SPC - No watches are valid as of Fri Nov 17 21:16:02 UTC 2017

No watches are valid as of Fri Nov 17 21:16:02 UTC 2017.


SPC - No MDs are in effect as of Fri Nov 17 21:16:02 UTC 2017

No Mesoscale Discussions are in effect as of Fri Nov 17 21:16:02 UTC 2017.


SPC Nov 17, 2017 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook
      
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0136 PM CST Fri Nov 17 2017

Valid 172000Z - 181200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are expected tonight across much of the Midwest from
Missouri to Ohio, with more isolated afternoon and evening
thunderstorms possible across parts of the central Rockies.

...MO and IL late tonight...
Latest CAM guidance suggests perhaps an elevated storm or two right
at the end of the day 1 period, from far northeast MO into west
central IL around 12Z. Forecast soundings indicate marginal
instability levels for severe storms, but some hail may be present.
Given such a limited area of potential and sparse storm
expectations, will maintain a general thunder area for tonight.

..Jewell.. 11/17/2017

.PREV DISCUSSION... /ISSUED 1010 AM CST Fri Nov 17 2017/

...Midwest...
A broad upper trough is deepening across the western states today,
while a band of strong west-southwesterly mid-level winds extends
from the Great Basin into the Midwest.  Southerly low-level winds
over the MO/IL/IN will help moisten/destabilize the air mass,
leading to scattered showers and a few thunderstorms - mainly after
dark.  One cluster of convection will move across northern IN and
southern Lower MI this evening.  At this time, no severe storms are
anticipated with this activity.  

Late tonight, 12z model guidance continues to indicate a risk of
thunderstorms developing after 10z near an approaching cold front
over north-central MO and central IL.  Forecast parameters suggest
some risk for hail in the strongest cells, but limited
areal/temporal confidence precludes an upgrade at this time.

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SPC Nov 17, 2017 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
1103 AM CST Fri Nov 17 2017

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID
MISSISSIPPI INTO THE OHIO VALLEY...

...SUMMARY...
A few strong to severe storms capable of marginal hail or damaging
wind gusts will be possible Saturday mainly over the Ohio Valley
region.

...Synopsis...
A strong shortwave trough will move from the Plains to the MS Valley
during the day, with a deepening surface low moving from St. Louis
to Lake Erie. A rapid increase of winds aloft will occur with a 100
kt midlevel jet into the OH Valley by 00Z. A strong cold front will
sweep eastward with southwesterly surface winds bringing a narrow
plume of mid 50s to lower 60s dewpoints northward into IL and IN.
Warm air advection in the low-levels will further be augmented by a
50-60 kt low-level jet. Despite the favorable synoptic scale setup,
instability will be minimal, with only a few marginally severe
storms expected during the day.

...Mid MS into the OH Valleys...
An area of mainly elevated thunderstorms is expected to occur early
in the day, perhaps across eastern MO, and then developing eastward
across IL and IN, with lift aided by warm air advection. Forecast
soundings show sufficient instability for marginally severe hail.
Other activity, perhaps surface based, will occur near the low, and
southward along the cold front. The main detriment to a more
substantial severe wind event appears to be the lack of heating,
with weak low-level lapse rates. This should keep warm sector
activity immediately along the front. Strong wind gusts will occur
with the frontal passage, and some of this could be convectively
enhanced. 

Farther south into TN, MS, and AL, instability will be even less,
with a capping inversion preceding the front. Here too, some
convectively augmented wind gusts will be possible during the
afternoon and early evening.

..Jewell.. 11/17/2017

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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
1052 AM CST Fri Nov 17 2017

Valid 171700Z - 181200Z

...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL NEW MEXICO INTO THE
CENTRAL TEXAS PANHANDLE...

