SPC Nov 28, 2020 0830 UTC Day 3 Severe Thunderstorm Outlook

SPC Nov 28, 2020 0830 UTC Day 3 Severe Thunderstorm Outlook

SPC 0830Z Day 3 Outlook
Day 3 Outlook Image
Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0226 AM CST Sat Nov 28 2020

Valid 301200Z - 011200Z


Isolated strong to severe thunderstorms capable of producing
damaging winds and perhaps a couple of tornadoes appear possible on
Monday from parts of Florida and coastal Georgia into the Carolinas
and Mid-Atlantic.

...Florida/Coastal Georgia into the Carolinas and Mid-Atlantic...
A large-scale upper trough should evolve into a closed low over the
Midwest/OH Valley and central Appalachians on Monday. A mid-level
vorticity maximum embedded within this upper trough is forecast to
move quickly northeastward from the central Appalachians into the
Mid-Atlantic through Monday afternoon. A deep surface low should
likewise develop northeastward in tandem with this vorticity
maximum. A cold front trailing from this surface low will likely
sweep eastward across much of the FL Peninsula and the East Coast
through the day. A warm front extending northeastward from the
surface low will probably make some northward progress across parts
of the Mid-Atlantic through Monday afternoon as well.

A line of low-topped showers/storms along or just ahead of the cold
front should be ongoing at the start of the period from near the
surface low in WV/western VA southward to northern FL. Although
instability may remain modest across most of the warm sector ahead
of this line, generally low to mid 60s surface dewpoints should be
enough to support weak surface-based instability through the day. A
very strong (50-60+ kt) south-southwesterly low-level jet should be
present over the central/eastern Carolinas and southern VA Monday
morning, and this feature is forecast to shift northward across the
Mid-Atlantic through the day. 

Given the strength of the low-level flow and sufficient, albeit
weak, forecast instability, strong to damaging winds may occur with
storms that either persist along the cold front or develop ahead of
it over the open warm sector. A couple tornadoes also appear
possible, mainly across parts of eastern SC/NC/VA to the Delmarva
Peninsula and perhaps NJ in associated with the low-level jet and
potentially greater low-level moisture and instability. Even so,
there is too much uncertainty regarding sufficient destabilization
to include higher severe probabilities for now.

Farther south, low-level convergence along the cold front and
deep-layer shear are both forecast to be somewhat weaker across
coastal GA and the FL Peninsula. Still, there may be isolated
strong/gusty winds with any storms through Monday afternoon.

..Gleason.. 11/28/2020

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SPC Day 2 Fire Weather Outlook

SPC Day 2 Fire Weather Outlook

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook Image
Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0136 AM CST Sat Nov 28 2020

Valid 291200Z - 301200Z

An amplifying upper-level pattern over the CONUS will feature a
deepening trough over the East with upper-level ridging over the
West by the late weekend. While this pattern will feature weak
mid-level winds across the Southwest, where conditions have been
fairly dry, surface high pressure over the central CONUS will
augment pressure gradient winds over the Plains and portions of
southern California. This could lead to localized fire weather

...Southern California...
Although upper-level ridging will continue to support weak winds
aloft for Sunday, a reinforced surface high over the central Rockies
and into the northern Great Basin will continue to foster offshore
pressure-gradient winds for southern CA. Poor overnight RH
recoveries are expected with RH values in the teens likely for
Sunday afternoon. The LAX-DAG pressure gradient is forecast to be
similar in magnitude as Saturday's, suggesting that elevated, to
locally critical, fire weather conditions will be possible again for
terrain-favored locations in the higher elevation of southern CA.
This idea is supported by recent high-res ensemble guidance and
deterministic model solutions.

...Central to Southern High Plains...
Building surface high pressure over the northern High Plains in the
wake of a cold front will help drive an increase in
pressure-gradient winds through the day on Sunday. Strong northerly
850 mb flow within a cold advection regime over the central to
southern Plains will help mix stronger winds down to the surface
with gusts up to 30-40 mph possible. Some deterministic solutions
and high-res ensemble members hint at the potential for RH
reductions into the low 20s across western KS and the OK/TX
Panhandles during the afternoon hours. However, confidence in this
scenario is not high due to the potential for cold advection to
limit RH reductions. Additionally, fuels across this region are only
modestly receptive and portions of the OK/TX Panhandles may see
prior precipitation on Saturday. As such, no highlights are
introduced in this outlook, though trends in guidance and
precipitation on Saturday will be monitored.

