Severe Storm Outlook Narrative (AC)
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000
ACUS01 KWNS 221242
SWODY1
SPC AC 221240

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0640 AM CST Fri Feb 22 2019

Valid 221300Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
THROUGH TONIGHT FROM THE ARK-LA-MISS REGION TO EAST TEXAS...

...SUMMARY...
Isolated large hail and/or damaging gusts will be possible today
through tonight across the Ark-La-Miss region, and early Saturday in
east Texas.

...Ark-La-Miss to east TX through early Saturday...
Lee cyclogenesis is expected today across northeast NM, within the
left-exit region of a strengthening mid-upper jet streak that will
rotate northeastward from northern Mexico to west central TX by
early Saturday.  The surface warm sector and a moist air mass across
the lower MS Valley and near the northwest Gulf coast will begin to
spread north-northwestward in response to the cyclogenesis later
today into tonight.  Diurnal convection within the warm sector is
quite uncertain given no clear forcing for ascent.  Much of the
convection is expected to remain on the immediate cool side of the
boundary through tonight, where low-level warm advection will be
strongest.  There will be sufficient vertical shear for some
organized/supercell structures, with an attendant threat for
marginally severe hail and isolated strong/damaging gusts with storm
close to the surface warm sector.

By tonight, steeper midlevel lapse rates will begin to overspread
the low-level moisture from east TX to the Ark-La-Miss, as vertical
shear increases in advance of the ejecting midlevel trough and
surface cyclone.  Isolated large hail will be possible with the
slightly elevated storms, with sufficient effective bulk shear
(generally 45-55 kt) for some supercell structures.  The more
concentrated convection tonight and early Saturday should be along
the warm conveyor belt from southeast AR into northwest MS/western
TN.  The steeper lapse rates to the west will also likely be
associated with some midlevel convective inhibition, which could
delay the majority of stronger storm development in east TX until
the D2 period as forcing for ascent increases.

..Thompson/Jewell.. 02/22/2019

$$


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