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000
FXUS65 KPSR 260512
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1010 PM MST Thu Apr 25 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
Breezy to windy and relatively cool conditions will continue through
Saturday. The windier day will be Friday. There will be a chance of
showers over portions of south-central Arizona Friday night and
Saturday morning, mainly over higher terrain areas. Rainfall
amounts, if any, will be light. A significant warming trend ensues
Sunday through Tuesday with little change Wednesday and Thursday.
That will mean desert highs well into the 90s for the workweek with
readings close to 100 at some spots by midweek.

&&

.DISCUSSION...
There is a sizable short wave centered over AZ with a potent vort
max within it over northeast AZ. That feature generated shower and
storm activity over western AZ early this morning with convective
showers developing over the northern half of AZ. Follow-on
convective showers associated with a cold pool aloft continue to be
limited to FGZ`s forecast area. The short wave will continue to
weaken with time as it tracks northeastward and largely be out of AZ
by 00Z this afternoon. For our forecast area, the most noticeable
impact is breeziness coupled with cooler temperatures. 24 hour
temperature trends early this afternoon are running roughly 5-10
degrees cooler. Some areas, most notably Imperial County, have been
experiencing strong winds where the surface pressure gradient is
best. As the wave weakens and moves further away, the flow aloft
will also weaken leading to a temporary weakening of winds.

The approach of another wave from the Pacific northwest along with
terrain effects, will lead to restrengthening of winds there and a
Wind Advisory remains in effect for later this afternoon and
evening. After something of an overnight and morning lull, strong
winds develop again Friday afternoon and evening. In fact, much of
Imperial County as well as western Joshua Tree N.P. and some higher
terrain portions of southern Gila County have anywhere from 60-100%
probability of wind gusts exceeding 40 mph. Thus, a Wind Advisory is
in effect. Elsewhere will still be windy but not as strong. Winds
won`t be as strong Saturday but still breezy to locally windy.

This second system will have a bit better potential to produce rain
for our area (more widespread chances over northern AZ). But, precip
chances will be limited mainly to higher terrain and foothill
locations of south-central AZ Friday night and Saturday morning.
Precipitation, if any, will be light. In fact, the 90th percentile
of the NBM 12 QPF ending 12Z Saturday is less than one tenth of an
inch for the lower elevations up to a quarter inch for above
4000ft). Very localized spots could see more if a thunderstorm
passes over but thunderstorm potential is less than 20% (less than
10% lower elevations). Snow flurries could be seen as low as 6000ft
with accumulations above 6500 ft.

With the exit of the second system later Saturday, a significant
warming trend ensues Sunday through Tuesday with little change
Wednesday and Thursday. That will mean desert highs well into the
90s for the workweek with readings close to 100 at some spots (incl.
Greater Phoenix) by midweek.

&&

.AVIATION...Updated at 0510Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Periods of gusty afternoon/early evening winds will be the primary
weather concern through Friday night under FEW-SCT midlevel decks.
Confidence is good wind directions will revert to light easterly
after midnight, however directions should veer back to S/SW quickly
by late Friday morning with gusts progressively strengthening during
the afternoon. By late afternoon, gusts reaching a 25-30kt range
should be common. Isold SHRA/TSRA across northern AZ should decay
before reaching terminals Friday evening, however there is a remote
chance (less than 20%) that a residual SHRA and outflow descends
into the Phoenix metro.


Southeast California/Southwest Arizona including KIPL and KBLH:
Strong, gusty W/SW winds will be the main weather concern through
Friday evening under clear skies. Gusts should generally relax
during the overnight hours, however stronger gusts should resume
fairly quickly Friday afternoon. Widespread 20-30kt gusts should
become common with KIPL likely experiencing gusts above 35kt at
times late Friday afternoon/evening. As a result, lofted dust and
regionally reduced slantwise visibilities are possible, though not
specifically mentioned at the surface at any particular TAF site.

&&

.FIRE WEATHER...
A period of enhanced winds continues through Saturday with portions
of southeast CA and southern Gila County seeing very strong winds at
times (mainly Friday). Fortunately, RH values are expected to remain
high enough (MinRH 20-30%) to avoid critical thresholds during the
time of strongest winds. RH trends down Saturday over the lower
elevations (MinRH 10-20%) but winds are not expected to reach
critical thresholds. Higher RH values (MinRH 25-35%) linger over
south-central AZ Saturday. A significant warming trend takes place
Sunday through Tuesday with little change Wed-Thu. RH trends down as
well with MinRH bottoming out around 10-15% by Tuesday (little
change through Thursday). MaxRH bottoms out around 25-45% by
Wednesday. Winds next week will be lighter.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory from noon Friday to midnight MST Friday night for
     AZZ557-558.

CA...Wind Advisory from noon Friday to midnight PDT Friday night for
     CAZ560-563-565>567.

     Wind Advisory until midnight PDT Friday night for CAZ562.

&&

$$

DISCUSSION...AJ
AVIATION...18
FIRE WEATHER...AJ