by SPC Forecast Products | Sep 22, 2023 | Weather and Emergency Alerts
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0219 AM CDT Fri Sep 22 2023
Valid 241200Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...
...SUMMARY...
Thunderstorms, associated with large hail and wind damage, will be
possible on Sunday from parts of central Texas northeastward into
southeast Oklahoma.
...Southern Plains/Ark-La-Tex...
A shortwave trough is forecast to move eastward across the southern
Plains on Sunday. A cold front will likely advance southward into
west-central and north Texas by afternoon. Warming surface
temperatures ahead of the front will result in moderate to strong
destabilization by afternoon, with MLCAPE expected to peak in the
2000 to 3000 J/kg range in many areas south of the front. As
instability and low-level convergence increase near the front,
scattered thunderstorms will likely form in the mid to late
afternoon. These storms will move southeastward into the stronger
instability across north-central and northeast Texas, with several
cell clusters persisting into the early to mid evening.
Forecast soundings by 00Z/Monday near and to the southwest of the
Dallas/Fort Worth Metroplex show moderate deep-layer shear and steep
low to mid-level lapse rates. The moderate deep-layer shear is
mostly due to mid-level speed shear, although some directional shear
is evident in the low levels. 700-500 mb lapse rates are forecast to
be near 8 C/km. This environment should support supercells
associated with isolated large hail. Large temperature-dewpoint
spreads will result in high storm bases, and a nearly adiabatic
lapse rate below 850 mb will contribute to downdraft acceleration.
As a result, a wind-damage threat is also expected to develop during
the late afternoon and early evening. The cold front is forecast to
be a bit faster than some of the model solutions are suggesting. For
this reason, the faster model solutions are favored and the slight
risk has been placed accordingly.
..Broyles.. 09/22/2023
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by SPC Forecast Products | Sep 22, 2023 | Weather and Emergency Alerts
No Mesoscale Discussions are in effect as of Fri Sep 22 07:22:02 UTC 2023.
by SPC Forecast Products | Sep 22, 2023 | Weather and Emergency Alerts
No watches are valid as of Fri Sep 22 07:22:02 UTC 2023.
by SPC Forecast Products | Sep 22, 2023 | Weather and Emergency Alerts
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0130 AM CDT Fri Sep 22 2023
Valid 231200Z - 241200Z
...NO CRITICAL AREAS...
...Synopsis...
Fire weather concerns should remain fairly localized for Saturday
along the High Plains. A surface low and an attendant surface trough
are forecast to deepen as they migrate east across the Plains on
Saturday. This will establish a zonal flow regime across much of the
Rockies and High Plains by late morning. Downslope warming/drying
along the CO Front Range and in the lee of the Sangre de Cristo and
Sandia/Manzano Mountains, augmented by diurnal heating, should
promote areas of 15-25% RH as winds increase to 15-20 mph (with
locally drier/windier in terrain-favored locations). Somewhat meager
mid to upper-level winds should confine the strongest surface winds
close to terrain features - with the exception of southeast WY into
adjacent portions of NE/northeast CO where surface gradient winds
will be stronger. This, combined with somewhat marginal fuel status
outside of far northeast NM and southern CO, will limit the coverage
of elevated conditions and the overall fire weather threat.
..Moore.. 09/22/2023
...Please see www.spc.noaa.gov/fire for graphic product...
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by SPC Forecast Products | Sep 22, 2023 | Weather and Emergency Alerts
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Sep 22 2023
Valid 231200Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT PLAINS...AND LOWER TO MID MISSOURI VALLEY...
...SUMMARY...
Thunderstorms, associated with large hail and wind damage, will be
possible on Saturday across eastern parts of the Great Plains, and
in the Lower to Mid Missouri Valley. Marginally severe storms will
also be possible in parts of the Mid-Atlantic.
...Great Plains/Lower to Mid Missouri Valley...
An upper-level low will move northeastward across the northern
Plains on Saturday as an associated mid-level jet moves through the
base of the trough. At the surface, a low will move quickly
northward from eastern Nebraska into western Minnesota, as a cold
front moves eastward through the central Plains. As surface heating
takes place ahead of the front, scattered thunderstorms are expected
to develop from parts of the eastern Dakotas south-southeastward
into parts of the lower to mid Missouri Valley. Cell coverage will
gradually increase in the late afternoon and early evening, with MCS
development likely across parts of the region.
By midday, a north-to-south corridor of moderate instability will
likely be in place from eastern Kansas northward into eastern
Nebraska, where MLCAPE is forecast to peak in the 1500 to 2500 J/kg
range. Moderate to strong deep-layer shear will also be present
along this corridor, with the strongest shear located beneath the
mid-level jet in the mid Missouri Valley. The thermodynamic and
kinematic environment should support supercell development, with the
greatest supercell threat located from near the axis of the jet
southward. This is forecast to be in far eastern Nebraska and
western Iowa, where the combination of instability and shear is
forecast to be the greatest. Supercells will have a threat for large
hail and wind damage.
Further north into parts of eastern South Dakota and western
Minnesota, there is some uncertainty concerning how much instability
will develop. The more aggressive solutions with instability suggest
that supercells will be possible with a threat for large hail and
wind damage. Because of the uncertainty concerning instability, the
slight risk over far eastern South Dakota and southwest Minnesota is
more conditional.
...Southern Plains...
At mid-levels, west-southwesterly flow will be in place on Saturday
across much of the Desert Southwest and southern Rockies, with
northwesterly divergent flow located over much of the southern
Plains. At the surface, a cold front will advance southeastward into
the southern High Plains. Isolated to scattered thunderstorms are
expected to form along and near the front by afternoon, as moderate
to strong instability develops. Several storm clusters appear likely
to become organized in the late afternoon, persisting into the early
to mid evening.
Forecast soundings ahead of the front, from Oklahoma City to Wichita
Falls, suggest that MLCAPE will peak in the 2000 to 3000 J/kg range
during the late afternoon. 0-6 km shear is forecast to be in the 35
to 45 knot range, with 700-500 mb lapse rates near 7.5 C/km. This
environment will likely support supercells with large hail. Wind
damage may also occur, especially with mixed mode cell clusters that
become organized. The severe threat from far southern Oklahoma to
west-central Texas will likely be marginal, due to a lack of
large-scale ascent.
...Mid-Atlantic...
A tropical system is forecast by the National Hurricane Center to
move through eastern North Carolina on Saturday. To the east of the
center, instability is forecast to increase during the day from
eastern north Carolina into eastern Virginia. A marginal tornado
threat may develop with bands of convection that move through the
stronger instability.
..Broyles.. 09/22/2023
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