MESOSCALE PRECIPITATION DISCUSSION 0843
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
341 AM EDT SAT SEP 30 2017

AREAS AFFECTED...SWRN TO CNTRL NM

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

VALID 300739Z - 301300Z

SUMMARY...A FLASH FLOOD THREAT WILL LINGER THROUGH THE REMAINDER
OF THE MORNING FROM SWRN TO CNTRL NEW MEXICO. RAINFALL RATES OF
1-1.5 IN/HR WITH PERIODS OF TRAINING ARE EXPECTED TO LEAD TO
LOCALIZED 2-3 INCH RAINFALL TOTALS THROUGH 13Z.

DISCUSSION...WATER VAPOR IMAGERY THROUGH 07Z SHOWED A WEAKENING
VORTICITY MAX OVER SERN ARIZONA APPROACHING NEW MEXICO. LOCAL
RADAR AND NON-OPERATIONAL GOES 16 INFRARED SATELLITE IMAGERY
SHOWED THE RECENT DEVELOPMENT OF THUNDERSTORMS OVER GRANT AND SRN
CATRON COUNTIES OUT AHEAD OF THE WEAKENING VORTICITY MAX AND
WITHIN AN ENVIRONMENT OF 500-1000 J/KG MUCAPE PER THE LATEST SPC
MESOANALYSIS. THESE CELLS HAD A GENERAL MOVEMENT TOWARD THE
NORTHEAST BUT SOME REPEATING CELLS FROM THE SOUTHWEST HAVE LED TO
RADAR ESTIMATED RAINFALL RATES APPROACHING 2 IN/HR IN CNTRL GRANT
COUNTY. DESPITE SOME POSSIBLE HAIL CONTAMINATION OF THESE
RATES...LOCALLY HEAVY RAINFALL WAS OCCURRING NEAR SILVER CITY AS
OF 07Z. TRENDS IN PRECIPITABLE WATER VALUES PER GPS SITE DATA WERE
UP NEAR THE SRN ARIZONA/NEW MEXICO BORDER WITH A 0.2 TO 0.3 INCH
RISE SINCE 00Z...WITH VALUES RANGING FROM 0.75 TO 1.25 INCHES
BETWEEN EL PASO AND THE GALLINA MOUNTAINS.

LOCALLY ENHANCED 700 MB FLOW OF 20-30 KT ALONG WITH LOW LEVEL
CONVERGENCE...PER RECENT RAP ANALYSIS FIELDS...SHOULD HELP TO
CONTINUE THE DEVELOPMENT OF NOCTURNAL CONVECTION OVER SWRN NEW
MEXICO OVER THE NEXT SEVERAL HOURS HOURS. THE RAP HAS ALSO HAD
GOOD RUN TO RUN CONSISTENCY WITH THE DEVELOPMENT OF AN 80 KT UPPER
LEVEL JET STREAK DEVELOPING FROM NRN NEW MEXICO INTO ERN COLORADO
BETWEEN 09Z-12Z...PLACING CNTRL NEW MEXICO IN A REGION OF
INCREASING UPPER LEVEL DIVERGENCE AND DIFFLUENCE. DESPITE WEAK
CAPE VALUES WHICH SHOULD CONTINUE TO GRADUALLY DIMINISH OVER THE
NEXT FEW HOURS...SUFFICIENT INSTABILITY AND INCREASING DYNAMIC
LIFT ARE EXPECTED TO PROLONG AN ENHANCED RISK FOR FLASH FLOOD
PRODUCING CONVECTION FROM SWRN TO CNTRL NEW MEXICO THROUGH THE
REMAINDER OF THE MORNING. ANOTHER CONTRIBUTING FACTOR FOR FLASH
FLOODING OVER CNTRL NEW MEXICO IS WET SOILS FROM RAINFALL OVER THE
PAST 24 HOURS...MAKING THE REGION MORE SUSCEPTIBLE TO RUNOFF.

OTTO

ATTN...WFO...ABQ...EPZ...

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

LAT...LON   35290727 34910588 33370611 32100754 32440865
            33810859