Graphic for MPD #0488

MESOSCALE PRECIPITATION DISCUSSION 0488...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
450 PM EDT THU JUL 13 2017

CORRECTED FOR SECOND PARAGRAPH

AREAS AFFECTED...SOUTHWEST NM & SOUTHEAST AZ

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

VALID 132046Z - 140246Z

SUMMARY...THUNDERSTORMS ARE EXPANDING IN COVERAGE ACROSS SOUTHWEST
NM AND MOVING SOUTHWEST.  HOURLY RAIN RATES UP TO 1.5" WITH LOCAL
AMOUNTS TO 3" APPEAR POSSIBLE.

DISCUSSION...THUNDERSTORMS ALONG A TROUGH IN THE 850/700 HPA LAYER
NEAR AND NORTH OF THE GILA REGION OF SOUTHWEST NM ARE EXPANDING IN
COVERAGE PER RADAR AND SATELLITE IMAGERY.  DIVERGENCE ALOFT IS
BEING AIDED BY TWO MID- TO UPPER-LEVEL LOWS -- ONE NEAR THE FOUR
CORNERS AND THE OTHER OVER NORTHEAST MEXICO.  PRECIPITABLE WATER
VALUES IN THE AREA ARE 1-1.5" PER EARLY MORNING GPS VALUES AND RAP
ANALYSES.  EFFECTIVE BULK SHEAR IS ROUGHLY 15 KTS.  THEIR
SOUTHWEST MIGRATION IS OCCURING ON THE WEST SIDE OF THE LOW LEVEL
"EASTERLY WAVE".  THE CIN ACROSS SOUTHERN AZ IS SLOWLY ERODING. 
ML CAPE VALUES IN SOUTHERN AZ ARE 500-2000 J/KG.

THE MESOSCALE GUIDANCE APPEARS TO BE STRUGGLING WITH THIS
ACTIVITY, WITH RECENT HRRR RUNS, THE 12Z NAM CONEST, AND THE 12Z
WRF NSSL HAVING THE BEST IDEA CONCERNING FUTURE CONVECTIVE
DEVELOPMENT.  ACTIVITY SHOULD CONTINUE MOVING SLOWLY SOUTHWEST
WITH TIME, URGED IN THAT DIRECTION BY THE WESTWARD MOVING
LOW-LEVEL BOUNDARY AND THE MEAN FLOW TO ITS WEST.  THE 850 HPA
FLOW ACROSS SOUTHERN AZ (WESTERLY) SHOULD BE ABLE TO LURE
INSTABILITY INTO SOUTHEAST AZ FROM THE WEST.  THE 12Z SSEO
NEIGHBORHOOD PROBABILITIES AND 12Z GFS-BASED GDI SHOW/IMPLY
INCREASING CELL COVERAGE WITH TIME, PEAKING AT OR JUST BEYOND 00Z
IN SOUTHEAST AZ.  HOURLY RAIN RATES UP TO 1.5", WITH LOCAL AMOUNTS
TO 3", ARE POSSIBLE.

ROTH

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

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

LAT...LON   34450757 32620783 31470808 31280819 31270906
            31251057 31291112 31621179 32681135 34190914
           


Last Updated: 450 PM EDT THU JUL 13 2017