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Storm Prediction Center Forecast

RSS Mesoscale Discussions from Storm Prediction Center

SPC - No watches are valid as of Wed Oct 18 17:55:02 UTC 2017

No watches are valid as of Wed Oct 18 17:55:02 UTC 2017.

SPC - No MDs are in effect as of Wed Oct 18 17:55:02 UTC 2017

No Mesoscale Discussions are in effect as of Wed Oct 18 17:55:02 UTC 2017.

SPC Oct 18, 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
1051 AM CDT Wed Oct 18 2017

Valid 181630Z - 191200Z


Isolated thunderstorms are possible today over portions of the
Florida Peninsula, western New Mexico and far west Texas. 
Isolated/brief thunder also is possible overnight near the Olympic
Peninsula of Washington.

A moist/unstable air mass remains across the central and southern FL
peninsula today, where scattered showers and thunderstorms are
expected through the period.  Elsewhere, isolated thunderstorms will
be possible beneath a weak mid-level impulse moving across
NM/southwest TX, and in the strong onshore flow along the WA coast. 
No severe storms are forecast today.

..Hart/Leitman.. 10/18/2017

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SPC Oct 18, 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
1144 AM CDT Wed Oct 18 2017

Valid 191200Z - 201200Z


Thunderstorm probabilities will be greatest across the southern
Rockies, along the Pacific Northwest Coast, and over parts of
Florida on Thursday. Other thunderstorms will be possible over a
portion of the Texas Coastal area.

...Southern Rockies through southern High Plains...

An upper trough will undergo modest amplification as it traverses
the central and southern Rockies and southern High Plains. Vorticity
maxima embedded within this feature along with steep mid-level lapse
rates and diabatic heating over the higher terrain will foster
marginal instability and the development of thunderstorms during the
afternoon. Some of this activity will spread into the southern high
plains during the evening and overnight. 

...Pacific NW...

Cold air aloft and steepening mid-level lapse rates accompanying an
amplifying upper trough will foster the development of showers and a
few thunderstorms along the Pacific Northwest coastal areas within a
post-frontal regime.

...Texas Coastal area...

A few showers and thunderstorms will be possible along the TX
coastal area where richer Gulf moisture will advect westward
contributing to weak destabilization within a low-level confluent
flow regime.

..Dial.. 10/18/2017

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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
1058 AM CDT Wed Oct 18 2017

Valid 181700Z - 191200Z

No substantial changes have been made to the elevated areas across
parts of southeastern WY and ND/northwestern MN/far eastern MT. See
the previous discussion below for more information.

..Gleason.. 10/18/2017

.PREV DISCUSSION... /ISSUED 1254 AM CDT Wed Oct 18 2017/

A quasi-zonal flow pattern will remain over much of the CONUS today,
with a mid-level trough moving eastward over central Canada. Strong
mid-level flow will reside near the base of the trough over the
Northern Plains. Meanwhile, an associated surface low is forecast to
shift eastward from Manitoba toward Hudson Bay, with a trailing cold
front moving from the Northern Plains into the Great Lakes region.
Amplification of a large scale mid/upper-level trough over the
Pacific Northwest is expected later tonight.

...North Dakota, Northwest Minnesota, and far eastern Montana...
The ongoing Elevated fire weather area has been maintained, with a
slight westward expansion into eastern Montana. Across the Elevated
area, strong post-frontal northwesterly winds around 15-30 mph (with
higher gusts) are forecast to occur in concert with afternoon
minimum RH values around 20-25% (locally lower). These
meteorological conditions are expected to overlap with an area of
increasingly receptive fuels, as fine fuels have dried out with the
lack of meaningful precipitation the past few weeks (AHPS suggests
less than a quarter of an inch over most of the area the past 14

While near/locally critical conditions may occur, it currently
appears that the strongest winds (generally near the Canadian
border) will not align well with the lowest minimum RH values
(generally across the southern half of ND) on more than a
brief/spotty basis. If trends in guidance suggest more
warming/drying than is currently expected, then a Critical area
could be needed across portions of the area in a future update.

...Southeast Wyoming...
Despite the stronger mid-level flow shifting northward away from the
area today, lingering downslope breeziness is expected to remain
around long enough into the afternoon to overlap with reduced RH
values. An Elevated area was introduced across portions of southeast
WY for locations where sustained westerly winds around 15-20 mph are
forecast to occur -- for at least a few hours during afternoon --
with RH values at or below 15%.

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

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