MESOSCALE PRECIPITATION DISCUSSION 0051
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
602 PM EDT MON MAY 04 2015
 
AREAS AFFECTED...EXTREME ERN NEW MEXICO INTO PORTIONS OF WEST
TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 042200Z - 050400Z
 
SUMMARY...THE FLASH FLOOD THREAT WILL INCREASE ACROSS EXTREME ERN
NEW MEXICO INTO WEST TEXAS PAST 00Z AS THE MAGNITUDE OF THE LOW
LEVEL JET CONTINUES TO INCREASE AND STORM COVERAGE EXPANDS.
RAINFALL RATES OF 2-3 INCHES IN 3 HOURS ARE POSSIBLE.

RADAR TRENDS OVER THE PAST 2 HOURS ACROSS WEST TEXAS...IN THE
VICINITY OF LUBBOCK...HAVE SHOWN AN EXPANDING COVERAGE OF
CONVECTION WITHIN AN UNCAPPED ENVIRONMENT OF 1000-2000 J/KG ML
CAPE...PER SPC MESOANALYSIS AND SPECIAL 18Z SOUNDING FROM MAF.
THESE STORMS ARE OCCURRING UNDER AN INCREASINGLY DIFFLUENT FLOW
ALOFT WITH THE SUBTROPICAL JET AXIS CURRENTLY AIMED TOWARD THE BIG
BEND REGION OF TEXAS...AND A SOMEWHAT BROAD UPPER TROUGH MOVING
ACROSS THE SOUTHWEST. MOISTURE IS VERY ANOMALOUS FOR EARLY MAY
ACROSS THE REGION AS EVIDENCED BY 21Z GPS PW FROM MAF OF 1.22
INCHES...NEAR THE 99TH PERCENTILE FOR EARLY MAY. 

AS MID-UPPER LEVEL HEIGHT FALLS CONTINUE ACROSS THE SRN HIGH
PLAINS PAST 00Z...UPPER DIFFLUENCE WILL PERSIST WHILE SSELY 850 MB
FLOW INCREASES FROM PRESENT 30 KT VALUES...PER VAD WIND PLOT...TO
40+ KTS BY 03Z PER RECENT RUNS OF THE RAP. WHILE STORM MODE IS
PRIMARILY DISCRETE AS OF 21Z...THE FLASH FLOOD CONCERN ARISES AS
INCREASING COVERAGE OF CONVECTION PRODUCES COLD POOLS BETWEEN MAF
AND LBB WITH COLD POOL PROPAGATION POTENTIALLY BEING OFFSET BY THE
MAGNITUDE OF THE LOW LEVEL JET PAST SUNSET...LEADING TO PERIODS OF
TRAINING...WITH CELL MOTIONS OFF TO THE NORTHEAST AT 15-20 KTS. 

CONFIDENCE IS MODERATE IN A FLASH FLOOD THREAT DEVELOPING
OVERNIGHT...BUT LESS SO WITH THE DETAILS AS HI-RES MODELS ARE
STRUGGLING WITH CURRENT CONVECTIVE PLACEMENT...EXCEPT FOR THE 12Z
SPC WRF. WHILE RAINFALL TOTALS FROM THE SPC WRF ARE TYPICALLY
HI-BIASED...ITS EVOLUTION SHOWS THE SIGNAL FOR FLASH FLOODING WITH
OTHER HI-RES MODEL QPF SHOWING THE POTENTIAL FOR RAINFALL
EXCEEDING FFG IN A FEW AREAS BY 04Z...WITH PERHAPS THE AREA
NEEDING ANOTHER MPD BEYOND 04Z.

OTTO

ATTN...WFO...ABQ...AMA...LUB...MAF...SJT...

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

LAT...LON   35060080 33550026 31210127 31070304 32160362 
            34040345 34980243