305
FXUS65 KPSR 231725
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1025 AM MST Mon Dec 23 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
Dry, warm weather will continue for the start of the week before a
cold front delivers much cooler temperatures Tuesday into Wednesday.
Winds will increase across the region with this cold front, but rain
chances will remain minimal across the lower deserts. Temperatures
are favored to trend back toward well above normal readings by this
weekend.

&&

.DISCUSSION...
Early morning WV imagery and mesoanalysis showed a weak shortwave
trough currently progressing across Arizona, with an associated band
of cloud cover along with some areas of virga currently pushing over
central portions of the state. Mostly clear skies will then prevail
later this morning as the disturbance pushes east. Temperatures will
continue to remain well above normal as transient ridging builds
across the region through Tuesday ahead of a more potent trough.
Afternoon highs today and Tuesday will be around 10 degrees above
normal as temperatures across the lower deserts top out in the mid
to upper 70s.

The aforementioned ridge of high pressure won`t stick around for
long as strong troughing currently about 1,500 miles west of the
Pacific Northwest Coast will send a shortwave trough into the
southwest CONUS during the Tuesday/Wednesday timeframe. This trough
will send a cold front sweeping through the region Tuesday into
Wednesday, bringing much cooler air along with increasing winds. By
Christmas Day following the passage of the cold front, lower desert
highs will only be in the mid to upper 60s across south-central
Arizona to around 70 degrees across southeast California and along
the Lower Colorado River Valley. Despite this cool down,
temperatures will still be near to slightly above normal for this
time of year. Winds will ramp up across southeast California going
into Tuesday evening as the cold front approaches. Wind gusts in
excess of 25-30 mph will be possible at times with localized 40+ mph
gusts primarily focused in southwest Imperial County. Meanwhile,
rain chances with this system will be quite meager for our area
given the lack of better moisture and forcing. The best chances for
precipitation will remain confined to the Arizona high terrain.

Going into the latter part of this week as the aforementioned trough
pushes out of the region, guidance currently depict a quick moving
shortwave potentially pushing through the Great Basin and into the
Four Corners region. This would primarily help to keep temperatures
near to slightly above normal while dry conditions are likely to
persist. Ensemble cluster analysis then show good agreement in upper
level ridging building back over the Desert Southwest this weekend.
As a result, forecast highs trend back to well above normal readings
with the latest NBM temperatures indicating highs in the mid 70s by
the latter part of this weekend.

&&

.AVIATION...Updated at 1722Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No major weather issues will exist through Tuesday afternoon under
periods of passing SCT-BKN high cirrus decks. Current VRB/Easterly
winds are expected to shift to westerly flow by 19-21Z for the
Phoenix terminals. Northerly flow expected at KBLH this afternoon
before westerly shift for both KBLH and KIPL.

&&

.FIRE WEATHER...
Dry conditions with temperatures around 10 degrees above normal will
continue for the beginning of the week. A weather system and an
associated cold front will bring cooler conditions along with
increasing winds to the region Tuesday into Wednesday. Winds will be
strongest across portions of southeast California where gusts could
climb in excess of 30 mph at times going into Tuesday evening. Rain
chances are expected to remain minimal with the best chances
remaining across the Arizona high terrain. Min RHs today will be
around 10-20% for most places before increasing to around 15-25%
Tuesday. Dry conditions with near to slightly above normal
temperatures are favored to persist through the end of the workweek
before temperatures trend back toward well above normal this weekend.

&&

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

$$

DISCUSSION...Smith
AVIATION...Ryan
FIRE WEATHER...Smith