066  
FXUS63 KDMX 272349  
AFDDMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DES MOINES IA  
647 PM CDT FRI MAY 27 2016  
   
..UPDATED FOR 28/00Z AVIATION DISCUSSION
 
 
   
SHORT TERM
 
/TONIGHT/  
ISSUED AT 349 PM CDT FRI MAY 27 2016  
 
NEGATIVELY-TILTED H300 TROUGH AXIS CURRENTLY OVER THE TEXAS  
PANHANDLE WILL LIFT NORTHEAST TONIGHT INTO EAST CENTRAL KS, HELPING  
TO FUEL THE NEXT ROUND OF SHOWERS AND STORMS FOR IOWA. AT THE  
SURFACE, A BROAD SURFACE TROUGH ENCOMPASSES THE STATE WITH MULTIPLE  
EMBEDDED OUTFLOW BOUNDARIES COURTESY OF THIS MORNING'S CONVECTION.  
THE BREAK BETWEEN THESE TWO ROUNDS OF PRECIS WILL BE SHORT-LIVED,  
WITH THE NEXT ROUND OF MULTI-CELLULAR CONVECTION ALREADY DEVELOPING  
ACROSS EASTERN KANSAS AND WESTERN MISSOURI. MOST SYNOPTIC AND  
MESOSCALE MODELS ARE IN GOOD AGREEMENT ON THE TIMING OF THIS PRECIS  
BUT ARE STRUGGLING WITH THE OVERALL AREAL EXTENT AND AMOUNTS. LEANED  
TOWARDS THE 27.18Z HRRR AND GFS WITH THE PLACEMENT OF THE HEAVIEST  
RAINFALL/HIGHEST POPS. AXIS OF ELEVATED H700-500 MIXING RATIOS WILL  
LIFT NORTH THROUGH IOWA BETWEEN 00 AND 09Z WITH THE BEST CHANCE OF  
HEAVY RAINFALL OVER THE SOUTHEAST CWA. RUC/NAM/GFS SOUNDINGS FOR DES  
MOINES AND WEST ARE RATHER DRY BELOW 800MB, LENDING FURTHER  
CONFIDENCE IN THE HEAVIEST RAINFALL FALLING IN THE EAST. LOCALIZED  
HEAVY RAINFALL WILL BE THE BIGGEST THREAT FROM THESE STORMS TONIGHT  
GIVEN THE WEAK TO MODEST INSTABILITY PROFILES AND WEAK FLOW BELOW  
600 MB.  
   
LONG TERM
 
/SATURDAY THROUGH FRIDAY/  
ISSUED AT 349 PM CDT FRI MAY 27 2016  
 
THE PRIMARY CONCERNS REMAIN THE SLOW EVOLUTION OF THE CURRENT PLAINS  
LONG WAVE TROUGH AND THE NEXT NORTHERN STREAM LONG WAVE CYCLE TOWARD  
THE MIDDLE OF NEXT WEEK. POTENT SHORT WAVE/PV ANOMALY SHOULD BE  
RIGHT ALONG THE NE/IA BORDER AT 12Z WITH FAIRLY DECENT SYNOPTIC  
SCALE RISE/FALL COUPLET MOVING THROUGH NORTHERN IOWA. THE HIGH RES  
MODELS DO NOT DEPICT THE AREAL COVERAGE ONE MIGHT EXPECT VERSUS THIS  
DEGREE OF FORCING, BUT CONFIDENCE IS STILL THERE THAT WEAK  
CONVECTION WILL BE LIFTING TOWARD THE MINNESOTA BORDER IN THE 09-15Z  
TIME FRAME SO POPS REMAIN HIGH. PEAK HEATING CONVECTION WILL LIKELY  
FOLLOW, MAINLY OVER CENTRAL AND SOUTHEASTERN SECTIONS BY  
AFTERNOON AS WELL. MLCAPES LOOKS TO BE IN THE 1.5-2.5K J/G RANGE  
WITH ONLY MODERATE DEEP BULK SHEAR. THUS AGREE WITH SPC MIDDAY DAY  
2 OUTLOOK PULLING THE MARGINAL RISK BACK FARTHER TO THE NORTH AND  
WEST. NONE OF THE THREAT PROBS ARE PARTICULARLY HIGH, BUT HAIL,  
WIND AND TORNADOES ARE ALL STILL ON THE TABLE DEPENDING ON HOW  
MUCH CELLS ORGANIZE DUE TO LIMITED SHEAR. EVEN NON-SUPERCELL  
TORNADOES ARE POSSIBLE CONSIDERING LOW LCLS AND 0-3KM CAPES 100  
J/KG OR MORE.  
 
