000
acus01 kwns 220550
swody1
Storm Prediction Center ac 220548
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
1248 am CDT Wednesday may 22 2013
Valid 221200z - 231200z
..there is a slight risk of severe thunderstorms across parts of the lower Great
Lakes...Ohio Valley and Tennessee Valley...
..lower Great Lakes/Ohio Valley/Tennessee Valley...
A positively-tilted upper-level trough will move eastward across the middle
to upper MS valley today with southwest flow located ahead of the
system from the Tennessee Valley northward into the lower Great Lakes. At the
surface...a low is forecast to move east-northeastward across lower Michigan with a
corridor of moisture with surface dewpoints in the lower to middle 60s f
extending northward from the Tennessee Valley into the upper Ohio Valley and lower
Great Lakes region. Model forecasts suggest several thunderstorm
clusters will be ongoing this morning with convective coverage
rapidly increasing across the western edge of moderate instability this
afternoon. Mesoscale convective system development will be possible across parts of the
slight risk area late this afternoon with several convective
clusters persisting into the evening ahead of the approaching
upper-level trough.
Forecast soundings at 21z at Rochester New York...Columbus Ohio and
Lexington Kentucky show SBCAPE values from 750 to 1250 j/kg with steep
low-level lapse rates and 35 to 40 knots of 0-6 km shear. This
environment should be favorable for damaging wind gusts as cells
increase in coverage and intensity late this afternoon. The greatest
potential for wind damage should exist from Lake Erie southward across
much of Ohio along the axis of a 30 to 40 knots low-level jet. The wind
damage threat could become enhanced if a linear mesoscale convective system can organize
across the upper Ohio Valley. A few tornadoes may occur with rotating
cell elements embedded in the mesoscale convective system. Large hail could also accompany
the more intense cells but the hail threat should remain isolated
mainly due to the relatively weak instability.
..cntrl Gulf Coast/lower MS valley...
The southern extension of an upper-level trough will move across the
lower MS valley today with a surface trough located across eastern Arkansas and
la. To the east of the surface trough...dewpoints should be in the middle
to upper 60s f with moderate instability developing by afternoon.
The models initiate scattered thunderstorms ahead of the surface trough
where forecast soundings show steep low-level lapse rates. This
along with the abundant low-level moisture could be enough for
marginally severe wet downbursts associated with the better
organized multicells.
.Broyles/Mead.. 05/22/2013
Mesoscale Discussion
000
acus11 kwns 220441
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 220441
alz000-msz000-laz000-220545-
Mesoscale discussion 0767
National Weather Service Storm Prediction Center Norman OK
1141 PM CDT Tuesday may 21 2013
Areas affected...central la / central and north-central MS
Concerning...Severe Thunderstorm Watch 209...
Valid 220441z - 220545z
The severe weather threat for Severe Thunderstorm Watch 209
continues.
Summary...pockets of strong to marginally severe wind gusts will
likely pose an isolated wind damage threat the next couple of hours
in places where the squall line exhibits a more eastward component to its
motion.
Discussion...subjective mesoanalysis shows an arcing gust front/cold
pool located over northestern MS where temperatures are around 70 with lower 60s
dewpoints. South of this boundary...temperatures in the middle 70s and
dewpoints ranging from the middle 60s-70 degree f characterize a more
unstable airmass --- potentially more conducive for wind gusts to
reach the surface. The qlcs is advancing towards the kdgx radar at
34 knots and inbound velocities show upwards of 40-50 kts at 1500 above ground level.
Additionally...ktvr observed a 40 knots wind gust during the past hour.
In summary...the region south of the outflow boundary from north-central
MS into southwestern MS --where the greatest eastward component to the qlcs
motion is located-- will remain the favored area for pockets of
35-50 knots wind gusts capable of isolated wind damage.
.Smith.. 05/22/2013
..please see www.Spc.NOAA.Gov for graphic product...
Attention...WFO...bmx...Meg...Jan...lix...
Latitude...Lon 33708831 33728940 32039099 31579177 31279106 31498969
32558874 33298813 33708831
