Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 231748
SPC MCD 231747

Mesoscale Discussion 0310
NWS Storm Prediction Center Norman OK
1247 PM CDT Thu Mar 23 2017

Areas affected...Central and southern Florida Peninsula

Concerning...Severe potential...Watch unlikely

Valid 231747Z - 232015Z

Probability of Watch Issuance...20 percent

SUMMARY...Thunderstorms will continue to increase in intensity and
coverage the next few hours but will pose a low threat for
marginally severe hail and brief wind gusts through the afternoon.

DISCUSSION...Widely scattered thunderstorms have percolated along
the east coast of the central and southern Florida peninsula through
the late morning hours ahead of a weak upper-level
perturbation...with one cell now showing some organization and weak
mid-level rotation moving southward into St. Lucie county.
Mixed-layer CAPE of 500-1250 J/kg aided by mid-level lapse rates of
7.5-8 C/km...somewhat larger than typical for late March in southern
Florida...should continue to allow for updrafts strong enough to
support small hail production. Marginally severe hail and brief
severe wind gusts are possible in the strongest updrafts that show
some mid-level rotation.

As low-level lapse rates steepen in afternoon heating, the larger
evaporative cooling should strengthen/amalgamate cold pools that
spread south and southwest to the Gulf of Mexico coast.  Weak wind
shear in the lowest 1 km directed toward the cold pool motion should
augment the tendency for cold pools to spread rapidly south and
west.  Although mean wind speeds are relatively weak, vertical bulk
wind shear magnitudes of 25-35 kt in the 1-8 km layer should
continue to support some thunderstorm organization for the expected
continuation of south-southwesterly storm motions.  Otherwise...the
primary mode will be multicellular/pulse in nature with storms
propagating somewhat discretely along the spreading cold pools.  The
intensity and coverage of the threat is expected to remain low
enough to prevent a watch.

..Coniglio/Hart.. 03/23/2017

...Please see for graphic product...


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