..Moore.. 11/28/2020

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

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SPC Nov 28, 2020 0700 UTC Day 2 Convective Outlook

SPC Nov 28, 2020 0700 UTC Day 2 Convective Outlook

SPC 0700Z Day 2 Outlook
Day 2 Outlook Image
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1250 AM CST Sat Nov 28 2020

Valid 291200Z - 301200Z


Isolated strong to severe thunderstorms may occur Sunday into Sunday
night across parts of the lower Mississippi Valley, Southeast, and
Carolinas. Damaging winds and perhaps a couple of tornadoes should
be the main threats.

...Lower Mississippi Valley into the Southeast and Carolinas...
A closed upper low centered over the southern Plains Sunday morning
will move eastward through the day. This upper low should begin to
merge with a positively tilted, northern-stream upper trough over
the eastern states Sunday evening into early Monday morning. A weak
surface low initially near the coast of southwestern LA is forecast
to develop northeastward across parts of LA/MS/AL through the day
while gradually deepening. Additional deepening of this surface low
should occur from Sunday night through the end of the period as it
continues developing northeastward along/near the spine of the
southern/central Appalachians. A warm front attendant to the surface
low will lift northward across parts of the Southeast and Carolinas,
while a trailing cold front sweeps eastward across these regions
through the period.

Most guidance indicates that storms will be ongoing Sunday morning
over the northern Gulf of Mexico near the LA Coast. Low-level warm
advection should be the primary forcing mechanism for this activity,
with the low-level jet forecast to shift northward across MS/AL
through the day. Some concern remains regarding how much low-level
moisture will be able to return inland given the potential for
numerous to widespread storms over the northern Gulf of Mexico
Sunday morning. If mid to upper 60s surface dewpoints can develop
inland across parts of southern LA/MS/AL and the FL Panhandle in
tandem with the deepening surface low and northward-advancing warm
front, then only modest diurnal heating would be needed to support
weak instability and surface-based storms. Strong effective bulk
shear of 45-60 kt will easily support organized convection, with
supercells possible along/ahead of the cold front. Isolated strong
to damaging winds should be a concern given the strength of the
low/mid-level flow and potential for storms to grow upscale into a
low-topped line along the cold front by Sunday evening. Low-level
shear also appears strong enough for updraft rotation, with a couple
tornadoes possible across the warm sector with any semi-discrete

This isolated severe threat will probably continue across parts of
GA into the Carolinas Sunday night and early Monday morning (end of
the Day 2 period), as low-level moisture return occurs from the
western Atlantic, and as a south-southwesterly jet rapidly
strengthens over these areas. However, even though the low-level
flow will likely be quite strong, instability is forecast to remain
rather weak (generally less than 500 J/kg of MLCAPE). The northern
extent of any meaningful damaging wind/tornado threat across the
Southeast remains unclear, as there is uncertainty in how far north
the mid 60s to upper surface dewpoints will advance. If confidence
increases in a narrow corridor of greater instability developing
across the warm sector on Sunday, then a Slight Risk for damaging
winds and/or tornadoes may be included across some portion of these
regions in a later outlook.

..Gleason.. 11/28/2020

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SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook Image
Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1237 AM CST Sat Nov 28 2020

Valid 281200Z - 291200Z

An upper-level closed low will continue to gradually shift eastward
into the southern Plains through the day today, bringing widespread
precipitation and cloud cover. To the north, a clipper low along the
Canadian border will usher in a weak cold front across the northern
High Plains. Breezy conditions behind this front could support brief
fire weather concerns. Upper-level ridging over the West will
mitigate most fire weather concerns for today. One exception will be
the higher elevation of southern California where continued offshore
flow may support a fire weather threat. 

...Southern California...
Although early morning surface observations show poor overnight RH
recoveries across southern CA, winds are weaker compared to 24 hours
ago with the exception of a few stations in the San Gabriel
Mountains. This is largely due to gradual upper-level ridging over
the West coast and diminishing winds throughout the column. Despite
an approaching low-amplitude offshore disturbance, mid-level winds
will continue to be weak through the day and limit the potential for
widespread critical fire weather conditions. However, persistent
offshore pressure-gradient winds will continue to support areas of
elevated, to locally critical, fire weather conditions for the
higher elevation of southern CA. The fire weather threat may be
highest during the morning hours when the LAX-DAG pressure gradient
is forecast to be the strongest before relaxing later in the day. 

