130  
FXUS63 KDMX 162004  
AFDDMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DES MOINES IA  
204 PM CST SUN FEB 16 2025  
   
KEY MESSAGES  
 
- ACCUMULATING SNOWFALL SOUTHWEST AND SOUTH LATE TONIGHT THROUGH  
MONDAY. AMOUNTS OF 2-3" LIKELY IN OUR SOUTHWESTERN COUNTIES  
AROUND BEDFORD AND MOUNT AYR. LIGHT SNOW MAY LINGER AT TIMES  
ACROSS THE AREA TUESDAY INTO WEDNESDAY, BUT WITH LITTLE TO NO  
ADDITIONAL ACCUMULATION.  
 
- PERIOD OF VERY COLD WEATHER FOR MUCH OF THIS WEEK, WITH  
TEMPERATURES FALLING BELOW ZERO EACH OF THE NEXT FIVE NIGHTS,  
AND WIND CHILLS BOTTOMING OUT AROUND 20 BELOW ZERO (SOUTHEAST)  
TO NEAR 40 BELOW ZERO (NORTHWEST) TUESDAY MORNING.  
 
- WARMER WEATHER APPEARS LIKELY FOR NEXT WEEKEND INTO EARLY THE  
FOLLOWING WEEK, PROVIDING A LIGHT AT THE END OF THE TUNNEL.  
 
 
   
DISCUSSION  
 
ISSUED AT 204 PM CST SUN FEB 16 2025  
 
A PERIOD OF NOTABLY COLDER WEATHER THAT BEGAN LAST NIGHT WILL  
PERSIST INTO MUCH OF THE COMING WEEK, WITH THE COLDEST PERIOD  
COMING GENERALLY FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT.  
BEFORE THAT, HOWEVER, ACCUMULATING SNOWFALL IS ANTICIPATED IN  
SOUTHWESTERN IOWA ON MONDAY.  
 
A LARGE RIDGE OF SURFACE HIGH PRESSURE IS SPILLING FROM SOUTHERN  
CANADA DOWN ACROSS THE DAKOTAS AND IOWA THIS AFTERNOON, BRINGING  
GUSTY NORTHWEST BREEZES AND COLD TEMPERATURES ONLY IN THE SINGLE  
DIGITS TO LOWER TEENS ACROSS MOST OF OUR AREA AT THIS TIME.  
WINDS WILL DIMINISH AFTER THIS EVENING AS THE CORE OF THE RIDGE  
BUILDS CLOSER AND DECOUPLING TAKES PLACE, WHICH WOULD NORMALLY  
FAVOR RAPID RADIATIONAL COOLING ESPECIALLY WITH FRESH SNOW ON  
THE GROUND ACROSS MUCH OF THE AREA. HOWEVER, THIS WILL BE  
COMPLICATED BY INCREASING CLOUDS FROM THE WEST/SOUTHWEST AS A  
ZONE OF MODEST FRONTOGENETICAL FORCING APPROACHES IN THE BRISK  
ZONAL STEERING FLOW ALOFT. HOURLY TEMPERATURE TRENDS TONIGHT  
WILL THUS BE VERY TRICKY TO FORECAST AS NIGHTTIME COOLING MAY  
INITIALLY BE SLOWED A BIT BY THE ORGANIZED WINDS, ACCELERATE AS  
THE WINDS DIMINISH, BUT THEN TEMPERATURES MAY STABILIZE OR EVEN  
RISE AS MID/HIGH LEVEL CLOUDS SPREAD IN LATE. GIVEN THESE  
COMPETING FACTORS OPTED TO STAY VERY CLOSE TO PREVIOUS FORECAST  
WHICH IS A LITTLE BELOW THE 50TH PERCENTILE OF THE GUIDANCE  
ENVELOPE, BUT ANY CHANGES IN THE WIND OR SKY COVER FORECAST  
COULD RESULT IN SIGNIFICANT TEMPERATURE VARIATIONS ACROSS OUR  
SERVICE AREA OVERNIGHT.  
 
