251
FXUS65 KPSR 012310
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
410 PM MST Tue Apr 1 2025

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
An unsettled weather pattern is bringing widespread gusty winds to
the region today along with cooler temperatures. The strongest winds
will remain focused across the southern Gila County higher terrain
as well as portions of southeast California through the evening into
tonight. Some chances for showers can be expected on Wednesday and
on again Friday, with most of the activity favoring the higher
terrain areas to the north and east of Phoenix. Temperatures will
remain well below normal through the rest of the workweek before a
warming trend takes shape starting this weekend.

&&

.DISCUSSION...
Early afternoon objective analysis shows a large trough over the
Intermountain West with a strong mid level jet continuing to sag
southward across our area. The increased gradient and higher
momentum air aloft mixing down has led to widespread gusty winds
this afternoon. Surface observations as of this afternoon showed
peak wind gusts upwards of 25-35 mph for many areas across our CWA,
while a few areas have seen gusts around 40 mph. The strongest winds
will continue to remain focused across the southern Gila County high
terrain as well as parts of southeast California, particularly
portions of Imperial County. Wind Advisories are in effect for these
areas through this evening into tonight. Given these winds, blowing
dust will be a concern, especially across Imperial County where
webcams are showing dust being lofted this afternoon. Blowing dust
could lead to some visibility reductions.

The longwave troughing pattern will settle across the Desert
Southwest through the end of the week, bringing much cooler than
normal temperatures as well as send a couple of shortwaves over the
area bringing some precipitation chances. WV imagery currently shows
one of these shortwaves near the northern California coast. This
shortwave will continue to propagate toward the southeast and into
Arizona going into Wednesday afternoon. While moisture will be quite
meager with PWATs around 0.3-0.4", the vort max is expected to
provide the necessary ascent needed to squeeze out some of this
moisture. HREF data shows light showers developing across parts of
south-central Arizona going into Wednesday afternoon, favoring areas
to the north of Phoenix. Forecast soundings also indicate CAPE
values up to 100-200 J/kg by early Wednesday afternoon and may lead
to a few isolated thunderstorms. Rainfall amounts across our area
will remain light generally around several hundredths with locally
higher amounts with any thunderstorms that were to develop.
Temperatures will bottom out well below normal Wednesday as highs
struggle to get out of the 60s for many lower desert communities.
Temperatures will gradually trend upwards for the latter part of
this week as height fields gradually recover. Temperatures, however,
will continue to remain well below normal Thursday and Friday as the
region remains under troughing. Another weather system will take
shape over the southwest CONUS going into Friday, bringing
additional chances for light showers across the higher terrain for
the end of the week.

Global ensembles show the troughing pattern weakening and shifting
east this weekend, leading to a more pronounced warming trend.
Ensemble cluster analysis shows good agreement amongst ensemble
members that upper level ridging will build into the region going
into the start of next week. NBM shows temperatures returning to
near normal readings Sunday before warming above normal early next
week. By the mid to latter part of next week, ensemble clusters
favor stronger ridging building across the West, boosting
temperatures well above seasonal normals.

&&

.AVIATION...Updated at 2310Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Abnormal trends in wind directions, occasional stronger gusts, and
periods of lower cigs will all be weather concerns through Wednesday
afternoon resulting in lower than usual forecast confidence. Gusty
W/SW winds 20-30kt should partially decouple and weaken after
sunset, however its unlikely a widespread shift to easterly will
occur overnight. Lofted dust will be common due to these wind gusts
and slantwise vsby impacted through mid evening. Some of the outer
terminals may briefly become SE or variable towards sunrise though
confidence is low to moderate.

Confidence is somewhat better that 050-070 AGL cigs will develop mid
morning through early afternoon with a tendency for bases to rise
through the afternoon though may hover not far from the 060
threshold. Another round of gusty SW winds 20-25kt is likely
mid/late afternoon. Isolated SHRA are possible around the airspace
during the afternoon, however coverage and probabilities are too low
to include in the TAF package. There is model evidence that some of
these SHRA north and west of Phoenix may create erratic winds and
create a northerly component late afternoon/early evening.


Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty winds will remain the greatest weather issue through Wednesday
afternoon under periods of passing high clouds and potential for
isolated lower cigs. Westerly gusts 25-35kt will be most pronounced
in duration and magnitude at KIPL with only a brief early morning
period of weakened decoupling. While some sfc visibility
restrictions are possible, its more likely dust will remain lofted
and impacting slantwise vsby. Gusts will be far weaker at KBLH,
however wind directions may be much more variable through the
period. There is model evidence of cigs 050-070 developing during
the mid morning hours, though confidence is only moderate.

&&

.FIRE WEATHER...
A weather system over the region will continue to promote widespread
gusty winds into this evening. The gusty winds combined with Min RHs
around 15-25% will continue to promote areas of elevated fire
weather conditions. The strongest winds will remain focused across
portions of southeast California, mainly across Imperial County, and
the higher terrain areas of Maricopa and southern Gila Counties
where gusts in excess of 40 mph are most likely to occur. Winds
elsewhere will range between 20-35 mph. Weaker winds are expected on
Wednesday but will likely gust between 15-30 mph, with the strongest
winds expected across the higher terrain areas of south-central
Arizona and across Imperial County. There will be some modest rain
chances (20-50%) across the foothills and higher terrain areas to
the north and east of Phoenix Wednesday afternoon, however, the CWR
will remain low at 10-20%. A few isolated thunderstorms will also be
possible, which could lead to locally erratic winds. Lighter winds
are anticipated from Thursday onward. MinRHs will range between 20-
30% Wednesday-Thursday, between 15-25% Friday, and between 10-25%
over the weekend. Overnight recoveries will be fair to good on most
days, generally between 40-70%. Well-below normal temperatures are
anticipated through the end of the week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory until 2 AM MST Wednesday for AZZ532.

     Wind Advisory until 8 PM MST this evening for AZZ558-560>563.

CA...Wind Advisory until 2 AM PDT Wednesday for CAZ560-563-565>567.

     Wind Advisory until 5 AM PDT Wednesday for CAZ562.

&&

$$

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