993  
FXUS63 KDMX 271144  
AFDDMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DES MOINES IA  
644 AM CDT SAT AUG 27 2016  
   
SHORT TERM
 
/TODAY/  
ISSUED AT 359 AM CDT SAT AUG 27 2016  
 
DRIER AIR HAS BEEN MOVING INTO CENTRAL AND WESTERN IOWA OVERNIGHT  
WITH THE BULK OF THE PRECIPITATION NOW MOVING INTO THE FAR EASTERN  
PORTION OF THE STATE. A FEW ADDITIONAL SHOWERS HAVE REDEVELOPED  
ALONG AND NORTH OF HIGHWAY 20 OVER THE NORTH AHEAD OF AN UPPER  
SHORT WAVE ENERGY AND IN THE REGION WHERE DEEPER MOISTURE IS MORE  
PREVALENT. THIS ACTIVITY OVER NORTHERN IOWA SHOULD EXPAND IN AREAL  
COVERAGE OVER THE NEXT FEW HOURS BUT PRECIPITATION WILL DECREASE  
BY MID MORNING. A COMPLEX OF STORMS IS MOVING ACROSS NORTHEAST  
KANSAS AND INTO SOUTHEAST NEBRASKA. EXPECT THIS SYSTEM TO AFFECT  
PARTS OF SOUTHERN IOWA THIS MORNING. A FEW ADDITIONAL SHOWERS OR  
THUNDERSTORMS MAY OCCUR OVER SOUTHEAST IOWA THIS AFTERNOON.  
 
CLOUD COVER IS THE OTHER FORECAST CHALLENGE TODAY. LOW STRATUS AND  
SOME FOG IS SPREADING OVER SOUTHWEST AND SOUTH CENTRAL IOWA. CLOUD  
BASES ARE BEGINNING TO DROP BELOW 500 FT AND VSBYS IN A FEW SITES  
DROPPING TO ONE MILE OR LESS. THIS AREA OF CLOUDS EXTENDS BACK WELL  
INTO EASTERN NEBRASKA. WITH A LACK OF GOOD FLOW AND SUBSIDENCE, IT  
MAY BE VERY DIFFICULT TO GET RID OF THE CLOUDS TODAY AND MAY JUST BE  
A RAISING OF CLOUD BASES DUE TO SOME DIURNAL HEATING. THAT SAID,  
CLOUDS AGAIN MAY LIMIT HIGH TEMPERATURES TODAY. THERE MAY BE  
LOCALIZED DRIZZLE ASSOCIATED WITH THESE CLOUDS. FOR NOW, EXPECT  
THERE SHOULD BE A FEW BREAKS IN THE CLOUDS CENTRAL AND SOUTH BUT MAY  
REMAIN OVER NORTHERN IOWA THROUGH THE DAY.  
   
LONG TERM
 
/TONIGHT THROUGH FRIDAY/  
ISSUED AT 359 AM CDT SAT AUG 27 2016  
 
MAIN FORECAST CONCERN WAS FOCUSED ON RAIN CHANCES MONDAY INTO  
TUESDAY AND THEN TRENDED TOWARDS A DRIER FORECAST MID TO LATE  
NEXT WEEK. LEANED TOWARD THE 27.00Z ECMWF FOR MUCH OF THE  
EXTENDED.  
 
TONIGHT INTO TUESDAY...GENERALLY ZONAL TO NORTHWEST FLOW ALOFT  
SETTLES IN OVER THE REGION WITH SURFACE HIGH PRESSURE BUILDING INTO  
THE STATE TONIGHT. THE SURFACE HIGH LOOKS TO SHIFT EAST ENOUGH  
SUNDAY NIGHT INTO MONDAY ALLOWING A BOUNDARY TO LIFT NORTHWARD INTO  
SOUTHERN IOWA. THIS BOUNDARY REMAINS THE FOCUS FOR THUNDERSTORM  
DEVELOP MONDAY INTO EARLY TUESDAY BEFORE A WEAK TROUGH/COLD FRONT  
TRANSITIONS SOUTH THROUGH THE STATE. FORCING WITH THIS SYSTEM IS  
WEAK AND UNORGANIZED AS WELL AS ANY TYPE OF SHEAR, BUT THERE IS A  
DECENT AMOUNT OF INSTABILITY THAT BUILDS OVER THE STATE MONDAY.  
THUS WITH THE CAPE AVAILABLE AND SOME VORTICITY AND  
FRONTOGENETICAL FORCING PRESENT, CANNOT RULE SOME THUNDERSTORM  
POTENTIAL UNTIL THE AFOREMENTIONED TROUGH MOVES THROUGH THE STATE  
BY TUESDAY. HOWEVER, ANY SEVERE THREAT REMAINS VERY LOW.  
 
WEDNESDAY THROUGH FRIDAY...TRENDED TOWARD A MUCH DRIER FORECAST THAN  
PREVIOUS FORECAST AS THE LATEST ECMWF AND EVEN SOME OF THE GFS  
ARE TRENDING THAT WAY AS WELL. MAINLY DUE TO LARGE SURFACE HIGH  
BUILDING INTO THE REGION WHICH WARDS OFF ANY KIND OF SIGNIFICANT  
MOISTURE AND THUS ANY SHORTWAVE THAT TRANSITIONS ACROSS THE UPPER  
LEVEL RIDGE WILL HAVE LITTLE TO WORK WITH. MORE CONFIDENT TO GO  
COMPLETELY DRY FOR MUCH OF THE EXTENDED NEXT WEEK THAN TO BLANKET  
EACH PERIOD WITH LOW CHANCE POPS.  
 

 
   
AVIATION
 
/FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING/  
ISSUED AT 644 AM CDT SAT AUG 27 2016  
 
WIDESPREAD IFR TO LIFR CIGS THIS MORNING ACROSS MUCH OF THE AREA.  
AREAS OF FOG MAY IMPACT KDSM/KOTM ALSO THIS MORNING. CIGS WILL  
GRADUALLY RISE LATER THIS MORNING AND INTO THE AFTERNOON.  
CONFIDENCE IS NOT HIGH ON TIMING OF RETURN TO VFR BUT SHOULD BEGIN  
TO OCCUR OVER THE SOUTHERN SITES THIS AFTERNOON BUT MAY BE DELAYED  
ACROSS THE NORTH UNTIL LATER AFTERNOON OR EVENING.  
 

 
   
DMX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM...DONAVON  
LONG TERM...PODRAZIK  
AVIATION...DONAVON  
 
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