MESOSCALE PRECIPITATION DISCUSSION 0819
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
131 AM EDT SAT SEP 23 2017

AREAS AFFECTED...SOUTHERN NM...EXT WESTERN TX PANHANDLE

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

VALID 230531Z - 231101Z

SUMMARY...NARROW BUT NEAR STATIONARY CORRIDOR OF HIGHER PACIFIC
MOISTURE SUPPORTIVE UPSTREAM REDEVELOPMENT AND TRAINING POSE
POSSIBLE FLASH FLOOD RISK.

DISCUSSION...03Z CIRA LAYERED PW DEPICTED A MARKED INCREASE IN
850-5H MOISTURE WITH 7-5H VALUES RAISING FROM .25 TO AROUND .5"
(THOUGH SOME CAUTION IS NEEDED BEING AT THE LIMB OF THE POLAR
PASS) LEADING TO TOTALS IN THE 1.25-1.4" RANGE.  CURRENTLY VERY
STRONG RETURN MOISTURE STREAM THROUGH THE RIO GRANDE/WESTERN TX
PANHANDLE IS ESTIMATED BY 3.9UM IR LOOP AND RAP ANALYSIS
SUGGESTIVE UP TO 30KTS.  THIS COMBINED WITH EPZ 850MB WIND
ESTIMATED AS WEST SUGGESTS FAIRLY STRONG CONVERGENCE IN THE
VICINITY.  SURFACE OBS ALSO DEPICT SHALLOW BUT IMPRESSIVE MOISTURE
WITH TDS IN THE LOWER 60S APPROACHING FROM THE EAST AS WELL. 
ABOVE THE BOUNDARY LAYER THE CONFLUENT 7H MST FLOW WILL SUPPORT
MEAN CELL MOTIONS TO THE NORTH WITH SOME SUGGESTION OF
BACKBUILDING PROPAGATION VECTORS GIVEN THE STRONGER LOW LEVEL
INFLOW BEFORE IT SLACKENS.  ADDITIONALLY...MODEST UPPER LEVEL
SUPPORT IN RIGHT ENTRANCE REGION OF 3H JET IS EXPECTED TO STEADILY
INCREASE THROUGH 10Z AS THE ORIENATION OF THE JET BACKS FROM SWLY
TO MORE SOUTHERLY OPENING AN INCREASED N-S AXIS OF DIVERGENCE
ALOFT. 

LIMITING FACTOR AT THIS TIME APPEARS TO BE OVERALL CONVECTIVE
COVERAGE AND BREADTH OF UPDRAFT/DOWNDRAFT CORES; AS ONLY ONE OR
TWO CBS CAN BE SEEN IN NORTHER CHIHUAHUA IN 10.3UM IR AND EPZ
RADAR.  STILL GIVEN INCREASED MOISTURE AND FLUX THE BULK OF HI-RES
GUIDANCE SUGGESTS INCREASED COVERAGE. RATES UP TO 1.25"/HR ARE
LIKELY THOUGH FORWARD PROGRESS MAY KEEP OVERALL TOTALS BELOW FFG
VALUE FOR ANY GIVEN INDIVIDUAL CELL.  UPSTREAM
INSTABILITY/MOISTURE WITH LIMITED EASTWARD PROGRESSION SHOULD
SUPPORT MORE UPSTREAM DEVELOPMENT WITHIN A TRAINING ENVIRONMENT. 
AS SUCH TOTALS UP TO 2-2.5" ARE POSSIBLE THROUGH 12Z AND AS SUCH
ISOLATED FLASH FLOODING IS CONSIDERED POSSIBLE.   

GALLINA

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

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

LAT...LON   34530507 33240476 32150483 31120493 30730509
            30870564 31220600 31420622 31630654 31750667
            31940668 32990644 34320584