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Area forecast discussion 
National Weather Service Phoenix Arizona
835 PM MST Tuesday Oct 25 2016


strong high pressure building over the region will lead to warming
temperatures through the end of this week with record highs possible
at some locations on Thursday. A slight cool down will occur for the
weekend and early next week, but temperatures will still remain well
above normal and the dry weather will continue for the majority of
the region.


00z plot data showed an upper ridge building into the Desert
Southwest behind the trof which passes thru the area last night; 500 mb
heights were up 20-40m across the area with heights up around 587dm
over the southern Arizona deserts. Infrared imagery at 8 PM showed that the few
cu over the deserts had dissipated leaving clear skies behind. For
the rest of tonight expect clear skies and light winds along with
mild overnight temps. OH, and Phoenix reached a high of 92 degrees
today making it 21 straight days in Phoenix with an October high of
at least 90 degrees. And we're looking at 90 plus pretty much
through the end of October. Might be 90 or more on trick or treat
day. Wow. Current forecasts look to be in great shape and no updates
are needed.

Previous discussion...
tonight through Thursday...

The latter part of this week will be dominated by an unseasonably
strong upper level ridge moving into the Desert Southwest with 500mb
heights rising into the 588-590dm range for Wednesday and Thursday.
850mb temperatures over southern Arizona warm into the 22-24c range
on Thursday which is aoa 99% of climo for this time of year. Highs
for Wednesday through Friday will easily make it into the low to mid
90s across the lower deserts with middle to upper 90s (with a few
spots reaching 100) possible on Thursday. Current Thursday forecast
highs of 96 for Yuma would be one degree short of the record for the
date, with the updated forecast of 98 at Phoenix tying the record
for the date.

Thursday night through next Tuesday...

Models continue to indicate the upper level ridge will get slightly
displaced to the east as a deep trough nears the West Coast by
Thursday night. The current track of this low pressure system keeps
it to our northwest, but enough moisture will likely move into
southeast California to bring clouds and a slight chance of showers
for Friday. This trough will drop our heights aloft and effectively
drop our temperatures a couple degrees for Friday. Dry southwesterly
flow with little change in temperatures is shown through this weekend
as highs will remain roughly 6-9 degrees above normal. A potential
weather system may affect the Desert Southwest either next Tuesday or
Wednesday, but quite a bit of model uncertainty remains.


Aviation...south-central Arizona including kphx, kiwa, and ksdl:

High pressure aloft building into the area from the west will result
in genly clear skies at the terminals over the next 24 hours. Maybe
a few high based cu tomorrow afternoon but nothing significant.
Light gradients will result in winds favoring normal diurnal trends
but with speeds on the light side mostly below 8kt. No aviation
concerns anywhere for at least the next 24 hours.

Southeast California/southwest Arizona including kipl and kblh:

No aviation concerns through the taf period. Skies will continue to
clear with a few high-level clouds passing overhead. At kblh, winds
will remain light and out of a northerly to northeasterly direction
through the taf period. At kipl, winds will remain light and out of
the west, turning more northerly by noon Wednesday.

Aviation discussion not updated for amended tafs.


Fire weather...
Friday through Tuesday...

Another weather system brushes the Desert Southwest Friday into
Saturday, bringing an increase in humidities and a slight chance of
showers in southeast California. Warmer and drier weather returns
Sunday before another system passing off to the west and north
pushes slightly cooler temperatures and elevated breezes on Monday
and Tuesday.

Minimum humidities in the 20 to 30 percent range Friday through
Sunday to fall into the 15 to 25 percent range on Monday and
Tuesday. Overnight recoveries will be in the good range.

Winds will remain light and follow normal diurnal headings through
the entire period, except for some afternoon breeziness up to 20 mph
in southeast California and southwest Arizona on Monday and Tuesday


Spotter information statement...
spotter activation will not be needed this week.


Psr watches/warnings/advisories...


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previous discussion...percha/Kuhlman
fire weather...percha/Hernandez

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