Graphic for MPD #0018

MESOSCALE PRECIPITATION DISCUSSION 0018
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1111 AM EST TUE FEB 20 2018

AREAS AFFECTED...CNTRL TO N-CNTRL TX INTO SERN OK

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

VALID 201605Z - 202105Z

SUMMARY...FLASH FLOODING WILL BE POSSIBLE ACROSS PORTIONS OF CNTRL
TO N-CNTRL TX INTO SERN OK THROUGH 21Z. RAINFALL RATES OF 1.5 TO
2.5 IN/HR COULD LEAD TO 6 HOUR RAINFALL AMOUNTS BETWEEN 3-5 INCHES
ON A LOCALIZED BASIS.

DISCUSSION...RADAR IMAGERY AT 1530Z SHOWED A BROKEN LINE OF
LARGELY ELEVATED CONVECTION EXTENDING SSW FROM THE CNTRL TX/OK
BORDER TO THE TX HILL COUNTRY. BRIEF PERIODS OF TRAINING WERE
NOTED ALONG THIS LINE OVER EASTLAND AND PALO PINTO COUNTIES WITH
DUAL-POL ESTIMATED RAINFALL RATES OF 1.5 TO 2.5 IN/HR. CIRA
LAYERED PRECIPITABLE WATER IMAGERY OVER THE PAST 12 HOURS SHOWED
LOW LEVEL MOISTURE SURGING NORTHWARD FROM THE GULF OF MEXICO INTO
ERN TX/ERN OK WITH THE MID AND UPPER LEVELS SHOWING A DIRECT
CONNECTION TO THE TROPICAL EAST PACIFIC. 12Z RAOB DATA FROM OUN
AND FWD ALONG WITH RECENT GPS MEASUREMENTS INDICATED PRECIPITABLE
WATER VALUES WERE ROUGHLY 1.25 TO 1.5 INCHES AHEAD OF A STRONG
COLD FRONT SURGING SOUTH THROUGH OK. INSTABILITY WAS SOMEWHAT OF A
LIMITING FACTOR FOR MORE ROBUST CONVECTION...BUT 250-750 J/KG
ESTIMATED MUCAPE PER RECENT DATA FROM THE SPC MESOANALYSIS PAGE IS
SUFFICIENT TO SUPPORT A HEAVY RAIN/FLASH FLOOD THREAT.

AS THE AFTERNOON PROGRESSES...INSTABILITY VALUES ARE EXPECTED TO
INCREASE...ESPECIALLY NEAR AND SOUTH OF I-20 AS SEEN IN RECENT
HRRR MODEL RUNS. RAP DATA SHOWS INCREASING UPPER LEVEL DIVERGENCE
TIED TO THE RIGHT ENTRANCE REGION OF A LARGE JET CORE EXTENDING
FROM THE SRN PLAINS INTO THE UPPER MS VALLEY ALONG WITH MODERATELY
DIFFLUENT WIND VECTORS. WINDS FROM 850-200 MB ARE UNIDIRECTIONAL
FROM THE SSW AND ESTIMATED INFLOW AT 850 MB MEETS OR EXCEEDS
OBSERVED STORM MOTIONS OF 30-40 KT ACROSS NRN TX... SUPPORTIVE OF
TRAINING.

THE EXPECTATION IS FOR CONVECTION TO INCREASE TO THE SOUTH TOWARD
CNTRL TX...CONNECTING WITH ONGOING CONVECTION TO THE NORTH...WITH
THE WHOLE AREA SLOWLY MIGRATING TOWARD THE EAST IN A BROKEN
FASHION. EMBEDDED ELEMENTS OF TRAINING ARE EXPECTED TO DEVELOP
ANYWHERE SOUTHWEST OF THE DFW METROPLEX INTO SERN OK AS EVIDENCED
BY A CONSENSUS OF THE 12Z HI-RES MODEL SUITE. A BROAD 1-3 INCHES
APPEARS LIKELY THROUGH 21Z ACROSS THE MPD THREAT AREA WITH
LOCALIZED POCKETS OF 3-5 INCHES POSSIBLE...WHICH SHOULD FALL ON A
2-4 HOUR TIME SCALE...IN EXCESS OF FLASH FLOOD GUIDANCE VALUES
ACROSS THE REGION.

OTTO

ATTN...WFO...EWX...FWD...OUN...SHV...SJT...TSA...

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

LAT...LON   35239546 34569496 33839519 32999582 31829695
            30989832 31069911 32719846 33639791 34419730
            35089639


Last Updated: 1111 AM EST TUE FEB 20 2018