Re: May 2023
Posted: Mon May 08, 2023 4:16 pm
Cold pool has now pushed the storms south towards I-10.With an outflow boundary moving southwest.Storms may slowly congeal into a MCS.
Mesoscale Precipitation Discussion 0238
NWS Weather Prediction Center College Park MD
334 PM EDT Mon May 08 2023
Areas affected...Southeast TX...West-Central to Southwest LA
Concerning...Heavy rainfall...Flash flooding possible
Valid 081933Z - 090133Z
SUMMARY...A cluster of heavy showers and thunderstorms will be
capable of growing upscale across portions of southeast TX over
the next few hours. Slow-moving cells and localized training will
favor some potential for flash flooding.
DISCUSSION...The latest radar imagery shows a relatively
small-scale axis of heavy showers and thunderstorms developing and
expanding in coverage to the northeast of the Houston metropolitan
area. The activity is forming around the southeast flank of a
shortwave/MCV over northeast TX. The airmass is strongly unstable
and quite moist with MLCAPE values of 2500 to 3000 J/kg and PWs of
1.8 to 2.0 inches.
Rainfall rates will be capable of being extremely heavy given this
combination of moisture and instability, and the latest GOES-16 IR
satellite trends continue to show convective cloud top cooling
with evidence of additional areas of showers and thunderstorms
beginning to develop more regionally across the coastal plain.
A few members of the 12Z HREF, and several runs of the HRRR
guidance has been insisting on there being some relatively
organized and slow-moving convection developing across areas of
southeast TX this afternoon and into the early evening hours as
the aforementioned shortwave energy lifts into the Arklatex
region. The southwest flank of any of the convective clusters that
do evolve will need to be closely monitored given the persistence
of very moist/unstable low-level flow up across the southeast TX
coastal plain. Some back-building and training of convection may
result with especially the cluster of cells that has set up
northeast of Houston and to the north of Beaumont. The HRRR
guidance has been insisting on some very heavy rainfall totals
locally across this region.
Some upscale convective growth in general should continue over the
next few hours, and it is possible that with sufficient cold pool
evolution, the convection may potentially brush into areas of
southwest LA later this afternoon or early this evening.
Some rainfall rates of as much as 2 to 3 inches/hour, and
localized storm totals of 4 to 6 inches will be possible through
00Z, and that certainly will favor some concerns for flash
flooding. This will especially be the case if any of these totals
were to get into the more urbanized areas across the coastal
plain. Will continue to closely monitor.