Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 240347
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
847 PM MST MON MAY 23 2016

.SYNOPSIS...
A large region of low pressure will continue over the Western States
through the weekend. There will be day to day fluctuations in
temperatures and afternoon breeziness as the system waxes and wanes.
Overall though, temperatures will remain below normal and conditions
will remain dry.

&&

.DISCUSSION...
Skies remain clear across the desert southwest this evening.
Southwesterly flow predominates ahead of a mid-level trough moving
through central CA. While temperatures are slightly warmer than they
were this time yesterday, they also remain below average due to the
persistent longwave trough across the western CONUS. Minor
adjustments were made to the short-term temperatures and dewpoints
this evening. Otherwise, the forecast remains on track.

&&

.PREVIOUS DISCUSSION...
Southwesterly dry flow continues across the Desert Southwest with a
large scale upper level trough entrenched across the Western United
States. The main upper level low circulation within the large scale
trough is currently just off the central California coast and is
forecast to eventually swing through the Desert Southwest sometime
Wednesday. In the meantime, heights aloft will remain below
climatological normals and thus provide below normal temperatures for
the region. Highs today and Tuesday will generally fall between 85-90
degrees over the deserts while falling a degree or so on Wednesday
as the low circulation passes through the region.

The passage of this upper low will still bring dry conditions for
our area with no precipitation in the forecast as PWATS remain below
a half an inch. Despite the cold core of the low moving overhead
across the central deserts, instability is marginal with little or no
MLCAPE advertised for southeastern CA or southern AZ. The only
potential impact will be breezy to windy daytime conditions on
Wednesday with some potential blowing dust and elevated fire danger
concerns. Wind gusts Wednesday afternoon will likely exceed 30 mph in
some spots, especially over the higher terrain east of Phoenix.

For Thursday into the weekend, the large scale trough will rebuild
across the Western United States with the main upper low center
situated over portions of the Pacific northwest. Arizona will be on
the far southern/southeastern flank of the trough and under
continued dry southwesterly flow aloft. High temperatures will stay
just below seasonal normals through the period while a slight warming
trend brings highs back into the middle 90s over the lower deserts
under generally sunny skies.

&&

.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL... and
Southeast California/Southwest Arizona including KIPL and KBLH...

Phoenix-area variable winds will eventually settle into SW-W headings
through the evening. Southeasterly drainage winds will develop back
into the terminals overnight. Elevated SW-W breezes will develop into
KBLH and KIPL, with gusts possible of 20kts. Another strong sundowner
event coupled with strong ridgetop winds will allow for strong west
winds for much of the evening for KIPL. Did not include BLDU in the
TAF, but cannot rule out some localized or vicinity dust around the
airfield. Clear skies to persist for the TAF period.

Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...
Wednesday through Sunday...a series of low pressure systems will
continue to move into the western states mainly north of Arizona
this period.  Although dry weather is forecast, the proximity of the
low pressure systems to Arizona will result in breezy to windy
afternoon/early evening southwest winds.  Wednesday is forecast to
be the windiest day with general 20 to 30 mph winds. On Thursday
through Sunday afternoon southwest breezes will range from 10 to 20
mph. Afternoon temperatures this period will remain below normal.
Minimum relative humidities will generally range from 12 to 15
percent. Fair recovery is expected at night.

&&

.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

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DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Kuhlman/CB
AVIATION...Nolte
FIRE WEATHER...Vasquez


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