Saturday 9/28/2019 Day 1 Slight

A place to discuss upcoming severe weather setups. Unless otherwise noted, all posts of weather graphics are for informational purposes only, by non-meteorologists. All posted weather models should be taken with a grain of salt. Please refer to your local news or radio and other official sources for up-to-date weather information.
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thunderchaser83
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Saturday 9/28/2019 Day 1 Slight

Post by thunderchaser83 » Thu Sep 26, 2019 4:02 pm

day3otlk_0730.gif
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SPC AC 260704

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0204 AM CDT Thu Sep 26 2019

Valid 281200Z - 291200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN AND CENTRAL PLAINS INTO THE OZARKS AND IN PARTS OF THE
NORTHEAST...

...SUMMARY...
Marginally severe thunderstorms are expected to occur on Saturday
from parts of the southern and central Plains into the Ozarks and in
parts of the Lower Great Lakes region.

...Southern and Central Plains/Ozarks...
An upper-level ridge is forecast to build northward across the
Mississippi Valley on Saturday as a high-pressure system strengthens
in the Southeast. An upper-level trough is forecast to develop in
the western states as southwest mid-level flow remains in the
central U.S. At the surface, a cold front is forecast to stall from
the central Plains into the mid Mississippi Valley. As mid-level
heights rise during the day, the front may begin to retreat
northward as low-level moisture increases to the south of the front.
Due to the rising heights and lack of large-scale ascent,
thunderstorm development along the front should remain isolated in
most areas. Although moderate instability will likely develop across
parts of the warm sector, deep-layer shear should remain weak enough
to keep any severe threat marginal. Thunderstorms that can develop
and persist through the late afternoon and early evening, could
become strong enough to produce marginally severe wind gusts and
hail.

...Lower Great Lakes...
A fast moving shortwave trough will affect the Northeast on Saturday
as mid-level flow becomes more westerly. At the surface, a cold
front is expected to advance southward across the lower Great Lakes
region. Surface dewpoints ahead of the front in the lower to mid 60s
F will contribute to some destabilization ahead of the front. This
combined with low-level convergence along the front should result in
scattered thunderstorm development Saturday afternoon. Although
instability should remain weak, moderate deep-layer shear may be
enough for a marginal wind-damage threat with the stronger
thunderstorms.

..Broyles.. 09/26/2019

thunderchaser83
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Posts: 19
Joined: Wed Sep 25, 2019 1:41 am

Re: Saturday 9/28/2019 Day 3 Marginal

Post by thunderchaser83 » Thu Sep 26, 2019 4:11 pm

Looks like this is going to just be a marginal hail threat...will need to wait for nam and hrrr to come into range...
500 MB Heights Valid 9/29/2019 00z
500 MB Heights Valid 9/29/2019 00z
500wh.conus.png (251.19 KiB) Viewed 132 times
EHI Valid 9/29/2019 00z
EHI Valid 9/29/2019 00z
ehi03.us_sc.png (295.86 KiB) Viewed 132 times
Surface Dew Point Valid 9/29/2019 00z
Surface Dew Point Valid 9/29/2019 00z
sfctd.us_sc.png (145.28 KiB) Viewed 132 times

thunderchaser83
Site Admin
Posts: 19
Joined: Wed Sep 25, 2019 1:41 am

Re: Saturday 9/28/2019 Day 2 Slight

Post by thunderchaser83 » Fri Sep 27, 2019 7:08 pm

SPC Day 2 Outlook
SPC Day 2 Outlook
day2otlk_1730.gif (29.94 KiB) Viewed 121 times
SPC AC 271735

Day 2 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1235 PM CDT Fri Sep 27 2019

Valid 281200Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHERN
OKLAHOMA...EASTERN KANSAS AND WESTERN MISSOURI...

CORRECTED FOR SOUTHERN PLAINS TEXT

...SUMMARY...
Isolated strong to severe thunderstorms will be possible on Saturday
from parts of the southern and central Plains into the Ozarks, and
across parts of New York into the Ohio Valley. A somewhat greater
chance for severe weather may exist Saturday afternoon across
portions of central/eastern Kansas into far western Missouri.

...Synopsis...

Shortwave trough now situated over southern AZ will deamplify as it
accelerates northeast in response to an amplifying synoptic trough
over the western states. This feature should reach the southern High
Plains early Saturday and continue through KS and MO during the
afternoon and evening. By 12Z a cold front will extend from the
lower Great Lakes southwest into eastern KS, northwest OK and the TX
Panhandle. Northern portion of this front will continue into the
Northeast States, while the southwestern extension stalls and begins
to advance northward as a warm front later in the day. A dryline
will reside from eastern NM into the TX Panhandle where it will
intersect the front.

...Northern Oklahoma, Central and eastern Kansas through west
central Missouri...

