
Mesoscale Precipitation Discussion 0828
NWS Weather Prediction Center College Park MD
539 PM EDT Sun Aug 21 2022
Areas affected...Parts of Permian Basin, Big Country & Edwards
Plateau of West Texas...
Concerning...Heavy rainfall...Flash flooding possible
Valid 212140Z - 220100Z
SUMMARY...Slow/Stationary Cells with capability of 2"/hr rates
pose localized totals up to 4" and possible flash flooding over
the next few hours.
DISCUSSION...Goes-E and Regional RADAR mosaic denote a line of
broken slow moving/stationary cells from Kent county to Irion to W
Crocket county along leading edge convergence band within the
southeast quadrant of deeply stacked tropical wave currently
located near KLLN. Inner band of the circulation is starting to
shift east-southeast with favorable mid to upper level flow
orientation to develop new cells as well. The outer band of cells
are back-building and remaining stationary due to approaching
mid-level support but also reside within a narrow north-south
oriented band of enhanced deep layer moisture. Instability that
had built up to 2000-2500 J/kg is being tapped for strong updrafts
with solid isallobaric inflow to support efficient rainfall
production, with some cores reaching up to 2"/hr rates. Given the
upstream wave is slow to approach, a hour or so more of these
rates will allow for small spots of 4" totals and possibly induce
localized flash flooding conditions. Additionally, as the
shortwave energy slips southeast, this will also support the cells
on the inner band to slow and pivot with a similar potential for
excessive rain associated with a subtle heavy rainfall signature
SHaRS event.
Localized flash flooding will be possible given FFG values in some
locations from King to Garza to Glasscock county are in the
1.5-2"/hr and <3"/3hr range, but similar areas just west into the
Big Country are more supportive of these rates. Still given the
slow motions, ample moisture and instability...localized flash
flooding is considered possible over the next few hours, and more
likely northward closer to better moisture pooling/forcing near
the low.
Gallina
ATTN...WFO...LUB...MAF...SJT...
ATTN...RFC...ABRFC...WGRFC...NWC...