Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 022049 CCA
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
150 PM MST Fri Dec 2 2016

.SYNOPSIS...

Strong surface pressure gradients between high pressure over the
Great Basin and and low pressure over northern Mexico will continue
to produce strong and gusty northerly winds across a large part of
southeast California and the Colorado River Valley tonight and
Saturday. Dry and warmer weather will return Sunday and Monday.
Another large Pacific low pressure system is forecast to move into
the western states next Tuesday and Wednesday, however this system
will track farther north across the central Rockies into the central
Plains. Thus, dry, breezy, and slightly below normal temperatures
are forecast for the middle of next week.

&&

.DISCUSSION...

Tonight through Saturday...

The strong upper low that moved rapidly southward down the Lower
Colorado River Valley last night and early this morning has moved
into extreme northern Sonora, Mexico. Behind this system, strong
northerly winds have developed, as expected, over SE CA and the
Lower Colorado River Valley. Gusts as high as 40 mph have been
reported at some locations, along with localized areas of blowing
dust. Although the upper low center will be moving rapidly away from
the region tonight and early Saturday, these winds are expected to
continue into at least late morning on Saturday as a 120kt northerly
jet maintains itself over the region, with good CAA and a rather
tight N-S sfc pressure gradient allowing from better-than-average
mixing of these strong winds aloft down to the sfc. NAEFS
Standardized Anomaly tables are currently showing 850mb winds 2-3 SD
above the mean and Climatological Percentiles in the 79.5-99 percent
range. along with the winds, considerable mid-level cloudiness, and
even some virga has developed over south-central AZ. Although a dry
subcloud layer is expected to keep precip from reaching the ground
at most locations, there is still a slight chance for a few showers
over the higher terrain of southern Gila County through Sat morning,
as seen on latest NAM4km high-res model output. Clearing skies and
diminishing winds area-wide are expected Saturday afternoon as the
upper low pressure center moves away and sfc pressure gradients
begins to relax.

Sunday and Monday...

Dry northwest flow aloft will develop over the region this period.
Nearly cloudless skies are expected with afternoon temperatures
approaching seasonal normals.

Tuesday and Wednesday...

Another deep cold Pacific trof is forecast to move into the western
states Tue and part of Wed. This system will track north of our
forecast area, southeast CA to south central AZ, basically across
the 4 corners region. Dry and breezy conditions can be expected with
afternoon temperatures near or slightly below normal.

Thursday and Friday...

Dry northwest flow aloft will develop over the region this period.
Nearly cloudless skies are expected with afternoon temperatures
near seasonal normals.

&&

.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:

No aviation concerns through this TAF period. Winds will stay out of
the northwest through around 03Z, then switch over to the northeast.
Speeds will remain light aob 6 kts. Skies will be partly to mostly
clear with few-sct clouds near 10 kft.

Southeast California/Southwest Arizona including KIPL and KBLH:

Breezy winds and localized blowing dust will be the two main
aviation impacts today. At KIPL, breezy northerly winds gusting up
to 30 kts will persist through early this evening, with lighter
winds aob 15 kts expected between the 00Z to 05Z time frame.
Thereafter, winds will pick up in speed again, remaining out of the
north-northwest and gusting up to 30 kts. At KBLH, sustained north-
northwesterly winds near 15 to 25 kts with gusts up to 25 to 35 kts
will be persist through the entire TAF period. Skies over both TAF
sites will remain mostly clear with few-sct clouds aoa 10kft.


Aviation discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Sunday through Thursday:

There is a slightly elevated fire danger potential on Sunday for
Southeast California and parts of Western Arizona. The main concerns
will be windy conditions and relative humidities below 15 percent.
However, the duration of these conditions is short lived and the
overnight recovery for relative humidity is fair. In addition,
breezy conditions on the order of 10 to 20 mph are likely for much of
South-Central Arizona and Southeast California beginning Tuesday and
lasting through Wednesday. Minimum RH will stay in the 12 to 30
percent range with decent overnight recoveries.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters are encouraged to report according to standard criteria.
Spotter reports of wind and dust may be needed Friday across
southeast CA and southwest/west AZ.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory until 9 PM MST Saturday for
     AZZ020-025.

CA...Wind Advisory until 8 PM PST Saturday for
     CAZ030>033.

&&

$$

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DISCUSSION...Percha/Vasquez
AVIATION...Hernandez
FIRE WEATHER...Deemer



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