SPC - No watches are valid as of Fri Sep 13 08:45:02 UTC 2024

No watches are valid as of Fri Sep 13 08:45:02 UTC 2024.

SPC - No MDs are in effect as of Fri Sep 13 08:45:02 UTC 2024

No Mesoscale Discussions are in effect as of Fri Sep 13 08:45:02 UTC 2024.

SPC Sep 13, 2024 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook
      
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1233 AM CDT Fri Sep 13 2024

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHEAST...

...SUMMARY...
An isolated tornado threat is expected to develop this morning and
afternoon across parts of Alabama, western Georgia and middle
Tennessee. A few isolated severe gusts will be possible in parts of
Alabama, southwest Georgia and the Florida Panhandle.

...Southeast...
The remnants of post-tropical cyclone Francine are expected to move
slowly across the lower to mid Mississippi Valley today. To the
southeast of the upper low, an axis of instability is forecast to be
in place across eastern Alabama this morning. As surface
temperatures warm, thunderstorm development be likely along and near
the instability axis. Storms will move northward across eastern
Alabama and middle Tennessee, along and near a corridor of maximized
low-level winds. RAP forecast soundings this morning near this
corridor have 0-1 km shear near 20 knots in northeast Alabama and
around 25 knots in middle Tennessee. This suggests a low-end
potential for tornadoes associated with semi-discrete rotating
cells. The threat may continue into the afternoon as instability
maximizes across the region. A potential for severe gusts will also
be possible across Alabama extending southward into the Florida
Panhandle, where low-level shear may not be as strong but moderate
instability is expected to develop.

..Broyles/Weinman.. 09/13/2024


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SPC Sep 13, 2024 0600 UTC Day 2 Convective Outlook

SPC 0600Z Day 2 Outlook
      
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1237 AM CDT Fri Sep 13 2024

Valid 141200Z - 151200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast on Saturday.

...Central High Plains to central/western SD...
As a Pacific cold front stalls and decays Friday night over the
northern Great Plains, a north/south-oriented surface trough should
redevelop west by late Saturday afternoon from northeast CO to the
western Dakotas. While a minority of models suggest isolated
thunderstorms may form along this boundary, the majority suggests
isolated to widely scattered thunderstorms should develop during the
afternoon in the modest low-level warm theta-e advection regime
ahead of the trough. This regime may be aided by a low-amplitude
upper-level trough trailing southward from the Canadian Prairies,
but neutral to weak mid-level height rises are forecast during the
period. Upper flow will be weak near the trough, but sufficient
veering of low to mid-level winds with height may yield effective
bulk shear of 25-30 kts. Amid steep mid-level lapse rates, a couple
of storms could produce marginally severe hail. Moderate spatial
uncertainty with this corridor of risk, along with the marginal
nature of the conditional severe threat, precludes an areal
delineation. 

...Southeast...
The remnants of post-TC Francine should slowly weaken and remain
nearly stationary in the Lower MS Valley. At least modest buoyancy
should be displaced well to its southeast across FL into south GA
and southeast AL on Saturday afternoon. Weaknesses in both
deep-layer shear and lapse rates above the boundary layer suggest
the threat for organized severe storms is negligible.

..Grams.. 09/13/2024


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SPC Sep 13, 2024 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook
      
Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0208 AM CDT Fri Sep 13 2024

Valid 151200Z - 161200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected on Sunday.

...Discussion...
At least isolated thunderstorm potential is evident across a larger
portion of the CONUS on D3, but the threat for organized severe
storms remains negligible.

A blocking upper pattern will hold in the East, with a stout
mid-level anticyclone over the Lower Great Lakes and the remnants of
post-TC Francine anchored in the Lower MS Valley. A strong mid/upper
jet approaching the Pacific Coast will amplify a closed mid/upper
low over northern/central CA by Monday morning. Strengthening
large-scale ascent downstream may yield a broadening swath of
low-probability thunderstorm potential in the West with only
scant/meager buoyancy north of AZ. Afternoon buoyancy should be
largest across parts of the central High to northern Great Plains.
This could support a few strong, sub-severe storms around to just
after peak heating, amid weak/modest deep-layer shear and a benign
synoptic pattern.

..Grams.. 09/13/2024


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SPC Sep 13, 2024 Day 4-8 Severe Weather Outlook

Day 4-8 Outlook
      
Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0341 AM CDT Fri Sep 13 2024

Valid 161200Z - 211200Z

...DISCUSSION...
Guidance has trended increasingly consistent with the evolution of a
closed mid/upper low initially over northern/central CA at 12Z
Monday. This low should become an open wave as it pivots northeast
towards the northern High Plains by late Tuesday, likely inducing
surface cyclogenesis in the eastern MT vicinity. Despite increasing
agreement in track/timing, the consensus trend is for a weakening
mid-level jet ejection, in the meridional flow regime ahead of the
trough. As such, the amplitude of the severe-storm risk is still
uncertain, but an area of interest for a future 15 percent highlight
remains evident across the northern High Plains. 

This shortwave trough should dampen and slow as it encroaches on the
persistent blocking pattern in the East. In the wake of this wave,
the next in a series of shortwave impulses should amplify along the
Pacific Coast mid-week. Thereafter, predictability drops
considerably by late week.


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SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook
          
Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0157 AM CDT Fri Sep 13 2024

Valid 131200Z - 141200Z

...NO CRITICAL AREAS...

...Synopsis...
A broad large-scale trough over the West will deamplify, though
moderate west-southwesterly midlevel flow across the Rockies will
maintain a lee trough/dryline along the central/southern High
Plains. Behind the dryline over northeastern NM into the TX
Panhandle, breezy west-southwesterly surface winds will develop in
response to a weak lee cyclone over the TX/OK Panhandles. These
winds will overlap a hot/dry boundary layer during the afternoon,
potentially yielding locally elevated fire-weather conditions.
However, the fire-weather threat appears too localized for an
Elevated area.

..Weinman.. 09/13/2024

...Please see www.spc.noaa.gov/fire for graphic product...


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SPC Day 2 Fire Weather Outlook

SPC Day 2 Fire Weather Outlook
          
Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0157 AM CDT Fri Sep 13 2024

Valid 141200Z - 151200Z

...NO CRITICAL AREAS...

...Synopsis...
A belt of midlevel westerly flow will strengthen from the Northwest
into the northern Plains, as a large-scale trough begins to amplify
over the western CONUS. Associated lee troughing over the northern
High Plains will favor dry/breezy conditions across portions of WY
during the afternoon. While this could result in locally elevated
fire-weather conditions, the overall threat appears too minimal for
highlights at this time. Farther west, breezy southerly surface
winds are expected across parts of the Great Basin ahead of the
gradually amplifying large-scale trough. However, a modest increase
in moisture/RH, and a lack of stronger sustained surface winds,
should generally limit fire-weather potential.

..Weinman.. 09/13/2024

...Please see www.spc.noaa.gov/fire for graphic product...


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