MESOSCALE PRECIPITATION DISCUSSION 0190
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
450 PM EDT WED MAY 23 2018

AREAS AFFECTED...SE NEW MEXICO...WEST TEXAS

CONCERNING...HEAVY RAINFALL

VALID 232049Z - 240119Z

SUMMARY...THUNDERSTORMS THAT HAVE DEVELOPED ALONG A DRYLINE THIS
AFTERNOON IN EASTERN NEW MEXICO AND WEST TEXAS HAVE REMAINED
ANCHORED NEAR THE DRYLINE AND ARE SHOWING CHAOTIC AND SLOW STORM
MOTIONS. THESE SLOW-MOVING AND MERGING STORMS COULD LEAD TO FLASH
FLOODING AND HOURLY RAIN RATES OF 1-2 IN/HR IN LOCALIZED AREAS.

DISCUSSION...GOES-16 SATELLITE IMAGERY AND GLM DATA...AS WELL AS
REGIONAL RADARS SHOWED A SIGNIFICANT INCREASE IN CONVECTIVE VIGOR
AND COVERAGE ALONG A DRY LINE FROM NEW MEXICO INTO WEST TEXAS
BETWEEN 1930Z AND 2030Z. HI-RES MODELS DO NOT APPEAR TO BE
HANDLING THE COVERAGE OR THE MOTION VERY WELL...AND ONGOING
CONVECTION HAS BEEN RELATIVELY ANCHORED TO THE DRYLINE WITH
SPLITTING AND MERGING CELLS CONTRIBUTING TO THE NEARLY STATIONARY
APPEARANCE OF SOME STORMS. IN SOME CASES...TERRAIN MAY BE AIDING
IN ANCHORING THE CONVECTION SUCH AS WITH THE DAVIS MOUNTAINS IN
THE TRANS-PECOS REGION OF WEST TEXAS...AND THE SACRAMENTO
MOUNTAINS IN NEW MEXICO. MODEL WIND FIELDS AND THE POSITION OF THE
AVAILABLE RESERVOIR OF INSTABILITY WOULD SUGGEST THAT THE
CONVECTION SHOULD EVENTUALLY PROPAGATE TO THE EAST OFF THE
DRYLINE...BUT IN THE NEAR TERM (THROUGH 23Z OR 00Z)...THE SLOW AND
CHAOTIC MOTIONS NEAR THE DRY LINE MAY CONTINUE.

GIVEN THE SEVERAL HOUR WINDOW FOR SLOW-MOVING STORMS...HIGH HOURLY
RAIN RATES ARE POSSIBLE AND HAVE ALREADY BEEN ESTIMATED BY KMAF
AND KFDX RADARS TO APPROACH 2 IN/HR IN SOME CASES. THE POSITION OF
CONVECTION OVERLAPS FAVORABLY WITH THE LOWEST FLASH FLOOD GUIDANCE
IN THIS REGION...WHICH IS VERY CLOSE TO THE CURRENT DRY LINE
POSITION WITH 1 HR FFG FAIRLY CLOSE TO 1.5 TO 2.5 IN/HR IN MOST
PLACES. FURTHER OFF THE DRYLINE...FFG INCREASES AND FLASH FLOODING
MAY BECOME LESS LIKELY DUE TO (1) LESS FAVORABLE HYDROLOGIC
CONDITIONS AND (2) POSSIBLE ACCELERATION OF STORM CLUSTERS AS COLD
POOLS DEVELOP AND MATURE. HOWEVER...FOR THE NEXT FEW HOURS IT
APPEARS THAT STORMS WILL BE CONCENTRATED ENOUGH TO SUPPORT A
CONTINUED FLASH FLOOD THREAT ALONG THE DRYLINE.

LAMERS

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

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

LAT...LON   34120556 34120435 33410339 32140346 30700257
            29880297 29130395 29780475 30920505 32010531
            33180584