MESOSCALE PRECIPITATION DISCUSSION 0289
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
534 PM EDT THU JUN 01 2017

AREAS AFFECTED...FAR WEST TX

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

VALID 012135Z - 020135Z

SUMMARY...SLOW CELL MOTIONS AND CELL MERGERS COULD POSE A FLASH
FLOOD THREAT ACROSS WEST TX THROUGH THE EARLY MORNING HOURS.

DISCUSSION...CONVECTION CONTINUES TO DEVELOP IN AN AXIS OF
1500-2500 J/KG OF MLCAPE EXTENDING FROM KELP TO NEAR KDRT (THOUGH
OUTFLOW FROM EARLIER CONVECTION HAS PRODUCED AN AREA OF LOW LEVEL
CIN NORTH OF KMRF). THE EXPERIMENTAL GOES-16 IR LOOP SHOWED CORES
OF COOLING TOPS IN THE AXIS OF BEST INSTABILITY...WITH THE COLDEST
CLOUD TOPS NEAR -67 DEGREES C.

A LOW LEVEL 15 KNOT SOUTHEAST FLOW CONTINUES TO TRANSPORT 1.00 TO
1.25 INCH PRECIPITABLE WATER AIR INTO WEST TX FROM THE WESTERN
GULF OF MEXICO (PER THE LATEST RAP ANALYSIS AND BLENDED TPW
PRODUCT). THE KMAF RADAR SHOWED HOURLY RAINFALL RATES NEAR 1.50
INCHES IN THE MOISTURE PLUME. HOWEVER...RAP MODEL SOUNDINGS
INDICATED DRY AIR IN THE MID LEVELS...AND THE LATEST KMAF HCA
PRODUCT STRONGLY SUGGESTED THE PRESENCE OF HAIL...WHICH COULD BE
CONTAMINATING THE RAINFALL RATES.

THE FLOW BECOMES INCREASING DIFFLUENT AHEAD OF A SHORT WAVE MOVING
ACROSS NORTHERN MEXICO THIS AFTERNOON. THE SYNOPTIC SCALE ASCENT
COULD AID IN THE EXPANSION OF THE CURRENT CONVECTIVE COVERAGE.

RAP PROPAGATION VECTORS SUGGEST THAT THE CONVECTION SHOULD BE
LARGELY OUTFLOW DOMINATED (AND THIS OCCURS TO THE CASE...BASED ON
THE RADAR PRESENTATION). HOWEVER...NEW CONVECTION FORMING ON
OUTFLOW BOUNDARIES COULD TRAIN OVER AREAS THAT RECEIVED HEAVY RAIN
EARLIER THIS AFTERNOON. THIS COULD POSE A FLASH FLOOD THREAT...
ESPECIALLY OVER FAR WEST TX...WHERE CELL MOTIONS ARE SLOWER THAN
FURTHER EAST.

THE LATEST HRRR INDICATED LOCAL 2.00 TO 3.00 INCHES OF
RAINFALL...PREDOMINATELY EAST OF A KFST-K6R6 LINE. THREE HOUR
FLASH FLOOD GUIDANCE VALUES ARE AS LOW AS 1.50 INCHES IN
SPOTS...SO CELL MERGERS AND/OR SHORT TERM TRAINING WOULD BE
NECESSARY TO INITIATE FLASH FLOODING.

THE THREAT FOR LOCALIZED FLASH FLOODING COULD EXTEND BEYOND
01Z...AS THE LATEST RAP
SHOWED INSTABILITY REMAINING PLACE THAT LONG.

HAYES

ATTN...WFO...EPZ...EWX...MAF...SJT...

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

LAT...LON   31850671 31810333 30850147 30020138 29140302
            30400525