479
FXUS63 KDMX 281137
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
537 AM CST FRI FEB 28 2025
...UPDATED FOR THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- MILD AND WINDY TODAY WITH WINDS GUSTS 40 TO 50+ MPH LIKELY. VERY
HIGH TO EXTREME FIRE DANGER AREAWIDE.
- MUCH COOLER ON SATURDAY WITH HIGHS BACK IN THE 30S.
- A MORE ACTIVE PATTERN NEXT WEEK. INCREASED PRECIPITATION
CHANCES (30-50%) FOR RAIN OR SNOW MONDAY.
- STRONG MIDWEEK SYSTEM TO BRING RAIN AND ISOLATED THUNDERSTORMS
TUESDAY. PRECIPITATION COULD CHANGEOVER TO SNOW ON TUES NIGHT
AND WEDNESDAY, WITH SOME SNOW ACCUMULATIONS POSSIBLE.
DISCUSSION
ISSUED AT 309 AM CST FRI FEB 28 2025
TODAY AND TONIGHT...
00Z UPPER AIR DATA AND WATER VAPOR IMAGERY INDICATED A POTENT UPPER
SHORTWAVE OVER THE NORTHERN PLAINS, WHICH WILL SLIDE SEWD INTO THE
GREAT LAKES REGION LATER TODAY. AT THE SFC, A SUB 990MB SFC
WILL CONTINUE TO DEEPEN AS IT ALSO TRACKS NEAR THE US/CANADA
BORDER. LOW LEVEL WINDS HAVE ALREADY RESPONDED TO THESE FEATURES
WITH H8 SW WINDS STRENGTHENING TO 40-50KTS EARLY THIS MORNING,
RESULTING IN A STOUT WAA PATTERN.
FOR TODAY, THE MAIN CONCERNS REMAIN ON THE WIND POTENTIAL AND
FIRE WEATHER CONDITIONS. HIGH CONFIDENCE ON REACHING WIND
ADVISORY CRITERIA OVER MUCH OF CENTRAL AND NORTHERN IOWA. A
DECENT SFC PRESSURE GRADIENT WILL LEAD TO SUSTAINED
WEST/SOUTHWEST WINDS IN THE 20 TO 30 MPH RANGE AFTER ABOUT 10AM
CST THIS MORNING, GRADUALLY TURNING NWLY BY AFTERNOON AS A COLD
FRONT DROPS SWD FROM THE NORTH. FORECAST SOUNDINGS CONTINUE TO
SHOW MIXED LAYER WINDS EASILY PUSHING 40KTS, WITH WINDS AT THE
TOP OF MIXED LAYER APPROACHING 50KTS. AS NOTED PREVIOUSLY, ITS
POSSIBLE A FEW OF THE TYPICAL WINDIER LOCATIONS COULD SEE WINDS
GUST NEAR 60MPH, BUT AT THIS TIME FEEL THESE SHOULD REMAIN
FAIRLY SPORADIC.
REGARDING FIRE WEATHER, WE HAVE EXPANDED THE RED FLAG WARNING FOR
ALL COUNTIES IN THE FORECAST AREA. THIS MORNING, AN IMPRESSIVE PUSH
OF WARM AIR IS ONGOING WITH H8 TEMPS SURGING FROM +5C TO +12C BY 12Z
THIS MORNING, AND TEMPERATURES OVERNIGHT HAVE REMAINED STEADY
OR SLOWING RISING. EXPECT TEMPERATURES TO WARM RELATIVELY
RAPIDLY IN THE MORNING AND EARLY AFTERNOON WITH HIGHS REACHING
THE LOWER 50S FAR NORTH TO THE MID 60S FAR SOUTH. RH VALUES
SHOULD CORRESPONDING DROP INTO THE 25% TO 35% RANGE BY
AFTERNOON. THERE IS STILL SOME CONCERN FOR HIGHER RH IN THE FAR
NORTH, DUE TO MOISTURE POOLING ALONG THE SOUTHWARD ADVANCING
COLD FRONT, AND THICKER CLOUD COVER AND LOWER MIXING ACROSS THE
FAR NORTHERN TIERS OF COUNTIES. THUS RH VALUES NEAR THE IA/MN
BORDER WILL REMAIN HIGHER, GENERALLY 35% TO 45%. HOWEVER, THESE
MORE MARGINAL RH VALUES SHOULD BE OFFSET BY THE VERY STRONG
WINDS AND DRY/CURED FUELS, RESULTING IN THE POSSIBILITY OF
RAPIDLY SPREADING AND DANGEROUS FIRE GROWTH THIS AFTERNOON. GFDI
VALUES WILL BE WELL INTO THE "EXTREME" CATEGORY SOMETHING THAT
DOESNT HAPPEN TOO OFTEN. IN FACT, RECENT FIRES EXHIBITED ERRATIC
BEHAVIOR YESTERDAY, WHICH MUCH LESS WIND. ANY BURNING IS STRONG
DISCOURAGED TODAY. WINDS WILL REMAIN BREEZY OUT OF THE NORTH
THROUGH THIS EVENING, AND TEMPERATURE WILL SHARPLY FALL INTO THE
20S IN MANY AREAS BY MIDNIGHT. LOWS FRIDAY NIGHT WILL DROP INTO
THE TEENS AND 20S.
SATURDAY AND SUNDAY...
MUCH COOLER, BUT STILL SEASONAL CONDITIONS WILL RETURN ON SATURDAY,
WE'VE BEEN SPOILED RECENTLY. HIGHS ON SAT WILL ONLY RISE INTO LOWER
30S NORTH TO AROUND 40F SOUTH. THIS COOL SPELL WILL BE SHORT LIVED
AS WAA QUICKLY RESUMES ON SUNDAY WITH HIGHS REBOUNDING INTO THE MID
40S. DRY CONDITIONS WILL PERSIST THIS WEEKEND WITH PLENTY OF
SUNSHINE, OVERALL NOT TERRIBLE WEATHER BY ANY MEANS.
