MESOSCALE PRECIPITATION DISCUSSION 0060
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
411 PM EDT TUE MAY 21 2013
 
AREAS AFFECTED...SERN OK...NERN TX INTO CNTRL AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 212010Z - 220010Z
 
SUMMARY...A CONTINUED THREAT FOR FLASH FLOODING WILL EXIST THROUGH
THE REMAINDER OF THE EVENING AS STRONG CONVECTIVE RAINS MOVE
ACROSS A WET ANTECEDENT ENVIRONMENT.

DISCUSSION...AT 19Z...A SLOW MOVING COLD FRONT WAS ANALYZED SWD
THROUGH NERN OK INTO A 1004 MB LOW LOCATED NEAR DAL...WITH THE
COLD FRONT EXTENDING SWWD FROM THE LOW THROUGH CNTRL TX. A
WELL-DEFINED OUTFLOW BOUNDARY EXTENDED EAST OF THE LOW...ACROSS
NERN TX INTO S-CNTRL AR. RADAR IMAGERY HAS SHOWN NEARLY STATIONARY
CONVECTION IN THE VICINITY OF THIS OUTFLOW BOUNDARY OVER THE PAST
SEVERAL HOURS WITH A FORWARD PROPAGATING MCS APPROACHING FROM THE
WEST. A MID-LEVEL SHORTWAVE SEEN ON WATER VAPOR IMAGERY OVER WRN
OK WILL CONTINUE EWD THIS EVENING WITH SUBSIDENCE BEHIND THE
SHORTWAVE EXPECTED TO END THE HEAVY RAIN FROM WEST TO EAST LATER
THIS EVENING. 

FLASH FLOOD GUIDANCE IS ROUGHLY 2-3 IN/3HR ACROSS MUCH OF ARKANSAS
WHILE FLASH FLOODING IS ONGOING ACROSS PORTIONS OF SERN OK. AS THE
CONVECTIVE LINE MOVES EAST ACROSS OK OVER THE NEXT FEW HOUR OR
TWO...THE FLASH FLOOD THREAT WILL CONTINUE ACROSS OK...WHILE
PROGRESSING INTO AR WITH THE APPROACH OF THE CONVECTIVE LINE THIS
EVENING. STRONG DIFLUENT FLOW ALOFT AND A CONTINUED INFLUX OF
MOISTURE FROM THE SOUTH...VIA 30-40 KT OF 850 MB FLOW AS SEEN IN
RECENT VAD WIND PROFILE IMAGERY FROM KFWS WILL CONTINUE TO SUPPORT
ADDITIONAL RAINFALL OF 2-4 INCHES THROUGH 00Z ACROSS PORTIONS OF
AR WITHIN THE THREAT AREA.  

OTTO


ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

LAT...LON   34969156 35529168 35859250 35789387 35249548 34639632
            33529679 32909676 32769632 32809654 32899445 33229306
            34079198 34969156