MESOSCALE PRECIPITATION DISCUSSION 0096
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
840 PM EDT FRI APR 13 2018

AREAS AFFECTED......ARKANSAS...NORTHEAST TEXAS...FAR SOUTHEAST
OKLAHOMA...NORTHWEST LOUISIANA...

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

VALID 140039Z - 140439Z

SUMMARY...CONVECTION WILL EXPAND ACROSS THE ARKLATEX AND AREAS
E-NE THIS EVENING, WITH HOURLY RAIN RATES OF 2 IN/HR AND TOTALS OF
4-6+ INCHES POSSIBLE THROUGH 04Z (11 PM CDT). THE THREAT OF FLASH
FLOODING IS EXPECTED TO CONTINUE BEYOND THE EXPIRATION TIME OF
THIS PRODUCT.

DISCUSSION...SOUTH-SOUTHWESTERLY 850 INFLOW OF 50-55 KTS PER THE
LATEST (00Z) RAOBS AND SPC MESOANALYSIS IS CONTINUING TO TRANSPORT
COPIOUS MOISTURE FROM THE WESTERN GULF OF MEXICO, AS PW'S APPROACH
1.75". IN ADDITION, THE STRENGTHENING LLJ WILL CONTINUE TO ALIGN
MORE PARALLEL TO (WHILE NEARING THE MAGNITUDE OF) THE MEAN 850-300
MB FLOW THIS EVENING. THIS WILL LEAD TO INCREASED UPWIND
PROPAGATION AND THUS TRAINING OF CONVECTION, AS CORFIDI VECTORS
BECOME SOUTHEASTERLY. MODEST DEEP-LAYER INSTABILITY WILL REMAIN IN
PLACE, WITH MUCAPES BETWEEN 1000-2000 J/KG.

LARGE-SCALE ASCENT AHEAD OF THE SURFACE FRONT WILL ALSO BE ON THE
UPSWING THIS EVENING ACROSS THE OUTLOOK AREA, OWING TO THE
INCREASED DIFLUENT UPPER FLOW AHEAD OF THE SLOW MOVING DEEP UPPER
TROUGH, ALONG WITH THE UPTICK IN LOW LEVEL FRONTOGENESIS SOUTH OF
THE S-N ORIENTED UPPER LEVEL JET STREAK OVER THE LOWER MISSOURI
VALLEY. THERE CONTINUES TO BE A MULTI-CAM CONSENSUS WITH THE QPF
THROUGH THIS EVENING, WITH POCKETS OF 3-6+ INCHES DEPICTED
(INCLUDING THE WRF-ARW AND ARW2). MOREOVER, PER THE LATEST (18Z)
HREF, 3 HOURLY PROBABILITIES OF EXCEEDING 3" WITHIN 3 HOURS
INCREASES TO 30-50% ACROSS A FAIRLY LARGE SWATH OF THE OUTLOOK
AREA. CONSIDERING THE ANTECEDENT SOIL MOISTURE AND CURRENT FLASH
FLOOD GUIDANCE VALUES, FLASH FLOODING WILL BE POSSIBLE THROUGH
THIS EVENING.

HURLEY

ATTN...WFO...FWD...LZK...MEG...SHV...TSA...

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

LAT...LON   36479208 36389122 35949071 35249067 33999154
            32489302 31939432 31899516 32289576 32979580
            34329467 35129400 36209296