AS THE AFOREMENTIONED FRONTOGENETICAL FORCING BUILDS IN AND  
SLIDES ACROSS NEBRASKA, SOUTHERN IOWA, AND NORTHERN MISSOURI IT  
WILL GENERATE SNOWFALL IN THESE AREAS BEGINNING LATE TONIGHT AND  
CONTINUING THROUGH MONDAY. AGAIN, THERE ARE COMPETING FACTORS  
SUPPORTING RELATIVELY HIGHER OR LOWER SNOWFALL AMOUNTS IN OUR  
SOUTHWESTERN COUNTIES. FORECAST SOUNDINGS INDICATE A DEEP  
SATURATED LAYER ALMOST ENTIRELY WITHIN THE DGZ (DENDRITIC GROWTH  
ZONE) ON MONDAY MORNING, SUPPORTING HIGH SLRS (SNOW TO LIQUID  
RATIOS) AND HIGHER SNOWFALL AMOUNTS. HOWEVER, THE FORCING IS  
MODEST AND FORECAST QPF LIGHT, ONLY AROUND 0.10 INCH IN OUR  
SOUTHWEST CORNER, PLUS NEAR-SURFACE DRY AIR FILTERING OUT OF THE  
HIGH PRESSURE RIDGE MAY UNDERCUT THE SNOW A BIT AND RESULT IN  
SOME FRAGMENTING/SUBLIMATION EFFECTS WHICH WOULD LOWER THE SLRS.  
ONCE AGAIN MAINTAINED ESSENTIALLY A PERSISTENCE FORECAST, WITH  
MAXIMUM ACCUMULATIONS DOWN AROUND RINGGOLD AND TAYLOR COUNTIES  
OF AROUND 2-3 INCHES. THAT IS ACTUALLY ABOVE MUCH OF THE  
GUIDANCE, RESPECTING THE DEEP DGZ DEPICTED IN FORECAST  
SOUNDINGS. DID MAKE TWO ADJUSTMENTS TO THE ONGOING WINTER  
WEATHER ADVISORY IN THE SOUTHWEST, ADDING ADAMS AND DECATUR  
COUNTIES WHERE FORECAST SNOW AMOUNTS APPROACH 2.5" OR SO, AND  
DELAYING THE START TIME OF THE ADVISORY TO 11Z/5AM MONDAY AS THE  
PRECIPITATION ONSET TIME HAS DELAYED A BIT. ALSO TIGHTENED UP  
THE POP GRADIENT ON THE NORTHERN EDGE OF THE SNOW, AS DRY AIR  
ENTRAINMENT FROM THE NORTH SHOULD RESULT IN A PRETTY SHARP  
CUTOFF WITH LITTLE TO NO ACCUMULATION EXPECTED NORTH OF A LINE  
ROUGHLY FROM ATLANTIC TO BLOOMFIELD.  
 
