328
FXUS65 KPSR 151800
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1100 AM MST Sat Mar 15 2025

.Update... 18Z Aviation Discussion

&&

.SYNOPSIS...
Dry conditions and a warming trend will follow through Monday
before another, mostly dry, system passes through late-Monday
through Tuesday. The warming trend will recommence following the
Tuesday system, as will drying conditions, with a return of 80
degree high temperatures during the latter half of the week.

&&

.DISCUSSION...
Shortly after midnight scattered light to moderate showers were
still developing in South-Central AZ and moving ESE. Favorable
low-level convergence and upper level divergence, with a strong
120-140 kt 300 mb jet, has been aiding this continued
development. Precipitation amounts have been very light, mostly
under 0.10" prior to midnight, and is expected to remain light
through the rest of this morning with additional amounts mostly
under 0.10". However, training of any stronger (40 dBZ) echoes may
lead to localized amounts up to 0.25". Radar melting layer
algorithm for KIWA radar was showing a snow level around the 5000`
level over Phoenix to a touch lower east of Phoenix. A Winter
Weather Advisory remains in effect until 5 AM MST for elevations
above 5000`. Highest snowfall is forecast for Pinal Peak, where
latest HREF even has a 40% chance of a foot of snow on the peak.
It should be a pleasant site for Phoenicians to again be able to
see snow on Four Peaks once daylight hits and lower clouds clear
up. The latest HREF has most of the precipitation coming to an end
and pushing east of the area just before sunrise this morning in
Phoenix and around to just after sunrise in Southern Gila County.
Aside from some fair- weather cumulus in South-Central AZ during
the day there will be plenty of sun today and temperatures will
warm from the mid-40s to start the day into the mid to upper 60s
this afternoon (around 70 in the western deserts), still around 10
degrees below normal.

While it would be nice to see the trend of cool and wet weather
systems continue to push through the lower deserts and help
alleviate some of the drought, it unfortunately looks like this
morning`s rain and snow may be the last for the lower deserts for
the next 1-2 weeks, and possibly longer. The short and long range
synoptic outlook favors low pressure system tracks shifting back
north. The next chance at precipitation will be with a trough
pushing through the region late-Monday through Tuesday, but this
trough looks to be mostly a wind impact for the lower deserts with
a track more through the Great Basin and Intermountain West.
Latest NBM PoPs for the lower deserts Tuesday are very low, around
5% for Phoenix and maxing out at 15% for the higher terrain east
of Phoenix. As mentioned, with the base of the trough passing over
southern AZ & CA, blustery conditions are anticipated. Winds are
not forecast to be nearly as strong as they were with Thursday`s
frontal system, but a Wind Advisory may still be needed for
portions of Imperial County. After Tuesday`s system, global
ensembles have low tracks and any moisture staying even further
north. While the global models do support a persistence of more
of a W-NW mid-level flow following the Tuesday system, this
historically is not a good trajectory for inducing low level
moisture advection, and thus conditions are expected to dry out
and warm up.

As far as temperatures go, a warming trend is expected today
through Monday, with high temperatures reaching back to around
normal Monday - around 80F for the lower deserts. The Tuesday
system is expected to cool temperatures back down briefly, back
below normal, with highs Tuesday and Wednesday mostly in the 70s.
Temperatures are then expected to warm up again heading into the
end of the week and next weekend, returning to lower desert highs
in the low to mid 80s. Looking a little beyond next weekend,
global ensembles are already showing good consensus for strong
ridging over the eastern Pacific and West Coast, which could lead
to a return of 90 degree highs.

&&

.AVIATION...Updated at 1800Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Westerly winds will become easterly late this evening. Speeds will
generally be aob 10 kt through the afternoon with some occasional
gusts into the mid-to-upper teens possible late this afternoon.
Speeds will lower to aob 5 kt for the overnight hours and tomorrow
morning. FEW-SCT clouds with bases generally aoa 4-6 kft will
continue through the afternoon. Clouds with bases around 2-3 kft
further east, near the higher terrain areas, could cause some
visibility issues with planes coming in to land from the east.
These clouds should start to scatter out later this afternoon. There
could also be some slantwise visibility issues through the
afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns are expected during the TAF period. AT IPL,
winds will be favored out of the W/NW through the overnight hours
and go southerly tomorrow morning. At KBLH, northerly winds will
continue through the afternoon becoming variable this evening
through the remainder of the TAF. Speeds, at both terminals, will
generally be aob 7 kt. Skies will be mostly clear with FEW high
cirrus clouds.


&&

.FIRE WEATHER...
Morning rain and high elevation snow showers in South-Central
Arizona will come to an end for most areas by sunrise today.
Rainfall totals will remain light for the lower deserts, but CWR
is high (70-90%) for areas east of Phoenix, while several inches
of snow are expected for the mountains (>5000`) east of Phoenix.
Conditions gradually dry out through this afternoon and drying
trend will continue through the rest of this weekend. Another,
mostly dry, system will pass by late-Monday through Tuesday.
Precipitation chances will mostly be in northern AZ, with CWR at
5% or lower in S. Gila county. Conditions dry further following
the Tuesday system. MinRH values go from 20-30% in the lower
deserts (40-60% in S. Gila Co.) today to widespread 5-15% by
Wednesday. Elevated to locally critical fire weather conditions
are forecast for Southeast CA and Southwest AZ Tuesday afternoon
with the passing system, as winds also increase, with afternoon
gusts potentially in excess of 30 mph, to go along with the dry
conditions out west. Aside from Monday night and Tuesday, winds
will be light and follow typical diurnal tendencies through the
next week.

&&

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

$$

DISCUSSION...Benedict
AVIATION...Berislavich
FIRE WEATHER...Benedict