Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 142002
SPC MCD 142002

Mesoscale Discussion 0182
NWS Storm Prediction Center Norman OK
0202 PM CST Tue Feb 14 2017

Areas affected...Portions of southern/eastern
LA...western/central/southern MS

Concerning...Severe potential...Watch unlikely

Valid 142002Z - 142230Z

Probability of Watch Issuance...20 percent

SUMMARY...Areas east of Tornado Watch 33 are being monitored for
isolated severe potential this afternoon. Present indications are
that additional/downstream Watch issuance is unlikely.

DISCUSSION...Substantial weakening has been noted with a convective
line crossing parts of western LA. As the broader precipitation
pattern associated with this MCS has transitioned from
trailing-stratiform to leading-stratiform, warm-sector
destabilization attendant to 1007-mb surface low analyzed in
northwest LA has been restricted. Furthermore, the 18Z Slidell LA
sounding indicates that the low levels north of the immediate Gulf
Coast are only modestly moist, with a lowest-100-mb mean mixing
ratio of 10.8 g/kg. Surface dewpoints have mixed out into the upper
50s to around 60F across many parts of central/southern MS and
southern LA where insolation has occurred peripheral to denser
MCS-related cloud canopies. As such, observational trends suggest
that inland destabilization remains quite muted ahead of any remnant
convection accompanying the MCS, and this activity may pose only
marginal/isolated severe potential through late afternoon as it
spreads across parts of the Lower MS Valley region.

Regardless, a well-defined surge of drying is evident on the upshear
side of the MCS -- based on the larger-scale bowed precipitation
pattern accompanying the aforementioned activity. The related
augmentation of a midlevel speed maximum by the remnant mesoscale
circulation may provide sufficient wind fields for conditional and
isolated damaging-wind potential if any more robust convective cores
were to evolve in the strongly sheared environment. Areas of partial
insolation -- especially from central MS to southeast LA -- may have
boosted low-level lapse rates sufficiently to support such
potential. Somewhat richer Gulf moisture just offshore may be
advected inland with time, and this could eventually translate to a
modest increase in severe potential near the coast. However,
substantial uncertainty in these scenarios remains.

..Cohen/Hart.. 02/14/2017

...Please see for graphic product...


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