124
FXUS63 KDMX 271745
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1145 AM CST THU FEB 27 2025
...UPDATED FOR THE 18Z AVIATION DISCUSSION...
KEY MESSAGES
- BREEZY AND MILD AGAIN TODAY WITH PLENTY OF SUNSHINE. ELEVATED
FIRE WEATHER CONDITIONS ONCE AGAIN.
- WINDY FRIDAY WITH WIND HEADLINES LIKELY NEEDED. NEAR CRITICAL
TO CRITICAL FIRE WEATHER CONDITIONS EXPECTED AREAWIDE DUE TO
STRONG WINDS, LOWERING RELATIVE HUMIDITY, AND CURED FUELS.
- DRY AND COOLER THIS WEEKEND, WITH A MORE ACTIVE PATTERN NEXT
WEEK WITH RAIN LIKELY, POSSIBLY MIXING OR CHANGING TO SNOW
MID/LATE WEEK.
DISCUSSION
ISSUED AT 255 AM CST THU FEB 27 2025
TODAY AND TONIGHT...
A FAIRLY AMPLIFIED UPPER AIR PATTERN NOTED OVER THE CONUS WITH
RIDGING OVER THE INTERMOUNTAIN WEST WITH UPPER TROUGHING OVER
THE GREAT LAKES REGION. AS A RESULT, MUCH OF THE UPPER MIDWEST
WILL REMAIN IN A DRY N/NWLY FLOW REGIME TODAY AND TONIGHT.
TYPICALLY, THIS COULD RESULT IN A COOL-ISH PATTERN, HOWEVER THE
DEEP, DRY ADIABATIC MIXED LAYER IN THE PBL WILL EXTEND TO ABOUT
850MB WHICH WILL ALLOW TEMPERATURES TO AGAIN CLIMB WELL ABOVE
SEASONAL AVERAGES, WITH HIGHS IN 50S EXPECTED AGAIN. THIS DEEPER
MIXED PROFILE WILL ALSO SUPPORT BREEZY CONDITIONS AGAIN TODAY,
WITH NW WINDS OF 15 TO 25 MPH COMMON, ALONG WITH A FEW GUSTS
OVER 30 MPH. THESE DRY AND BREEZY CONDITIONS WILL AGAIN SUPPORT
HIGH TO VERY HIGH GRASSLAND FIRE DANGER, AND WE RECENTLY HAVE
SEEN AN UPTICK IN GRASS FIRES PER DRY FUELS. PLENTY OF SUNSHINE
EXPECTED, WITH CLEAR TO PARTLY CLOUDY SKIES. MOSTLY CLEAR AND
MILD CONDITIONS EXPECTED TONIGHT, WITH WINDS ALOFT RAMPING UP
AFTER MIDNIGHT, WITH BREEZES CONTINUING THROUGH THE OVERNIGHT.
LOWS WILL REMAIN MILD, ONLY FALLING INTO THE 30S.
FRIDAY AND FRIDAY NIGHT...
A STRONGER AND DEEPENING UPPER SHORTWAVE WILL TRACK FROM ND
INTO THE GREAT LAKES AREA ON FRIDAY. THE STRONGEST SYNOPTIC
SCALE QG FORCING AND LIFT, AND RESULTANT PRECIPITATION SHIELD
SHOULD REMAIN WELL NORTH AND EAST OF OUR FORECAST AREA ON
FRIDAY. HOWEVER, VERY STRONG W/NWLY WINDS SOUTH OF THE
DEEPENING 850MB LOW WILL INCREASE OVER IA WITH 850MB WINDS AT OR
ABOVE 50KTS LIKELY THROUGH FRIDAY. WINDS WILL BEGIN TO INCREASE
IN EARNEST BY MID-MORNING FRIDAY AS MIXING DEPTH INCREASES. AN
ACCOMPANYING COLD FRONT WILL THEN DROP SWD THROUGH THE REGION
AFTER 18Z, RESULTING IN A SECONDARY PUSH OF WIND PER INCREASING
SUBSIDENCE AND MODEST CAA. VERY WINDY CONDITIONS WILL OCCUR ON
FRIDAY WITH A HIGH PROBABILITY (>70% CHANCE) OF SUSTAINED WINDS
EXCEEDING 30 MPH, AND WIND GUSTS EXCEEDING 40 MPH. THE VARIOUS
GEFS AND ECMWF ENSEMBLE GUIDANCE, ALONG WITH NBM PERCENTILE DATA
IS ALSO SUGGESTING PORTIONS OF THE THE CWA NORTH OF US 20 COULD
VERY WELL SEE WIND GUST VALUES EXCEED 50 MPH, ESPECIALLY IN THE
TYPICAL WIND PRONE AREAS /E.G. KEST AND KMCW/. WHILE CONFIDENCE
FOR WIND HEADLINES IS RELATIVELY HIGH FOR FRIDAY, PER
COORDINATION WITH NEIGHBORING WFOS WE DECIDED TO HOLD OFF
ISSUANCE ON THIS SHIFT TO BETTER FINE TUNE THE EXACT AREA AND
PROPER HEADLINE.
