316
FXUS65 KPSR 282151
AFDPSR

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

.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 1737Z.

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

Light winds, generally aob 7 kts, following typical diurnal
directional patterns will prevail at all terminals. Extended
periods of calm to light and variable winds are anticipated as
well. SKC skies will prevail with no VIS impacts.

&&

.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...Benedict
FIRE WEATHER...Smith/Salerno