Elevated storms may be ongoing early Saturday north of stalled front
from northern KS into northern MO, but this activity should diminish
as the low-level jet veers and weakens. The warm sector south of the
front should become moderately unstable with upper 60s to low 70s F
dewpoints in the presence of modest mid-level lapse rates, resulting
in 2000 J/kg MLCAPE. Storms are expected to redevelop during the
afternoon as the northeast-ejecting shortwave trough interacts with
the front, contributing to modest forcing for deep ascent. Greatest
storm coverage is expected from near the KS/OK border northeast into
eastern KS. Vertical wind profiles with 30-40 kt effective bulk
shear should promote some storms developing supercell structures,
but a trend toward mixed modes is expected as storms consolidate
along/north of the front and move east into western MO. Isolated
damaging wind and hail should be the main threats through mid
evening.

...Southern Plains...

Some storms may be ongoing across northwest TX early Saturday in
association with the progressive shortwave trough, but this activity
should diminish through the morning. The warm sector across western
TX should become moderately unstable supported by upper 60s F
dewpoints, diabatic warming of the boundary layer and modest
(6.5-7.5 C/km) mid-level lapse rates. This region will reside within
zone of weak mid-level subsidence west of the shortwave trough, and
low-level convergence will also be weak in vicinity of the dryline.
These factors suggest storm coverage will probably remain isolated
across west TX during the day, but up to 40 kt effective shear will
promote updraft rotation with any sustained updrafts. Primary
threats will be isolated large hail and strong wind gusts.

...New York into the Mid-Atlantic and Ohio Valley...

A shortwave trough will advance quickly eastward across the
Northeast and Mid-Atlantic on Saturday, with an associated cold
front at the surface likewise moving eastward over these same
regions. Isolated to scattered storms are expected to form along or
just ahead of the front by early Saturday afternoon. Although
instability is forecast to remain modest, westerly flow will
strengthen through low/mid levels. Some strong to locally severe
storms capable of producing mainly damaging winds appear possible
from parts of the OH Valley into the Mid-Atlantic and NY through
early Saturday evening. This region will continue to be monitored
for a possible SLGT risk in day 1 updates.

...Utah/Wyoming...

Strong mid/upper-level flow will be present Saturday across much of
the Great Basin into the northern/central Rockies as large-scale
upper troughing amplifies over the western CONUS. There appears to
be some potential for a narrow corridor of weak instability to
develop across parts of UT into WY as mid-level temperatures cool.
Gusty winds could occur with low-topped convection across this
region. But, the thermodynamic environment appears too marginal to
include any severe probabilities at this time.

...MAXIMUM RISK BY HAZARD...
Tornado: 5% - Slight
Wind: 15% - Slight
Hail: 15% - Slight

..Dial.. 09/27/2019

minime
Posts: 4
Joined: Sat Sep 28, 2019 5:50 pm

Re: Saturday 9/28/2019 Day 1 Slight

Post by minime » Sat Sep 28, 2019 6:01 pm

Day 1 Slight 9/28/2019
Day 1 Slight 9/28/2019
day1otlk_1630.gif (30.46 KiB) Viewed 116 times
SPC AC 281630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sat Sep 28 2019

Valid 281630Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN KS AND
WESTERN MO...

...SUMMARY...
The threat for severe thunderstorms, with large hail as the primary
threat, appears most concentrated during the late afternoon and
early evening over parts of eastern Kansas and western Missouri.

...Eastern KS and western MO vicinity...
A low-amplitude shortwave impulse near the north-central
OK/south-central KS border will track northeast towards the Mid-MS
Valley. A quasi-stationary front extends across east-central KS to
northeast MO downstream of a weak surface cyclone that is expected
to undergo cyclolysis. Differential heating across the front amid
persistent, but weak low-level southerlies should support late
afternoon to early evening scattered storm development along and to
the cool side of the front. The aforementioned weak low-level winds
should limit hodograph curvature, but adequate mid to upper-level
speed shear should foster a few rotating updrafts. Residual steep
mid-level lapse rates as sampled by 12Z Norman and Lamont, OK
observed soundings will foster a level 2-Slight risk for hail with
locally severe wind gusts possible as well.

...TX Panhandle vicinity...
Trailing portion of the Great Plains quasi-stationary front
currently bisects the Panhandle. This feature should be the focus
for late afternoon thunderstorm development near its intersection
with the dryline in far east-central NM. Weak forcing for ascent
coupled with 35-40 kt effective shear may foster a couple discrete
supercells. The primary uncertainty is the coverage of any
individual severe hazard. Mid-level lapse rates will be modest amid
weak height rises, which will be a limiting factor to hail growth.
In addition, a recently decayed gravity wave pushed richer
boundary-layer moisture southeast of an Abilene to Wichita Falls
line, which suggests guidance might be a bit too aggressive with the
degree of buoyancy return by 00Z. A strengthening low-level jet this
evening could still be enough to yield a small cluster with isolated
severe wind gusts.

