Area Forecast Discussion
Issued by NWS Phoenix, AZ
FXUS65 KPSR 272209
Area Forecast Discussion
National Weather Service Phoenix AZ
309 PM MST THU OCT 27 2016
A large and wet Pacific weather system is forecast to move into
mostly central California tonight and northern Nevada on Friday.
However, this system will spread considerable clouds over the region
through Friday, with a slight chance of showers over the southeast
California deserts and mountains. Dry weather with mostly clear
skies will return Saturday through Monday, with desert temperatures
continuing in the lower 90 degree range. Another massive Pacific
weather system will approach the central California coast later
Tuesday, then move into the western states Wednesday providing
mostly cloudy skies and cooler afternoon temperatures to southeast
California and southern Arizona.
Tonight through Friday...
A strong high pressure system over the area will weaken tonight as a
fairly potent Pacific storm approaches the central and southern CA
coast. Increasing high clouds this afternoon and especially tonight
are fore-runners of this massive weather system. Unfortunately the
Pacific storm and its precipitation is forecast to track into
central CA tonight, then into northern Nevada Friday. This will
leave most of our forecast area, southeast CA to south central AZ
cloudy but dry, with the exception of the southeast CA mountains and
higher deserts where dense cloud spill-over will generate a slight
chance of showers Friday. The tail end of a cold front will move
through southeast CA around 9 am Friday, and with increasing low
level west wind, rain shadow type, it should limit shower activity
to sprinkles or an occasional light shower especially over the
mountains of Joshua Tree N.P.
Saturday through Monday...
Dry west to southwest flow aloft with occasional high clouds are
forecast Saturday through Monday. Unseasonably warm temperatures
will continue, i.e. lower 90s on the deserts due to a fairly
vertically thick atmosphere as the storm track remains well north of
AZ. However on Monday, afternoon temperatures will likely decrease
as another very large Pacific low pressure system edges toward the
west coast and closer to AZ.
Tuesday through Thursday...
This period is somewhat uncertain with regards to how far south the
massive Pacific weather system will move, and its affects on
southern AZ. All models forecast this system to take a deep
southward turn into southern CA and northern AZ. However a very
progressive flow pattern across the Pacific should continue, and
quite possibly eject this approaching Pacific weather system farther
north than forecast, just like all the earlier weather systems.
Confidence is low this period, and all offices decided to take a
wait and see position regarding storm magnitude this far south,
and precip if any.
.AVIATION...South-Central Arizona including KPHX, KIWA, and KSDL:
Winds from the southeast will weaken and attempt to swing to the
south then west through this evening. Later tonight, easterly winds
will redevelop. Persistent high clouds.
Southeast California/Southwest Arizona including KIPL and KBLH:
Light winds into Friday morning then increasing from the south. High
clouds will thicken and gradually lower, approaching 10kft late
Friday morning. Thick mid/high clouds persist late Friday morning
through the afternoon along with some light showers.
Aviation discussion not updated for amended TAFs.
Saturday through Wednesday...
High temperatures this weekend will remain well above normal, then a
gradual cool down is expected through the middle of next week as a
a low pressure system moves across southern California Tuesday night
and into Arizona Wednesday. As of now, little moisture is expected to
accompany this system, and the greatest impacts will be the slight
cool down in temperatures.
Minimum humidities will remain near the 20 to 30 percent range each
day with good overnight recoveries. Winds will remain light and
follow normal diurnal headings through the entire period, except for
some periods of afternoon breeziness up to 20 to 25 mph in southeast
.SPOTTER INFORMATION STATEMENT...
Spotter activation will not be needed this week.
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