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Storm Prediction Center Forecast

RSS Mesoscale Discussions from Storm Prediction Center

SPC - No watches are valid as of Thu Dec 14 17:56:01 UTC 2017

No watches are valid as of Thu Dec 14 17:56:01 UTC 2017.

SPC - No MDs are in effect as of Thu Dec 14 17:56:01 UTC 2017

No Mesoscale Discussions are in effect as of Thu Dec 14 17:56:01 UTC 2017.

SPC Dec 14, 2017 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
1026 AM CST Thu Dec 14 2017

Valid 141630Z - 151200Z


Thunderstorm areas are not forecast across the contiguous U.S.

...Synopsis and Discussion...
A shortwave trough over the Southwest this morning will move
southeastward towards the southern Plains and merge with a nearly
closed upper low now over Baja California by late tonight. At the
surface, a reinforcing cold front will likewise develop
southeastward across TX today, and then off the TX Gulf Coast
tonight. Post-frontal precipitation will likely occur across Deep
South TX and adjacent coastal waters late this evening into early
Friday morning as large-scale ascent associated with the upper
trough overspreads the southern Plains. While meager low-level
instability (MUCAPE around 100-200 J/kg) may be present across this
region, forecast soundings show very poor mid-level lapse rates, and
the likelihood for charge separation and resultant isolated
lightning strikes over land appears too low to include a general
thunderstorm area.

..Gleason.. 12/14/2017

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SPC Dec 14, 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
1129 AM CST Thu Dec 14 2017

Valid 151200Z - 161200Z


Thunderstorms are not expected across the contiguous states Friday
and Friday night.

As a mid-level short-wave trough -- embedded in broader cyclonic
flow over eastern North America -- sweeps across the eastern U.S. on
Friday, a reinforcement of cold/continental low-level air will
continue to inhibit prospects for thunderstorm activity across the
continental U.S. through the period.

..Goss.. 12/14/2017

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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
0946 AM CST Thu Dec 14 2017

Valid 141700Z - 151200Z


The ongoing forecast is on track and rationale is unchanged from the
previous forecast.  Areas of elevated to critical fire weather
conditions are expected in portions of southern California as an
offshore gradient persists.  Easterly winds in terrain-favored areas
are already exceeding 20 mph (with gusts in excess of 45 mph) and RH
values are below 10% at many observation sites.  These conditions
will persist for at least a few more hours, with poor overnight
recovery resulting in elevated to critical conditions persisting
well after dark.

Near-critical conditions are also expected in portions of the Lower
Colorado River Valley as dry northerly flow and low RH persists.

See the previous discussion below for more information.

..Cook.. 12/14/2017

.PREV DISCUSSION... /ISSUED 0133 AM CST Thu Dec 14 2017/

A shortwave trough embedded in larger-scale flow will dig southward
across the southwestern U.S. into northwest Mexico today. This will
result in a strong mid/upper level north/northeasterly jet streak
overspreading portions of the Great Basin and the Lower CO River
Valley and adjacent southern CA. At the surface, strong high
pressure will remain over the Intermountain West. This will result
in continued fire weather concerns across parts of southern CA as
well as the Lower CO River Valley. 

...Southern CA...

Critical fire weather conditions will persist today. Very dry
conditions continue, with single-digit RH values expected by early
afternoon. Some diurnal weakening of the pressure gradient is
anticipated, which may yield some lightening of winds speeds during
the afternoon/early evening before the gradient once again increases
overnight, with a corresponding increase in wind speeds once again.
Winds of 20-30 mph with gusts of 40-55 mph are possible. Overnight
RH recovery will remain very poor.

...Lower CO Valley...

Gusty north winds and low RH values will bring elevated to locally
critical conditions to the region today. High temperatures will
approach the low to mid 70s and boundary-layer mixing will result in
downward transport of strong midlevel winds. Sustained north winds
of 15-20 mph with higher gusts are expected. RH values will fall
into 10-20 percent range. Wind speeds will diminish overnight and RH
values will increase to the 30-40 percent range.

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

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