Subj : MESO: Heavy rain - floodi
To   : All
From : Mike Powell
Date : Wed May 31 2023 15:38:00

AWUS01 KWNH 311802
FFGMPD
TXZ000-OKZ000-COZ000-NMZ000-010000-

Mesoscale Precipitation Discussion 0394
NWS Weather Prediction Center College Park MD
200 PM EDT Wed May 31 2023

Areas affected...Portions of the Southern High Plains

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

Valid 311800Z - 010000Z

SUMMARY...Localized clustering of showers and thunderstorms over
eastern NM will give way to a more regional threat of scattered
convection going through the afternoon hours. Given the moist
antecedent conditions and elevated streamflows, the additional
rainfall may result in scattered instances of flash flooding.

DISCUSSION...The latest satellite imagery in conjunction with
radar shows a relatively concentrated and organized area of
convection across areas of eastern NM to the southeast of the
Sangre De Cristo range.

This activity has been associated with the arrival of left-exit
region upper jet dynamics associated with the nose of the
subtropical jet extending eastward across northern Mexico and far
southern AZ/NM. This is occurring as a well-defined upper low over
the Southwest gradually advances off to the east. The convection
is also being strongly facilitated by the nose of elevated
instability up across the southern High Plains with MUCAPE values
of as much as 1000 to 1500+ J/kg with a notable contribution from
steep mid-level lapse rates reaching 8.5 to 9.0 C/km.

Gradually the current activity should advance off to the east into
the High Plains where it may encounter a sufficient level of
boundary layer stabilization/CINH to weaken in the near-term.
However, in time, strong diurnal heating will result in stronger
surface-based instability which will set the stage for a more
regional threat of heavy showers and thunderstorms. This activity
will likely tend to redevelop farther west across some of the
higher terrain of the southern Rockies initially (including the
Sangre De Cristo range) and then more broadly across adjacent
areas of the southern High Plains involving eastern NM and
portions of the TX Panhandle by late afternoon.

By late afternoon, the airmass will likely be quite unstable and
should be increasingly moist as low-level south to southeast flow
increases ahead of the upper low approaching from the Southwest.
This coupled with at least some vertical shear will favor a threat
of organized convective cells, including some supercells, capable
of producing heavy rainfall rates that may reach 1 to 2
inches/hour.

The 17Z experimental WoFS depicts this threat rather strongly, and
its ensemble does support the potential for localized storm totals
to reach 2 to 4 inches given locally multiple rounds of
convection. This coupled with the already moist soil conditions
and elevated streamflows from heavy rainfall over the last week
may result in scattered instances of flash flooding. Additional
MPDs will likely be needed this evening from a persistence of the
convective threat and especially over the TX Panhandle.

Orrison

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

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

LAT...LON   37020388 36570287 35630216 33990193 32100218 
            30960290 30630404 31030495 32890536 34350579 
            35370605 36410581 37000502 

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