Mesoscale Discussion 0706
NWS Storm Prediction Center Norman OK
1059 AM CDT Fri May 12 2017
Areas affected...Portions of AR...northern LA...northwest MS
Concerning...Severe potential...Watch unlikely
Valid 121559Z - 121830Z
Probability of Watch Issuance...5 percent
SUMMARY...Hail -- generally small, though perhaps reaching
marginally severe levels on an isolated basis -- may accompany
thunderstorms developing through the afternoon hours. Watch issuance
is unlikely.
DISCUSSION...Diurnal surface heating combined with low-level
moisture characterized by middle 60s surface dewpoints is supporting
an increase in buoyancy and initial convective development. This is
occurring amid the broader midlevel cold pool accompanying a
southeastward-moving upper low. With 500-mb temperatures around -15C
to -13C, and little convective inhibition, pulse-type convection
will continue developing through the late morning and into the
afternoon hours. While deep shear will be weak in association with
the weak midlevel height gradient, relatively low freezing-level
heights and sufficient midlevel buoyancy will support hail with the
most intense updrafts. Small hail is expected. A few isolated
instances of marginally severe hail could occur where
convection-preceding cloud thinning/breaks permit the greatest
insolation and diabatic surface-layer heating -- which is already
evident in visible satellite trends across portions of the region.
The lack of stronger deep shear will greatly limit convective
organization and prevent a more robust severe risk from evolving.
..Cohen/Goss.. 05/12/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...JAN...LZK...SHV...
LAT...LON 35189238 34899107 34409054 33569050 32899089 32729174
32939296 33829369 34899330 35189238
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