000
FXUS65 KPSR 011039
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
339 AM MST Sat Apr 1 2023

.SYNOPSIS...
A warming trend will continue this weekend, with above normal
temperatures likely across southeastern California Sunday. Another
storm system moving through intermountain West will result in a
period of strong winds Monday followed by a return to cooler
conditions Tuesday. A warming trend will follow through the end of
the week, though temperatures will likely remain several degrees
below normal.

&&

.DISCUSSION...
Latest water vapor imagery reveals a well-defined vort max near
San Diego. This system will have little impact on our weather this
weekend, other than some high clouds this morning. Otherwise, the
warming trend will continue today and tomorrow as the subtropical
ridge nudges a bit northward. Across the Phoenix area, the NBM
temperature distribution remains tight, suggesting high
temperatures in the lower-mid 80s Sunday. Further west in El
Centro, forecast high of 87 degrees would be the warmest reading
so far this year. In addition to the warmth, breeziness is
anticipated Sunday afternoon, particularly across southeastern
California and southwestern Arizona, where the pressure gradient
will begin to tighten ahead of a trough across the Pacific
Northwest.

The aforementioned trough will slide eastward into the Great
Basin Monday. Moisture will increase ahead of a cold front, but
latest IVT projections remain inadequate to generate
precipitation. The greater sensible impact will instead be the
wind mainly behind the front, and latest trends in the model
ensembles are concerning. Model clusters are exhibiting very
little variance, which points to a high probability event.
Meanwhile, ECMWF EFIs have been steadily increasing, with
widespread values of 60-80 percent suggesting the potential for a
high-impact event Monday afternoon and early evening. At this
time, the ECMWF ensemble mean wind gust is 40 mph for Phoenix,
with higher gusts likely across the higher terrain, particularly
north and east of Phoenix. A High Wind Watch has been hoisted
across northern Arizona and the Mojave Desert. Further south
though, it is likely widespread Wind Advisories will be needed for
wind gusts of at least 40-50 mph. Winds of this magnitude will
also be capable of producing blowing dust.

Winds will subside somewhat Tuesday as the low pressure system
ejects into the Plains. In its wake, cooler and drier air will
overspread the Desert Southwest. Latest NBM has trended a few
degrees warmer, nevertheless temperatures 15 to 20 degrees below
normal are anticipated. A warming trend remains a good bet
Wednesday through next weekend, though persistent negative height
anomalies will translate into a continuation of the below normal
temperatures. There are even a handful of ensemble members
indicating the development of a cutoff/closed low pressure system
in the eastern Pacific next weekend, capable of tapping into
deeper subtropical moisture and possibly increasing rain chances
from Arizona eastward.

&&

.AVIATION...Updated at 0520Z.

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

No aviation concerns are expected throughout the forecast period
as tranquil conditions prevail. Winds will favor a light and
diurnal pattern through tomorrow evening with occasional periods
of variability. Lingering high clouds will clear out in the coming
hours as FEW to SCT mid level clouds pass through the region
overnight into tomorrow morning. Clear skies will follow for the
rest of the day tomorrow.

&&

.FIRE WEATHER...
Weak high pressure will build northward this weekend, generally
resulting in mostly clear skies and light winds today. The
warming and drying trend will continue, though temperatures will
remain below normal. Min RHs will likely drop to around 10 percent
this afternoon while wind gusts will top out at 10-15 mph. The
warming trend will continue into Sunday, particularly across
southeastern California, where above normal temperatures are
likely. Afternoon breeziness will also develop in these areas
ahead of a deepening storm system across the Pacific Northwest.

Strong winds are anticipated Monday as this low moves into the
Great Basin and Desert Southwest. Winds gusts in excess of 50 mph
will be possible in some areas, particularly across the higher
terrain north and east of Phoenix. A return to well below normal
temperatures is anticipated Tuesday followed by a gradual warming
trend through the week.

&&

.HYDROLOGY...

Verde River: Bartlett Dam releases continue to decrease to near 2000
cfs. However, water lingering in the channel and backed up from
increased flow near the confluence of the Salt River is causing
river stages to remain elevated. These river levels along with
debris and erratic currents could still be dangerous for
recreational interests, and the flood warning has been extended
through Monday.

Lower Salt: Water releases around 6500 cfs from Lake Roosevelt have
necessitated increased downstream releases at Stewart Mountain Dam
(~7000 cfs) and Granite Reef Dam (~12500 cfs). Recreation areas
along the Salt river remain dangerous, and several are closed due to
elevated water levels, erratic currents, and debris carried from
upstream. In addition, numerous roads built into the river channel
continue to be closed around the Phoenix metro.

Gila: Upstream water releases on the Salt River continue to spill
into the Gila basin pooling behind Painted Rock Dam. USGS data below
Painted Rock Dam continues to show modest increases in depth and
release volume. These releases have the potential to flood multiple
unbridged river crossings and low lying farm fields. High
uncertainty persists regarding the potential for any downstream
impacts into Yuma County.

&&

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

$$

DISCUSSION...Hirsch
AVIATION...Leffel
FIRE WEATHER...Hirsch
HYDROLOGY...18

NWS PSR Office Area Forecast Discussion