SPC Mar 11, 2019 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook

Day 3 Outlook Image

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0230 AM CDT Mon Mar 11 2019

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL/EAST TX TO THE LOWER/MID MS VALLEY...

...SUMMARY...
Isolated strong to severe thunderstorms may occur from parts of
central/east Texas to the lower/mid Mississippi Valley on Wednesday.

...Synopsis...
A negatively tilted shortwave trough initially over the southern
High Plains should evolve into a closed upper low over the central
Plains and Upper Midwest on Wednesday. Continued northward low-level
moisture transport will occur across east TX into the lower/mid MS
Valley through the period as a northeastward-moving surface low
occludes in tandem with the upper trough/low.

...East TX into the Lower/Mid MS Valley...
A line of thunderstorms will likely be ongoing at the start of the
period across parts of central/east TX along a cold front extending
southward from the previously mentioned surface low. Even though a
moist low-level airmass should be in place ahead of this convection,
weak low/mid-level lapse rates should tend to limit instability
across most of the warm sector. Still, there appears to be potential
for some restrengthening of the line as it encounters a weakly
unstable airmass across east TX into LA and AR Wednesday afternoon.
Isolated strong to damaging winds will probably be the main threat
given the likely linear nature of the convection. An embedded QLCS
tornado cannot be ruled out either with strong low-level shear
forecast to be present across the warm sector. Due mainly to the
poor thermodynamic environment expected, the potential for a more
concentrated corridor of wind damage currently appears too
conditional/uncertain to include any more than a Marginal risk. The
northern extent of surface-based thunderstorm potential will likely
be constrained by the presence of lower to mid 60s surface dewpoints
across the mid MS Valley. Convection should spread eastward into
parts of MS and western TN Wednesday evening with a continued
marginal wind threat.

..Gleason.. 03/11/2019

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Flood Watch issued March 11 at 3:24AM CDT by NWS

…FLOOD WATCH IN EFFECT FROM TUESDAY EVENING THROUGH WEDNESDAY EVENING… The National Weather Service in Topeka has issued a * Flood Watch for portions of north central and northeast Kansas, including the following areas, Clay, Cloud, Ottawa, Republic, Washington, Marshall, Nemaha, Pottawatomie, and Riley Counties.

SPC Mar 11, 2019 0600 UTC Day 2 Convective Outlook

SPC 0600Z Day 2 Outlook

Day 2 Outlook Image

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1256 AM CDT Mon Mar 11 2019

Valid 121200Z - 131200Z

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

...SUMMARY...
Severe thunderstorms capable of producing isolated damaging winds,
large hail, and perhaps a tornado or two will be possible beginning
mainly late Tuesday afternoon and continuing through the overnight
hours across parts of the southern Plains.

...Synopsis...
A closed upper low over the lower CO River Valley and adjacent Baja
Peninsula will evolve into a negatively tilted shortwave trough as
it ejects east-northeastward across the Southwest and southern
Plains on Tuesday. Strong ascent preceding this shortwave trough
will encourage surface cyclogenesis across the southern/central High
Plains through the day, with a deep surface low eventually
consolidating over southeastern CO. Low-level mass response will
bring at least partially modified Gulf moisture westward and
northward across the southern Plains.

...Southern Plains...
Isolated to perhaps widely scattered elevated thunderstorms posing a
marginal hail threat may be ongoing Tuesday morning across parts of
eastern NM into west TX in a low-level warm air advection regime.
This convection should spread northeastward across the TX/OK
Panhandles and main body of OK through the afternoon. At least some
diurnal heating should occur across the higher terrain of
central/eastern NM into west TX in the wake of this morning
activity. This heating combined with steep mid-level lapse rates
emanating from the higher terrain of northern Mexico and surface
dewpoints in the mid 50s to lower 60s should foster MLCAPE of
500-1000 J/kg across the southern High Plains through peak diurnal
heating.

Convective initiation appears likely by late Tuesday afternoon as a
strong southwesterly mid-level jet attendant to the shortwave trough
overspreads eastern NM and west TX. Effective bulk shear exceeding
50 kt will easily support supercells with mainly an isolated large
hail threat. A Pacific cold front will eventually overtake this
convection Tuesday evening, with upscale growth into squall line
likely. Isolated damaging winds should be the primary threat with
this linear convection as it moves quickly eastward across
central/east TX overnight. A tornado or two also cannot be ruled out
within the line due to the strong low-level shear that will be
present owing to a 45-60+ kt southerly low-level jet. Eventually
this squall line should weaken some as it encounters a less unstable
airmass across east TX late in the period.

