MESOSCALE PRECIPITATION DISCUSSION 0392
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
404 PM EDT MON JUL 27 2015
 
AREAS AFFECTED...SOUTHERN IA, NORTHERN MO, & WESTERN IL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 272004Z - 280104Z
 
SUMMARY...CONVECTION IS FORMING ALONG THE DIRECTION OF ITS
EXPECTED PROPAGATION IN SOUTHERN IA.  FLASH FLOODING IS POSSIBLE.

DISCUSSION...MORNING THUNDERSTORM ACTIVITY HAS REINFORCED A
STATIONARY FRONT LOCATED NEAR THE MO/IA BORDER, SETTING UP A NEAR
20F TEMPERATURE GRADIENT.  SOUTHWEST FLOW AT 850 HPA OF 15 KTS --
SLIGHTLY EXCEEDING THE 850-400 HPA MEAN WIND -- IS ADVECTING
MLCAPES OF 3000-4000 J/KG INTO THE REGION.  SOILS HAVE BEEN
SATURATED BY DAYS OF THUNDERSTORM ACTIVITY, WHICH HAS LOWERED
FLASH FLOOD GUIDANCE VALUES.

THE GUIDANCE BEST HANDLING THIS ACTIVITY CURRENTLY IS THE 17Z
EXPERIMENTAL HRRR, WHICH SHOWS LOCAL AMOUNTS IN THE 3-4" RANGE --
THE 18Z HRRR AND 12Z ARW SOMEWHAT SHOWING THIS ACTIVITY.  HOURLY
RAIN RATES UP TO 2.5" ARE SUPPORTED BY THE AVAILABLE MOISTURE, SO
THE RAINFALL COULD FALL QUICKLY.  STORM MOTION SHOULD BECOME MORE
TOWARDS THE EAST-SOUTHEAST AT 20 KTS, ALONG THE LINES OF THE
FORWARD PROPAGATING CONVECTIVE VECTORS, AS A COMBINATION OF
DIRECTIONAL WIND SHEAR WITH HEIGHT AND THE SIGNIFICANT INSTABILITY
SHOULD URGE CONVECTION ALONG.  NEW ACTIVITY COULD FORM IN THE
WESTERN FRINGE OF THIS AREA AFTER 22Z AS 850 HPA INFLOW INCREASES
OUT OF THE SOUTH.  CELL TRAINING IS THE MAIN FLASH FLOOD CONCERN. 
CONSIDERING RECENT RAINS, FLASH FLOODING IS POSSIBLE.

ROTH

ATTN...WFO...DMX...DVN...EAX...ILX...LSX...OAX...

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   41479456 41369197 40349038 39349086 39429290 
            40759587