889
FXUS65 KPSR 070049
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
549 PM MST Thu Mar 6 2025

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Unsettled weather conditions will persist through the end of the
workweek as a couple weather disturbances traverse the region.
Breezy to locally windy conditions areawide today will be followed
by widespread precipitation chances and well below normal
temperatures tomorrow. Tranquil conditions and warming temperatures
can be expected as high pressure builds over the weekend. Another
series of weather systems will likely affect the region next week,
one late Monday into Tuesday and another during the latter half of
the week, turning conditions unsettled once again.

&&

.DISCUSSION...
Light shower activity associated with a cold front that passed
overhead this morning has moved well to the east of the Phoenix Area
and dissipated. Measurable rainfall amounts within the CWA have been
at or below 0.1" today, focused over NE La Paz, northern Maricopa,
and portions of southern Gila County. Behind the front, skies have
become mostly clear. The main concern through the remainder of the
day will be strong postfrontal winds out of the WSW, as guidance
continues to indicate 850 mb winds to 35-45 kts this afternoon, and
thanks to the sunny skies, daytime mixing should help some stronger
winds to be realized at the surface over the western deserts.
Widespread gusts to 25-35 mph will be common through the afternoon.
There will be a corridor of wind gusts exceeding 40 mph across much
of southeast CA through northern Yuma and La Paz Counties in
southwest AZ, and as such, Wind Advisories remain in effect through
early this evening for those areas. With the strong gusty winds,
there can also be areas of blowing dust resulting in temporary
reductions in visibilities. Lofted dust has already led to hazy
conditions for much of the area.

The core of a more potent upper low, evident in 500 mb RAP analysis
currently diving southward along the California Coast is expected to
pivot eastward over the region tomorrow. This will send another cold
front across the region, with a broad area of moist isentropic
ascent ahead of this feature bringing widespread precipitation to
the forecast area. Shower activity is expected to blossom over
portions of southeast CA and southwest AZ late tonight and then will
likely become more expansive as it moves into south-central AZ by
early Friday morning. Even though most of the activity will likely
be east of Phoenix by the late morning hours, some wrap around
showers associated with cold core will likely develop during the
afternoon hours, although activity will be more hit or miss. Total
QPF amounts from this system will range from less than 0.10" across
the western deserts, to between 0.25-0.5" across the south-central
AZ lower deserts, and between 0.6-1.0" across the foothills and
higher terrain areas to the north and east of Phoenix. As increased
cloud cover and a colder air mass will be over South-Central AZ
tomorrow, highs will struggle to reach 60F in the Phoenix Area,
though locations further west (e.g., Yuma, Blythe, El Centro) could
see highs in the upper 60s to near 70F Friday afternoon. Regardless,
these highs are around 8F-15F below normal for the time of year.

Given the cold core nature of this system, snow levels are likely to
drop pretty low close to 4000-4500 feet, yielding some snowfall
accumulations across the higher terrain areas. In fact, locations
above 5000 feet across southern Gila County through the Mazatzal,
Pinal and Superstition mountains will likely (HREF probabilities
near 80-95%) see accumulations locally exceeding 4" and thus Winter
Weather Advisories have been maintained for these locations from 6
AM to 5 PM MST Friday.

In the wake of the upper low, high pressure will build over much of
the Western US this weekend, leading to quieter weather and
warming temperatures into early next week. By Sunday, forecast
afternoon highs are near their normal values, in the middle to
upper 70s, and the NBM continues to advertise some of the
typically warmer lower desert locales potentially reaching the
lower 80s on Monday. Late Monday into Tuesday, ensembles are still
in fairly good agreement that another upper level trough will
influence the region, with some differences in timing apparent
between the WPC Clusters. However, all solutions look to result in
decent precipitation chances for the region, as the most likely
trajectory will be far enough south to bring better quality
moisture into the forecast area. Along with the increased
precipitation potential, there will be some locally gusty winds as
well as temperatures trending much cooler once again to below
normal levels. After this system departs eastward by midweek,
ensembles are in good agreement of yet another deep trough moving
through the western CONUS by the latter half of the week,
potentially bringing additional precipitation chances as well as
maintaining temperatures below normal.

&&

.AVIATION...Updated at 0048Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Low cigs, showers, and potential for reduced visibilities Friday
morning will be the main weather hazards this TAF period. Strong
winds gusting upwards of 25-30 kts will weaken through the evening
with directions favoring the W into the overnight period. Blowing
dust generated by this afternoon`s strong winds may result in
some slantwise visibility concerns through sunset. Confidence is
low in an easterly transition overnight with any easterly
transition expected to remain brief.

Confidence is excellent that widespread -SHRA will spread into the
Phoenix area just prior to sunrise Friday morning with cigs likely
falling into an MVFR category. There is a 20-30% chance of brief
IFR vsby/cig conditions in any heavier rainfall, but this category
would be rather brief into the mid morning hours. By late
morning, there may be more breaks in -SHRA activity, however
models suggest persistent MVFR cigs and more spotty -SHRA well
into the afternoon before clearing late afternoon prior to sunset
Friday afternoon. Thunderstorm chances Friday morning into the
afternoon will remain below 10%. VFR conditions will prevail by
late afternoon/early evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
Very gusty SW winds with a few areas of lofted blowing dust will
remain the primary aviation weather concern through the next few
hours, then a period of -SHRA and cigs potentially touching in
MVFR category will be the primary weather impact late
tonight/early Friday morning. Gusts upwards of around 30 kts will
continue to weaken this evening, but any blowing dust generated
may result in some slantwise visibility issues through sunset.
Confidence is good that -SHRA and lowering cigs will arrive across
SE California around midnight, and impact the area during the
overnight hours. There`s a 20-40% chance of vsby/cigs touching
into MVFR category before conditions rapidly improve around
sunrise Friday morning. Gusty W/NW winds will increase late
morning into the afternoon with gusts climbing upwards of 20-25
kts.


&&

.FIRE WEATHER...
Unsettled weather conditions and well-below normal temperatures are
expected through Friday as a series weather disturbances move across
the region. Some shower activity is expected early this morning
along a cold front across portions of south-central AZ followed by
strong gusty winds later this morning and afternoon. Widespread
gusts ranging between 20-35 mph will be common with higher gusts in
excess of 40 mph across the western districts. More widespread
precipitation activity is expected on Friday with good chances
(>60%) of wetting rainfall across much of south- central AZ. MinRHs
through the end of the week will remain above 20%, with much of
south-central AZ likely remaining above 40% on Friday.

Warmer and drier conditions along with generally light winds can be
expected through the upcoming weekend. Conditions will then turn
unsettled once again next week as another series of weather systems
affect the region with one system moving through late Monday into
Tuesday and another by the latter half of the week. Both of these
systems will potentially result in more wetting rainfall, some gusty
winds, and temperatures cooling down once again to below normal
levels.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory until 7 PM MST this evening for AZZ530-531-533.

     Winter Weather Advisory from 6 AM to 5 PM MST Friday for AZZ557-
     558-563.

CA...Wind Advisory until 6 PM PST this evening for CAZ563>567-569-570.

     Wind Advisory until 10 PM PST this evening for CAZ562.

&&

$$

DISCUSSION...Whittock/Lojero
AVIATION...Smith/18
FIRE WEATHER...Lojero