Valid 082000Z – 091200Z
…NO SEVERE THUNDERSTORM AREAS FORECAST…
A few thunderstorms are possible across the central Rockies, Plains,
and southwest Texas, but severe weather is not expected.
Adjustments have been made to the 10% general thunderstorm lines to
account for current observations and trends in forecast guidance.
The airmass across the Four Corners is very dry, despite moistening
mid/upper levels. Sporadic lightning flashes have been noted in
northern NM and south-central CO. Additional isolated flashes may
continue into the evening as a shortwave impulse located over UT/AZ
continues to eject east/northeast. Additional isolated thunderstorm
development also is possible across southwest TX and over portions
of the central Plains through tonight as modest boundary layer
moisture increases ahead of a cold front and deepening midlevel
trough. A dearth of surface moisture and scant instability will
preclude severe thunderstorm development.
.PREV DISCUSSION… /ISSUED 1113 AM CDT Sun Mar 08 2020/
A mid-level shortwave currently located across the Desert Southwest
will migrate northeastward, reaching the central Plains by the end
of the forecast period. The combination of surface
heating/insolation and cooling mid-level temperatures aloft
associated with the wave will promote showers and isolated
thunderstorms initially over UT/CO through the afternoon hours.
This evening, lift associated with the advancing wave, and
increasing low-level flow, and steepening lapse rates associated
with an EML will result in a few elevated thunderstorms that may
produce small hail near the CO/KS/NE border area. Warm-advection
will also contribute to development of bands of showers and isolated
thunderstorms northeastward through Iowa and vicinity. Limited
instability should mitigate any severe risk in these areas.
Additional thunderstorms are expected across west Texas and vicinity
during the evening – primarily in response to lift associated with
the aforementioned mid-level wave. Though low-level and deep shear
profiles are impressive, weak/negligible surface-based instability
(owing to 50-55F dewpoints and weak lapse rates) should mitigate the
severe threat in this area. The primary window for thunderstorm
activity should exist between 21Z and 04Z.