Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS11 KWNS 151851
SPC MCD 151850
Mesoscale Discussion 0185
NWS Storm Prediction Center Norman OK
1250 PM CST Wed Feb 15 2017
Areas affected...Portions of north and central FL
Concerning...Severe potential...Watch unlikely
Valid 151850Z - 152115Z
Probability of Watch Issuance...20 percent
SUMMARY...An isolated severe risk may spread inland and across parts
of north and central FL through the mid/late afternoon hours. While
Watch issuance is unlikely, convective and environmental trends will
continue to be monitored.
DISCUSSION...A line of convective cells -- some producing
lightning -- has developed along a weak baroclinic zone/confluence
axis over the east Gulf, and this activity is tracking eastward
toward the coast of the FL Peninsula. Mosaic radar imagery suggests
that convection is maintaining semi-discrete and cluster-mode
characteristics, owing to the weak low-level ascent and sufficient
boundary-orthogonal mean flow/deep shear component.
Meanwhile, insolation amidst an adequately moist air mass downstream
across the FL Peninsula is supporting MLCAPE around 500-1000 J/kg --
strongest in proximity to the Gulf Coast. As the aforementioned
convection spreads inland -- especially around and after the
1930Z-2030Z time frame and ingests destabilizing inflow, isolated
severe potential may evolve. Deepening boundary-layer circulations
over inland areas may support earlier convective intensification
ahead of the previously mentioned activity.
Given 35-45 kt of effective shear, organized/sustained convective
structures -- perhaps including weak supercells -- may occur.
Isolated damaging wind gusts, or even marginally several hail, may
accompany this activity. The Tampa Bay VAD wind profile indicates
slight veering of winds with height in the lowest 1 km above ground,
yielding sufficient low-level SRH for the possibility of a
brief/weak tornado. However, the veered character of the warm-sector
low-level flow will tend to temper convective inflow and SRH,
lessening such potential. Furthermore, an overall dearth of
large-scale ascent should tend to limit the severe coverage.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 28668272 29738259 29858149 28768086 28108109 27698254