29.6F
Current conditions from King Hill
Updated every 5 minutes
 
  Tuesday November 24, 2020

RSS Mesoscale Discussions from Storm Prediction Center

SPC - No watches are valid as of Tue Nov 24 08:28:02 UTC 2020

No watches are valid as of Tue Nov 24 08:28:02 UTC 2020.


No Mesoscale Discussions are in effect as of Tue Nov 24 08:28:02 UTC 2020.

SPC Nov 24, 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
1133 PM CST Mon Nov 23 2020

Valid 241200Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...

...SUMMARY...
Severe thunderstorms are possible late afternoon Tuesday into
Tuesday night across portions of the southern/central Plains,
Ozarks, Mid-South, and lower Mississippi Valley.  Large hail and
severe gusts are the primary hazards.

...Central/Southern Plains to Lower MS Valley...

Strong mid-level vort with an accompanying 90kt+ speed max are
digging into the lower CO River Valley at 0530z. This feature will
shift east into southern NM by 18z then into the southern High
Plains by late afternoon. 120m 12hr height falls, along with a
focused exit region of the aforementioned jet, suggest convection
will develop by early afternoon along the front over the western
OK/TX Panhandle region. Forecast soundings suggest the strongest
boundary-layer heating will be noted across this region, and despite
the relatively dry boundary layer, profiles exhibit more than
adequate instability for surface-based convection along the front.
RAP forecast sounding for DHT exhibits ~900 J/kg SBCAPE with steep
lapse rates and -22C at 500mb. Hail production should be efficient
with this activity, although it may be initially sub-severe.

Late-evening surface data suggests mid 50s surface dew points are
advancing north across the Edwards Plateau and this moisture plume
should return across western OK prior to the main convective
development. While large-scale forcing for ascent should ultimately
lead to more organized line segments downstream, initial activity
across the far northeastern TX Panhandle into northwestern OK should
be supercellular in nature. This early activity could certainly
produce very large hail before the convective mode is disrupted.
Prior to this disruption, a few brief tornadoes are also possible.
As large-scale forcing spreads across western OK, a more organized
band of storms should evolve then propagate east with an attendant
hail/wind threat. Given that the LLJ will be focused into northeast
OK/Ozark Plateau region, the primary corridor for organized
convection should spread north of I-40 across OK into this region.

Farther south, it's not entirely clear how active the warm sector
will be prior to the cold frontal passage across northeast TX into
western AR. HRRR is the most aggressive high res model in generating
discrete storms in the warm sector by 25/00z, then along the front
as it advances into this more moist air mass. However, stronger
forcing will remain north of this region and there is reason to
believe convection may be a bit more isolated across this region.
Will maintain MRGL Risk across this area due to uncertainty in storm
coverage/intensity.

..Darrow/Squitieri.. 11/24/2020

Read more

SPC Nov 24, 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
1255 AM CST Tue Nov 24 2020

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER/MID MISSISSIPPI VALLEY INTO THE OHIO/TENNESSEE VALLEYS AND
SOUTHEAST...

...SUMMARY...
Isolated strong to severe thunderstorms may occur Wednesday across
parts of the lower/mid Mississippi Valley into the Ohio/Tennessee
Valleys and Southeast. Locally damaging winds should be the main
threat, although a tornado or two also appears possible.

...Lower/Mid Mississippi Valley into the Ohio/Tennessee Valleys and
Southeast...
A closed upper low with associated mid-level southwesterly jet
should be centered over the lower/mid MS Valley at the start of the
period Wednesday morning. These features are forecast to track
eastward across the OH/TN Valleys and Southeast through the day. At
the surface, a low initially over northern MO should develop
east-northeastward towards the lower Great Lakes by Wednesday
evening while gradually weakening. A trailing cold front is expected
to move generally eastward across the lower/mid MS Valley, OH/TN
Valleys, and parts of the Southeast through the day.

A line of showers and thunderstorms should be ongoing along or just
ahead of the cold front Wednesday morning across parts of the lower
MS Valley into the Mid-South. Only weak destabilization is forecast
ahead of this line as low-level moisture gradually increases across
these areas. Still, the presence of around 40-50 kt of effective
bulk shear and enhanced low-level southwesterly flow suggests a
continued threat for isolated damaging winds with the line as it
moves eastward through the morning. A tornado or two also cannot be
ruled out. The more pronounced large-scale forcing for ascent
associated with the upper low is forecast to gradually shift away
from the Southeast and TN Valley regions through the day. Additional
robust storm development Wednesday afternoon/evening appears
uncertain, with low-level convergence along the front providing the
main source of lift. If additional storms can form Wednesday
afternoon across parts of MS/AL and perhaps middle TN, they could be
strong to severe given at least weak instability and sufficient
deep-layer shear. Strong/gusty winds would remain the primary threat
with this activity through early Wednesday evening.

Farther north across parts of the mid MS Valley into the OH Valley,
low-level moisture should remain more limited, with mainly mid to
upper 50s surface dewpoints possible. These regions will be in close
proximity to both the surface and upper low, with somewhat stronger
low/mid-level wind fields compared to locations farther south. Cool
mid-level temperatures (around -18 to -20 C at 500 mb) associated
with the upper low combined with modest diurnal heating ahead of the
cold front may support weak surface-based instability by early
Wednesday afternoon. A broken, low-topped line of storms may develop
across parts of the Midwest into the OH Valley in this high
shear/low instability environment. Given the strength of the
low-level flow, isolated damaging winds would be the main threat if
adequate destabilization occurs.

