MESOSCALE PRECIPITATION DISCUSSION 0127...CORRECTION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1235 AM EDT TUE JUN 25 2013
 
AREAS AFFECTED...NORTHEAST MT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 250431Z - 250731Z
 
SUMMARY...A PROGRESSIVE LINE OF THUNDERSTORMS WITH HEAVY RAINFALL
COULD LEAD TO FLASH FLOODING AS IT MOVES ACROSS NORTHEAST MT OVER
THE NEXT FEW HOURS.

DISCUSSION...A LINE OF THUNDERSTORMS IS ORGANIZING AHEAD OF A
NEGATIVELY-TILTED UPPER LEVEL TROUGH ACROSS NORTHEAST MT.  VAD
WIND PROFILES SHOW 30 KNOTS OF LOW-LEVEL INFLOW INTO THE REGION
AND PRECIPITABLE WATER VALUES BETWEEN 1.25-1.50 INCHES, WHICH IS
NEAR THE 99TH PERCENTILE FOR JUNE.  SATELLITE-DERIVED CAPE VALUES
ARE IN THE 3000-5000 J/KG RANGE.  THE 03Z RAP RUN IN COMBINATION
WITH 04Z SURFACE OBSERVATIONS INDICATE THAT THE THUNDERSTORMS ARE
CONCENTRATED ALONG A LOW-LEVEL BOUNDARY -- OR TROWAL -- WHICH IS
EXPECTED TO MOVE EASTWARD ACROSS EASTERN MT OVER THE NEXT FEW
HOURS NORTH OF A SYNOPTIC-SCALE CYCLONE.  THE BEST LOW-LEVEL
INFLOW FEEDING INTO THE LINE IS EXPECTED TO LIFT UP INTO
SASKATCHEWAN IN A FEW HOURS.  FLASH FLOOD GUIDANCE IS QUITE LOW
ACROSS THE REGION -- ONE INCH IN THREE HOURS -- SO BELIEVE THERE
IS A THREAT FOR FLASH FLOODING OVER THE NEXT FEW HOURS.  LOCAL
RAINFALL AMOUNTS OF 1-2 INCHES ACROSS THE REGION COULD CAUSE FLASH
FLOODING.

ROTH

ATTN...WFO...BYZ...GGW...TFX...

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

LAT...LON   47790831 48890846 49170798 49210641 49050491 48080464
            46920491 46750691 46940811 47790831