RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Tue Oct 16 16:52:02 UTC 2018.
No Mesoscale Discussions are in effect as of Tue Oct 16 16:52:02 UTC 2018.
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Tue Oct 16 2018
Valid 161300Z - 171200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Widely scattered thunderstorms will occur from Texas eastward to the
Carolinas.
...Synopsis...
Neutral or rising midlevel heights are expected across the southern
states, above a slow-moving front from the northwest Gulf of Mexico
to the Carolinas. Weak elevated convection and occasional lightning
strikes will continue atop the frontal surface across TX/LA. The
surface warm sector will be largely removed from the stronger flow
aloft across the lower MS Valley, and midlevel lapse rates will
remain poor, so severe storms are not expected along this portion of
the front. The slow-moving front will coincide with the southern
fringe of the stronger midlevel westerlies across the Carolinas. A
few storms will be possible this evening near the NC/SC border as a
diffuse mid-upper speed max moves from the Mid South to the
Carolinas by tonight. Deep-layer vertical shear will be sufficient
for some storm cluster organization, but the severe-storm threat
will be limited by poor midlevel lapse rates and modest low-level
flow/shear along and south of the front. Will opt not to add any
damaging wind probabilities to the Carolinas, but this area will
still be monitored for a marginal severe threat in later updates.
..Thompson/Mosier.. 10/16/2018
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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1127 AM CDT Tue Oct 16 2018
Valid 161630Z - 171200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CAROLINAS...
CORRECTED FOR THUNDER LINES
...SUMMARY...
Isolated damaging winds are possible across parts of the Carolinas
this evening.
...Carolinas...
Have added a Marginal Risk given increased confidence in a few
mid-level rotating storms this evening.
Despite neutral mid-level height change, convergence along a
quasi-stationary front may strengthen during the late afternoon and
evening. As surface temperatures warm through the 80s within the
warm sector amid weak mid-level lapse rates, MLCAPE of 500-1000 J/kg
should develop. A few storms may form between 22-00Z near the
upstate NC/SC border area as a diffuse mid/upper-level speed max
moves from MS toward the Carolinas. Deep-layer vertical shear will
be favorable for mid-level rotation, but the overall storm intensity
should be limited by the modest combination of lapse rates/low-level
winds along and south of the front. Given the increased CAM signal
for scattered convection near the boundary, locally strong wind
gusts might yield tree damage and thus have added a corridor of
damaging wind probabilities.
..Grams/Bentley.. 10/16/2018
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1135 AM CDT Tue Oct 16 2018
Valid 171200Z - 181200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated convective showers and a few thunderstorms are possible
over Florida on Wednesday.
...Synopsis...
A split upper-level flow pattern on Wednesday will feature a
longwave trough in the East and a low in the Desert Southwest. A
frontal zone over the central Gulf Coast will push into the northern
Gulf of Mexico as surface high pressure strengthens over the middle
MS Valley. A couple of general thunderstorms are possible over FL
and scattered thunderstorm activity is possible over the western
half of the Gulf of Mexico. Poor lapse rates and a weak wind
profile will preclude strong thunderstorm development over FL.
...MAXIMUM RISK BY HAZARD...
Tornado: <2% - None
Wind: <5% - None
Hail: <5% - None
..Smith.. 10/16/2018
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1148 AM CDT Tue Oct 16 2018
Valid 161700Z - 171200Z
...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHERN CALIFORNIA...
Minor adjustments have been made to the critical area across
southern California. Latest surface observations show the strongest
winds occurring over the higher terrain. The 12Z NKX sounding shows
25-30 kts of 850 mb flow that will likely support critical winds in
those locations for a few more hours today, which is supported by
guidance. With the pressure gradient weakening with time, critical
winds in lower elevations will become less likely, thus, those areas
have been trimmed. The surrounding elevated area has been trimmed
out of parts of Kern and Santa Barbara Counties as winds are not
expected to exceed 15 mph.
In northern California, the elevated area has been expanded to
include northern portions of the Sacramento Valley where some
channeled flow may reach 15-20 mph this afternoon.
..Wendt.. 10/16/2018
.PREV DISCUSSION... /ISSUED 0145 AM CDT Tue Oct 16 2018/
...Synopsis...
A closed upper low centered over AZ early this morning should move
little through the period. The enhanced mid and upper-level
northerly winds on the back side of this upper low should gradually
weaken by this evening as the upper low slowly fills. At the
surface, high pressure centered over the Rockies is also forecast to
weaken somewhat, with the pressure gradient across southern CA
likely diminishing by early Wednesday morning.
...Portions of Southern CA...
Elevated to critical fire weather conditions are ongoing early this
morning across several locations in the higher terrain of southern
CA per 06Z observations. Critical fire weather conditions will occur
over a greater portion of southern CA today, mainly early in the
period, before a reduction in the surface pressure gradient occurs.
The most likely areas to experience 20-25 mph northeasterly to
easterly winds and RH values of 5-15% should be the mountains and
favored passes/canyons of Ventura and Los Angeles counties. Still,
elevated to critical fire weather conditions should occur for at
least a few hours across much of the remainder of coastal southern
CA later this morning per consensus of short-term high-resolution
guidance. Therefore, a critical delineation remains over most of
this region to address the continued threat for large fire spread
given generally dry/receptive fuels.
...Portions of Northern CA...
Locally strong/gusty easterly winds around 15-20 mph that are
ongoing early this morning across western slopes of the Sierras and
vicinity should persist for at least a few hours later this morning.
RH values of 15-20% will also be present across this region as the
already dry boundary layer remains well mixed, and downslope
warming/drying occurs. A small elevated area has therefore been
included where these conditions appear most likely. The modestly
enhanced surface pressure gradient will weaken and mid-level flow
will diminish through mid-morning, leading to a gradual reduction in
surface winds.
...Please see www.spc.noaa.gov/fire for graphic product...
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