SPC AC 050559
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Mon Jun 05 2023
Valid 051200Z - 061200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE CENTRAL APPALACHIANS...DEEP SOUTH TEXAS...AND WESTERN MONTANA...
...SUMMARY...
Isolated strong to severe thunderstorms may occur today across
portions of the central Appalachians, deep south Texas, and western
Montana. Both occasional damaging winds and hail appear possible.
...Synopsis...
A mid-level trough will meander along the Northeast coastline as a
second upper trough impinges on the Southwest today. Adequate
low-level moisture will continue to overspread much of the western
and central U.S. into the Southeast amid weak tropospheric flow,
encouraging the development of at least scattered pulse
thunderstorms from late morning into the evening hours. Given
adequate buoyancy associated with these storms, a sparse severe gust
or instance of large hail may occur. However, embedded within the
broad area encompassing thunderstorm potential are a few regions
where organized rounds of strong to isolated severe thunderstorms
are possible.
...Central Appalachians...
A mid-level impulse, embedded in the broader northwesterly flow on
the backside of the aforementioned mid-level trough, will graze the
central Appalachians during the afternoon. By this time, adequate
boundary-layer heating will support 70+ F surface temperatures amid
low 60s F dewpoints and 6.5-7.5 low to mid-level lapse rates,
contributing to 2000-3000 J/kg MLCAPE. Modest speed shear above 700
mb will encourage somewhat elongated hodographs, which may promote a
few organized multicellular clusters and longer-lived single cells
capable of producing some large hail and a couple of strong to
potentially severe gusts.
...Deep South Texas...
An MCV is expected to drift slowly southward across central into
southern TX through the forecast period, with an increase in
thunderstorm development and intensity expected by late morning into
the afternoon in tandem with surface heating. While lapse rates are
not forecast to become particularly steep, 6-7 C/km tropospheric
lapse rates atop mid 80s/low 70s F surface temperatures/dewpoints
will contribute to 2500-3500 J/kg SBCAPE. Furthermore, some
veering/strengthening of winds with height to the right of the MCV
trajectory will contribute to elongated and curved hodographs.
Multicellular clusters and transient supercells are possible. Large
hail and damaging gusts are the main threats, though a brief tornado
cannot be ruled out.
...Western Montana...
A mid-level impulse will graze western MT this afternoon as the
boundary layer destabilizes. While low-level moisture will be
modest, 7-8 C/km low to mid-level lapse rates will contribute to
tall, thin MLCAPE over 1500 J/kg. While tropospheric flow will be
predominantly unidirectional, adequate speed shear will promote
elongated hodographs, supporting some longer-lived, organized
multicells capable of an isolated severe gust/hail threat.
..Squitieri/Goss.. 06/05/2023
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