Graphic for MPD #0718

MESOSCALE PRECIPITATION DISCUSSION 0718
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
900 PM EDT WED AUG 23 2017

AREAS AFFECTED...SOUTHERN AZ INTO WESTERN AND CENTRAL NM

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

VALID 240100Z - 240600Z

SUMMARY...SLOW CELL MOTIONS AND CELL MERGERS OVER AREAS THAT
RECEIVED HEAVY RAINFALL EARLIER WILL FOSTER A FLASH FLOOD THREAT
THROUGH THE LATE EVENING HOURS.

DISCUSSION...THE EXPERIMENTAL GOES-16 CLEAN IR LOOP SHOWED THAT
TOPS WERE STILL COOLING ACROSS SOUTHERN AZ/NM EARLY THIS
EVENING... AS CONVECTION CONTINUES TO FIRE IN THESE AREAS. THE
CONVECTION IS FEEDING ON 1000-1500 J/KG OF OF MLCAPE (SUPPORTED BY
1500 J/KG OF SBCAPE ON THE 00Z EPZ SOUNDING)...THOUGH PORTIONS OF
FAR SOUTHEAST AZ AND FAR SOUTHWEST NM HAVE ACQUIRED SOME CIN AS
THE AIRMASS IN THESE LOCATIONS HAS BEEN OVERTURNED BY EARLIER
CONVECTION.

THE BEST MOISTURE IS ALIGNED IN AN AXIS OVER SOUTHERN AZ IN A
MODIFIED MONSOONAL FLOW...BUT THE 00Z EPZ SOUNDINGS INDICATED 1.25
INCH PRECIPITABLE WATER AIR REMAINING IN PLACE ACROSS SOUTHERNMOST
NM. THE RADARS IN KEMX AND KEPZ SHOWED HOURLY RAINFALL RATES IN
EXCESS OF 1.50 INCHES IN THIS AIRMASS. DRY AIR IN THE MID LEVELS
COULD SUPPORT HAIL...SO THESE AMOUNTS COULD BE HAIL CONTAMINATED.

BASED ON RADAR TRENDS...IT HAS BECOME CLEAR THAT THE BEST
CONVECTION WILL BE ASSOCIATED WITH THE MCV TRACKING NORTH ACROSS
SOUTH CENTRAL AZ...WHERE THE ADDED ASCENT SHOULD RESULT IN
ORGANIZATION. FURTHER EAST OVER SOUTHEAST AZ INTO SOUTHERN
NM...THE CONVECTION IS NOT AS ROBUST...BUT OUTFLOW BOUNDARIES FROM
EXISTING CONVECTION ARE ACTING TO SUPPORT FURTHER CONVECTIVE
DEVELOPMENT.  THE SLOW CELL MOTIONS ALONG THE OUTFLOW BOUNDARIES
COULD PROMOTE FLASH FLOODING...SO SOUTHEAST AZ AND SOUTHERN NM
WILL CONTINUE WITH A FLASH FLOOD THREAT... ALBEIT NOT AS ROBUST AS
PORTIONS OF SOUTH CENTRAL AZ.

THE LOSS OF HEATING SHOULD ALLOW THE CONVECTION TO WEAKEN BEFORE
06Z...BUT OUTFLOW DRIVEN CONVECTION COULD CONTINUE THE THREAT INTO
THE LATE EVENING HOURS.

HAYES

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

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

LAT...LON   35120567 35090447 34270420 32480540 31580678
            31361152 32091248 32871257 33281200 33341077
            34130889 34730725


Last Updated: 904 PM EDT WED AUG 23 2017