Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS11 KWNS 300837
SPC MCD 300836
Mesoscale Discussion 0608
NWS Storm Prediction Center Norman OK
0336 AM CDT Sun Apr 30 2017
Areas affected...Southern and eastern AR...and northern LA
Concerning...Severe Thunderstorm Watch 178...
Valid 300836Z - 301000Z
The severe weather threat for Severe Thunderstorm Watch 178
SUMMARY...Severe weather threat continues across WW 178, along and
east of the cold front as it advances east across AR and
northern/western LA overnight to early this morning. Meanwhile,
counties and parishes can be cleared in the wake of the cold front
DISCUSSION...08Z surface analysis indicated a synoptic low centered
near the border of northeast OK and southeast KS, with a secondary
low located in south-central AR, while the cold front trailed
southward through northwest and west-central LA to extreme southeast
TX/upper TX coast area.
Water vapor imagery indicated an apparent midlevel shortwave trough
currently tracking to the north/northeast across LA toward southern
and eastern AR and western MS by 12Z. Forcing for ascent attendant
to this midlevel trough and low-level confluence along the cold
front and a pre-frontal trough has resulted in an increase in
thunderstorm coverage across southern into central LA thus far.
This activity with further development is expected to spread across
northern LA into southern and eastern AR within the valid portions
of WW 178. Strengthening deep-layer winds is supporting an increase
in low-level shear (surface-1 km of 40-50 kt) and effective bulk
shear of 40-50 kt within a moderately unstable environment suggests
damaging winds and some tornado threat remains possible across
northern LA into southern and eastern AR.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 33049204 31999206 31519217 31419281 31429320 32779292
33809279 34549210 35379193 35909159 35869111 34919099
34059098 33639110 33239184 33049204