MESOSCALE PRECIPITATION DISCUSSION 0189
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1145 PM EDT FRI JUL 11 2014
 
AREAS AFFECTED...NORTHEAST CO, SOUTHEAST SD, CENTRAL NE, CENTRAL
IA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 120345Z - 120945Z
 
SUMMARY...A CONVECTIVE BAND FORMING BETWEEN NORTHEAST CO AND
NORTHEAST NE SHOULD EXTEND INTO IA WITH TIME.  HOURLY RAIN RATES
OF 2.5" COULD LEAD TO FLASH FLOODING WHERE CELLS BACKBUILD AND/OR
TRAIN.

DISCUSSION...A BROAD AREA OF 30-40 KTS OF INFLOW AT 850 HPA --
JUST EXCEEDING THE MEAN 850-400 HPA WIND -- IS OVERRIDING A
STATIONARY FRONT DUE TO SOME LOW- TO MID-LEVEL CAPPING,
REPRESENTED BY 12C+ AIR AT 700 HPA ACROSS SOUTHERN NE AND
ADVERTISED CIN FROM THE 12Z ARW.  THE LOW-LEVEL INFLOW IS FORMING
A CONVECTIVE BAND DIAGONALLY ACROSS NE, CLOSE TO THE FRONT'S
INTERSECTION WITH THE 850 HPA PRESSURE SURFACE.  PRECIPITABLE
WATER VALUES IN THE REGION ARE AROUND TWO INCHES, NEAR THE 99TH
PERCENTILE FOR NE IN MID-JULY.  CAPE VALUES IN THE WARM SECTOR ARE
2000-4000 J/KG, AT THE HIGH END FOR THE WET MULTI-CELL
ENVIRONMENT.  THE GOODLAND KS WFO PASSED ALONG A SPOTTER REPORT
FROM 15 MILES SOUTHWEST OF LIBERTY CO WHERE 2.49" WAS MEASURED IN
ONE HOUR RECENTLY, WHICH IS INDICATIVE OF THE PRECIPITATION
EFFICIENCY POSSIBLE IN THIS REGION.

INFLOW AT 850 HPA IS EXPECTED TO BROADEN, WITH 25+ KTS OVERRIDING
THE FRONTAL SURFACE AS FAR EAST AS NORTHEAST MO, WHICH COULD ALLOW
THE BAND TO EXTEND INTO IL WITH TIME.  THE 18Z WRF NSSL IS
CONSIDERED THE CLOSEST MATCH TO THE EXPECTED PRECIPITATION PATTERN
OVER THE NEXT SEVERAL HOURS.  FOR NOW, WILL EXTEND THE THREAT AREA
INTO EASTERN IA, AND IF CONVECTION EXTENDS FARTHER EASTWARD, AN
UPDATED MPD CAN BE SENT.  AS THE BAND INITIALLY FORMS, A FOUR-HOUR
PERIOD OF BACKBUILDING COULD ALLOW FOR LOCALLY HEAVY RAINS AND
FLASH FLOODING -- THE EXPECTATION IS FOR HOURLY RAIN RATES UP TO
2.5" AND A QUICK 3-5" LOCALLY.  DRY AIR NEAR 850 HPA IN THE OAX
AND DVN SOUNDINGS IMPLY THAT FORWARD PROPAGATION IS POSSIBLE,
WHICH IF IT OCCURS, COULD CHANGE THE SITUATION FROM A BACKBUILDING
TO A TRAINING THREAT.  EITHER WAY, SEVERAL OCCURRENCES OF FLASH
FLOODING COULD OCCUR WITHIN AND NEAR THE DEFINED AREA.

ROTH

ATTN...WFO...DVN...ARX...DMX...FSD...OAX...GID...LBF...UNR...
GLD...BOU...

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

LAT...LON   41449123 41669287 41889681 40920008 39930192 40580255
            41310180 41700155 42700136 43170094 43219967 43229680
            42979266 42409119 41449123