144  
FXUS63 KDMX 192020  
AFDDMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DES MOINES IA  
320 PM CDT FRI APR 19 2019  
   
DISCUSSION
 
/TONIGHT THROUGH FRIDAY/  
ISSUED AT 320 PM CDT FRI APR 19 2019  
 
THE FORECAST PERIOD CAN BE EFFECTIVELY SPLIT INTO THREE PERIODS  
WITH THREE DIFFERENT SENSIBLE WEATHER/THREAT REGIMES. THIS WEEKEND  
WILL BE MOSTLY SUNNY AND MILD WITH AN ENHANCED FIRE DANGER. SUNDAY  
NIGHT INTO TUESDAY WILL BE CLOUDY WITH INTERMITTENT SHOWERS AND  
THUNDERSTORMS. THE MIDDLE TO LATTER PART OF NEXT WEEK WILL BE  
GENERALLY DRY, QUIET, AND MODERATE IN TEMPERATURE.  
   
..THIS WEEKEND...FROM THIS AFTERNOON THROUGH SUNDAY EVENING
 
 
THIS AFTERNOON WE HAVE SEEN GENERALLY NORTH WINDS OF 10 TO 20  
MPH, WITH OCCASIONAL GUSTS OVER 25 MPH, AND RH FALLING INTO THE  
30S AT TIMES. THIS HAS LEAD TO AN ENHANCED DANGER OF SPREADING  
FIRES, A LARGE NUMBER OF WHICH HAVE BEEN OBSERVED ACROSS THE AREA.  
A COOL SURFACE HIGH PRESSURE RIDGE WILL SLIDE ACROSS IOWA  
TONIGHT, CAUSING WINDS TO DIMINISH QUICKLY AFTER SUNSET AND BE  
NEARLY CALM AT TIMES OVERNIGHT, BUT THEN ON SATURDAY AS THE RIDGE  
MOVES AWAY SOUTHERLY WINDS WILL INCREASE ONCE AGAIN, WITH SPEEDS  
AND GUSTS ON SATURDAY AFTERNOON ONLY SLIGHTLY LESS THAN THOSE  
OBSERVED TODAY. MEANWHILE A DEEP THERMAL RIDGE WILL MOVE OVER THE  
REGION THIS WEEKEND, ESPECIALLY FROM SATURDAY AFTERNOON THROUGH  
SUNDAY MORNING, LEADING TO NOTABLY WARMER WEATHER AND CAUSING RH  
TO FALL FURTHER. ON SATURDAY AFTERNOON RH IS FORECAST TO BE IN THE  
25-30 PERCENT RANGE, SO THERE MAY BE INFREQUENT OBSERVATIONS  
RIGHT AT RED FLAG CRITERIA - 25 PERCENT WITH GUSTS OVER 25 MPH -  
BUT THESE SHOULD BE SPORADIC AND SHORT-LIVED. HOWEVER,  
WIDESPREAD/FREQUENT NEAR-RED FLAG CONDITIONS ARE LIKELY AND  
PLANNED BURNS SHOULD TAKE THIS INTO ACCOUNT. WE WILL BE  
HIGHLIGHTING THIS CONCERN IN OUR MESSAGING AND FIRE WEATHER  
PRODUCTS FROM NOW THROUGH THE WEEKEND. ASIDE FROM THE FIRE WEATHER  
CONCERNS IT WILL BE AN ABSOLUTELY GORGEOUS SPRING WEEKEND, LONG-  
AWAITED BY MANY, WITH MOSTLY SUNNY SKIES, SOUTHERLY BREEZES, AND  
TEMPERATURES PEAKING IN THE 70S ON SATURDAY AND MID 70S TO LOWER  
80S ON SUNDAY.  
   
..FROM SUNDAY NIGHT THROUGH TUESDAY
 
 
A SERIES OF 500 MB SHORTWAVE TROUGHS EJECTING OUT OF THE ROCKIES  
WILL PUSH THE THERMAL RIDGE OFF TO OUR EAST AND BRING MORE ACTIVE  
SOUTHWESTERLY FLOW TO THE REGION, ALSO PUSHING A SURFACE COOL  
FRONT ACROSS IOWA. THERE ARE DIFFERENCES AMONG THE PROGNOSTIC  
MODELS IN THE TIMING AND ORIENTATION OF THE SHORTWAVES WITHIN THE  
SERIES, CAUSING SOME UNCERTAINTY IN TIMING/EXTENT OF RESULTING  
PRECIPITATION, BUT IT IS CLEAR THAT INTERMITTENT SHOWERS AND  
THUNDERSTORMS WILL AFFECT MUCH OF IOWA. THE MOST LIKELY AREAS  
APPEAR TO BE ACROSS THE NORTHWEST HALF OF THE STATE, WITH THE MOST  
LIKELY TIME FRAME LATE SUNDAY NIGHT. INSTABILITY AND SHEAR ARE  
LIMITED AND SEVERE WEATHER AND HEAVY RAINFALL ARE NOT ANTICIPATED,  
SO ANY IMPACT WILL BE MINIMAL OTHER THAN PROVIDING SOME WATER FOR  
AWAKENING VEGETATION AND MAKING FOR GRAY, DAMP WEATHER AT TIMES  
EARLY IN THE WEEK.  
   
..IN THE LATTER HALF OF NEXT WORK WEEK
 
 
IOWA WILL RESIDE BENEATH THE SOUTHERN PERIPHERY OF BRISK WEST  
NORTHWESTERLY STEERING FLOW SPREADING ACROSS THE UPPER MIDWEST.  
THIS WILL KEEP US GENERALLY DRY AND QUIET, WITH PARTLY CLOUDY  
SKIES AND SLOWLY MODERATING TEMPERATURES. NO PRECIPITATION IS  
FORECAST DURING THIS TIME, THOUGH IT IS POSSIBLE WE COULD SEE A  
COUPLE OF LOW RAIN CHANCES ACROSS NORTHERN IOWA LATER IN THE WEEK.  
AT ANY RATE NO HAZARDOUS WEATHER IS EXPECTED WHILE HIGH  
TEMPERATURES CLIMB FROM THE 60S ON WEDNESDAY INTO THE LOW TO MID  
70S BY THURSDAY AND FRIDAY, AT LEAST ACROSS CENTRAL AND SOUTHERN  
IOWA.  
 

 
   
AVIATION
 
/FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON/  
ISSUED AT 1233 PM CDT FRI APR 19 2019  
 
VFR CONDITIONS WILL PERSIST THROUGH THE PERIOD. NORTHERLY WINDS  
THIS AFTERNOON WILL GUST TO 25-35 KTS AT TIMES ACROSS SOUTHERN TO  
EASTERN IOWA. WINDS SHOULD DIMINISH THIS EVENING. AS A FRONT  
MOVES THROUGH FROM NORTH TO SOUTH THIS EVENING WINDS ACROSS THE  
STATE WILL TRANSITION FROM NORTHERLY WINDS TO SOUTHERLY.  
 

 
   
DMX WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
DISCUSSION...LEE  
AVIATION...HAGENHOFF  
 
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