From Mike Powell@618:250/1 to All on Sat Apr 20 10:42:00 2024
AWUS01 KWNH 201523
FFGMPD
TXZ000-OKZ000-202118-
Mesoscale Precipitation Discussion 0165
NWS Weather Prediction Center College Park MD
1123 AM EDT Sat Apr 20 2024
Areas affected...western through northern Texas
Concerning...Heavy rainfall...Flash flooding possible
Valid 201518Z - 202118Z
Summary...A broad axis of rain and thunderstorms should repeat
across the discussion area for most of the day today. The
orientation of the axis is favoring repeating and multiple areas
of 0.75+ inch/hr rain rates (locally greater than 1.5 inch/hr in
spots). This long-duration event could lead to isolated/minor
flash flood potential especially in the most sensitive areas.
Discussion...An axis of deep convection continues to extend from
west-southwest to east-northeast along an 850mb front subjectively
analyzed from near Midland to near Dallas this morning. Along
this boundary, scattered convection continues to move from west to
east and has contributed to areas of 1-3 inch rainfall totals this
morning. A couple of areas are experiencing more
focused/concentrated convection likely tied to subtle shortwave
troughs moving through the region: 1) across northeast Texas where
a line of storms was propagating eastward along I-20 and I-30 near
Mount Pleasant and Tyler, and 2) north/northeast of Midland, TX
where steep mid-level lapse rates (>7C/km) were likely aiding in
robust updrafts amid 1000+ J/kg MUCAPE. Scattered convection
persists between these two areas across north-central Texas
currently. Also, a slightly higher-amplitude mid-level wave was
located over eastern Arizona this morning that will likely
continue to foster convective development along the discussion
area from west to east throughout the day today.
While 1-hr FFG thresholds are not likely to be exceeded on a
widespread basis today, the concern with the ongoing scenario is
that a continuation of scattered convection will likely repeat
over the same areas along the 850mb frontal zone for much of the
day. Additional 2-4 inch rainfall totals are expected through 21Z
given the scenario. These long-duration rainfall rates could lead
to a few areas of excessive runoff - especially in low-lying
and/or urban areas.