|Mesoscale Discussion 146|
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Mesoscale Discussion 0146
NWS Storm Prediction Center Norman OK
1018 AM CST Tue Feb 07 2017
Areas affected...southeast Louisiana through southern Mississippi
Concerning...Tornado Watch 26...
Valid 071618Z - 071815Z
The severe weather threat for Tornado Watch 26 continues.
SUMMARY...Threat for a few tornadoes, large hail and damaging wind
will continue from southeast Louisiana through southern Mississippi
into early to middle afternoon.
DISCUSSION...Late this morning numerous storms are developing from
southeast LA through southern MS within a corridor of ascent
associated with a secondary branch of the low-level jet and its
attendant vorticity maximum moving into western LA. Storms are
forming along eastern periphery of an axis of moderate instability
that extends from eastern TX through LA into AR. While low-level
winds are veered to south southwesterly, 0-1 km storm relative
helicity is sufficient for a few low-level mesocyclones and
tornadoes, especially in vicinity of a poorly defined coastal warm
front across southern LA. Otherwise strong 40-50 kt effective bulk
shear will continue to promote supercell structures and some bowing
segments with large hail and damaging wind.
Primary severe threat is expected to transpire from late morning
through the early afternoon across WW 26. However, with time
tendency will be for the deeper forcing for ascent to move east of
the instability axis. While some upstream development will be
possible later this afternoon, subsidence and ewd expansion of eml
suggest the environment will become increasingly hostile to more
than isolated thunderstorm development within the corridor of
greater instability. Some destabilization may occur downstream
across the central gulf cost area this afternoon where a severe
threat may evolve.
LAT...LON 30108868 29568996 29529104 29889231 30379272 31069257
31739197 32349066 32428902 31438827 30108868
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