Potential Severe Weather Outbreak | TX and Southeast | 4/11-4/12, 2020
Posted: Wed Apr 08, 2020 4:18 am
I was waiting for SPC to highlight this before I created this thread and they just did so a few minutes ago.
..DISCUSSION...
While considerable uncertainties remain, a substantial severe
episode appears possible this weekend, from Texas into portions of
the lower MS Valley on Saturday, and especially from the lower MS
Valley into portions of the Southeast on Sunday.
...D4/Saturday: Southern Plains into the Arklatex/Lower MS Valley...
Extended-range guidance continues to vary regarding the timing of
the ejecting cutoff low over the Southwest, though all solutions are
in generally good agreement in the development of a deep surface low
over the central/southern High Plains on Saturday as the upper low
ejects eastward. As low-level moisture streams northward, moderate
destabilization appears possible as far north as the Red River, as
deep-layer shear increases in advance of the ejecting trough. Severe
thunderstorm development will be possible during the
afternoon/evening across much of TX. Late Saturday night, an
increasing low-level jet may help to advect very rich low-level
moisture inland and potentially provide an additional focus for an
overnight severe thunderstorm threat from the TX Gulf Coast into the
lower MS Valley.
...D5/Sunday: Arklatex/Lower MS Valley into the Southeast...
Timing differences continue among the extended-range guidance into
D5/Sunday, with the GFS notably faster, while the 08/00Z ECMWF has
trended slower compared to other guidance as well as its own
previous cycles. Regardless of timing, most guidance depicts the
ejecting trough as taking on a neutral to negative tilt, with a
deepening surface low moving into portions of the MS/TN Valleys.
While the northward extent of substantial destabilization remains
uncertain due to the potential for widespread convection, sufficient
instability and increasing low-level and deep-layer shear will
support a severe thunderstorm threat across much of the Southeast
throughout the day into Sunday night. If very rich low-level
moisture (low 70s dewpoints) over the Gulf can spread inland in
advance of this dynamic system, as depicted by recent ECMWF/UKMET
runs, then a substantial severe thunderstorm event could evolve,
with all hazards possible. Higher probabilities will be required if
guidance continues to trend in that direction.
I'll do my own detailed analysis of the 12z model suites tomorrow afternoon.
..DISCUSSION...
While considerable uncertainties remain, a substantial severe
episode appears possible this weekend, from Texas into portions of
the lower MS Valley on Saturday, and especially from the lower MS
Valley into portions of the Southeast on Sunday.
...D4/Saturday: Southern Plains into the Arklatex/Lower MS Valley...
Extended-range guidance continues to vary regarding the timing of
the ejecting cutoff low over the Southwest, though all solutions are
in generally good agreement in the development of a deep surface low
over the central/southern High Plains on Saturday as the upper low
ejects eastward. As low-level moisture streams northward, moderate
destabilization appears possible as far north as the Red River, as
deep-layer shear increases in advance of the ejecting trough. Severe
thunderstorm development will be possible during the
afternoon/evening across much of TX. Late Saturday night, an
increasing low-level jet may help to advect very rich low-level
moisture inland and potentially provide an additional focus for an
overnight severe thunderstorm threat from the TX Gulf Coast into the
lower MS Valley.
...D5/Sunday: Arklatex/Lower MS Valley into the Southeast...
Timing differences continue among the extended-range guidance into
D5/Sunday, with the GFS notably faster, while the 08/00Z ECMWF has
trended slower compared to other guidance as well as its own
previous cycles. Regardless of timing, most guidance depicts the
ejecting trough as taking on a neutral to negative tilt, with a
deepening surface low moving into portions of the MS/TN Valleys.
While the northward extent of substantial destabilization remains
uncertain due to the potential for widespread convection, sufficient
instability and increasing low-level and deep-layer shear will
support a severe thunderstorm threat across much of the Southeast
throughout the day into Sunday night. If very rich low-level
moisture (low 70s dewpoints) over the Gulf can spread inland in
advance of this dynamic system, as depicted by recent ECMWF/UKMET
runs, then a substantial severe thunderstorm event could evolve,
with all hazards possible. Higher probabilities will be required if
guidance continues to trend in that direction.
I'll do my own detailed analysis of the 12z model suites tomorrow afternoon.