Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 042049
FFGMPD
LAZ000-ARZ000-TXZ000-OKZ000-050147-

MESOSCALE PRECIPITATION DISCUSSION 0304
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
448 PM EDT SAT JUL 04 2015

AREAS AFFECTED...NORTHEAST TEXAS...NORTHWEST LOUISIANA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 042047Z - 050147Z

SUMMARY...PERSISTENT CONVECTION OVERRUNNING SLOW MOVING OUTFLOW
BOUNDARY ALLOWING FOR PROLONGED TRAINING OF CELLS FOR CONTINUED
FLASH FLOOD THREAT THROUGH THIS EVENING.

DISCUSSION...WELL DEFINED OUTFLOW BOUNDARY FROM SOUTHERN ARKANSAS
COMPLEX EARLY THIS MORNING CONTINUES TO DRIFT SOUTHWEST TOWARD
INCREASING INSTABILITY AXIS ACROSS NORTH TEXAS.  A BROAD AREA OF
SURFACE AND BOUNDARY LAYER SOUTHWESTERLY FLOW FROM WEST TO
SOUTHWEST ACROSS NORTH TEXAS IS ALLOWING FOR ISENTROPIC LIFT TO
MAINTAIN CONVECTIVE DEVELOPMENT FROM THE RED RIVER SOUTH INTO
NORTHWEST LOUISIANA.  GPS/GOES SOUNDER AND RAP ANALYSIS SHOWS AN
AREA OF INCREASED MOISTURE ACROSS NORTH TEXAS WITH VALUES TO 1.8"
AND INSTABILITIES IN EXCESS OF 2000 J/KG TO KEEP CELLS
EFFICIENT...THOUGH CURRENT VIS/IR DOES SHOW THE DEPTH OF THE
CONVECTION IS A BIT LOWER WITH IR TOPS IN THE -60C RANGE...SO
LIKELY RATES ARE NOT EXTREME AT THIS TIME WITH 1.5-2"/HR RATES
LIKELY.

WV LOOP SHOWS MAIN MCV/SHORTWAVE CONTINUING A EAST-SOUTHEAST TRACK
ACROSS EASTERN ARKANSAS AT THIS TIME...ALLOWING THE OUTFLOW
BOUNDARY TO BE GENERALLY ORIENTED PARALLEL AND CONFLUENT ACROSS
SOUTHEAST OKLAHOMA. THIS ALLOWS FOR UPPER LEVEL FLOW TO GENERALLY
BE OUT OF THE NORTHWEST FROM 700MB TO JET LEVEL ALLOWING FOR THE
CELLS TO QUICKLY TURN RIGHT AND BEGIN TO TRAIN GENERALLY PARALLEL
TO THE OUTFLOW BOUNDARY.  AN UPSTREAM VERY SUBTLE SHORTWAVE ACROSS
SOUTH CENTRAL KANSAS WILL ALSO BE DROPPING INTO OKLAHOMA TO ALLOW
FOR CONTINUED FLOW WITHIN THE DIFFLUENT EXIT OF THE UPPER LEVEL
JET...LIKELY INCREASING UVVS ACROSS NORTH TEXAS INTO THE EARLY
EVENING AND PROLONGING THE FLASH FLOOD THREAT LIKELY LEADING TO A
SWATH OF AN ADDITIONAL 2-4" TOTALS ACROSS THE DISCUSSION AREA.
HI-RES MODEL GUIDANCE HAS NOT BEEN HANDLING THE CONVECTION VERY
WELL PARTICULARLY WITH REGARD TO THE ORIENTATION OF THE LINE AND
PERSISTENT SOUTH-SOUTHEASTWARD MOVEMENT.

OF ADDITIONAL NOTE...VISIBLE LOOP HAS SHOWN THAT A FEEDER BAND OF
CU AND TCU IS PARALLELING THE RED RIVER...KEEPING THE UPSTREAM
EDGE OF THE CONVECTIVE COMPLEX WEDGE SHAPED AND SOUTH OF THE RED
RIVER.


GALLINA

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FWD...OUN...SHV...

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

LAT...LON   33859582 33739487 33529425 32949363 32019302
            31829369 31939457 32519589 33479647



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