There is still considerable uncertainty whether there will be
sufficient low-level moisture return across western/central OK to
support surface-based thunderstorms. Have therefore refrained from
making any substantial changes to the Marginal and Slight risk
delineations across this area.

...MAXIMUM RISK BY HAZARD...
Tornado:   2%     - Marginal
Wind:     15%     - Slight
Hail:     15%     - Slight

..Gleason.. 03/11/2019

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SPC MD 178

MD 0178 CONCERNING TORNADO WATCH 15…16… FOR FAR NORTHEAST MS…NORTHERN AL…MIDDLE TN

MD 0178 Image


Mesoscale Discussion 0178
NWS Storm Prediction Center Norman OK
0720 PM CST Sat Mar 09 2019

Areas affected...Far Northeast MS...Northern AL...Middle TN

Concerning...Tornado Watch 15...16...

Valid 100120Z - 100245Z

The severe weather threat for Tornado Watch 15, 16 continues.

SUMMARY...Potential for isolated damaging wind gusts and/or a brief
tornado will continue across northeast MS, northern AL, and middle
TN for the next hour or two.

DISCUSSION...KGWX radar imagery has shown sporadic and brief
low-level rotation within the supercell now moving through southern
Lowndes county. However, latest scans have shown a trend towards
less low-level inflow/low-level organization with velocity values
decreasing and the previously observed ZDR arc losing definition.
Echo tops have also decreased over the past 30 min or so. Strongest
updraft (based on echo top) appears to be associated with the storm
in Franklin and Cobert counties in far northwest AL. Downstream air
mass from both of these storms suggests a gradual decrease in
intensity as instability wanes. Even so, given the strong low-level
shear, brief low-level organization capable of isolated wind
damaging and or a brief tornado remains possible.

Farther north, the convective line moving across middle TN has shown
modest intensification, particularly over the last 30 min or so.
Downstream thermodynamic environment is characterized by
temperatures in the 60s, dewpoints in the limited instability. Even
so, very strong low-level shear (sampled well by the 00Z BNA
sounding) could still support instances of damaging wind gusts and
perhaps a brief tornado before the line moves into cooler, more
stable air north of the warm front.

..Mosier.. 03/10/2019

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

ATTN...WFO...OHX...BMX...HUN...MEG...JAN...

LAT...LON   33438845 34048830 34668788 35608684 36578600 36268543
            34718643 33818712 33158788 33138822 33438845 

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SPC MD 163

MD 0163 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR PARTS OF EASTERN OKLAHOMA…SOUTHEAST KANSAS…THE SOUTHWESTERN QUARTER OF MISSOURI…AND THE NORTHWEST QUARTER OF ARKANSAS

MD 0163 Image


Mesoscale Discussion 0163
NWS Storm Prediction Center Norman OK
0158 AM CST Sat Mar 09 2019

Areas affected...parts of eastern Oklahoma...southeast Kansas...the
southwestern quarter of Missouri...and the northwest quarter of
Arkansas

Concerning...Severe potential...Watch possible 

Valid 090758Z - 090930Z

Probability of Watch Issuance...60 percent

SUMMARY...Risk for hail emanating from elevated storms will likely
increase over the next 1-2 hours, possibly warranting WW issuance.

DISCUSSION...Latest surface analysis shows a warm front from
extending from east-central Oklahoma east-southeast across
central/southern Arkansas.  North of the front, a very stable
boundary layer is indicated, with temperatures and dewpoints
generally in the 40s.

Water vapor imagery depicts the intense trough crossing the southern
Rockies at this time, which is gradually acquiring negative tilt,
and a broad zone of increasing ascent is also indicated downstream
of the axis, west of -- and spreading into -- the discussion area. 

Model soundings across the region, and special 06Z ROABs, both
indicate steep lapse rates above 850mb, atop the low-level stable
air, with CAPE becoming increasingly sufficient for stout, elevated
updrafts as additional moistening/theta-e advection aloft occurs in
advance of the advancing trough.  With flow aloft also increasing
ahead of this feature, shear will support rotating updrafts where
CAPE becomes sufficient for updraft longevity.  Given these factors,
risk for large hail should steadily increase over the next couple of
hours -- possibly warranting WW issuance.

..Goss/Edwards.. 03/09/2019

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

ATTN...WFO...LSX...LZK...SGF...EAX...TSA...TOP...ICT...OUN...

LAT...LON   35039624 35209682 35979683 37719592 38309552 38559367
            38269191 36219211 34899295 35039624 

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