..Gleason.. 11/24/2020

Read more

SPC Nov 24, 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
0224 AM CST Tue Nov 24 2020

Valid 261200Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States on Thursday, but small hail may occur with
thunderstorms across parts of east Texas into the ArkLaTex late
Thursday night.

...Synopsis and Discussion...
A de-amplifying shortwave trough should move across the Mid-Atlantic
and southern New England on Thursday. A weak surface low associated
with this feature is forecast to fill further through the day. An
eastward-moving cold front should extend from the Mid-Atlantic
southwestward along parts of the East Coast and into the Southeast.
The stronger mid-level flow attendant to the shortwave trough should
remain displaced to the north of greater low-level moisture across
the Carolinas and Southeast. Although enough weak elevated
instability may develop across the eastern part of the Mid-Atlantic
and southern New England to support isolated thunderstorms,
surface-based convection appears unlikely at this time. From the
Carolinas into the Southeast, additional storms may occur through
the day along/ahead of the cold front. These areas will remain
generally to the south of stronger forcing for ascent related to the
previously mentioned shortwave trough, with overall storm coverage
expected to remain fairly low.

As a positively tilted upper trough moves southeastward over the
western/central CONUS, low-level moisture return should occur across
parts of coastal/east TX and the ArkLaTex region late Thursday into
early Friday morning. Modestly steepened mid-level lapse rates
emanating from the higher terrain of west TX and northern Mexico may
overspread this region late in the period. Weak to perhaps moderate
MUCAPE should develop along/north of a front, with sufficient
mid-level west-southwesterly flow to support some deep-layer shear.
At this point, small hail appears possible with any storms that can
form in a weak low-level warm advection regime. However, confidence
in an isolated large hail threat from elevated storms remains low
owing to nebulous large-scale forcing with the upper trough
remaining well to the west, and differences in model guidance
regarding both the placement and overall coverage of storms.

..Gleason.. 11/24/2020

Read more

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
0122 AM CST Tue Nov 24 2020

Valid 241200Z - 251200Z

...Synopsis...
A progressive mid-level shortwave trough will eject into the central
CONUS as a surface cyclone matures and moves eastward across the
Plains states through the period. Dry westerly winds are expected
behind a dryline across portions of the central/southern High
Plains, prompting wildfire-spread concerns. West of the Rockies,
upper ridging will occur during the day, with a second trough
approaching the West Coast towards the end of the period. Surface
high pressure will dominate the Great Basin, with a weak offshore
flow pattern expected across portions of the southern California
Transverse Ranges.

...Southern High Plains...
Behind the dryline, RH is expected to dip as low as 15-20% by
afternoon peak heating, coinciding with 25+ mph sustained westerly
surface winds. With fuels becoming increasingly dry across eastern
New Mexico into western Texas, Elevated highlights have been
maintained. Confidence exists in more widespread Critical conditions
occurring across portions of the Trans Pecos Mountains towards
southern Parts of the Permian Basin in western Texas. However, the
biggest factor precluding an introduction to Critical highlights
continues to be ongoing higher surface RH across the area, which
will likely dampen some of the finer fuels until late morning into
early afternoon, when Elevated/Critical conditions are expected. 

Across northernmost portions of the Texas Elevated, a few
thunderstorms may develop atop a drier boundary layer. These storms
are expected to be relatively high-based in nature, with instances
of gusty, erratic winds possible. While these storms may be on the
wet side, a couple lightning flashes on the periphery of the
stronger cores may be possible. Dry strikes are expected to remain
sparse, precluding an isolated dry thunderstorm area. However, it is
not out of the question that a peripheral strike occurring with
erratic thunderstorm wind gusts may locally enhance wildfire spread,
particularly where the finer fuels are most receptive.

...Southern California...
Through the period, weak offshore flow is expected across portions
of the southern California Transverse Ranges. Nonetheless, very
localized Elevated conditions (15-25 mph sustained winds and 15-25%
RH) may occur across terrain-favoring areas, particularly over the
San Gabriel Mountains per latest high-resolution model guidance.

..Squitieri.. 11/24/2020

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

Read more

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
0210 AM CST Tue Nov 24 2020

Valid 251200Z - 261200Z

...Synopsis...
A mid-level trough will move across the central/eastern U.S while a
second trough aloft traverses the Inter-mountain West during the Day
2/Wednesday period. Given the approach of the western trough,
surface lee troughing is expected to develop across the High Plains
states, with dry and breezy downslope flow likely across portions of
eastern New Mexico. Meanwhile, towards the end of the period,
surface high pressure will build across the western CONUS, with a
pressure gradient developing across California, setting the stage
for the beginning of prolonged dry offshore flow.

...Southern High Plains...
By afternoon peak heating, surface lee troughing will encourage
downslope flow along the lee of the southern Rockies into western
parts of the Llano Estacado across the southern High Plains. Latest
guidance consensus depicts 15-25 mph sustained westerly winds
coinciding with 15-25% RH. Fuels across the area are modestly
receptive to fire spread, and Day 1 precipitation accumulations are
expected to be very light at best, warranting an Elevated
delineation.

...Southern California...
Short-range guidance shows the development of a surface pressure
gradient across central into southern California towards the end of
the period (early Thursday Morning). Some of the high resolution
model guidance depicts 15-25 mph offshore flow developing in the
higher terrain of the southern Santa Lucia Range towards the Santa
Ynez Mountains after 06Z. However, some overnight RH recovery is
likely, with RH dropping mainly into the 25-40% range. As such, an
Elevated area will be withheld for now, with trends in RH being
closely monitored for the need of fire weather highlights in future
outlooks.

..Squitieri.. 11/24/2020

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

Read more


 
 
Current Radar Loop:

Copyright © WestfordWeather.net 2007-2020. All rights reserved.