MESOSCALE PRECIPITATION DISCUSSION 0084
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
439 PM EDT SAT MAY 31 2014
 
AREAS AFFECTED...NORTHEAST MT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 312039Z - 010024Z
 
SUMMARY...THUNDERSTORMS ARE INCREASING IN COVERAGE AND INTENSITY
OVER AN AREA WITH LOW FLASH FLOOD GUIDANCE.  REGIONAL FLASH
FLOODING IS CONSIDERED POSSIBLE OVER THE NEXT FEW HOURS.

DISCUSSION...SATELLITE AND RADAR IMAGERY SHOW A RECENT UPWARD
SPIKE IN INTENSITY/COVERAGE OF THUNDERSTORMS ACROSS NORTHEAST MT,
WHICH ARE FOCUSING NEAR AND AHEAD OF A TROWAL.  CONVECTION RIGHT
NEAR THE MT/ SASKATCHEWAN BORDER APPEARS TO BE SHOWING SOME
BACKBUILDING CHARACTERISTICS TOWARDS A SURFACE CONVERGENCE ZONE AS
THE LOW-LEVEL FLOW AT 850 AND 700 HPA IS INCREASING AHEAD OF AN
UPPER-LEVEL LOW.  PRECIPITABLE WATER VALUES ARE APPROACHING 1.25",
THE 99TH PERCENTILE FOR THE END OF MAY.  CAPES ARE 1000-2000 J/KG
IN THE AREA AND 0-3 KM SHEAR IS 30-40 KNOTS, WHICH MEET THE
THRESHOLD FOR THE WET MULTI-CELL ENVIRONMENT.

CELL TRAINING AND POTENTIAL BACK BUILDING CELLS COULD CAUSE LOCAL
AMOUNTS OF 2-3", PER MOST OF THE RECENT MESOSCALE GUIDANCE. 
HOURLY RAINFALL RATES OF 1-1.5" ARE EXPECTED IN STRONGER STORMS,
WHICH COULD EXCEED THE LOW FLASH FLOOD GUIDANCE IN THE REGION. 
REGIONAL FLASH FLOODING IS CONSIDERED POSSIBLE.

ROTH

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

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

LAT...LON   46670697 47950829 48841005 49140951 49140742 48980503
            47400573 46670697