Mesoscale Discussion 0897
NWS Storm Prediction Center Norman OK
1059 AM CDT Sun May 28 2017
Areas affected...Parts of southern
Louisiana/Mississippi/Alabama/Georgia and the Florida panhandle
Concerning...Severe potential...Watch unlikely
Valid 281559Z - 281800Z
Probability of Watch Issuance...20 percent
SUMMARY...Intensifying thunderstorm development is expected across
southern portions of the central Gulf states and associated coastal
areas through 18-21Z. This probably will be accompanied by at least
some localized severe weather potential. It is not yet clear that a
watch will be needed, but trends will be monitored.
DISCUSSION...Forcing for ascent along the leading edge of outflows
associated with extensive overnight convective development is
maintaining a narrow corridor of sustained thunderstorm development.
The composite outflow boundary has been steadily advancing
southward, and appears likely to progress south of the stronger
westerlies, toward Gulf coastal areas, through 18-21Z. However,
mid-level height falls and the southward suppression of a lingering
plume of warm elevated mixed layer air, coupled with insolation, are
contributing to weakening of inhibition for seasonably moist
boundary layer air ahead of activity. This may lead to a general
intensification of thunderstorm development during the next few
hours, with locally enhanced convergence along the composite outflow
boundary eventually supporting some rapid intensification in the
presence of moderate to large CAPE (on the order of 2000-4000 J/kg).
This degree of latent instability is being supported by steep
mid-level lapse rates, which probably will contribute to
thermodynamic profiles conducive to frequent lightning, some severe
hail, and locally strong downbursts in the most vigorous storms.
Strengthening of the larger-scale cold pool may also support
increasing gusts along its leading edge which could approach severe
levels by mid to late afternoon.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 30439358 30289242 30379090 30619022 31018928 31128769
31258685 31518609 30698540 30208585 29898794 29298924
29149078 29379320 29709376 30439358