THE POTENTIAL SHOULD DECREASE INTO THE EVENING WITH THE LOSS OF  
LARGE SCALE FORCING AND HEATING WITH ONLY LOW CHANCES RELEGATED TO  
FAR NORTHEASTERN SECTIONS INTO EARLY SUNDAY MORNING. THIS WILL LEAD  
TO A RELATIVE MIN AND DRY BREAK SUNDAY INTO SUNDAY NIGHT BEFORE THE  
ATTENTION AGAIN TURNS UPSTREAM. UNFORTUNATELY THE EVOLUTION OF THE  
LONG WAVE PATTERN NEXT WEEK IS NOT CLEAR CUT WITH INITIALLY SOME  
TIMING ISSUES WITH THE SURFACE REFLECTIONS INTO TUESDAY, AND THE  
DEGREE OF LONG WAVE PHASING INTO THURSDAY. THERE IS LOW CONFIDENCE  
IN THIS TIME WINDOW WITH INDIVIDUAL GEFS H5 MEMBERS LEANING BOTH  
TOWARD THE OPERATIONAL RUN AND THE ECMWF. AS FAR AS SENSIBLE  
WEATHER, THIS WOULD RESULT IN RELATIVELY HIGHER CONFIDENCE IN  
WEAK WARM ADVECTION CONVECTION CROSSING THE MISSOURI VALLEY SUNDAY  
NIGHT INTO MONDAY. THIS COULD POTENTIALLY CONTINUE INTO TUESDAY AS  
WELL, BUT QUESTIONS ARISE WITH REGARD TO THE PROXIMITY TO THE  
SURFACE TROUGH AND POTENTIAL LOW LEVEL CONVERGENCE DURING  
AFTERNOON PEAK HEATING. THE FASTER ECMWF SOLUTION WOULD BE MORE  
CONDUCIVE WITH THE SLOWER GFS LESS SO AND FAVORING WEAK WARM  
ADVECTION PRECIS LINGERING INTO THE NIGHT WITH A FARTHER WEST  
GENESIS REGION. THE ECMWF WOULD SUGGEST PRECIS EXITING WITH  
MAINLY DRY NORTHWEST FLOW WHILE THE GFS HANGUPS UP A DRIFTING  
UPPER LOW THROUGH THE CENTRAL PLAINS. WOULD TEND TO FAVOR MORE  
PHASED ECMWF SOLUTION AT THIS POINT WITH THE GEFS AND ECMWF  
ENSEMBLES POINTING IN THAT DIRECTION AND ALTHOUGH NEITHER ARE  
GREAT, THE ECMWF HAS SLIGHTLY BETTER RUN TO RUN CONTINUITY AND  
PASSES THE EYE BALL TEST BETTER. THUS HAVE KEEP ONLY SOME SLIGHTS  
GOING INTO THE END OF THE NEXT WORK WEEK LENDING THE GFS JUST A  
LITTLE CREDENCE.  
 

 
   
AVIATION
 
/FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING/  
ISSUED AT 647 PM CDT FRI MAY 27 2016  
 
WIDESPREAD SHRA AND TSRA EXPECTED ACROSS THE REGION TONIGHT...AS AN  
UPPER LEVEL STORM SYSTEM MOVES THROUGH. HAVE GONE MVFR CIGS AND  
VSBYS AT WORST. WINDS WILL BE LIGHT FROM THE SOUTH TO SOUTHEAST  
THROUGH TONIGHT.  
 

 
   
DMX WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
SHORT TERM...SKOW  
LONG TERM...SMALL  
AVIATION...ZOGG  
 
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