182  
AWUS01 KWNH 221151  
FFGMPD  
LAZ000-ARZ000-TXZ000-221750-  
 
MESOSCALE PRECIPITATION DISCUSSION 0348  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
751 AM EDT FRI JUN 22 2018  
 
AREAS AFFECTED......SOUTHERN ARKANSAS...NORTHERN LOUISIANA...FAR  
NORTHEAST TEXAS...  
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE  
 
VALID 221150Z - 221750Z  
 
SUMMARY...SHOWERS AND THUNDERSTORMS WILL EXPAND AND BACKBUILD THIS  
MORNING AHEAD OF A QUASI-STATIONARY SURFACE FRONT. HOURLY RAINFALL  
RATES PEAKING BETWEEN 2-3 INCHES MAY RESULT IN FLASH FLOODING.  
 
DISCUSSION...THE LATEST GOES-16 LONGWAVE IR IMAGERY SHOWS A  
COMPACT AREA OF COOLING CLOUD TOPS ACROSS SOUTHERN ARKANSAS, ALONG  
AND JUST SOUTH OF A STATIONARY FRONTAL BOUNDARY AND ON THE  
SOUTHERN PERIPHERY OF THE MID-UPPER LEVEL LOW. THE UPPER LEVEL  
CONFLUENCE SOUTH OF THIS UPPER LOW IS INDUCING A RIBBON OF  
STRONGER UPPER LEVEL FLOW THROUGH CENTRAL ARKANSAS -- 70 TO 90+  
KTS AT 250 MB PER THE LATEST VAD WIND PROFILES AND RAP/HRRR  
ANALYSIS. THE ENHANCED UPPER LEVEL DIVERGENCE WITHIN THE RIGHT  
ENTRANCE REGION OF THIS JET STREAK, AND ENSUING UPTICK IN THE  
LOW-LEVEL MOISTURE FLUX CONVERGENCE ALONG THE FRONT, WILL FURTHER  
THE CONVECTIVE GROWTH/ORGANIZATION, ESPECIALLY THROUGH 1500 UTC.  
 
THE THERMODYNAMIC ENVIRONMENT WITHIN THE OUTLOOK AREA IS QUITE  
FAVORABLE FOR HEAVY AND POTENTIALLY EXCESSIVE RAINFALL,  
PARTICULARLY FOR THE TIME OF DAY, WITH MUCAPES BETWEEN 2000-3000  
J/KG AND PWATS OF 1.75-2.0" PER THE LATEST SPC MESOANALYSIS. IN  
ADDITION, AS THE WEST-SOUTHWEST 925-850 MB FLOW ALONG AND SOUTH OF  
THE SURFACE BOUNDARY INCREASES TO 25-30 KTS, THE RESULTANT UPWIND  
PROPAGATION WILL ALLOW THE CONVECTION TO BACKBUILD AND TRAIN.  
HOURLY RAINFALL RATES OF 2-3" ARE LIKELY WITHIN THE STRONGEST  
CORES, WITH EVENT TOTALS OF 4-7 INCHES POSSIBLE IN A FEW AREAS PER  
THE LATEST HIGH-RES CAM GUIDANCE.  
 
HURLEY  
   
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...JAN...LZK...SHV...  
 
ATTN...RFC...ABRFC...LMRFC...  
 
LAT...LON 34169385 33889236 33689163 33449128 33069120  
32639141 32289210 32419328 32879413 33639441  
34069426  
 
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