Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 251107

Area Forecast Discussion
National Weather Service Phoenix AZ
407 AM MST TUE OCT 25 2016

.UPDATE...Updated Aviation & Fire Weather Discussion.


High pressure and drying conditions will move in behind an exiting
low pressure system today. This high pressure will lead to warming
temperatures through the end of this week with near record highs on
Thursday. A slight cool down will occur for the weekend, but
temperatures will still remain well above normal and the dry weather
will continue for the majority of the region.


After a somewhat active evening across our area, much of the shower
and thunderstorm activity has pushed into central and northern
Arizona. The main force behind this activity, an upper level trough,
is now pushing through central Arizona with increasing anti-cyclonic
and subsident flow now moving into southeast California and southwest
Arizona. The potential for a couple stray showers will be possible
across the northern fringes of our CWA, but only for the next few
hours. Significant drying and warming aloft is now taking place and
should overtake the rest of southern Arizona by mid morning. Skies
will also become mostly clear by around sunrise and the rest of
Tuesday should be warm and sunny.

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 to near 588dm for Wednesday and Thursday. 850mb
temperatures over southern Arizona warm to around 22C on Thursday
which is 97-99% of climo for this time of year. Highs for Wednesday
through Friday will easily make it into the lower 90s across the
lower deserts with some middle 90s possible on Thursday. Current
Thursday forecast highs of 95 for Yuma and 96 for Phoenix each fall
two degrees shy of records.

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:

No aviation concerns through the TAF period. Dry air will continue
to filter into the area resulting in a decrease in precipitation
chances and cloud cover. Skies will continue to clear, with only few
to scattered mid- and high- level clouds passing overhead. Winds
will remain light and follow normal diurnal headings.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns through the TAF period. Skies will continue to
clear with few to scattered mid- and high- level clouds passing
overhead. At KBLH, winds will remain light and out of the northwest
with a brief period of northeasterly winds this afternoon. At KIPL,
winds will remain light and out of the west.

Aviation discussion not updated for amended TAFs.


Thursday through Monday...

High pressure redeveloping over the Desert Southwest will bring dry
conditions and well-above normal temperatures to the region on
Thursday. 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 and Monday.

Minimum humidities will rise from the 15 to 25 percent range on
Thursday into the 20 t0 30 percent range Friday through Sunday and
then slightly lower on Monday in the lower deserts. Overnight
recoveries will be good.

Winds will remain light and follow normal diurnal headings through
Saturday. Sunday and Monday, winds will remain generally on the light
side, except for some afternoon breeziness up to 20 mph in southeast
California and southwest Arizona.


Spotter activation will not be needed this week.




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