TEMPERATURES ON FRIDAY ARE ALSO EXPECTED TO TREND UPWARD AS THE
THERMAL RIDGE PUSHES THROUGH THE AREA AHEAD OF THE COLD FRONT. HIGHS
ARE EXPECTED TO RISE INTO THE LOWER 50S FAR NORTH TO THE LOWER 60S
SOUTH. THIS COMBINATION OF SEASONALLY WARM AND WINDY CONDITIONS
WILL ALSO LEAD TO FIRE WEATHER CONCERNS ONCE AGAIN. THE TRICKY
PART OF THE FIRE WEATHER EQUATION IS THE RH FORECAST. MODEL
SOUNDINGS SHOW CLOUDS INCREASING IN THE NORTH ALONG AND AHEAD OF
THE COLD FRONT /WITH EVEN A FEW HIGH BASED SHOWERS POSSIBLE/,
AND THIS COULD IMPACT THE DEPTH OF VERTICAL MIXING, ALONG WITH
EXTENT OF HEATING. CURRENTLY WE HAVE MINRH VALUES DROPPING TO
THE MID 40S NORTH, TO AROUND 30% IN THE SOUTH. THESE VALUES ARE
CLOSE TO, BUT STILL ABOVE OUR RED FLAG WARNING CRITERIA /RH <
25%/. IF IT BECOMES MORE EVIDENT THAT RH VALUES WILL FALL CLOSER
TO CRITERIA, FIRE WX HEADLINES WILL ALSO NEED TO BE CONSIDERED.
WINDS WILL GRADUALLY DIMINISH FRIDAY NIGHT, BUT COLDER
CONDITIONS WILL RETURN, ALBEIT CLOSER TO SEASONAL AVGS. LOWS ON
FRIDAY NIGHT WILL FALL BACK INTO THE TEENS AND 20S.
THIS WEEKEND INTO EARLY NEXT WEEK...
DRY AND COOLER CONDITIONS ARE ON TAP FOR SATURDAY WITH HIGHS IN THE
30S TO LOWER 40S A WEAK UPPER LOW SHOULD PASS WELL TO THE SOUTH OF
THE AREA ON SUNDAY AND MONDAY, BUT AS WINDS TURN AROUND TO MORE
SOUTHWESTERLY, MODEST WAA WILL AGAIN LEAD TO WARMING TREND.
THERE IS A LOW CHANCE FOR A FEW SHOWERS ON MONDAY PER THE WEAK
WAA/ISENTROPIC LIFT REGIME. THE 00Z DETERMINISTIC MODELS AND
ENSEMBLES ARE IN DECENT AGREEMENT SHOWING A MUCH STRONGER SYSTEM
IMPACTING MUCH OF THE MIDWEST ON TUESDAY THROUGH WEDNESDAY
NIGHT. THE LATEST GUIDANCE SUGGESTS ABOUT A 30-60% CHANCE OF
RAINFALL AMOUNTS > 0.50" - POTENTIALLY ONE OF THE WETTER SYSTEMS
IN SOME TIME. DEPENDING ON THE TRACK OF THE SYSTEM, THERE IS
POTENTIAL THAT THE PRECIP TYPE MAY TRANSITION TO SNOW, OR A
RAIN/SNOW MIX IN THE DEFORMATION ZONE ON THE BACKSIDE OF THE
SYSTEM. PLENTY OF TIME TO FINE TUNE DETAILS, BUT THE SYSTEM
BEARS WATCHING NEXT WEEK.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1145 AM CST THU FEB 27 2025
MAIN CONCERN WILL BE WINDS AFT 12Z AND WIND SHEAR AFT 06Z AND
LASTING THROUGH AROUND 12-15Z. RATHER DEEP MIXING IS ANTICIPATED
FROM 15Z FRIDAY THROUGH 00Z SATURDAY (NEXT FORECAST PERIOD),
WITH SOME GUSTS OCCASIONALLY REACHING 40 TO 45KTS 18Z THROUGH
00Z SATURDAY - JUST A HEADS UP. TROUGH PASSAGE AROUND 12Z
SIGNALS A WIND SHIFT TO WEST FOLLOWED BY A NORTHWEST WIND AFT
15Z THROUGH REMAINDER OF PERIOD. /REV
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...FOWLE
AVIATION...REV
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