ASIDE FROM THE SNOW IN THE SOUTH/SOUTHWEST ON MONDAY, THE BIG  
STORY WILL BE THE INTENSE COLD COMING FOR SEVERAL DAYS THIS  
WEEK. THE PRIMARY GENERATOR OF THIS COLD SNAP WILL BE THE  
AFOREMENTIONED SURFACE HIGH PRESSURE RIDGE BUILDING DOWN FROM  
CANADA, WHICH WILL DOMINATE THE MIDWEST AND IOWA UNTIL AT LEAST  
FRIDAY. THE SNOW PACK IN PLACE ACROSS MUCH OF THE AREA WILL ACT  
AS A POSITIVE REINFORCEMENT AS WELL, HOWEVER, CLOUD COVER WILL  
PROVIDE SOME MITIGATING EFFECTS AT TIMES. IN PARTICULAR, FROM  
MONDAY NIGHT THROUGH WEDNESDAY A 500 MB TROUGH WILL ROTATE  
SLOWLY INTO AND OVER THE UPPER MIDWEST, RESULTING IN MID/HIGH  
LEVEL CLOUDS AT TIMES WHICH MAY DAMPEN DAYTIME "WARMING" A BIT  
AND COULD LIMIT NIGHTTIME COOLING SOMEWHAT SIGNIFICANTLY. IN ANY  
EVENT IT WILL BE VERY COLD, BUT THE COMBINED AND SOMETIMES  
COMPETING EFFECTS OF SNOW COVER, WIND VARIATIONS, AND  
INTERMITTENT CLOUDS WILL INFLUENCE COLD WEATHER WATCH, WARNING,  
AND ADVISORY DECISIONS OVER THE NEXT SEVERAL DAYS. AT THIS TIME  
HAVE NOT MADE ANY CHANGES TO THE ONGOING COLD WEATHER ADVISORY  
FOR TONIGHT THROUGH MONDAY MORNING, OR THE EXTREME COLD WATCH  
FOR MONDAY NIGHT THROUGH TUESDAY MORNING. IT STILL APPEARS  
LIKELY WARNING CRITERIA WILL BE MET ACROSS AT LEAST PARTS OF THE  
AREA, IF NOT MOST OF IT, EVEN IF MID/HIGH CLOUDS TO PERSIST  
THROUGH MONDAY NIGHT. HOWEVER, THAT WOULD IMPACT WHICH PARTS OF  
THE AREA MEET WARNING CRITERIA AND WHICH DO NOT, SO HAVE  
DEFERRED THIS DECISION IN FAVOR OF MAINTAINING THE WATCH AT THIS  
TIME. ON TUESDAY NIGHT AND WEDNESDAY NIGHT LOW TEMPERATURES  
ACTUALLY FALL TO EVEN LOWER LEVELS, HOWEVER WINDS ARE LIGHTER SO  
WIND CHILL VALUES ARE SLIGHTLY LESS COLD. EVEN SO, IT IS  
ANTICIPATED THAT EITHER ADVISORIES OR WARNINGS WILL BE NEEDED  
FOR THESE PERIODS AT SOME POINT AS WELL.  
 
IN THE EXTENDED FORECAST PERIOD, AROUND NEXT WEEKEND INTO EARLY  
THE FOLLOWING WEEK, IT APPEARS WE WILL SEE WEAKER AND MORE  
BENIGN WEST NORTHWESTERLY 500 MB FLOW, RESULTING IN ALTERNATING  
PERIODS OF MODEST THERMAL RIDGING AS WELL AS A RETURN OF  
GENERALLY SOUTHWESTERLY SURFACE FLOW. THIS SHOULD SUPPORT  
NOTABLY WARMER WEATHER AND CURRENTLY THE FORECAST HIGH  
TEMPERATURES FOR NEXT SATURDAY AND SUNDAY ARE IN THE 20S AND  
30S, SO THAT WILL PROVIDE SOMETHING TO LOOK FORWARD TO DURING  
THE COLD DAYS AHEAD.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z MONDAY/  
 
ISSUED AT 1113 AM CST SUN FEB 16 2025  
 
SCATTERED CLOUDS BASED ANYWHERE FROM FL011 TO FL100 WILL AFFECT  
THE AREA THIS AFTERNOON, PRODUCING BRIEF AND TRANSIENT MVFR  
CEILINGS AT SOME SITES (MAINLY FOD/DSM/OTM) BEFORE BREAKING UP  
LATER TODAY. VFR CONDITIONS ARE THEN FORECAST OVERNIGHT WITH  
DIMINISHING WINDS. LOW CLOUDS AND LIGHT SNOW WILL MOVE INTO  
SOUTHERN IOWA ON MONDAY AND MAY AFFECT DSM/OTM AFTER ABOUT 15Z,  
BUT IMPACTS ARE MORE LIKELY AFTER 18Z AND HAVE HELD OFF MENTION  
IN THE 18Z TAFS FOR NOW.  
 
 
   
DMX WATCHES/WARNINGS/ADVISORIES  
 
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST MONDAY  
FOR IAZ004>007-015>017-023>028-035>039-050.  
 
EXTREME COLD WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY  
MORNING FOR IAZ004>007-015>017-023>028-033>039-044>050-057>062-  
070>075-081>086-092>097.  
 
WINTER WEATHER ADVISORY FROM 5 AM TO 6 PM CST MONDAY FOR  
IAZ081-092>094.  
 
 
 
 
 
DISCUSSION...LEE  
AVIATION...LEE  
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