...Northern High Plains...
Morning guidance continues to show the potential for elevated fire
weather conditions this afternoon for western ND and eastern MT as
winds increase behind a southeastward moving cold front. Fuels
remain dry and/or dormant across this region and wind gusts upwards
of 25-35 mph appear possible. However, uncertainty remains somewhat
high regarding the degree of RH reductions with most guidance
remaining above elevated RH thresholds. Additionally, the temporal
window for elevated conditions appears limited to a couple of hours
during the late afternoon. Due to these concerns no highlights are
introduced, but conditions will continue to be monitored through the

..Moore.. 11/28/2020

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

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SPC Nov 28, 2020 0600 UTC Day 1 Convective Outlook

SPC Nov 28, 2020 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1120 PM CST Fri Nov 27 2020

Valid 281200Z - 291200Z


Severe thunderstorms appear unlikely across the contiguous United
States today.

As a trough within the fast northern-stream westerlies moves quickly
across the Northeast today, an upper low south of the main belt of
polar flow will move gradually eastward out of New Mexico and across
the southern Plains.

As this low advances, weak surface cyclogenesis is expected to begin
later in the day, along a remnant baroclinic zone extending from
south Texas eastward across the northern Gulf of Mexico/Gulf Coast
region.  Elsewhere, high pressure will prevail across most of the
remainder of the country.

At the start of the period Saturday morning, two main areas of
convection will be ongoing -- one over the Southeast near the
remnant front, in conjunction with an eastward-moving disturbance,
and the second over Texas and the western Gulf.

With time, the southeastern U.S. convection is forecast to move
eastward/offshore, though a few showers and storms may linger over
northern Florida through the afternoon near the surface front. 
Meanwhile, the Texas convection is expected to increase in coverage
and spread eastward with time, eventually spreading into Louisiana
and vicinity into the overnight hours as quasi-geostrophic forcing
for ascent persists ahead of the advancing upper low.  However,
inland instability will remain weak and elevated, and post-frontal
convection acting to reinforce the cool/stable boundary layer.  

The only exception to this overall expectation could evolve along
the immediate coastal counties of the middle Texas coast.  Here,
proximity to the evolving frontal low could allow modest
surface-based instability near the coast, along with a somewhat
favorable wind profile.  However, this appears to be a very
low-probability scenario at this time, with the low expected to
remain just offshore.  Therefore, no risk areas will be added at
this time.

..Goss/Moore.. 11/28/2020

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Severe Thunderstorm Warning

Severe Thunderstorm Warning

This is an automatic message WUUS52 KGSP 150312

Severe Thunderstorm Warning
National Weather Service Greenville-Spartanburg SC
1112 PM EDT Sun Apr 14 2019

The National Weather Service in Greenville-Spartanburg has issued a

* Severe Thunderstorm Warning for…
Eastern Lincoln County in the Piedmont of North Carolina…
Southeastern Cleveland County in the Piedmont of North Carolina…
Gaston County in the Piedmont of North Carolina…
Northwestern York County in Upstate South Carolina…
Northeastern Cherokee County in Upstate South Carolina…

* Until midnight EDT.

* At 1112 PM EDT, severe thunderstorms were located along a line
extending from near Shelby to 19 miles west of Gastonia to 6 miles
east of Gaffney, moving east at 35 mph.

HAZARD…60 mph wind gusts.

SOURCE…Radar indicated.

IMPACT…Expect damage to trees and power lines.

* Locations impacted include…
Gastonia, Shelby, Kings Mountain, Mt Holly, Belmont, Cherryville,
Bessemer City, South Gastonia, Clover and Dallas.


Scattered trees and power lines will be blown down in the warned
area. Seek shelter inside an interior room.

These storms are also producing extremely heavy rainfall. Flooding of
drainage ditches and low lying areas may occur. Small streams will
rise rapidly. Do not drive through areas where water is flowing over
the road.

Please report damaging winds, hail, or flooding to the National
Weather Service Greenville-Spartanburg by calling toll free, 1, 800,
2 6 7, 8 1 0 1, or by posting on our Facebook page, or Tweet it using
hashtag nwsgsp. Your message should describe the event and the
specific location where it occurred.


A Tornado Watch remains in effect until 500 AM EDT for the Piedmont
of North Carolina…and Upstate South Carolina.

LAT…LON 3535 8097 3530 8100 3527 8102 3517 8100
3515 8101 3514 8105 3510 8103 3509 8106
3495 8165 3515 8157 3530 8163 3555 8106
3555 8096 3550 8096 3549 8095 3545 8094
3543 8096 3539 8095 3537 8099 3536 8092
TIME…MOT…LOC 0312Z 248DEG 32KT 3526 8153 3518 8150 3504 8155

HAIL…<.75IN WIND...60MPH $$ HG