MESOSCALE PRECIPITATION DISCUSSION 0595
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
215 PM EDT TUE AUG 23 2016
 
AREAS AFFECTED...FOUR CORNERS REGION 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 231814Z - 240010Z
 
SUMMARY...A THREAT OF FLASH FLOODING WILL INCREASE THROUGH THE
REMAINDER OF THE AFTERNOON ACROSS THE FOUR CORNERS REGION. SLOW
STORM MOTIONS WILL FAVOR RAINFALL RATES OF 1 TO 1.5 IN/HR WITH
ISOLATED RAINFALL TOTALS OF 3-4 INCHES THROUGH 00Z. 

DISCUSSION...WATER VAPOR IMAGERY SHOWED THE PRESENCE OF A
MID-LEVEL LOW IN N-CNTRL AZ AS OF 18Z WHILE VISIBLE IMAGERY
INDICATED TWO LOWER LEVEL CIRCULATIONS IN CNTRL ARIZONA...SOUTH OF
THE 500 MB LOW. DAYTIME HEATING...ESPECIALLY WHERE VISIBLE IMAGERY
SHOWS BREAKS IN CLOUD COVER...IS ALLOWING WEAK INSTABILITY TO
BUILD ACROSS THE REGION. A FEW THUNDERSTORMS HAVE ALREADY
DEVELOPED ACROSS THE HIGHER TERRAIN OF THE SAN JUANS AND
WASATCH...AND THESE AREAS ARE EXPECTED TO EXPAND OVER THE NEXT FEW
HOURS WITH CONTINUED SURFACE HEATING.

WHILE PRECIPITABLE WATER VALUES ARE ONLY WEAKLY ANOMALOUS ACROSS
THE FOUR CORNERS REGION...MEAN STORM MOTION VECTORS ARE FORECAST
TO BE LESS THAN 10 KTS THROUGH 00Z...ESPECIALLY NORTH OF THE LOW
TRACK. THIS SHOULD FAVOR LOCALLY HEAVY RAINFALL RATES...1-1.5
IN/HR...GIVEN FORECAST MOISTURE/INSTABILITY PROFILES. THE 12Z RAOB
FROM GJT SHOWED SIZABLE CIN REMAINING BETWEEN 700-600 MB WHEN
MODIFYING FOR CURRENT SURFACE/DEWPOINT TEMPERATURES...BUT AS THE
MID-LEVEL LOW CONTINUES TO TRACK NEWD THIS AFTERNOON...ADDED
DIFFLUENCE WILL OVERSPREAD THE REGION AND THE MID-LEVEL WARM LAYER
SHOULD ERODE ALLOWING CONVECTION TO OVERSPREAD LOCATIONS FARTHER
NORTH ACROSS THE CNTRL UT/CO BORDER. GIVEN THE MOISTURE IS ONLY
WEAKLY ANOMALOUS...THE EXTENT OF FLASH FLOODING IS EXPECTED TO BE
ISOLATED TO SCATTERED AT BEST WITH SLOW STORM MOTIONS DRIVING THE
FLASH FLOOD THREAT.

OTTO

ATTN...WFO...ABQ...FGZ...GJT...PUB...SLC...

ATTN...RFC...ABRFC...CBRFC...WGRFC...

LAT...LON   40090748 39990693 39300640 38250621 37260662 
            36770730 36460892 36451047 36551174 36911218 
            37581249 38091235 38731191 39091084 39310997 
            39480943 39740881