN OVER SOUTHERN IOWA, AND WILL
CONTINUE NORTH THROUGH THE MORNING HOURS. THESE CLOUDS WILL
PRECEDE SCATTERED RAIN MOVING INTO THE AREA IMPACTING ALL SITES
AT SOME POINT TODAY/TONIGHT. THAT SAID, WIDESPREAD
PRECIPITATION OCCURRING IN THE MORNING HOURS IS BECOMING MUCH
LESS LIKELY AS THIS RAINFALL MEETS THE DRY AIR OVERHEAD.
THEREFORE, HAVE PUSHED BACK THE START TIME OF RAINFALL IN TAFS,
WITH MOST OF THE RAIN EXPECTED TO FALL IN THE MID TO LATE
AFTERNOON AND BEYOND. AS SATURATION OCCURS AND RAIN FALLS,
CEILINGS WILL ALSO DROP INTO MVFR AND POTENTIALLY IFR
OVERNIGHT. ISOLATED THUNDER WILL BE POSSIBLE THIS AFTERNOON AND
EVENING AS WELL, ESPECIALLY AT KDSM AND KOTM, BUT CONFIDENCE IN
LOCATION AND TIMING IS TOO LOW TO INCLUDE IN TAFS AT THIS TIME.
RAIN AND DRIZZLE PERSISTS THROUGH THE END OF THE PERIOD.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...JIMENEZ
AVIATION...DODSON
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