MESOSCALE PRECIPITATION DISCUSSION 0821
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
735 PM EDT SAT SEP 23 2017

AREAS AFFECTED...ERN NM INTO FAR W TX

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

VALID 232334Z - 240530Z

SUMMARY...LOCALIZED FLASH FLOODING WILL BE POSSIBLE ACROSS
PORTIONS OF ERN NM INTO FAR WRN TX THROUGH 06Z WITH REPEATING
CELLS AND PERIODS OF TRAINING. WHILE LOCALIZED MAXIMA OF 3-4
INCHES WILL BE POSSIBLE...LOCATIONS FARTHER SOUTH ARE EXPECTED TO
HAVE THE GREATEST THREAT FOR HEAVY RAINFALL RATES AND FLASH
FLOODING.

DISCUSSION...23Z REGIONAL RADAR IMAGERY SHOWED A BROKEN
NORTH-SOUTH AXIS OF CONVECTION OVER FAR ERN NM INTO THE TX
PANHANDLE...PROPAGATING TOWARD THE EAST AT ABOUT 20 KT. RADAR
DERIVED RAINFALL RATES HAVE BEEN GENERALLY 0.5 TO 1.0 IN/HR WITHIN
THIS AXIS OF CONVECTION...LOCALLY HIGHER WITHIN STRONGER CORES.
THE RAINFALL APPEARS TO BE CO-LOCATED WITH AN AXIS OF LOW LEVEL
CONFLUENCE...NOTED ON RAP ANALYSES AND AREA VAD WIND PLOTS OVER
ERN NM. FARTHER TO THE SOUTH AND WEST...MORE ROBUST UPDRAFTS WERE
NOTED VIA COLDER CLOUD TOPS ON INFRARED IMAGERY FROM PORTIONS OF
THE TRANS PECOS INTO HUDSPETH COUNTY WHERE EARLIER GREATER SOLAR
INSOLATION HAD ALLOWED 500-1500 J/KG MLCAPE TO DEVELOP VIA THE
LATEST SPC MESOANALYSIS PAGE. GREATER CLOUD COVER OVER THE NRN
TX/NM BORDER AND ONGOING CONVECTION HAS RESULTED IN REDUCED CAPE
VALUES GENERALLY BELOW 1000 J/KG. ALOFT...FLOW IS BROADLY
DIFFLUENT WHICH HAS BEEN AIDING IN EVACUATION ALOFT AND STORM
MAINTENANCE.

WATER VAPOR IMAGERY SHOWED ONLY SLOW EWD MOVEMENT OF A LARGE
CLOSED LOW CENTERED OVER SRN NV AND THIS SLOW MOVEMENT IS EXPECTED
TO CONTINUE THROUGH 06Z. THE SLOW APPROACH OF THE UPPER LOW IS
FORECAST TO AID IN INCREASING 850-700 MB WINDS FROM THE SOUTH INTO
THE 35-40 KT RANGE BY 06Z ALONG THE NM/TX BORDER. BURSTS OF
CONVECTIVE ACTIVITY ARE EXPECTED TO CONTINUE OVER FAR ERN NM AND
WEST TX WITH PERIODS OF TRAINING AND REPEATING CELL MOVEMENTS
GIVEN QUASI-UNIDIRECTIONAL FLOW FROM THE SOUTH. DUE TO INCREASED
INSTABILITY OVER SOUTHERN LOCATIONS...THERE IS GREATER POTENTIAL
FOR HIGHER RAINFALL RATES HERE THAN LOCATIONS FARTHER NORTH. LOCAL
MAXIMA OF 3-4 INCHES ARE EXPECTED THROUGH 06Z BUT MANY LOCATIONS
SHOULD SEE ABOUT 0.25 TO 1.5 INCH TOTALS.

OTTO

ATTN...WFO...ABQ...AMA...EPZ...LUB...MAF...

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

LAT...LON   36330262 36010213 34940203 33080244 31230300
            30240356 29860417 29830462 30100500 30770507
            32520449 34880385 36050299