NEXT WEEK...
SUM IT UP IN ONE WORD, ACTIVE.
THE SYNOPTIC PATTERN IS EXPECTED TO UNDERGO A CHANGE TO A
SOUTHWESTERLY FLOW PATTERN ACROSS THE CENTRAL CONUS AS A DEEP UPPER
TROUGH DEVELOPS OVER THE WESTERN US LATE THIS WEEKEND. AN INITIAL
SHORTWAVE, AND SMALL CLOSED LOW, WILL IMPACT THE AREA SUNDAY NIGHT
INTO MONDAY. RECENT MODEL RUNS HAVE TRENDED STRONGER, AND FARTHER
NORTH WITH THIS FEATURE. AS SUCH, A DECENT PERIOD OF WAA/ISENTROPIC
ASCENT AND MOISTURE ADVECTION WILL PRODUCE A SWATH OF
PRECIPITATION MOVING ACROSS THE AREA LATE SUNDAY NIGHT INTO
MONDAY. POPS WERE BOOSTED INTO THE HIGH CHANCE CATEGORY /30-50%/
AND CORRESPONDING VALUES OF QPF NOW INDICATE THE POSSIBILITY OF
~0.25" OF PRECIP. THERMAL PROFILES AND MODEL SOUNDINGS
GENERALLY SUPPORT RAIN AS THE PRIMARY P-TYPE BUT SEVERAL MODELS
ARE SUPPORTING A SLIGHTLY COLDER PROFILE, AND PERHAPS A
RAIN/SNOW MIX AT THE ONSET. NO SNOW ACCUMULATION EXPECTED
HOWEVER.
THE WELL ADVERTISED, MUCH STRONGER SYSTEM IS STILL EXPECTED TO
IMPACT THE REGION TUESDAY INTO WEDNESDAY NIGHT. THE LATEST 00Z
DETERMINISTIC MODELS AND ENSEMBLES DID NOT CHANGE SIGNIFICANTLY FROM
THE PREVIOUS RUNS, GENERALLY TRACKING A STRONG SFC LOW FROM
KS/OK NEWD ACROSS MO AND INTO THE GREAT LAKES. BEING THAT THE
SYSTEM IS STILL 4 TO 5 DAYS OUT, THERE ARE THE USUAL DIFFERENCES
IN THE TRACK OF FEATURES AND STRENGTH OF THE SYSTEM.
REGARDLESS, CONFIDENCE IS MEDIUM TO HIGH THAT PRECIPITATION WILL
IMPACT THE AREA BEGINNING LATE TUESDAY IN THE FORM OF RAIN, AND
WITH BETTER INSTABILITY, ISOLATED THUNDERSTORMS ARE ALSO
POSSIBLE. AS THE SYSTEM DEEPENS AND OCCLUDES, A MAJORITY OF THE
MODELS STILL SHOW A WELL DEFINED DEFORMATION ZONE DEVELOPING
TUESDAY NIGHT INTO WEDNESDAY. THIS IS THE PERIOD WHEN A
CHANGEOVER FROM RAIN TO SNOW IS POSSIBLE. THE GEFS AND ECMWF
ENSEMBLES ARE STILL NOT GOING WILD REGARDING SNOWFALL AMOUNTS,
WITH ENSEMBLE PROBABILITIES OF GREATER THAN 3" OF SNOW STILL
GENERALLY LESS THAN 20%. HOWEVER, THINGS CAN STILL CHANGE AND
INDIVIDUAL OPERATIONAL MODEL RUNS HAVE SHOWN HEAVIER SNOWFALL
POTENTIAL. THIS SYSTEM WILL NEED TO BE MONITORED. REGARDLESS OF
SNOWFALL, IT WILL LIKELY BECOME WINDY AND COLDER ON WEDNESDAY
AND THURSDAY, AND TEMPS MAY EVENTUALLY NEED TO BE TRENDED DOWN.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 529 AM CST FRI FEB 28 2025
MAINLY VFR CONDITIONS EXPECTED THIS PERIOD. INITIAL CONCERN WILL
BE A PERIOD OF LLWS THROUGH MID-MORNING /~15Z/ AS WINDS SHARPLY
INCREASE FROM THE SFC UP THROUGH 1000-2000 FT AGL. AFTER 15Z,
AND ESPECIALLY AFTER 17-18Z, SFC WINDS WILL INCREASE WITH
SUSTAINED WINDS OF 20-30KTS AND PEAK GUSTS IN EXCESS OF 45KTS,
WITH THE STRONGEST WINDS AT KMCW AND KALO. WINDS WILL START
W/SW, THEN TRANSITION TO NW BY LATE AFTERNOON AS A COLD FRONT
DROPS SWD ACROSS THE STATE. THERE WILL BE PERIODS OF CLOUDS
MOVING THROUGH, BUT AT THIS POINT CIGS SHOULD REMAIN AOA 3K
FEET. THERE IS A LOW CHANCE FOR MORE PERSISTENT MVFR STRATUS
TONIGHT, BUT CONFIDENCE TO LOW TO INCLUDE DURING THIS ISSUANCE.
DMX WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY FROM 10 AM THIS MORNING TO 6 PM CST THIS EVENING
FOR IAZ004>007-015>017-023>028-033>039-044>050-057>062-073>075.
RED FLAG WARNING FROM NOON TODAY TO 6 PM CST THIS EVENING FOR
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097.
DISCUSSION...FOWLE
AVIATION...FOWLE
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