879
FXUS65 KPSR 290508
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1005 PM MST Sun Apr 28 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
Temperatures will return to seasonal levels today over the forecast
area. An overall dry and benign weather pattern will set up across
the Desert Southwest this week with highs rising slightly above
normal starting tomorrow. Breezier conditions will be possible
during the middle part of the week. Otherwise, warm and dry
conditions with no precipitation is anticipated through the week.

&&

.DISCUSSION...
Another quiet weekend afternoon is ongoing across the forecast area
as a tranquil pattern sets up for the start of the new week.
Currently, objective analysis showed the southwest CONUS under the
influence of broad cyclonic flow while an upper low is currently
centered over Nebraska/South Dakota. Locally in Arizona, a weak vort
max is pushing across the state, aiding in the development of an
expansive cloud field over the northern AZ high terrain/orographic
features with no sensible impacts across the lower elevations.
Temperatures today will warm back up to near normal readings as
heights rise in response to a quasi-zonal flow pattern that will
prevail for the start of the new workweek. Temperatures this
afternoon will be ~5-7 degrees warmer than yesterday as highs top
out in the upper 80s to near 90 degrees across the lower deserts.

As mentioned before, quasi-zonal flow will prevail for the start of
the new workweek, pushing 500 mb heights to around 575-578 dm
through the first part of the week. Temperatures will respond by
rising near to slightly above normal as highs climb into the lower
90s starting tomorrow. Uncertainty increases heading into the mid to
latter half of this week in regards to the evolution of a trough
that will move into the northwest CONUS early in the week. Ensemble
cluster analysis reveal the bulk of global members favor a solution
where greater negative height anomalies remain to our north, while a
minority of members (predominantly comprised of GEFS members) show
troughing deepening further south closer to our area. The latter
solution would favor a cooler, breezier pattern for our area. As of
now, NBM deterministic highs remain in the low to mid 90s through
the week before increasing into the mid to upper 90s for the
weekend, though larger temperature spread is seen in the
interquartile range due to the aforementioned uncertainties. Despite
these uncertainties, ensembles agree that dry conditions are favored
to persist through the week.

&&

.AVIATION...Updated at 0505Z.

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 Monday night under clear
skies. Timing of the usual diurnal wind shifts will be typical for
this time of year while any enhanced gusts remains minimal or
absent. In fact, extended periods of nearly calm conditions may be
common.

&&

.FIRE WEATHER...
A warming trend will continue through the first part of this week as
afternoon temperatures rise near to slightly above normal in the low
to mid 90s across the lower deserts. Along with the warmer
temperatures, it will be consequently drier each afternoon with
minimum relative humidity values bottoming out around 8-15% over the
next several days. Overnight Max RHs will initially be in the 30-50%
for the first part of the week before gradually decreasing during
the latter half of the week. Lighter winds will follow typical
upslope/downvalley patterns through the first part of this week.
Winds are expected to stay below 15-20 mph through Tuesday, however
there is potential for some increased breeziness toward the middle
to latter half of this week as a dry weather system passes north of
the area.

&&

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

&&

$$

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