240
FXUS63 KDMX 301902
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
202 PM CDT WED APR 30 2025
KEY MESSAGES
- SPOTTY LIGHT SHOWERS TODAY INTO TONIGHT, THEN CHANCES OF
SHOWERS/ISOLATED THUNDERSTORMS AT TIMES FROM THURSDAY INTO
FRIDAY.
- MOSTLY DRY FROM FRIDAY NIGHT INTO EARLY NEXT WEEK, INCLUDING A
QUIET WEEKEND WITH WARMING TEMPERATURES CLIMBING INTO THE 70S
BY SUNDAY AFTERNOON.
DISCUSSION
ISSUED AT 201 PM CDT WED APR 30 2025
AT 500 MB, BROAD TROUGHING OVERLIES MOST OF THE CONUS WITH A
SOUTHERN WAVE ROUNDING ACROSS THE HIGH PLAINS THIS AFTERNOON,
WHILE A NORTHERN STREAM TROUGH DIGS FROM FAR SOUTHERN CANADA
INTO THE FAR NORTHERN U.S. AROUND MONTANA AND NORTH DAKOTA. THE
LEADING, SOUTHERN SYSTEM IS GENERATING LIGHT RAIN ACROSS PARTS
OF IOWA BUT A RELATIVE LACK OF MOISTURE AND FORCING PRECLUDES
ANYTHING MORE THAN GLORIFIED SPRINKLES. AS A SLUG OF LIFT MOVES
ACROSS THE MID-MISSISSIPPI RIVER VALLEY TONIGHT CONCURRENT WITH
CONTINUING MOISTURE ADVECTION, A SHIELD OF MORE WIDESPREAD
MODERATE RAIN AND ISOLATED THUNDERSTORMS WILL MOVE ACROSS THE
REGION, BUT LARGELY OVER MISSOURI AND ILLINOIS WITH ONLY OUR
SOUTHEASTERN COUNTIES SEEING AN UPTICK IN PRECIPITATION
CHANCES/AMOUNTS. ON THURSDAY THE FIRST OF TWO NORTHERN STREAM
WAVES WILL MOVE THROUGH THE NORTHERN HIGH PLAINS, APPROACHING
IOWA AND BRINGING A BROAD SWATH OF SHOWERS AND THUNDERSTORMS
THROUGH OUR FORECAST AREA MAINLY IN THE AFTERNOON AND EVENING. A
RELATIVE LACK OF INSTABILITY MITIGATES ANY SEVERE WEATHER
THREAT, BUT HAVE MAINTAINED 40-60% RAIN CHANCES AS THIS ZONE
MOVES THROUGH. THE FINAL TROUGH WILL FINALLY MOVE OVERHEAD
DURING THE DAY ON FRIDAY, PROVIDING ONE LAST ROUND OF SCATTERED
SHOWERS/STORMS BUT AGAIN, WITH LIMITED MOISTURE AND INSTABILITY
PRECLUDING A SEVERE WEATHER THREAT.
FROM FRIDAY NIGHT ONWARD THE FORECAST IS GENERALLY QUIETER, BUT
BECOMES INCREASINGLY UNPREDICTABLE BECAUSE OF HOW THE LONG-RANGE
MODELS ARE RESOLVING THE EVOLUTION OF THE TROUGH EAST OF IOWA.
THE NEWEST GEM AND ECMWF RUNS ARE RAPIDLY CLOSING IT OFF AS A
500 MB CYCLONE OVER THE OHIO RIVER VALLEY BY SUNDAY, THEN
STALLING OR EVEN SLIGHTLY RETROGRADING IT IN THE EARLY PART OF
NEXT WEEK. MEANWHILE, THE GFS PUSHES THE TROUGH MUCH FARTHER
EAST BEFORE CLOSING IT OFF ALONG THE U.S. ATLANTIC COAST. THIS
IS IMPORTANT BECAUSE THERE IS UNANIMOUS AGREEMENT ON A LARGE,
DEEP-LAYER RIDGE BUILDING OVER THE ROCKIES AND HIGH PLAINS THIS
FRIDAY AND SATURDAY, AND THE DEGREE TO WHICH ITS INFLUENCE WILL
SPREAD INTO IOWA IS SOMEWHAT IMPACTED BY THE PROXIMITY OF THE
EASTERN 500 MB LOW. IN ALL SOLUTIONS, THE BULK OF THE PERIOD
FROM FRIDAY NIGHT THROUGH MONDAY NIGHT IS DRY WITH PERHAPS JUST
SOME SLIGHT CHANCE (10-20%) POPS IN OUR EASTERN COUNTIES AT
TIMES WITH THE GEM/EC SOLUTIONS, BUT FORECAST TEMPERATURES ARE
NOTABLY WARMER IN THE GFS SOLUTIONS WHERE THE RIDGE IS MORE
DOMINANT. THE GOOD NEWS IS THAT OVERALL, THE PERIOD FROM FRIDAY
NIGHT INTO EARLY NEXT WEEK IS BENIGN AND GENERALLY PLEASANT FOR
MOST OUTDOOR INTERESTS.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1222 PM CDT WED APR 30 2025
VFR CONDITIONS WILL PREVAIL THIS AFTERNOON WITH A FEW BRIEF
LIGHT SHOWERS EXPECTED TO HAVE LITTLE TO NO IMPACT. BY TONIGHT
LOWER CEILINGS WILL WORK IN, FIRST MVFR AND THEN LOWERING TO IFR
AT MOST TERMINALS ESPECIALLY AFTER MIDNIGHT. MORE SHOWERS AND
ISOLATED THUNDERSTORMS ARE ALSO FORECAST AND HAVE INCLUDED
PROB30 GROUPS AROUND THE RELATIVELY LIKELIER TIME FRAMES,
HOWEVER, CONFIDENCE IN TIMING AND COVERAGE IS LOW AND UPDATES
AND AMENDMENTS ARE LIKELY OVERNIGHT.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...LEE
AVIATION...LEE
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