527  
AWUS01 KWNH 220131  
FFGMPD  
TXZ000-220630-  
 
MESOSCALE PRECIPITATION DISCUSSION 0112  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
930 PM EDT SAT APR 21 2018  
 
AREAS AFFECTED...SOUTHEAST TEXAS  
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE  
 
VALID 220130Z - 220630Z  
 
SUMMARY...POTENTIAL FOR TRAINING CELLS WITH RAIN RATES UP TO 2"/HR  
AND POSSIBLE FLASH FLOODING  
 
DISCUSSION...RECENT GOES-16 VISIBLE/3.9 SWIR/10.3 IR AND WSR-88D  
RALA MOSAIC DEPICT INCREASED CONVECTION ACTIVATING ALONG COASTAL  
BOUNDARY GENERALLY COLLOCATED WITH DEEP MOISTURE AXIS OF SSW TO  
NNE WARM CONVEYOR BELT THAT EXTENDS FROM DEEP SOUTH TEXAS TO THE  
ARKLATEX REGION. RADAR AND SURFACE OBSERVATIONS ALSO DENOTE A  
WEAK SFC INFLECTION ALONG THE LINE MOVING INTO LAVACA COUNTY,TX.  
NORTH AND EAST OF THIS INFLECTION...LOW LEVEL MOISTURE FLUX AND  
CONVERGENCE WERE MAXIMIZED WITH ABOUT 1000 J/KG OF SBCAPES AIDING  
DEVELOPMENT. ADDITIONALLY THE AREA IS ALSO FAVORABLE ALOFT WHERE  
GOES-16 WV SUITE SHOW THE APEX OF THE ANTICYLONIC SUBTROPICAL JET  
CLOUD STREAKS WITH 3-4H LOWER FLOW BACKING TOWARD THE NORTHEAST  
PROVIDING A LOCALIZED MAXIMA OF DIVERGENCE TO FURTHER STRENGTHEN  
UPDRAFTS.  
 
SFC TDS UP TO 70F AND 10-15 KTS AND MODESTLY DEEP SATURATION  
(1.75" TPW) IN THE PROFILES (PER CIRA LAYERED PW SUITE) IN THE  
WARM CONVEYOR SUPPORT GOOD FLUX BUT ALSO EFFICIENT RAINFALL  
PRODUCTION. THIS IS REFLECTED WELL WITH RECENT 01Z HRLY  
OBSERVATION OF 1.99". LIMITING FACTORS ARE IN PLACE MAINLY  
FOCUSED ON DRY/ABSORPTIVE SOILS CONDITIONS WITH 1HR FFG VALUES  
OVER 3 AND 3HRLY OVER 4" MAKING FLASH FLOODING LIMITED TO VERY  
ISOLATED AREAS OF MAXIMIZED TRAINING AND URBAN/HYDROPHOBIC  
SURFACES. MEAN CELL MOTIONS WITHIN THE WARM SECTOR (SE OF THE  
WARM CONVEYOR) ARE FLATTER RELATIVE TO THE INFLECTION POINT  
SUGGESTING TRAINING IS POSSIBLE. RECENT HRRR SUGGESTS 3-4" ARE  
POSSIBLE BUT OVER A SMALL DOMAIN. AS SUCH FLASH FLOODING IS  
CONSIDERED POSSIBLE BUT ONLY BARELY ABOVE THRESHOLD...SUGGESTING  
VERY LIMITED AREAL CONCERN OR DURATION.  
 
GALLINA  
   
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...EWX...HGX...LCH...SHV...  
 
ATTN...RFC...WGRFC...  
 
LAT...LON 31239408 30989363 30309406 29509581 29339690  
30139662 30879609 30969558  
 
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