604
AWUS01 KWNH 180916
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-181400-
MESOSCALE PRECIPITATION DISCUSSION 1181
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
415 AM EST WED DEC 18 2024
AREAS AFFECTED...SOUTHERN ARKANSAS...ADJ SE OK/NE TX/N LA...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 180915Z - 181400Z
SUMMARY...FLATTENING CONVECTIVE LINE SHOWS POTENTIAL FOR TRAINING
OVER THE NEXT FEW HOURS WHILE CROSSING SATURATED SOILS FROM RECENT
HEAVY RAINFALL ACROSS SOUTHERN AR.
DISCUSSION...RECENT GOES-E 10.3UM AND REGIONAL RADAR TRENDS
SUGGEST UPWIND EDGE OF BEST ISENTROPIC CONVERGENCE ACROSS SE OK
HAS SEEN A RECENT UPTICK IN CONVECTIVE DEVELOPMENT. WV SUITE
DEPICTS THE RIGHT ENTRANCE OF A SPEED MAX IN THE CIRRUS ACROSS
CENTRAL OK AT THIS TIME. THIS IS RESULTING A DOWNSTREAM SHORTWAVE
RIDGING AND FLATTENING OF THE 500-1000MB THICKNESS RIDGE ALLOWING
FOR A MORE EASTWARD PROPAGATION OF THE CONVECTIVE LINE LIKELY OVER
THE NEXT FEW HOURS. CAPE ANALYSIS FIELDS SUGGEST HIGHEST THETA-E
AXIS IS IDEALLY ORIENTED FOR THE ISENTROPIC ASCENT ALONG THE RED
RIVER VALLEY. COOLING TOPS BELOW -65C SUGGESTS STRONGER UPDRAFTS
AND DEEPER MOISTURE FLUX/RAINFALL PRODUCTION. CIRA LPW PLACES .6
TO .75" SFC-850MB MOISTURE WITH ADDITIONAL 850-700MB LAYER OVER
.3-.5" ALLOWING FOR TOTALS OF 1.25" TO 1.4"; GIVEN 30-35KTS OF
FLOW; FLUX CONVERGENCE WILL SUPPORT RATES OF 1.5-1.75" AND GIVEN
THE ORIENTATION MAY ALLOW FOR 1-2 HOURS OF TRAINING BEFORE THE
CORE OF HEIGHT-FALLS ACROSS W OK/NW TX DIG MORE AND START TO
ACCELERATE THE COLD FRONT SOUTH AND EASTWARD AND REDUCE THE BEST
ASCENT ANGLE TO THE FRONT FROM THE LLJ. AS SUCH A STREAK OR TWO
OF 1.5-2.5" TOTALS REMAIN PROBABLE ACROSS TEXARKANA AND SOUTHERN
ARKANSAS.
UNFORTUNATELY, HEAVY RAINFALL LAST EVENING HAS REDUCED UPPER LEVEL
SOIL CAPACITY ACROSS THIS AREA WITH NASA SPORT 0-40CM SATURATION
RATIOS WELL ABOVE NORMAL IN THE 65-75% RANGE. SO BELIEVE FFG
VALUES MAY HAVE LIKELY RECOVERED TOO FAST AND GROUNDS MAY BE MORE
SUSCEPTIBLE TO INCREASED RUN-OFF AND POTENTIAL FOR LOCALIZED FLASH
FLOODING. BY NO MEANS WILL THE RAINFALL TOTALS BE GREAT ENOUGH
FOR SIZABLE AREAL COVERAGE AND/OR MAGNITUDE OF FLASH FLOODING, BUT
THE POTENTIAL REMAINS SUFFICIENT FOR AN INCIDENT OR TWO TO OCCUR
THROUGH MID-MORNING ACROSS S ARKANSAS.
GALLINA
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...JAN...LZK...SHV...
ATTN...RFC...ABRFC...LMRFC...NWC...
LAT...LON 34969203 34799153 34209115 33829110 33209133
32859199 32859382 33179485 33789516 34319482
34629404 34939286
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