Mesoscale Precipitation Discussion 0685
NWS Weather Prediction Center College Park MD
951 PM EDT Fri Aug 17 2018

Areas affected...Wrn TX Panhandle, NE NM, SE CO

Concerning...Heavy rainfall...Flash flooding possible

Valid 180150Z - 180700Z

Summary...Thunderstorms were becoming increasingly concentrated in
the southern High Plains from near Tucumcari, New Mexico southeast
to near Plainview, Texas. These storms may collide and stall in
some areas, producing locally heavy rainfall and the potential for
flash flooding. Further north, near the eastern portion of the
Colorado and New Mexico border, other thunderstorms may develop in
the late evening and could also pose a risk of flash flooding.

Discussion...Regional radars (KAMA, KFDX, KLBB) showed an
increasingly concentrated area of convection that coincided with
convergent surface wind observations. This stretched from near
KTCC to near KPVW, and happened to also be a region of generally
reduced flash flood guidance. 3-hour values in some parts of this
focused region were as low as 1.5 inches, certainly achievable
given dual pol and MRMS rain rate estimates in the 1-2 in/hr range
already. Therefore, purely based on ongoing observational trends,
there does appear to be an increasing risk of flash flooding in
this small area of northeast New Mexico and the western Texas
Panhandle. This would be most likely when thunderstorm clusters
collide and may result in stalling or chaotic storm motions,
lengthening the duration of heavy rain in some localized areas.

Further north, radar trends from KPUX indicated a likely MCV just
northeast of Pueblo, with a trailing line of convection to the
southeast. At the moment this was showing reasonably fast
progress, which was limiting rainfall totals despite high
instantaneous rain rates. However, RAP analysis shows a low-level
jet (850mb) nosing into far northeast New Mexico, near the
Colorado border. This, the MCV, and outflow associated with the
convective line, may provide enough focus for additional
thunderstorm growth and the possibility of localized flash
flooding. However, the probability would be lower than locations
further south in the KTCC-KPVW corridor.

Lamers

ATTN...WFO...ABQ...AMA...LUB...PUB...

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

LAT...LON   37850373 37400289 36220257 35570210 34990149
            34220160 34110242 34420350 35650430 36720452
            37650446