Graphic for MPD #0564

MESOSCALE PRECIPITATION DISCUSSION 0564
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
601 PM EDT TUE JUL 25 2017

AREAS AFFECTED...WESTERN CO

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

VALID 252200Z - 260300Z

SUMMARY...SCATTERED CONVECTION DEVELOPING IN A POOL OF MONSOONAL
MOISTURE COULD TRAIN IN A QUASI UNIDIRECTIONAL FLOW THROUGH THE
EVENING HOURS. 

DISCUSSION...REGIONAL RADARS ACROSS EASTERN UT AND CO SHOWED A
GENERAL INCREASE IN RADAR COVERAGE OF CONVECTION FORMING IN THE
EASTERNMOST BAND OF MONSOONAL MOISTURE. THE MOST RECENT RAP
ANALYSIS SHOWED AN AXIS OF 1.50 INCH PRECIPITABLE WATER AIR (WHICH
IS GREATER THAN THREE STANDARD DEVIATIONS ABOVE THE MEAN) ACROSS
FAR EASTERN UT INTO A PORTION OF NORTHWEST CO.

INSTABILITY IS RECOVERING AFTER CLOUDINESS OVER A PORTION OF
WESTERN CO LIMITED INSOLATION...BUT THE MOST RECENT EXPERIMENTAL
GOES-1R VISIBLE IMAGES SHOWED LARGE ENOUGH BREAKS FOR 500-1000
J/KG OF MLCAPE...AND THIS SHOULD BE SUFFICIENT TO ALLOW THE
SCATTERED CONVECTION TO INCREASE IN COVERAGE GOING INTO THE LATE
AFTERNOON. THE KGJX RADAR SHOWED POCKETS OF 0.75 INCH HOURLY
RAINFALL RATES OVER WESTERN CO... WITH A RAWS SITE SHOWING 1.13
INCHES IN AN HOUR RECENTLY WEST OF KGJT.

THE MOST RECENT RAP SUGGESTS THAT MOISTURE AND INSTABILITY REMAIN
AT THEIR CURRENT LEVELS INTO THE EARLY EVENING HOURS. A WEAKLY
DIVERGENT FLOW AT 300 MB SHOULD PROVIDE ENOUGH SYNOPTIC SCALE
ASCENT FOR A GRADUAL INCREASE IN COVERAGE. RAP MODEL SOUNDINGS
ACROSS WESTERN CO SHOWED WET BULB ZERO VALUES APPROACH THE
FREEZING LEVEL AS THE COLUMN MOISTENS...AND COULD ALLOW FOR
GREATER RAINFALL EFFICIENCY IN STORMS THAN IS TYPICAL FOR THIS
AREA.

WHILE THE OVERALL CONVECTIVE COVERAGE COULD LIMIT A GREATER FLASH
FLOOD THREAT...THE MOISTURE SHOULD BE DEEP ENOUGH FOR LOCAL HOURLY
RAINFALL RATES 1.00 TO 1.50 INCH... AND THE QUASI UNIDIRECTIONAL
FLOW SHOULD ALLOW FOR SHORT TERM TRAINING...INCREASING THE FLASH
FLOOD THREAT.

THE LOSS OF DAYTIME HEATING SHOULD ALLOW THE THREAT TO WANE AFTER
0300Z.

HAYES

ATTN...WFO...ABQ...BOU...GJT...PUB...

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

LAT...LON   40790549 38750533 37700557 37410571 37080615
            36940704 37090912 38930981 40650919


Last Updated: 601 PM EDT TUE JUL 25 2017