MESOSCALE PRECIPITATION DISCUSSION 0064
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
134 AM EDT SUN MAY 26 2013
 
AREAS AFFECTED...EXTREME SOUTHERN ND...EASTERN SD...SOUTHWEST
MN...NORTHWEST IA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 260533Z - 260933Z
 
SUMMARY...A GRADUAL INCREASE IN REPEATING AND LOCALLY TRAINING
CONVECTIVE CELLS IS EXPECTED OVERNIGHT...WHICH WILL DRIVE AN
ELEVATED FLASH FLOOD THREAT.

DISCUSSION...LATEST IR/WV IMAGERY SHOWS A BKN MCS MOVING ACROSS
SOUTHERN ND AND NRN SD. THERE IS SOME SUGGESTION ESP IN RADAR
IMGERY OF A WEAK MCV IN FAR NRN SD WHICH IS MOVING ESE ATTM.
MEANWHILE...THERE IS A GROWING AND SLOWLY ORGANIZING AXIS OF HVY
SHOWERS AND THUNDERSTORMS IN A NW/SE ORIENTED FASHION INVOLVING
SERN SD AND STRETCHING DOWN IN NWRN IA. THIS ACTIVITY IS ASSOCD
WITH THE NOSE OF A 30 TO 40 KT SRLY LOW LEVEL JET BASED ON THE
LATEST RAP ANALYSIS OVERRUNING A WARM FRONT. THE LATEST 00Z GLOBAL
MODEL GUIDANCE SUPPORTS SOME INCREASE IN THIS LOW LEVEL JET
BETWEEN 06Z AND 12Z. THEREFORE...WILL BE EXPECTING SOME ADDITIONAL
INCREASE IN ISENTROPIC LIFT THAT WILL BE SUFFICIENT TO SUSTAIN THE
CURRENT ACTIVITY AND FAVOR AN AXIS OF REPEATING CONVECTION FOR THE
NEXT SEVERAL HOURS. THIS ACTIVITY MAY BE ENHANCED DYNAMICALLY BY
THE AFOREMENTIONED WEAK MCV OVER NRN SD. GIVEN AN AXIS OF 1.2 TO
1.4 INCH PWATS OVER THE REGION...WHICH IS LOCALLY UP TO 2 STD DEV
ABOVE NORMAL...HVY RAINFALL RATES WILL BE EXPECTED. THE REPEAT
NATURE OF THE ACTIVITY ALONG WITH SOME TRAINING WILL FAVOR THE
POTENTIAL FOR SEVERAL INCHES OF RAIN THE NEXT FEW HOURS...AND THIS
WILL SUPPORT AN ELEVATED FLASH FLOOD THREAT. WILL CONTINUE TO
MONITOR.

ORRISON


ATTN...WFO...MPX...DMX...FSD...ABR...BIS...

LAT...LON   45709744 44989628 44239548 43369472 42689475 42399528
            42569644 43119751 43899853 44339959 44670001 45090010
            45720075 46410005 46089838 45709744