MESOSCALE PRECIPITATION DISCUSSION 0447
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1002 PM EDT FRI JUL 13 2018

AREAS AFFECTED...SRN NV...SW UT...FAR NW AZ

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

VALID 140201Z - 140430Z

SUMMARY...SCATTERED THUNDERSTORMS MAY LINGER INTO THE EVENING WITH
THE POTENTIAL FOR LOCALIZED FLASH FLOODING... PARTICULARLY FROM
SOUTHERN LINCOLN COUNTY NEVADA EAST TO NEAR ZION NATIONAL PARK.
RAIN RATES UP TO AROUND 2 IN/HR WILL BE POSSIBLE WITH ANY STRONGER
STORMS THAT CAN BE SUSTAINED FOR AN HOUR OR MORE.

DISCUSSION...RAP MODEL ANALYSIS SHOWS A RIBBON OF SURFACE BASED
CAPE OF AT LEAST 1000 J/KG FROM FAR SRN NEVADA INTO THE
ARIZONA-UTAH BORDER REGION...BUT THAT CINH HAS INCREASED IN THE
PAST SEVERAL HOURS. THIS SHOULD ALLOW CONVECTION TO GRADUALLY
DIMINISH IN COVERAGE AND INTENSITY THIS EVENING... BUT KICX AND
KESX RADARS SHOWED SOME ISOLATED VIGOROUS CONVECTION ONGOING AT
02Z. GIVEN THE AVAILABLE INSTABILITY... THESE STORMS MAY BE ABLE
TO PERSIST FOR ANOTHER COUPLE HOURS. CONVECTION MAY BE MORE
FOCUSED IN FAR SOUTHERN UTAH IN THE VICINITY OF ZION NATIONAL
PARK... WITH UNSTABLE SOUTHWESTERLY INFLOW AROUND 10 KNOTS
(OBSERVED AT KAZC AND KSGU) INTO AN ARC OF SCATTERED STORMS... AND
AN ESTABLISHED COLD POOL TO THE NORTH (TEMPERATURE OF 63 DEGREES
AT KBCE AT 01Z). THIS MAY CREATE A ZONE OF ENHANCED CONVERGENCE IN
THE FAR SOUTHWEST PORTION OF UTAH. THIS REGION OF SW UTAH IS
SUSCEPTIBLE TO FLASH FLOODING WITH NUMEROUS SMALL AND NARROW
BASINS THAT CAN CHANNEL AND FOCUS RUNOFF...SO THIS IS THE AREA
WITH THE GREATEST CHANCE OF FLASH FLOODING OVER THE NEXT SEVERAL
HOURS.

THE STRONGEST INSTABILITY IN THE IMMEDIATE VICINITY EXISTS FROM
NEAR LAS VEGAS SOUTH TOWARD THE MOHAVE VALLEY...AND THERE WILL BE
THE POTENTIAL FOR SLOW-MOVING CONVECTION IN SOUTHERN LINCOLN
COUNTY NEVADA TO BUILD SOUTH INTO THIS AREA OF INSTABILITY...BUT
THE CHANCES OF FLASH FLOODING MAY BE SLIGHTLY LOWER AS COMPARED TO
PARTS OF SW UTAH.

LAMERS

ATTN...WFO...FGZ...SLC...VEF...

ATTN...RFC...CBRFC...CNRFC...

LAT...LON   37731524 37401445 37571385 37571313 37481266
            37411194 36941189 36721327 36181418 36241519
            36691564 37451566