MESOSCALE PRECIPITATION DISCUSSION 0112
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1133 PM EDT WED JUN 19 2013
 
AREAS AFFECTED...NORTHEAST MT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 200333Z - 200933Z
 
SUMMARY...CONTINUING CONVECTION WILL PRODUCE  RAINFALL TOTALS WITH
MAXIMA CLOSE TO EXISTING 3 HOUR FLASH FLOOD GUIDANCE OVER
NORTHEAST MT.

GUIDANCE IS IN GOOD AGREEMENT ON A BAND OF SHOWERS/THUNDERSTORMS
MOVING EAST FROM CENTRAL INTO NORTHEAST MT OVER THE NEXT SEVERAL
HOURS. 
STRONGLY DIFLUENT FLOW ALOFT SUPPORTS A WELL DEFINED COUPLET OF
UPPER DIVERGENCE/LOWER CONVERGENCE TO SUPPORT CONTINUING ACTIVITY
OVERNIGHT AS THE BAND SHIFTS EAST ACROSS THE REGION. 

THE AXIS OF MOISTURE WITH HIGHER PRECIPITABLE WATER EXTENDS EAST
OF THE BOUNDARY WITH AN INFLOW 850 MB JET OF 35 KT IN THE 00Z
GLASGOW SOUNDING TO LOCALLY 40 KT IN THE GFS FORECAST. 
STANDARDIZED PRECIPITABLE WATER ANOMALIES OF +1 TO +2 COINCIDE
WITHIN THIS MOISTURE AXIS AND OVERLAP WITH FLASH FLOOD GUIDANCE
VALUES OF 1.0 TO 1.5 IN / 3 HR.

00Z SOUNDINGS AND MODEL FCSTS SHOW DEEP LAYER SFC-6 KM FLOW OUT OF
THE SOUTH TO SOUTH SOUTHEAST...PROMOTING PRIMARILY NORTHERLY
MOVEMENT OF SHOWERS/STORMS.  BRIEF TRAINING OF ECHOES COULD LEAD
TO 1-2 INCHES OF RAIN IN 1-2 HOURS BEFORE THE ACTIVITY ENDS. 
THESE AMOUNTS ARE SHOWN IN THE NSSL WRF/SPC WRF/NCEP WRF ARW AND
WRF NMM QPF. 
 
PETERSEN

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

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

LAT...LON   49320554 48600485 48050473 47540577 47220612 46770666
            46530755 48130864 49140912 49550860 49700694 49320554