000
acus01 kwns 201219
swody1
Storm Prediction Center ac 201217
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
0717 am CDT Monday may 20 2013
Valid 201300z - 211200z
..there is a MDT risk of severe thunderstorms this afternoon and tonight over
parts of North Texas...central and eastern OK...northwest Arkansas...extreme
southeast Kansas...and southern MO....
..there is a slight risk of severe thunderstorms from central Texas into much of
the upper MS valley and Great Lakes region....
...
Morning water vapor loops show a broad upper trough over the western
and central states...with a progressive shortwave trough tracking
eastward across northern nm. This feature will move into the
Southern Plains by early afternoon...helping to initiate another
round of strong to severe thunderstorms over the Southern Plains.
A surface cold front currently extends roughly from lts-bvo. This
front is likely to move slightly southeastward today and will
provide the focus for afternoon thunderstorm development. Various
mesoscale models differ on timing of strong/severe storms...but
agree on storms forming over central OK by about 20z and building
quickly northeastward into southeast Kansas and western MO. The initial
storms will likely be supercelluar with very large hail...damaging
winds...and tornadoes possible. Those storms that form over
southern OK into North Texas appear to have the greatest chance of
remaining discrete and posing a risk of significant severe weather
for several hours into the evening. Meanwhile...storms that form
from central OK northeastward into southeast Kansas and MO appear likely
to organize into broken lines and clusters by early evening capable
of widespread damaging winds...large hail...and a few tornadoes.
Similar to yesterday...middle level lapse rates of 7.5-8.0 c/km...very
large cape...and favorable shear values will pose a risk of isolated
strong tornadoes across portions of the moderate risk area.
..upper MS valley and western Great Lakes...
Early visible satellite imagery shows only broken cloud cover over
parts of Iowa/WI eastward into mi/OH. Relatively strong daytime
heating and little cap should result in scattered thunderstorms
today and tonight to the east of a surface low over Minnesota. MLCAPE
values of 1500-2000 j/kg will promote vigorous updrafts in this
region...while sufficiently strong vertical shear helps to organize
the convection. Present indications are that multiple
lines/clusters of thunderstorms will affect this region...with a few
supercells possible. Hail and damaging winds are the main
threats...but isolated tornadoes cannot be ruled out.
...
South of the moderate risk area in Texas...confidence is a little
higher today compared to last few days that isolated storms will
form along the dryline. Any storm that can form in this area will
pose a risk of very large hail and damaging winds for a few hours
this evening.
.Hart/leitman.. 05/20/2013
Mesoscale Discussion
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acus11 kwns 201346
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 201346
moz000-ksz000-201445-
Mesoscale discussion 0724
National Weather Service Storm Prediction Center Norman OK
0846 am CDT Monday may 20 2013
Areas affected...southeastern Kansas...W-cntrl MO
Concerning...severe potential...watch possible
Valid 201346z - 201445z
Probability of watch issuance...40 percent
Summary...a narrow corridor of thunderstorms has formed within the past hour
across parts of southeastern Kansas and into west-central MO. This activity should
pose a primary risk for large hail...and a lesser threat for strong
to potentially severe wind gusts. It is uncertain whether thunderstorms will be
sustained for long enough to require a ww...but trends will continue
to be monitored.
Discussion...visible satellite imagery shows a corridor of
intensifying convection developing within an elevated baroclinic
zone and ahead of an approaching upper impulse over S-central Kansas...in
the wake of overnight convection which has moved into central MO and
has weakened. Regional soundings /E.G. Sgf and top/ suggest this
activity is likely rooted above the boundary layer...and located
along the periphery of a plume of steep midlevel lapse
rates...posing a primary risk for large hail. There is some
uncertainty whether convection will be sustained for more than 1-2
hours with northeastward progression into west-central MO...where convection
overnight may have stabilized the air mass somewhat.
However...should trends indicate convection will maintain current
intensity or strengthen...and show signs of becoming rooted within
the boundary layer...then a ww may need to be considered.
.Rogers/Kerr.. 05/20/2013
..please see www.Spc.NOAA.Gov for graphic product...
Attention...WFO...sgf...eax...top...ict...
Latitude...Lon 38359312 37809417 37429535 37449591 37579620 37929622
38419550 38869480 39099426 39149368 39089330 38779300
38359312
