Graphic for MPD #0501

MESOSCALE PRECIPITATION DISCUSSION 0501...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
901 PM EDT MON JUL 17 2017

CORRECTED FOR TYPO IN SUMMARY SECTION

AREAS AFFECTED...NWRN AZ INTO SRN NV

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 180054Z - 180530Z

SUMMARY...FLASH FLOODING REMAINS LIKELY IN THE NEAR TERM OVER NWRN
AZ PERHAPS EXTENDING INTO FAR SWRN NV AND NERN CA...BUT GRADUAL
WEAKENING IS ANTICIPATED THROUGH 04-05Z.

DISCUSSION...KESX RADAR SHOWED NUMEROUS SMALL CORES OF HEAVY RAIN
ONGOING OVER WRN COCONINO INTO ERN MOHAVE COUNTY AT 0030Z WITH
ESTIMATED RAINFALL RATES OF 1-2 IN/HR. ADJUSTMENTS FOR INCREASED
SURFACE TEMPERATURES TO THE SSE OF LAS VEGAS ON THE 00Z RAOB
INDICATE 2000 J/KG OF CAPE IS PRESENT JUST WEST OF THE ONGOING
THUNDERSTORM ACTIVITY...HIGHER THAN WHAT IS SEEN IN THE RAP AND
HRRR. PRECIPITABLE WATER VALUES VARY QUITE A BIT BUT RANGE FROM
1.1 TO 1.7 INCHES PER A COMBINATION OF GPS SITES...EXPERIMENTAL
GOES TPW AND THE 00Z RAOB FROM VEF. 00Z UPPER AIR PLOTS SHOW THE
CONVECTION IS OCCURRING DIRECTLY BENEATH A MID-UPPER LEVEL RIDGE
WHICH PUTS INTO QUESTION THE ABILITY FOR CONVECTION TO SUSTAIN
ITSELF THROUGH THE NIGHT...HOWEVER GOES 15 INFRARED IMAGERY CLOUD
TOPS OF -60 TO -70C COVER A SIZABLE PORTION OF NWRN AZ.

WHILE RECENT RUNS OF THE HRRR AND EXPERIMENTAL HRRR INITIALIZE THE
ONGOING AREA OF CONVECTION WELL...THEY APPEAR TO BE WEAKENING THE
CONVECTION TOO SOON...PERHAPS DUE TO UNDERFORECASTING INSTABILITY
OR OVERFORECASTING CIN. HOWEVER...GIVEN A LACK OF BETTER KINEMATIC
SUPPORT...IT IS EXPECTED THAT THE CONVECTION WILL BEGIN TO WEAKEN
AND PERHAPS DISSIPATE BY ABOUT 04Z OR 05Z. SHORT TERM TRENDS
SUPPORT CONTINUED FLASH FLOODING FOR THE NEXT 1-2 HOURS AT
LEAST...WITH SOME UNCERTAINTY BEYOND THAT TIME FRAME. TRENDS WILL
CONTINUE TO BE WATCHED.

OTTO

ATTN...WFO...FGZ...PSR...VEF...

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

LAT...LON   36741393 36471342 35771282 34871261 33981307
            33831380 33841409 34241457 35011498 35831510
            36571469


Last Updated: 901 PM EDT MON JUL 17 2017