SPC - No watches are valid as of Mon Sep 23 07:11:02 UTC 2019

No watches are valid as of Mon Sep 23 07:11:02 UTC 2019.


SPC - No MDs are in effect as of Mon Sep 23 07:11:02 UTC 2019

No Mesoscale Discussions are in effect as of Mon Sep 23 07:11:02 UTC 2019.


SPC Sep 23, 2019 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook
      
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1234 AM CDT Mon Sep 23 2019

Valid 231200Z - 241200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE DESERT SOUTHWEST...

...SUMMARY...
Thunderstorms with wind damage and isolated large hail will be
possible today across parts of Arizona. Storms with a few strong
wind gusts will be possible in parts of the Northeast.

...Desert Southwest...
An upper-level low will dig southward across the Desert Southwest
today. At the surface, a low will deepen across far southeastern
California as a moist airmass advects slowly northward across
southwestern Arizona. Surface dewpoints will reach the upper 60s and
lower 70s F across parts of southwest Arizona where moderate
instability should be in place by midday. Model forecasts suggest
scattered thunderstorms will develop across south-central Arizona
during the afternoon with convection spreading east-northeastward
into north-central Arizona by early evening. RAP forecast soundings
in the 21Z to 00Z timeframe across south-central Arizona show MLCAPE
values reaching the 1500 to 2500 J/kg range. Wind profiles show
substantial speed shear in the low to mid-levels with 850 to 500 mb
lapse rates around 7.0 c/km. This should support the development of
supercells with isolated large hail and wind damage. If cells can
congeal into a bowing line segment, then the more dominant threat
could transition toward wind damage by early evening.

...Northeast...
An upper-level trough will move across the lower Great Lakes region
today as southwest mid-level flow remains over much of the
Northeast. At the surface, a low will develop across southern Quebec
as a corridor of maximized low-level moisture sets up ahead of a
cold front moving southeastward into the Northeast. Scattered
thunderstorms are forecast to develop this afternoon along and ahead
of the front across western Pennsylvania, New York and western New
England. Surface dewpoints in the mid 60s F will contribute to weak
destabilization ahead of the front. In addition, strong deep-layer
shear will be present making condition supportive of an isolated
severe threat. Short multicell line segments should be able to
produce a few marginally severe wind gusts this afternoon especially
as low-level lapse rates become maximized.

..Broyles/Elliott.. 09/23/2019

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SPC Sep 23, 2019 0600 UTC Day 2 Convective Outlook

SPC 0600Z Day 2 Outlook
      
Day 2 Outlook Image
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1225 AM CDT Mon Sep 23 2019

Valid 241200Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER EASTERN
NEBRASKA...IOWA...SOUTHERN MINNESOTA...AND WESTERN WISCONSIN...

...SUMMARY...
Severe storms are possible Tuesday across much of Iowa, western
Wisconsin, eastern Nebraska, and southern Minnesota, with isolated
storms from parts of the central Plains to the Upper Great Lakes. A
few strong storms may linger over southern Arizona as well.

...Synopsis...
Strong cyclonic flow aloft will broaden over the north-central U.S.
with the nose of an upper level jet developing across the Dakotas,
MN, and WI. Cooling aloft will coincide with this jet max which will
work with a cold front to provide a focus for severe storms. The
front will stretch roughly from southern MN into eastern NE by 00Z,
with increasing low-level moisture aiding destabilization. The tail
end of this front will stall over KS, where a moist and unstable air
mass will remain.

To the west, an upper low will continue dropping south across
western AZ and into the northern Gulf of CA, with cool temperatures
aloft and antecedent moisture maintaining a risk of thunderstorms
mainly over southern AZ.

...IA/MN/WI area, and NE/KS...
Southwest surface winds will increase throughout the period, with
30-40 kt at 850 mb aiding moisture transport ahead of the cold
front. At least mid 60s F dewpoints are expected to spread north
into southern MN, with upper 60s F possible depending on
evapotranspiration and mixing. This should yield at least 2000 J/kg
MUCAPE, with steep lapse rates aloft. Storms are expected to form
late in the day along the front where the cap will be breached due
to lift. The increasing west/northwest winds aloft will result in
favorable shear vector orientation along the front for supercells, a
few of which may produce very large hail. A tornado or two is
possible as well with effective SRH increasing above 200 m2/s2. The
main limiting factors to an Enhanced Risk category are expected
storms coverage due to capping and boundary layer moisture quality.
Isolated severe storms are possible as far southwest as eastern
Nebraska along the front, where dewpoints are likely to be higher,
though large-scale lift will not be as favorable. Isolated severe
storms capable of hail or wind may also occur over central KS during
the afternoon as heating will be strong over southwest KS ahead of
the boundary. A storm or two may approach northern OK during the
evening.

...Southern AZ...
Scattered thunderstorms are likely to be ongoing over parts of
southern AZ, and cool temperatures aloft may support a few strong
storms with gusty winds or small hail. Additional storms cannot be
ruled out during the afternoon with heating, while temperatures
aloft remain cool. By this time, shear will be weaker, thus
widespread severe is not expected.

