MESOSCALE PRECIPITATION DISCUSSION 0242
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
549 PM EDT THU SEP 12 2013
 
AREAS AFFECTED...SOUTH-CENTRAL NM 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 122148Z - 130103Z
 
SUMMARY...HEAVY RAINFALL IS SPREADING ACROSS AREAS WITH SATURATED
SOILS ACROSS SOUTHERN NM.  REGIONAL FLASH FLOODING IS CONSIDERED
POSSIBLE IN THIS AREA.

DISCUSSION...LOW-LEVEL INFLOW UP THE RIO GRANDE VALLEY OF 20-25
KNOTS HAS BEEN STREAMING TOWARDS A SURFACE TROUGH FEEDING
THUNDERSTORM ACTIVITY WHICH HAS MOVED NORTHWARD FROM WESTERNMOST
TX INTO SOUTHERN NM.  NEW CELLS ARE ATTEMPTING TO DEVELOP NEAR
RUIDOSO AND BAYARD NM.  THE AREA IS DIVERGENT ALOFT TO THE
SOUTHEAST OF A DEEP-LAYERED CYCLONE ACROSS NORTHERN NV.  THE
STORMS HAVE HAD RECENT RAINFALL RATES OF AN INCH AN HOUR, WHICH
WELL EXCEED FLASH FLOOD GUIDANCE VALUES IN THE REGION.  THE
EFFICIENT RAINFALL RATES ARE BEING FED BY PRECIPITABLE WATER
VALUES OF 1.50-1.75 INCHES, WHICH ARE IN THE 95TH PERCENTILE FOR
MID-SEPTEMBER.

THUNDERSTORMS ARE EXPECTED TO CONTINUE MOVING NORTHWARD AT 5-10
KNOTS PER 850-400 HPA MEAN LAYERED WINDS.  SOME OF THE NEW
ACTIVITY ACROSS NORTH-CENTRAL MEXICO SHOULD MOVE INTO THIS AREA
FROM THE SOUTH, PER THOUGHTS FROM SAB AND RECENT SATELLITE TRENDS.
 SHOULD CELLS ORGANIZE, THEY COULD START DRIFTING EASTWARD PER THE
12Z GFS CORFIDI VECTORS, SO ALLOWED SOME EAST-WEST WIDTH OF THE
DEFINED AREA TO COMPENSATE FOR THIS POSSIBILITY.  THE 12Z ARW
INDICATES THAT CAPE VALUES IN THE REGION OF 500-1000 J/KG SHOULD
BEGIN TO FADE AROUND 01Z, SO CHOSE THIS AS THE TIME HORIZON OF THE
MPD.  THE SLOW CELL MOVEMENT EXPECTED AND THE LOW FLASH FLOOD
GUIDANCE VALUES IN THE REGION -- ON THE ORDER OF AN INCH IN THREE
HOURS -- ARE BIG PLUSES FOR REGIONAL FLASH FLOODING.  HOWEVER,
SCATTERED CELL COVERAGE SHOULD LEAD TO REGIONAL FLASH FLOODING
BEING POSSIBLE ACROSS SOUTH-CENTRAL NM.

ROTH

ATTN...WFO...ABQ...EPZ...

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

LAT...LON   34760541 33480499 32190535 31600584 31550638 31780735
            32520813 33760802 34760736 35110643 34760541