413
FXUS65 KTWC 020849
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
149 AM MST Wed Apr 2 2025

.SYNOPSIS...A weather system will track across Southeast Arizona
today. The frontal boundary associated with this system will bring
a trace of rainfall across the Tucson Metro Area this evening.
Another weather system will then move in behind this first system,
resulting in a slightly better chance of light precipitation
Friday and Saturday. Thereafter, a strong ridge of high pressure
will move into the area. This will bring a significant warm-up in
afternoon temperatures begining this weekend and persisting
through next week.

&&

.DISCUSSION...The upper pattern this morning is defined by a
trough across the Intermountain West with a distinct upper-low
positioned over central California, and a high-amplitude ridge
across the Eastern Pacific with its axis extending north into the
Gulf of Alaska. The upper-low in California is progged to dive
south around the base of the mean trough today, making its way
into into west-central Arizona by 02/21Z, then lift NE into the
Four Corners by late tonight. The frontal boundary along the
southern periphery of this feature will drag across SE Arizona
this afternoon into this evening resulting in a slight chance of
light showers across the Tucson Metro Area this evening. The
02/00Z HREF ensemble members are not too excited for pcpn with
this frontal passage, but my thinking is that there is just enough
mid-level moisture to accompany the boundary to result in a trace
to maybe a few hundredths of an inch of rain. In any event, this
feature will have little to no impact on SE Arizona.

Given the high amplitude of the upper ridge to the west, expect
the troughing to remain the next couple of days, with another
upper-low diving into SW AZ by Friday morning. Still a general
lack of moisture available with this system, but I would expect
some instability showers to develop Friday and Friday night.
Precipitation amounts Friday into Saturday will be around a tenth
inch south of Tucson with a quarter to half inch possible in the
higher elevations of northern Graham and northern Greenlee
counties. This should result in up to an inch of snowfall for the
Sky Islands above 7500 feet, with 3 to 5 inches of snow possible
in the White Mountains above 7000 feet.

The upper ridge begins to track into the West Coast Saturday and
into Arizona Sunday. There are some differences with the ensemble
members of the GEFS and the ECMWF, with the European members
trying to hang the troughing back across Arizona through Sunday.
Given the neutral orientation of the approaching ridge, my guess
is that the trough will move out of our neck of the woods a bit
faster (Saturday) like the GEFS members are suggesting. In any
event, given the uncertainty, I will keep some low end pops across
the far eastern portions of the forecast area Sunday.

Thereafter, the ridge becomes the dominant feature across the
west with a fairly significant warm-up in store. I would expect a
25 degree warm-up across all of Southeast Arizona between Friday
afternoon and Wednesday afternoon of next week. The 02/04Z NBM
probability for the Tucson International Airport (KTUS) to reach
our first 100 degree temperature of the year is 25 percent on both
Friday and Saturday of next week. Ick.

&&

.AVIATION...Valid through 03/12Z. SFC winds below 10 kts and
following diurnal trends thru 02/18Z, then southwest to west 10-15
kts with gusts 25-30 kts. The strongest winds will be southeast of
Tucson along the Arizona/New Mexico border. This would include
KDUG. SCT-BKN clouds AOA 15-20k ft AGL through the period with
SCT-BKN low clouds between 6-8k ft AGL developing aft 02/18Z and
persisting through the end of the period. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...A weather system will track across Southeast
Arizona today. Expect breezy southwest winds east of Tucson this
afternoon, but will be significantly less than winds Tuesday. A
few areas in Cochise county may briefly near critical fire
weather conditions this afternoon. Another weather system will
then move in behind this first system, resulting in a slightly
better chance of light precipitation Friday and Saturday.
Thereafter, a strong ridge of high pressure will move into the
area bringing with it a significant warm-up in afternoon
temperatures begining this weekend and persisting through next
week.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

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