...Southern High Plains...
Widespread elevated fire weather conditions are still anticipated
for a few hours this afternoon as increasing mid-level flow coupled
with deep boundary layer mixing and a strengthening surface pressure
gradient combine to support sustained winds from 20 to 30 mph. High
temperatures across the region will range from the mid 70s to upper
80s (15 to 25 degree above-average), supporting afternoon RH values
in from the low teens to mid 20s. Highest confidence in critical
conditions remains from east-central NM northeastward into the
central TX Panhandle. Near-critical conditions are anticipated
farther south/southwest into southern NM with slightly weaker winds
(sustained around 15 to 20 mph) precluding critical meteorological
conditions. As mentioned in the previous discussion, fuels do not
appear particularly receptive but given the strength of the winds
and the anomalously warm temperatures, a widespread elevated to
locally critical fire weather threat still exists.

..Mountains and Foothills of Southern CA...
Current onshore gradient is expected shift offshore tonight as a
front moves through the Great Basin and high surface pressure
follows in its wake. Guidance indicates that the LAX-DAG and LAX-TPH
gradients will be around -6 mb and -10 mb, respectively, by 12Z
Saturday. Gradients of this strength will likely support wind gusts
from 35-40 mph. RH values are expected to remain above critical
thresholds across most of the region but some locally elevated fire
weather conditions are still anticipated for a few hours early
Saturday morning.

..Mosier.. 11/17/2017

.PREV DISCUSSION... /ISSUED 0147 AM CST Fri Nov 17 2017/

...Synopsis...
Strong mid-level flow will develop across the southern Plains on
Friday as a mid-level trough quickly moves east into the central
United States. This strong mid-level flow will result in downslope
warming/drying across the southern Plains. Here, widespread
temperatures in the mid-70s to mid-80s will combine with poor
low-level moisture to result in minimum afternoon relative-humidity
values falling into the teens in some locations. These warm/dry
conditions will combine with surface-wind speeds gusting into the
20-30 mph range to support elevated-to-critical fire-weather
conditions. The most likely area for critical conditions will be
from east-central New Mexico into the central Texas Panhandle, where
surface winds around 30 mph sustained in the presence of mid-teen
relative humidity. One potential mitigating factor is that ERCs are
generally near or below the 50th percentile across the region, which
may preclude a more widespread, larger-scale fire-weather threat.

Late in the period (Saturday morning), north/north-east winds will
develop across coastal areas of southern California. These weak
Santa Ana winds may gust near 40-45 mph in wind favored areas. These
strong winds will help dry out finer fuels. However, even with the
drying, relative humidity looks to remain high enough to preclude
elevated highlights.

...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
1056 AM CST Fri Nov 17 2017

Valid 181200Z - 191200Z

...Mountains and Foothills of Southern CA...
A few hours of elevated fire weather conditions are anticipated
across the region early Saturday morning, primarily across the
mountains of Santa Barbara, Ventura, and Los Angeles counties.
Offshore gradient will decrease diurnally before increasing again
Saturday night/Sunday morning. Winds are expected to be slightly
weaker Saturday night/Sunday morning than Saturday morning but poor
overnight recovery will likely still result in elevated fire weather
conditions over the mountains and foothills of Santa Barbara,
Ventura, and Los Angeles counties.

..Mosier.. 11/17/2017

.PREV DISCUSSION... /ISSUED 0147 AM CST Fri Nov 17 2017/

...Synopsis...
Northerly surface winds will be ongoing across southern California
at the start of the forecast period. These winds will act to help
dry out fine fuels across the area. By mid-to-late morning, the
Santa Ana winds are anticipated to weaken, ending this low-end
elevated fire-weather threat. 

Overnight Saturday into Sunday, northerly surface winds are expected
to develop once again. These winds will usher in a cooler/drier
airmass. By afternoon, minimum relative humidity will fall to the
5-15 percent range; however, surface winds will be decreasing by
this time. Because the strongest surface winds and lowest
relative-humidity values will be out of phase, critical fire-weather
conditions do not appear likely. Thus, elevated fire-weather
highlights will be introduced.

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

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