MESOSCALE PRECIPITATION DISCUSSION 0863
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
215 AM EDT THU OCT 05 2017

AREAS AFFECTED...NEW MEXICO...TEXAS PANHANDLE...FAR WRN OKLAHOMA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 050615Z - 051215Z

SUMMARY...FLASH FLOODING WILL BE POSSIBLE ACROSS NEW MEXICO...THE
TEXAS PANHANDLE...AND FAR WESTERN OKLAHOMA WHERE THUNDERSTORMS CAN
BE SUSTAINED ALONG OR NEAR MESOSCALE BOUNDARIES FOR SEVERAL HOURS.

DISCUSSION...EXPERIMENTAL GOES-16 AIR MASS RGB AND LOW-LEVEL WATER
VAPOR (BAND 10) IMAGERY SHOWS ONGOING CONVECTION ALONG A BROAD ARC
FROM NEW MEXICO INTO THE SOUTHERN PLAINS...ROUGHLY ALONG THE
PERIPHERY OF A PLUME OF HIGHER ATMOSPHERIC MOISTURE. THIS IS
LARGELY FORECAST TO CONTINUE THROUGH THE REMAINDER OF THE
OVERNIGHT HOURS BY MOST AVAILABLE MODEL GUIDANCE...ALTHOUGH THE
SPATIAL EXTENT MAY SHRINK WITH TIME AS INSTABILITY WANES AND
BECOMES FOCUSED IN THE REGIONS OF POOLING LOW-LEVEL MOISTURE.
WHEREVER RESIDUAL INSTABILITY CAN ALIGN WITH MESOSCALE
BOUNDARIES...FLASH FLOODING WOULD BE POSSIBLE...PARTICULARLY IF
THE BOUNDARIES ROUGHLY ALIGN WITH THE MEAN FLOW. AS OF 06Z THERE
APPEARED TO BE SEVERAL LOCATIONS WHERE THIS SORT OF SETUP WOULD BE
FAVORED...ALTHOUGH THIS DOES NOT EXCLUDE THE POSSIBILITY OF
FLOODING ELSEWHERE IN THE OUTLINED DISCUSSION AREA.

FIRST...THE REGION NEAR THE OKLAHOMA AND TEXAS PANHANDLE BORDER
WHICH HAS FEATURED SEVERAL BACKBUILDING THUNDERSTORM CLUSTERS
ANCHORED TO THE NORTH OF AN OUTFLOW BOUNDARY. CONVECTION IN THIS
AREA SHOULD CONTINUE TO HAVE A PROPENSITY TO BUILD BOTH SOUTH
(INTO MOIST LOW-LEVEL INFLOW) AND WEST (TOWARD BETTER INSTABILITY
AND AWAY FROM RAIN-COOLED AIR MASS IN SW OK). THIS HAS ALREADY
BEEN OBSERVED WITH SEVERAL CELLS WHICH KAMA DUAL POL AND MRMS BOTH
ESTIMATE RAIN RATES UP TO 2 IN/HR. ONE POTENTIAL MITIGATING FACTOR
IS THAT FLASH FLOOD GUIDANCE IS HIGHER IN THE TWO EASTERN-MOST
ROWS OF COUNTIES IN THE TEXAS PANHANDLE.

SECOND...A CORRIDOR OF LOW-LEVEL MOISTURE CONVERGENCE FROM CENTRAL
TO NORTHEAST NEW MEXICO HAS SUSTAINED CONVECTION FOR SEVERAL HOURS
AND THIS SEEMS LIKELY TO CONTINUE WITH THE HIGHEST ANALYZED MLCAPE
VALUES IN THE REGION SITUATED IN THE INFLOW REGION OVER EASTERN
NEW MEXICO. IN FACT...THE QPF SIGNAL ON THE HREF HI-RES ENSEMBLE
IS MOST PRONOUNCED IN THIS REGION...PARTICULARLY FROM JUST EAST OF
ALBUQUERQUE NM TO NEAR DALHART TX. THIS HAPPENS TO COINCIDE WITH
LOWER FLASH FLOOD GUIDANCE VALUES CENTERED NEAR SAN MIGUEL COUNTY
IN NORTHEAST NEW MEXICO. IF CONVECTION CAN CONTINUE TO TRAIN IN
THIS AREA...THIS MAY BE AN AREA MORE CONDUCIVE TO FLASH FLOODING.

FINALLY...A SURFACE TROUGH AND CONVERGENCE ZONE WAS SITUATED TO
THE WEST OF THE SAN ANDRES MOUNTAINS IN SOUTHWEST NEW MEXICO AND
WAS PROVIDING A FOCUS FOR AN AREA OF CONVECTION. THE RAP MODEL
MAINTAINS MUCAPE AROUND 1000 J/KG IN THIS REGION FOR MUCH OF THE
NIGHT...SO PERSISTENCE OF CONVECTION WILL ALSO BE POSSIBLE IN THIS
AREA. THE ORIENTATION OF THE BOUNDARY AND CONVECTION IS ROUGHLY
PARALLEL WITH THE MEAN FLOW...AND THE MEAN FLOW IS SLOWER HERE
THAN ELSEWHERE IN THE REGION (ABOUT 15 KNOTS).
THEREFORE...SLOW-MOVING AND TRAINING CELLS WILL BE POSSIBLE.

LAMERS

ATTN...WFO...ABQ...AMA...EPZ...LUB...MAF...OUN...

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

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