238
AWUS01 KWNH 092044
FFGMPD
TXZ000-NMZ000-100200-

Mesoscale Precipitation Discussion 0413
NWS Weather Prediction Center College Park MD
444 PM EDT Sun Jun 09 2024

Areas affected...Southeast High Plains of NM through the northern
TX Hill Country

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

Valid 092043Z - 100200Z

Summary...Showers and thunderstorms will expand across portions of
the Southern High Plains through this evening with clusters moving
very slowly across the area. Rain rates are expected to reach
2-3"/hr, which through slow storm motions could produce 1-3" of
rain with locally higher amounts. Flash flooding is possible.

Discussion...The GOES-E IR imagery this afternoon indicates two
distinct areas of cooling cloud tops and increased lightning
frequency associated with deepening convection. The first is
across far southeast NM along an inverted surface trough analyzed
by WPC behind a cold front, with secondary blossoming occurring
along a weak 700mb deformation axis draped across the Permian
Basin and into the northern Hill Country. These forcing mechanisms
are driving strong lift into favorable thermodynamics
characterized by PWs of 1 to 1.5 inches, highest east, and
accompanying MLCape of 1500-3000 J/kg. A weak shortwave ejecting
out of southern NM will traverse northeast through the evening as
well, contributing additional lift, and this will result in
widespread thunderstorm coverage across the region. Rainfall rates
have already been estimated around 1.5"/hr via local radars, and
these rates should increase as available moisture continues to
increase on post-frontal easterly flow.

The high res is admittedly struggling with the current activity,
leading to some lower confidence in the evolution the next several
hours, although the recent HRRR and FV3 are most accurately
depicting the current radar. As forcing persists and
thermodynamics subtly enhance on the easterly flow, the
ingredients suggest storms should become more widespread, lending
credence to the HRRR/FV3 solutions. Thunderstorms should generally
initialize along the surface trough and mid-level deformation
axis, but with minimal weak shear, pulse convection is anticipated
to be the primary storm mode which will result in additional
development along outflows and mergers. This will lead to
widespread coverage into the evening, with rain rates of 1-2"/hr
common, possibly pulsing to briefly 2-3"/hr through storm
interactions. Mean 850-300mb winds will remain light at just 5-10
kts, and collapsed Corfidi vectors at also just around 5 kts will
remain nearly anti-parallel to this weak mean flow. This suggests
that storms will move chaotically and could train/repeat in many
areas, lengthening the duration of heavy rain to produce 1-3" of
rainfall with locally higher amounts.

0-40cm soil moisture according to NASA SPoRT is generally near to
below normal, but spots reaching the 70th-80th percentiles also
exist. In these areas, FFG is still elevated, but somewhat lower
than the surrounding soils, falling to 1.5-2.5"/1hr, which could
be exceeded as reflected by HREF exceedance probabilities of
10-15%. This suggests that at least isolated instances of flash
flooding are possible through the evening, focused primarily where
repeating storms can occur or across any more sensitive terrain
features.

Weiss

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABQ...AMA...EWX...LUB...MAF...SJT...

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

LAT...LON   35470365 35160275 34770250 34340218 33250199
            32180090 31609983 31079891 30469874 30109958
            30140130 30300222 30780319 31410403 32310451
            33740516 34780540 35380470