MESOSCALE PRECIPITATION DISCUSSION 0316
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
851 PM EDT SUN JUN 17 2018

AREAS AFFECTED...WESTERN WY...EASTERN ID...EXTREME NORTHERN UT

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

VALID 180050Z - 180530Z

SUMMARY...STRONG DYNAMIC FORCING WITH POTENTIAL FOR
REPEAT/TRAINING STORMS MAY POSE HIGHLY LOCALIZED FLASH FLOODING
RISK THROUGH THIS EVENING.

DISCUSSION...DEEP LAYERED CLOSED LOW OVER NW NV CONTINUED TO EASE
TOWARDS THE SOUTHEAST LATE THIS AFTERNOON/EARLY EVENING WITH
MID-LEVEL DEFORMATION EXTENDING NORTHEAST.  THE UPPER FLOW REMAINS
VERY DIFLUENT BASED ON MID/UPPER LEVEL WATER VAPOR IMAGERY.  AS
THAT WAS OCCURRING...THE 300 MB JET WAS ALREADY REDUCING IN SPEED
OVER THE AREA OF CONCERN WITH UNDERCUTTING JET THROUGH THE GREAT
BASIN ALLOWING FOR STRONG RIGHT EXIT DYNAMICS TO INCREASE
DIVERGENCE AND SPIN UP VORTICITY CENTER SOUTH OF THE AREA OF
DISCUSSION.  THIS WILL PROVIDE VERY STRONG DYNAMIC ASCENT ALOFT
WITH THE DIVERGENCE AND DPVA AND ALLOW FOR INCREASED EASTERLY LOW
LEVEL FLOW.  THIS...IN TURN...LEADS TO MODEST LOW LEVEL MOISTURE
ADVECTION AS SHOWN BY MID 40 TO LOWER 50 DEGREE DEWPOINTS NOW IN
PLACE.  AFTERNOON INSOLATION HAS ALLOWED FOR INCREASED SURFACE
TEMPS TO SUPPORT AREAS OF MUCAPE IN THE 750 TO 1000 J PER KG CAPE
INTO THE EVENING.  AS THE EVENING PROGRESSES...CAPES SHOULD DROP
IN RESPONSE TO THE LACK OF INSOLATION.

RAIN RATES INITIALLY AROUND .5-.75"/HR RATES LATE THIS AFTERNOON
WILL INCH UP TOWARDS SOME RATES OF 1 INCH PER HOUR AS LOCAL
MID-LEVEL PROFILES MOISTEN WITH INITIAL DOWNDRAFTS/CELL
EVAPORATION.  

GENERALLY UNIDIRECTIONAL CLOUD BEARING FLOW CONTINUED TO SUPPORT A
TRAINING PROFILE BUT WITH SOME PROPAGATION VECTORS TOWARD THE
INFLOW EAST...IDEAL TRAINING MAY BE A BIT LIMITED.  HOWEVER...THE
STRENGTH OF UPSTREAM DYNAMICS...REPEAT DEVELOPMENT IS LIKELY. 

HI-RES CAMS SUGGEST MAX TOTALS SCATTERED THROUGH THE AREA OF
CONCERN OF 1.5-2" OVER A 2-3 HOUR TIME PERIOD.  AS SUCH HIGHLY
LOCALIZED FLASH FLOODING IS POSSIBLE GIVEN LOW FFG VALUES IN THE
REGION ESPECIALLY IN AND NEAR THE COMPLEX TERRAIN IN AND NEAR THE
TETON/JACKSON RANGES. 

BANN

ATTN...WFO...PIH...RIW...SLC...TFX...

ATTN...RFC...CBRFC...MBRFC...NWRFC...

LAT...LON   44800914 43190884 42440885 41290953 40691084
            40971147 41531168 42851199 43911301 44571229
            44641097