SPC May 12, 2019 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook
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Day 1 Convective Outlook NWS Storm Prediction Center Norman OK
1240 AM CDT Sun May 12 2019 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE SOUTHEAST FROM ALABAMA TO THE CAROLINAS... ...SUMMARY...
Scattered severe storms with severe wind gusts are possible from
eastern Alabama to the Carolinas on Sunday. Other marginally severe
thunderstorms are possible across the southern High Plains Sunday
afternoon. ...Portions of the Southeast...
Mid-level flow will gradually increase throughout the day in
response to an approaching mid-level wave over the Mid-Mississippi
Valley. Meanwhile, a front will extend from central Virginia
southwestward to southeastern Louisiana by mid-afternoon. Surface
cyclogenesis will occur along the front across central Virginia and
vicinity. Meanwhile, southwesterly low-level flow ahead of the
front will maintain upper 60s dewpoints ahead of the front, and
although scattered convection should be ongoing in portions of the
region throughout the morning, pockets of strong insolation will
result in development of weak to moderate surface-based instability
(1000-2000 J/kg MUCAPE) by afternoon. Models generally depict scattered deepening convection through the
afternoon - especially across the Slight risk area. These storms
should tend to grow upscale into linear bands and forward-propagate
from west-southwest to east-northeast throughout the day given the
strong west-southwesterly mid-level flow and unidirectional vertical
wind profiles. Downward momentum processes within downdrafts will
result in a risk of damaging wind gusts especially with any linear
segments. An isolated instance of hail cannot be completely ruled
out. Some uncertainty exists regarding degree of destabilization
from central NC into southeastern VA with expected convection during
the morning hours. It is likely that some portions of the Slight
risk (and associated 15% wind probabilities) will need to be
reconfigured once the extent of destabilization is clearer in this
area. Storms should generally persist into the overnight hours,
although a weakening is expected after sunset with the loss of
boundary-layer heating. ...Portions of west Texas and southeastern New Mexico...
A cut-off low over northwestern Mexico will begin the process of
evolve into an open wave late in the forecast period while migrating
eastward. As this occurs, an axis of 35-45 knot mid-level flow will
extend from the Transpecos eastward atop very light southeasterly
low-level flow. Meanwhile, steep (7-8 deg C/km) mid-level lapse
rates will persist and surface heating will result in minimal
inhibition by mid-afternoon. A few thunderstorms are expected to
develop in higher terrain and migrate eastward during the afternoon,
with deep shear supportive or organization into multicells or
loosely organized clusters. These storms should be outflow dominant
given weak boundary layer flow, though steep lapse rates will result
in isolated hail and wind beneath the strongest cores. These storms
should weaken and become elevated overnight with nocturnal boundary
layer cooling/stabilization. ..Cook/Squitieri.. 05/12/2019 

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