Storm Prediction Center Forecast


RSS Mesoscale Discussions from Storm Prediction Center

SPC - No watches are valid as of Tue Dec 11 18:02:02 UTC 2018

No watches are valid as of Tue Dec 11 18:02:02 UTC 2018.


SPC - No MDs are in effect as of Tue Dec 11 18:02:02 UTC 2018

No Mesoscale Discussions are in effect as of Tue Dec 11 18:02:02 UTC 2018.


SPC Dec 11, 2018 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook
      
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1008 AM CST Tue Dec 11 2018

Valid 111630Z - 121200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms will be possible late this evening through
tonight along the Pacific Northwest coast.

...Synopsis...
Relatively cool/dry air in the low levels will dominate the majority
of the CONUS, with no threat for thunderstorms.  A southern stream
shortwave trough will move over northern Baja through tonight,
though any substantial low-midlevel moistening and related threat
for deep convection will remain south of the AZ border.  A northern
stream shortwave trough over the southeast Gulf of AK will progress
inland over WA/northern OR this evening into tonight.  Steep
low-midlevel lapse rates with the midlevel thermal trough, in the
post-frontal onshore flow regime, will support weak surface-based
buoyancy (SBCAPE generally 100-300 J/kg) and an attendant threat for
isolated, low-topped thunderstorms late this evening into tonight.

..Thompson.. 12/11/2018

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SPC Dec 11, 2018 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook
      
Day 2 Outlook Image
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1130 AM CST Tue Dec 11 2018

Valid 121200Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are expected to develop across a portion of southeast
and east Texas into the lower Mississippi Valley Wednesday night.
However, the risk for severe weather still appears low at this time.

...Eastern Texas through western LA...

A shortwave trough currently over southern CA will accelerate
eastward in response to an upstream impulse, reaching central and
southern TX late Wednesday night. The surface cyclone that will
develop in response to this feature is forecast to be located over
north central TX with a Pacific cold front extending southward to
near Del Rio by the end of this period. 

As of mid day Tuesday, northeast trajectories are maintaining the
advection of modified continental polar air across the western Gulf
with near surface dewpoints mostly in the 40s F. Surface winds will
veer to southerly over the western Gulf and eastern TX early
Wednesday as high pressure over the southeast U.S. moves farther
east. This will result in northward advection of modifying
continental polar air with dewpoints reaching the low 50s F over
northeast TX to low 60 F along the TX coast tomorrow night. A
corridor of weak instability (MUCAPE at or below 500 J/kg) should
evolve from the TX coastal area through east central TX overnight. 
Storms are expected to develop along evolving warm conveyor belt and
zone of deepening ascent from southeast through east TX as the
shortwave trough approaches Wednesday night. Vertical wind profiles
including size of low-level hodographs will increase within this
zone, but current indications are that moisture return will probably
be insufficient for complete removal of the near-surface stable
layer, and storms will remain slightly elevated which, along with
the very marginal thermodynamic environment, should limit overall
severe threat. For this reason will not introduce any severe
probabilities at this time, but at least a marginal risk category
might be needed in day 1 updates.

...MAXIMUM RISK BY HAZARD...
Tornado:  <2%     - None
Wind:     <5%     - None
Hail:     <5%     - None

..Dial.. 12/11/2018

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SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook
          
Day 1 Fire Weather Outlook Image
Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0937 AM CST Tue Dec 11 2018

Valid 111700Z - 121200Z

...NO CRITICAL AREAS...

No changes. See previous discussion below for additional details.

..Bentley.. 12/11/2018

.PREV DISCUSSION... /ISSUED 0112 AM CST Tue Dec 11 2018/

...Synopsis...
An active synoptic pattern will continue across the Lower 48 today,
with stout mid-level disturbances centered over the northern/central
Great Plains, Northeast, southern California, and the Pacific
Northwest.  The Great Plains wave will induce cyclogenesis in
northeastern New Mexico and vicinity, while Great Basin high
pressure will assist in development of an offshore pressure gradient
across southern California.  Although highlights have been withheld
for this outlook, areas of locally elevated fire weather conditions
will develop at times across the central Plains and along coastal
ranges of southern California.

...Northeastern New Mexico northeastward into western Kansas...
10-15 mph westerly downslope flow will develop in vicinity of the
deepening surface low and west of a front/wind shift from the
Panhandles into central Kansas.  Minimum RH values will fall to
around 20-35% west of the wind shift, and fuels are not expected to
support large fires on a widespread basis.  Nevertheless, where
finer fuels are cured, locally elevated fire weather will develop
for a couple of hours during peak heating.

...Southern California...
Gusty offshore flow will develop throughout the day in response to
the aforementioned pressure gradient.  Minimum RH values should only
fall to around 20-30% however, and fuels are not cured on a
widespread basis owing to recent rainfall across the area.  Locally
elevated fire weather conditions can be expected where fine fuels
are dry.

...Please see www.spc.noaa.gov/fire for graphic product...

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SPC Day 2 Fire Weather Outlook

SPC Day 2 Fire Weather Outlook
          
Day 2 Fire Weather Outlook Image
Day 2 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1018 AM CST Tue Dec 11 2018

Valid 121200Z - 131200Z

After fuels collaboration with the local offices, it was decided
that fuel conditions and weather conditions warrant an elevated fire
weather area in eastern New Mexico and the far western Texas
panhandle Wednesday afternoon. Winds are expected to be around 20
mph with RH values falling to around 20%.

..Bentley.. 12/11/2018

.PREV DISCUSSION... /ISSUED 0114 AM CST Tue Dec 11 2018/

...Synopsis...
A vigorous mid-level system will amplify southeastward from the
Pacific Northwest toward the southern High Plains, while closing off
late in the forecast period.  This system will result in another
episode of strong cyclogenesis in northeastern New Mexico and
vicinity, with resultant strengthening of downslope flow and locally
elevated fire weather across eastern New Mexico.  Meanwhile, gusty
winds in southern California will take on more of an onshore
component, with limited low-level drying resulting in only a locally
elevated fire weather threat.

...Eastern New Mexico...
Areas of 25-35 mph westerly surface flow will develop during peak
heating hours in response to aforementioned cyclogenesis. 
Meanwhile, some low-level drying is expected, with RH values falling
into the 18-35% range during the afternoon.  While typically these
conditions would justify an elevated fire weather delineation, fuels
appear to be driest just north of this region and ERCs are not
particularly high.  Thus, locally elevated fire weather conditions
are expected, and elevated delineations may be needed in later
outlooks.

...Please see www.spc.noaa.gov/fire for graphic product...

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