154
FXUS65 KPSR 072320
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Fri Feb 7 2025

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
High pressure will continue to encompass the region for the next
several days, promoting above-normal temperatures through at least
the start of next week. An unsettled pattern is then expected to
take hold across much of the western United States, leading to a
drop in temperatures toward near and below normal values, and
increasing rain chances during the middle and latter portion of next
week.

&&

.DISCUSSION...
High pressure, centered across northern Mexico, continues to stretch
from coast-to-coast, providing dry and warm conditions to the Desert
Southwest. The upper-level jet orientation continues to direct any
significant disturbances well off to our north, with periods of high
clouds being the only noticeable change observed over the past few
days. As a result, temperatures through the this weekend will remain
generally steady in the middle to upper 70s across lower desert
areas, with a few locations reaching into the lower 80s through this
weekend. Troughing located across the Pacific Northwest and northern
California will attempt to nudge at the dominant areas of high
pressure, which will result in a enhanced regional pressure gradient
across Arizona and southern California. The strongest winds should
be observed over northern Arizona, but enhanced gusts, generally
maxing out between 30-35 mph, are expected across parts of
southeastern California this afternoon and evening. Advisory level
gusts (40 mph or greater) will be possible for a few spots,
primarily in far western Imperial County, but due to the isolated
nature of these higher gusts, a Wind Advisory will not be issued at
this time.

Heading into the start of next week, the ridging pattern will begin
to dissolve as a potent trough begins to dive across the Great
Basin. This will begin what looks to be a fairly unsettled pattern
that will see regional temperatures fall, winds increase, and rain
chances rise. By Tuesday, afternoon highs will fall to near and
below normal levels, with readings in the middle to upper 60s. Even
cooler conditions are forecasted for Wednesday, with afternoon MaxTs
in the lower to middle 60s for lower desert areas. Due to the
enhanced pressure gradient associated with this initial shortwave,
breezy to locally windy conditions should be anticipated, this time
over a larger area, and potentially for a longer duration (Monday
into Tuesday), compared to the winds expected tonight across SE
California. Wind Advisory potential appears to be higher for this
timeframe, so it would not be surprising to see wind products issued
in the coming days. Since this system will be diving in from the
north, moisture availability should be mostly limited so rain
chances for most of our forecast area remain below 10%. However,
there might just enough moisture to help spark a few orographically
influenced showers over high terrain areas to the north and east of
the Phoenix metro.

Behind this initial trough, a secondary system is projected to
traverse the Desert Southwest, helping to keep temperatures near to
slightly below seasonal values, and increasing rain chances. Global
ensembles show PWAT values increase to the tune of 200% of normal
across the region, plenty of moisture to support widespread rain
chances for even lower desert areas. However, the main uncertainty
that may limit rain activity over these areas will be the track of
this system, with the model consensus indicating the best dynamics
may pass to north. This would not eliminate rain chances for lower
elevation areas entirely, but it would result in more widespread
activity outside of our forecast, mainly for northern Arizona. If a
deeper system comes to fruition, then decent, widespread rainfall
would become more likely. Nonetheless, as long as moisture
projections stay where they are, orographic influences would once
again aid in the development of rainfall activity, so better rain
chances (currently 30-40%) exist for our Arizona high terrain areas.
Breezy to windy conditions will also likely make a return due to the
tightening of the pressure gradient once more, but any discussion on
potential wind products will be shelved until next week when
confidence increases.

&&

.AVIATION...Updated at 2320Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No weather issues will exist through Saturday afternoon under
periods of thick high cirrus cigs. Wind trends will again be very
similar to the past 24 hours with good confidence of light westerly
flow transitioning to east by midnight.


Southeast California/Southwest Arizona including KIPL and KBLH:
Periods of gusty winds early this evening will be the greatest
weather issue under periods of thick cirrus cigs. W/SW gusts 20-25kt
will be common at both terminals through the evening before relaxing
overnight. Winds will trend to northerly Saturday with speeds much
weaker than previous days.

&&

.FIRE WEATHER...
Weak high pressure over the region will continue to bring above
normal temperatures and dry conditions through the weekend. MinRHs
today will range from the 30-40% range over the western districts to
20-30% over the eastern districts before lowering into the teens
areawide by Sunday. Winds will remain fairly light through the
period, but for today expect some afternoon and evening breeziness
with gusts of 20-25 mph across the western districts. The weather
pattern will become more unsettled next week with temperatures
cooling back to around normal starting Tuesday, but expect overall
dry conditions and low humidities to last through the middle of the
week.

&&

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

&&

$$

DISCUSSION...RW
AVIATION...18
FIRE WEATHER...Kuhlman