MESOSCALE PRECIPITATION DISCUSSION 0278
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1011 PM EDT SUN OCT 13 2013
 
AREAS AFFECTED...SOUTHERN TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 140210Z - 140730Z
 
SUMMARY...ADDITIONAL HEAVY RAINS ARE EXPECTED OVER THE NEXT
SEVERAL HOURS ACROSS PORTIONS OF THE LOWER RIO GRANDE VALLEY.
GIVEN ALREADY LOCALLY SATURATED SOIL FROM EARLIER RAINFALL...THE
THREAT FOR FLASH FLOODING WILL BE ELEVATED.

DISCUSSION...A COLD-TOPPED MCS CONTINUES TO FOCUS ACROSS PORTIONS
OF THE LOWER RIO GRANDE VALLEY AND ESPECIALLY SOUTHEAST OF KCOT.
AN OUTFLOW BNDRY WHICH WAS ORIGINALLY GENERATED BY CONVECTION MUCH
EARLY IN THE DAY HAS ESSENTIALLY STALLED OUT JUST SOUTHEAST OF THE
ACTIVITY...BUT WILL BE TENDING TO BE REINFORCED WITH A VERY SLOW
SOUTHEAST ADVANCE. IR/WV SAT IMAGERY SHOWS PERSISTENTLY DIV FLOW
ALOFT IN ASSOC WITH H25 RRQ JET DYNAMICS AND OUTFLOW ASSOCD WITH
T.S. OCTAVE IN THE E PAC SOUTH OF MEXICO. A DEEP AMOUNT OF
TROPICAL MOISTURE IS IN PLACE...WITH A COMBINATION OF SELY LOW
LEVEL MOISTURE TRANSPORT IN OFF THE GULF OF MEXICO...AND SWLY
MID/UPR LEVEL FLOW EMANATING FROM THE E PAC WITH T.S. OCTAVE AND
CROSSING MAINLAND MEXICO INTO THE SOUTHERN PLAINS. THE LATEST RAP
ANALYSIS SHOWS MUCAPE VALUES OF 1000 TO 2000 J/KG OVER SOUTH TX
FEEDING INTO THE MCS WITH THE AID ESP OF THE LOW LEVEL FLOW. WHILE
THE INSTABILITY IS RATHER MODEST...THE JET DYNAMICS ALOFT ARE
YIELDING SUSTAINABLE DEEP LYR ASCENT...AND IT IS LIKELY AS A
RESULT THAT THE ONGOING MCS WILL PERSIST FOR SEVERAL MORE HOURS.

GIVEN THE HEAVY RAINFALL ACROSS PORTIONS OF THE REGION ON
SUN...SOIL CONDITIONS ARE BECOMING LOCALLY SATURATED AND ANY
ADDITIONAL HEAVY RAINFALL IS EXPECTED TO DRIVE AN ELEVATED RISK OF
FLASH FLOODING. OBSERVED RAINFALL RATES HAVE BEEN ON THE ORDER OF
2 TO 3 INCHES/HR...AND THAT WILL CONTINUE WITHIN THE STRONGER
CONVECTIVE ELEMENTS. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...CRP...EWX...BRO...

ATTN...RFC...WGRFC...

LAT...LON   28280052 28619956 29279827 29049713 28079701 27319779
            26989869 26919951 27140025 27550068 28280052