MESOSCALE PRECIPITATION DISCUSSION 0357...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EDT THU JUL 16 2015
 
CORRECTED FOR SECOND PARAGRAPH

AREAS AFFECTED...NORTHERN MO, SOUTHERN IA, & NORTHWEST IL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 161800Z - 170000Z
 
SUMMARY...THUNDERSTORMS WITH RAINFALL RATES UP TO 2" AN HOUR ARE
EXPECTED TO FORM OVER AN AREA OF PARTIALLY SATURATED SOILS.  FLASH
FLOODING IS POSSIBLE WHERE CELLS TRAIN.

DISCUSSION...AN EFFECTIVE WARM FRONT IS ADVANCING NORTHWARD IN THE
WAKE OF AN EARLY MORNING MCV AND ITS RELATED CLOUD COVER, WITH THE
BAROCLINIC ZONE ROUGHLY ALIGNED WITH THE 40TH PARALLEL.  UPSTREAM,
AN IMPRESSIVE SHORTWAVE SEEN ON WV IMAGERY IS MOVING EASTWARD
THROUGH SD AND WESTERN NE.  INFLOW AT 850 HPA REMAINS 30 KTS OUT
OF THE WEST-SOUTHWEST -- NEAR THE MAGNITUDE OF THE 850-400 HPA
MEAN FLOW -- WITHIN AN ATMOSPHERE WITH UNIDIRECTIONAL FLOW WITH
HEIGHT.  MLCAPES HAVE REBUILT TO 1500-2500 J/KG ACROSS MO, WHICH
SHOULD CONTINUE TO INCREASE DUE TO DAYTIME HEATING.  PRECIPITABLE
WATER VALUES OF 1.75-2" LURK ACROSS THIS REGION PER GPS
INFORMATION.

THUNDERSTORMS ARE EXPECTED TO DEVELOP SHORTLY AS THE REMAINING CIN
ERODES PER RAP FORECASTS AND SPC MESOANALYSES.  FORWARD
PROPAGATING CONVECTIVE VECTORS INDICATING AN EAST MOVEMENT OF
20-25 KTS APPEAR TO BE TAKING INTO THE ACCOUNT THE NORTHEAST
LIFTING OF THE WARM FRONT AND THE SOUTHEAST TENDENCY CONVECTION
WOULD OTHERWISE HAVE PER THE 1000-500 THICKNESS PATTERN.  CELL
TRAINING IS THE MAIN FLASH FLOOD THREAT, THOUGH A SLIGHT INCREASE
IN THE 850 HPA INFLOW TOWARDS 00Z COULD CAUSE SOME BACKBUILDING
ACROSS NORTHWEST IL TOWARDS 00Z.  BELIEVE THE 12Z ARW HAS THE BEST
IDEA CONCERNING THE AREA OF HIGHEST THREAT.  INCLUDED AREAS
FARTHER WEST NEAR THE MO/IA BORDER DUE TO THE CURRENT POSITION OF
THE THERMAL BOUNDARY AND THEIR SATURATED SOILS CAUSED BY THIS
MORNING'S RAINFALL.  THE AVAILABLE MOISTURE SUPPORTS HOURLY RAIN
RATES UP TO 2".  IN GENERAL, THE MESOSCALE QPF GUIDANCE SHOWS
LOCAL MAXIMA OF 3-4" IN THIS REGION, WHICH CONSIDERING MAXIMUM
HOURLY RAIN RATES COULD FALL QUICKLY AND EXCEED FLASH FLOOD
GUIDANCE VALUES.  THE SCATTERED NATURE OF THE THREAT AND THE MODEL
DISAGREEMENT ARGUED FOR THE SELECTION OF THE POSSIBLE CATEGORY FOR
THIS DISCUSSION.

ROTH

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

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

LAT...LON   42148920 41468865 40628895 40228970 40109103 
            40299331 40409544 40629561 40879498 41359332 
            41859119