...MAXIMUM RISK BY HAZARD...
Tornado:   5%     - Slight
Wind:     15%     - Slight
Hail:     15% SIG - Slight

..Jewell.. 09/23/2019

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SPC Sep 23, 2019 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook
      
Day 3 Outlook Image
Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0208 AM CDT Mon Sep 23 2019

Valid 251200Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...

...SUMMARY...
A few strong storms are possible over parts of southern
Kansas/Missouri, and northern Oklahoma/Arkansas on Wednesday.

...Synopsis...
A strong upper jet will develop east across the Great lakes, with
the upper trough taking on a negative tilt as it approaches the
Northeast overnight. High pressure will build eastward across the
northern Plains and Midwest, with a cold front becoming east-west
oriented from KS to the OH River. South of the stalled front, a
moist and unstable air mass will exist across the central Plains
with mid to upper 60s F dewpoints. Farther east along the front,
little if any instability will be present to support more than
general thunderstorms from the OH Valley into the Great Lakes.

Elsewhere, an upper low will remain over the Southwest, and will
support sporadic thunderstorms through the period.

...KS/OK/MO/AR...
Convergence near the front or any outflow boundaries from antecedent
storms will provide a focus for daytime storms. Although moderately
unstable, this zone will be just south of the stronger winds aloft,
thus effective shear will not be strong, but perhaps sufficient for
a few southeastward-moving clusters of storms capable of marginal
hail and wind.

...AZ...
An upper low will remain over the northern Gulf of CA, drifting
slowly north Wednesday night. While cool temperatures aloft will
remain with this system, several days of rain and storms will likely
reduce overall lapse rates and instability. Several hundred J/kg
MUCAPE and daytime heating will likely lead to scattered storms, but
the severe threat appears low at this time. However, strong wind
gusts or small hail are possible.

..Jewell.. 09/23/2019

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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
0145 AM CDT Mon Sep 23 2019

Valid 231200Z - 241200Z

...Synopsis...
A strong mid/upper-level trough is forecast to become cutoff from
the main flow as it moves from the Great Basin southeastward to the
Southwest Desert through tonight. As this occurs, an area of
enhanced northerly mid-level flow -- located on the west side of the
trough -- will overspread much of California as it shifts southward
through the day.  

...Northern California...
Breezy northerly low-level flow is forecast to develop during the
early afternoon across portions of the Sacramento Valley and
adjacent Coastal Mountains behind the aforementioned mid-level
trough. While sustained surface winds are forecast to generally
remain around 10-20 mph (locally greater), wind gusts of 30-40 mph
are possible. Elevated to locally critical fire weather conditions
are likely as these winds overlap minimum RH values of 15-20%
(locally lower) and at least marginally receptive fuels.

Poor overnight RH recoveries (15-25%) and lingering breezy/gusty
northerly winds should continue to foster elevated to locally
critical fire weather conditions late this evening and into tonight
across the higher elevations (e.g., > 1 kft) of the North/East Bay
Hills, the Diablo Range, and the Northern Coast Mountains.
Additionally, gusty northeasterly downslope winds (gusts up to 50
mph) on the western slopes of the Northern Sierra's and adjacent
foothills should promote elevated to locally critical fire weather
conditions late this evening/tonight amidst poor overnight RH
recoveries (around 20-25%).  

...Southern California...
A dry offshore low-level flow is forecast to increase late tonight
over the mountains of Ventura, Los Angeles, and Santa Barbara
Counties as the aforementioned area of enhanced mid-level flow
overspreads the area. While the timing of the stronger winds and RH
reductions remains somewhat uncertain, at least a few hours of
elevated to locally critical fire weather conditions are possible
late tonight.

..Elliott.. 09/23/2019

...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
0147 AM CDT Mon Sep 23 2019

Valid 241200Z - 251200Z

...Synopsis...
A closed mid/upper-level low is forecast to gradually shift from the
Desert Southwest to Baja California through Day 2/Tuesday. 
  
...Southern California...
Pockets of elevated to locally critical fire weather conditions will
likely be ongoing early Day 2/Tuesday across the mountains of
Ventura, Los Angeles, and Santa Barbara Counties as increasing
offshore surface winds overlap areas with poor overnight RH
recoveries. While winds are forecast to weaken through the day as
upper-level support associated with the aforementioned upper low
shifts away from the area, elevated fire weather conditions should
remain as RH values continue to decrease. At least locally elevated
fire weather conditions are possible into Day 2/Tuesday night as RH
recoveries remain poor amidst breezy winds. 

...Northern California...
Pockets of elevated to locally critical fire weather conditions will
likely be ongoing across the higher elevations (e.g., > 1 kft) of
the North/East Bay Hills, the Diablo Range, the Northern Coast
Mountains, and the western slopes of the Northern Sierra's and
adjacent foothills Day 2/Tuesday morning as poor overnight RH
recoveries occur in conjunction with gusty surface winds. By
afternoon, elevated fire weather conditions should spread to the
lower elevations of the Sacramento Valley as sustained surface winds
of around 15 mph develop in conjunction with near critical RH
values. At least locally elevated fire weather conditions are
possible at higher elevations (e.g., > 1 kft) into Day 2/Tuesday
night as RH recoveries remain poor amidst breezy winds.

..Elliott.. 09/23/2019

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

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