MESOSCALE PRECIPITATION DISCUSSION 0320
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
207 PM EDT MON JUN 18 2018

AREAS AFFECTED...NORTH CENTRAL WYOMING AND CENTRAL MONTANA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 181807Z - 190007Z

SUMMARY...SHOWERS AND THUNDERSTORMS WILL CONTINUE TO INCREASE IN
COVERAGE THIS AFTERNOON OVER CENTRAL MONTANA AND NORTH CENTRAL
WYOMING.  PERIODS OF TRAINING CONVECTION COULD LEAD TO INSTANCES
OF FLASH FLOODING WHERE RATES COULD EXCEED AN INCH PER HOUR.

DISCUSSION...A NEARLY STATIONARY CLOSED DEEP LAYERED LOW OVER
SOUTHERN IDAHO IS RESULTING IN ENHANCED MID-UPPER LEVEL DIVERGENCE
OVER THE FRONT RANGE OF THE NORTHERN ROCKIES.  AN AXIS OF LOW
LEVEL MOISTURE IS BEING ADVECTING INTO THE REGION BY 30 KNOTS OF
ESE 850MB FLOW, AND OROGRAPHIC FORCING IS FURTHER AIDING WITH
ASCENT OVER THIS AREA.  INCREASING DESTABILIZATION OVER CENTRAL
WYOMING IS RESULTING IN SURFACE BASED CAPE NEARING 1000 J/KG PER
SPC MESOANALYSIS, AND THIS IS RESULTING IN ADDITIONAL CONVECTION
JUST SOUTH OF THE MPD AREA AND WILL PIVOT NORTHWARD FOR ADDITIONAL
ROUNDS OF HEAVY RAIN.

RECENT HIGH RES GUIDANCE IS INDICATING THE POTENTIAL FOR LOCAL 1
TO 2 INCH RAINFALL AMOUNTS THROUGH THE AFTERNOON, WITH SOME OF
THIS FALLING OVER A SHORT PERIOD OF TIME GIVEN PWS APPROACHING
1.25 INCHES PER LATEST RAP ANALYSIS.  WITH ALREADY REDUCED FLASH
FLOOD GUIDANCE OVER PARTS OF THIS REGION, LOCALIZED INSTANCES OF
FLASH FLOODING ARE POSSIBLE.

D. HAMRICK

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

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

LAT...LON   47920975 47700848 46800760 45660692 44560655
            43940668 43520721 43490818 43870897 44600981
            45841065 46861104 47661066