MESOSCALE PRECIPITATION DISCUSSION 0395
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1131 AM EDT SUN SEP 21 2014
 
AREAS AFFECTED...SE NM...FAR SW TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 211530Z - 211900Z
 
SUMMARY...CONVERGENCE CENTERED AROUND A SMALL...WEAKLY
WARM-CORE...700 MB LOW WILL ALLOW HEAVY RAIN RATES TO PERSIST
THROUGH 18 OR 19Z. THIS WILL PERPETUATE ONGOING FLOODING AND MAY
INDUCE NEW FLASH FLOODING.

DISCUSSION...THE MODELS HAD STRUGGLED TO TRACK THE LONG AGO
REMNANT CIRCULATION ASSOCIATED WITH FORMER TROPICAL CYCLONE
ODILE...BUT THE NAM AND RAP LATCH ONTO A SMALL 700 MB CIRCULATION
IN SE NM THIS MORNING. NEAR AND EAST OF THE LOW...CONVERGENT
SFC-700 MB WINDS WILL FOSTER NEW CONVECTIVE DEVELOPMENT WITHIN A
WEAKLY UNSTABLE...TROPICAL LOW-LEVEL AIRMASS. FARTHER NORTH THE
UPSLOPE COMPONENT OF LOW-LEVEL WINDS WILL PROMOTE FORCED
CONVECTION...ALTHOUGH WITHIN AIR POSSESSING VERY MINIMAL POTENTIAL
INSTABILITY IN THE FOOTHILLS W THROUGH NW OF ROSWELL.

AVERAGE 700-300 MB STEERING FLOW FOR SMALL SCALE CONVECTIVE
VORTICES IS NEARLY OPPOSED TO 0-6 KM STEERING FLOW FOR INDIVIDUAL
UPDRAFTS...LIGHT EAST AND LIGHT NORTHWEST RESPECTIVELY...YIELDING
NEAR ZERO MOTION. THE RESULT IS SPORADIC EPISODES OF CELLS
BECOMING ANCHORED AND DROPPING UP TO A RADAR-ESTIMATED 2.5 TO 3
INCHES IN AN HOUR. GIVEN RECENT VERY WET WEATHER...SURFACE RUNOFF
WILL BE GREATER THAN USUAL...AS REFLECTED BY THE LOW FLASH FLOOD
GUIDANCE VALUES FROM WGRFC. THE HI-RES MODELS...ESPECIALLY 00Z WRF
ARW AND 12Z HRRR...SHOW A STRONG SIGNAL FOR CONTINUED HEAVY
RAINFALL THROUGH 18 OR 19Z...AND ESPECIALLY CONCENTRATED NEAR THE
700 MB LOW CENTER EVIDENT IN RADAR IMAGERY AND RAP OUTPUT BETWEEN
LOVING AND EUNICE IN LEA COUNTY NM. THIS FEATURE MAY DRIFT
WESTWARD...WHILE SLACKENING OF INFLOW AND STRENGTHENING OF
SUBSIDENCE ALOFT SHOULD CAUSE THE CONVECTIVE EVENT TO BREAK UP
DURING THE AFTERNOON.

BURKE

ATTN...WFO...ABQ...EPZ...LUB...MAF...

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

LAT...LON   34480439 34140323 33420173 32840121 32340138 
            31870198 31300354 31460479 32190556 34270561