MESOSCALE PRECIPITATION DISCUSSION 0629
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
351 PM EDT SAT AUG 05 2017

AREAS AFFECTED...NORTHERN/EASTERN AZ...WESTERN NM

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

VALID 051950Z - 060100Z

SUMMARY...MONSOONAL SHOWERS AND THUNDERSTORMS ARE BEGINNING TO
DEVELOP AND WILL EXPAND A BIT IN COVERAGE THROUGH THE AFTERNOON
HOURS. SOME FLASH FLOODING IS POSSIBLE AND ESPECIALLY NEAR THE
MOGOLLON RIM.

DISCUSSION...THE LATEST NON-OPERATIONAL GOES-16 6.9/7.3 MICRON/WV
BANDS SHOW AN ELONGATED CHANNEL OF SHORTWAVE ENERGY STRETCHING
FROM FAR NORTHERN AZ AND SOUTHERN UT EAST-SOUTHEAST DOWN ACROSS A
LARGE AREA OF CENTRAL/NORTHERN NM. EMBEDDED WITHIN THIS AXIS OF
WEAK MID LEVEL TROUGHING/ENERGY IS AN MCV WHICH IS SHOWING UP IN
VISIBLE SATELLITE IMAGERY OVER NORTHWEST AZ. THIS HAS ALREADY
BEGUN TO HELP CONCENTRATE AN AREA OF CONVECTION OVER PARTS OF
COCONINO COUNTY.

CONVECTIVE INITIATION IS UNDERWAY FARTHER OFF TO THE EAST OVER
ADJACENT AREAS OF NORTHERN AND EASTERN AZ AND INTO WESTERN NM WITH
THE AID OF WEAKLY CYCLONIC FLOW...STRONG DIURNAL HEATING AND AT
LEAST A MODERATELY MOIST ENVIRONMENT.

PWATS OVER NORTHWEST AZ ARE NEAR 1.5 INCHES WHICH ARE ABOUT 1 TO 2
SIGMAS ABOVE NORMAL...BUT THEN TAPER DOWN CLOSER TO 1 INCH FARTHER
EAST OVER EASTERN AZ AND WESTERN NM WHICH IS CLOSER TO NORMAL.
THESE PWATS WILL NOT RESULT IN THE MOST EFFICIENT OF RAINFALL
PROCESSES SINCE THE 12Z MORNING RAOB DATA AND CIRA-LPW PLOTS ARE
ALSO SHOWING A DRYING TREND IN THE 500/300 MB LAYER. HOWEVER...THE
AVAILABLE INSTABILITY AND MOIST MID LEVELS WILL TEND TO STILL
FAVOR RAINFALL RATES CAPABLE OF REACHING 1.5 INCHES/HR WITHIN THE
STRONGER CONVECTIVE CORES AS CONVECTION GRADUALLY EXPANDS IN
COVERAGE THROUGH THE AFTERNOON.

THE LATEST HRRR GUIDANCE AT LEAST THROUGH 00Z IS FAVORING THE MOST
ORGANIZED CONVECTION TO BE OVER NORTHERN AZ WHERE THE LATEST
HRRR/HRRRX GUIDANCE SUPPORT SOME RAINFALL AMOUNTS PERHAPS AS HIGH
AS 2 TO 2.5 INCHES. THE GREATEST THREAT WILL BE GENERALLY NEAR AND
NORTH OF THE MOGOLLON RIM AREA...AND THESE AMOUNTS MAY BE ENOUGH
TO CAUSE SOME ADDITIONAL FLASH FLOODING. ELSEWHERE OVER EASTERN AZ
AND WESTERN NM...THE CONVECTION WILL TEND TO BE MORE
SCATTERED...BUT WITH SLOW CELL MOTION AND LOCAL OROGRAPHICS...SOME
1.5 TO 2 INCH AMOUNTS CANNOT BE RULED OUT...WITH SOME RESULTING
RUNOFF PROBLEMS AGAIN POSSIBLE.

ORRISON

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...VEF...

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

LAT...LON   36971337 36971164 36900895 36260749 35000665
            33930656 33120692 32820736 32850797 33200882
            33771029 34201152 34721323 35591414 36521410