000
acus01 kwns 220101
swody1
Storm Prediction Center ac 220059
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
0759 PM CDT Tuesday may 21 2013
Valid 220100z - 221200z
..there is a slight risk of severe thunderstorms across parts of the Tennessee
Valley...lower MS valley and Southern Plains...
..there is a slight risk of severe thunderstorms across parts of eastern
New York...VT...NH and Massachusetts...
..TN valley/lower MS valley/Southern Plains...
Several linear mesoscale convective systems are ongoing from western Tennessee
southwestward across northwest MS into northwest la and East Texas. The storms are located on
the northwestern edge of a corridor of moderate instability. MLCAPE values
across the warm sector are estimated in the 2000 to 3000 j/kg range
from the Southern Plains east-northeastward into the lower MS valley. This along with
large-scale ascent associated with an upper-level trough in the Southern
Plains will continue to support mesoscale convective system development this evening. In
addition...a 50 to 65 knots middle-level jet is analyzed over the eastern
parts of the Southern Plains. This feature is creating moderate deep
layer shear profiles across much of the warm sector which will help
to maintain a severe threat through the middle evening. Regional
WSR-88D vwps across the warm sector show unidirectional winds in the
boundary layer with about 20 to 30 knots of flow. This coinciding with
0-3 km lapse rates of 7.0 to 7.5 c/km should be favorable for
damaging wind gusts with the more organized bowing line segments. An
isolated threat for hail and a brief tornado will be possible with
rotating cells elements. However...the low-level wind profiles
appear most favorable for damaging wind gusts.
... Appalachian Mountains...
the latest water vapor imagery shows an upper-level ridge in place
across the Appalachian Mountains with a disturbance moving eastward across the
top of the ridge into New York and New England. This feature is supporting
an arching line of thunderstorms extending southwestward across northestern...central
and southern New York. MLCAPE values ahead of the line are estimated to be in
the 500 to 1500 j/kg range. This combined with moderate to strong
deep layer shear profiles will help support the line for several
more hours this evening. The Albany New York WSR-88D vwp shows directional
turning below 2 km above ground level with 25 to 30 knots of flow in the low to
mid-levels. The low-level wind appears favorable for wind damage as
a bowing line segment moves eastward across eastern New York...VT...NH and Massachusetts over
the next few hours. Hail will also be possible with the more intense
cells.
.Broyles.. 05/22/2013
Mesoscale Discussion
000
acus11 kwns 220040
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 220039
alz000-msz000-laz000-txz000-220245-
Mesoscale discussion 0764
National Weather Service Storm Prediction Center Norman OK
0739 PM CDT Tuesday may 21 2013
Areas affected...central - northestern la / central MS
Concerning...severe potential...watch likely
Valid 220039z - 220245z
Probability of watch issuance...80 percent
Summary...a locally damaging wind threat will probably move into
northestern la and central MS by the middle-late evening. Additional
strong-severe potential will increase farther SW over central la.
Discussion...radar mosaic shows an extensive squall line segmented
into several qlcs interconnected by a modifying outflow boundary
located from the southern extension of the northern MS qlcs westward to the southern
Arkansas/northwestern la qlcs. Although some slight surface cooling will occur
prior to the approach of the qlcs from the northwest...the 00z/22 Jan radiosonde observation
exhibited a moist and moderately unstable boundary layer with deep
layer shear /25-30 knots/ supportive of a linear mesoscale convective system. Recent kshv vwp
data show a 40-45 knots rear inflow jet associated with the qlcs and a
35 knots gust was observed at kshv. As a result...a continuation of a
35-50 knots wind gust threat capable of pockets of wind damage will
likely move into the discussion area over the next several hours.
.Smith/corfidi.. 05/22/2013
..please see www.Spc.NOAA.Gov for graphic product...
Attention...WFO...bmx...Jan...lix...lch...shv...
Latitude...Lon 33548896 33398845 33018819 32558835 30389326 30629355
31029356 31399341 32509186 33548896