...Northeast...
A remnant convectively induced mid-level impulse near the IN/MI/OH
border will progress east. This feature will aid in isolated to
scattered late afternoon and early evening storm development across
mainly PA into southern NY and NJ. The combination of buoyancy and
deep-layer shear should be modest amid weak mid-level lapse rates.
However, steep low-level lapse rates will support a risk for locally
strong gusts and damaging winds given near-record to record warm
temperatures.

...Northern UT to central WY...
Although buoyancy should remain meager, occasional thunderstorms
will persist along a pronounced baroclinic zone/differential heating
corridor into this evening. Fast mid-level southwesterlies will
support marginally severe hail and locally severe wind gusts.

..Grams/Elliott.. 09/28/2019

minime
Posts: 4
Joined: Sat Sep 28, 2019 5:50 pm

Re: Saturday 9/28/2019 Day 1 Slight

Post by minime » Sat Sep 28, 2019 6:20 pm

Current radar for SE Kansas.
ktwx radar.png
ktwx radar.png (784.9 KiB) Viewed 114 times

thunderchaser83
Site Admin
Posts: 19
Joined: Wed Sep 25, 2019 1:41 am

Re: Saturday 9/28/2019 Day 1 Slight

Post by thunderchaser83 » Sat Sep 28, 2019 6:26 pm

It looks very messy so far this afternoon. Also a lot of cloud cover.

thunderchaser83
Site Admin
Posts: 19
Joined: Wed Sep 25, 2019 1:41 am

Re: Saturday 9/28/2019 Day 1 Slight

Post by thunderchaser83 » Sat Sep 28, 2019 7:24 pm

KICT radar.png
KICT radar.png (949.03 KiB) Viewed 101 times
Current radar as of about 2:22 Central Time.

thunderchaser83
Site Admin
Posts: 19
Joined: Wed Sep 25, 2019 1:41 am

Re: Saturday 9/28/2019 Day 1 Slight

Post by thunderchaser83 » Sat Sep 28, 2019 7:46 pm

severewarn.png
severewarn.png (461.78 KiB) Viewed 98 times
Severe Thunderstorm Warning

minime
Posts: 4
Joined: Sat Sep 28, 2019 5:50 pm

Re: Saturday 9/28/2019 Day 1 Slight

Post by minime » Sun Sep 29, 2019 7:03 pm

day1otlk_1630 (1).gif
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SPC AC 291629

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Sun Sep 29 2019

Valid 291630Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WESTERN SD TO THE
UPPER RED RIVER VALLEY...

...SUMMARY...
A few severe thunderstorms with large hail as the primary hazard are
most likely from western South Dakota into the Upper Red River
Valley, mainly this evening through tonight.

...Dakotas...
Amplified upper-level trough will remain anchored across the West.
An embedded shortwave impulse will induce weak mid-level height
falls across the northern High Plains at peak heating and should aid
in storm development centered on northeast WY during the late
afternoon.

Outside of the Black Hills, the region is completely encompassed by
stratus as a plume of rich low-level moisture continues to advect
poleward beneath a slowly spatially expanding elevated mixed-layer.
This suggests the opportunity for surface-based storm development
should be rather short-lived and spatially confined to the western
SD area during early evening. Convection should be or will become
predominately elevated north of the surface warm front as it spreads
east-northeast across northern SD into southeast ND. The quality of
low-level moisture will favor an influx of moderate to large
buoyancy. In conjunction with strong speed shear through the
cloud-bearing layer, the setup could favor a long-track supercell or
two capable of producing a swath of large hail, some of which may be
significant.

...Eastern NE to IL and MN...
Clusters of warm-advection driven elevated, non-severe convection
are ongoing from the Mid-MO to the Mid-MS Valleys. This activity
should persist through this afternoon as it shifts east into IL.
Some guidance does suggest intensification may occur near the
surface warm front as destabilization is occurring across eastern MO
into central IL. However, based on the pervasiveness of
stratus/convection north of the front amid a weak mid-level lapse
rate environment, the scenario appears to favor maintenance of a
level 1-Marginal Risk.

A separate area of warm-advection elevated convection will develop
tonight in the central to northern MN vicinity. More muted effective
shear relative to areas farther west should yield a predominant
cluster mode. Marginally severe hail is possible as the periphery of
the High Plains elevated mixed-layer spreads toward the Upper
Midwest.

...Far West TX to eastern NM...
Latest guidance is fairly consistent in simulating isolated to
scattered storm development over the higher terrain of the
Trans-Pecos northward into eastern NM along/ahead of the dryline.
Effective shear will be weaker (20-30 kt) with southern extent where
convective coverage should be greater due to orographic ascent. Amid
moderate mid-level lapse rates, overall setup should tend to favor
isolated instances of severe wind and hail.

..Grams/Elliott.. 09/29/2019

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