Forecast Discussion

Forecast Discussion for TWC NWS Office
000
FXUS65 KTWC 290944
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
244 AM MST Fri Mar 29 2024

.SYNOPSIS...Warm temperatures will continue into Saturday before a
weather system brings colder temperatures and widespread
precipitation chances Sunday into early next week. Rain and
accumulating mountain snow is likely. Winds will increase ahead of
this system on Friday, with windy conditions lasting through the
weekend especially Saturday.

&&

.DISCUSSION...High clouds are streaming in from the southwest as a
trough moves into the western United States. The center of this
low is situated off the coast of northern California and will be
the main weather driver over the next several days. Over the next
couple days its main impact will be strong gusty winds as it moves
down the west coast increasing the pressure gradient for the
desert Southwest. Because of this a Wind Advisory has been issued
for the entire CWA Saturday. It will be breezy to windy area
wide, but the strongest winds will be in Santa Cruz and Pima
Counties. Blowing dust will likely be an issue downwind of the
Wilcox Playa and in portions of Pima and Pinal Counties.
Temperatures today and Saturday will be at or a couple degrees
above normal.

The upper level low moves starts to move on shore Saturday
evening into Saturday night accompanied by a fairly well defined
cold front. This front will serve as the focus for the beginning
of precipitation. Models bring the front into western Pima County
early Sunday morning, then Tucson late to mid morning, and the
AZ/NM border by late afternoon/early evening. Still some small
differences in timing between models, but that`s to be expected
48-60 hours out. Winds will again be gusty out ahead of the front
with the strongest winds Sunday expected to be in Cochise County.
Rain intensity will be moderate along the front with widespread
showers likely behind the front. Snow levels will initially be
around 7000 feet dropping to 6000-6500 feet Sunday night into
Monday morning. Precipitation chances continue into Monday as a
shortwave rotates around the main trough providing support for
continued rain and possibly isolated thunderstorms as well.

Current forecast rain totals Sunday into Monday range from
0.3"-1.3" in the valleys with Pima, Santa Cruz, and Pinal Counties
on the middle to higher end of that range. Elsewhere in Cochise,
Graham, and Greenlee Counties rain totals looks to be under 0.5".
NBM 48 hour QPF probabilities for 0.5" or greater range from 40-80
percent for the western half of the CWA with the highest
probabilities in Pinal County and the mountains. Snow totals
above 7000 feet for the Sunday-Monday time frame range from 6-12
inches with locally higher amounts at the peaks.

Temperatures will also drop significantly with the passage of
this system with highs running 20 degrees below normal Sunday and
Monday. Freezing temperatures will be possible Tuesday morning
east of Tucson.

Tuesday lingering showers will be possible mainly from Tucson
eastward thanks to residual moisture. The trough begins to split
Tuesday with a shortwave pinching off from the main flow and
moving into northern Mexico and the rest of the trough moving
eastward. Ensembles show ridging to our north through the middle
of the week which will lead to a gradual warmup through Thursday.
Then ensembles show another deep low moving into the western U.S.
during the last half of the work week. So looks like Arizona is
not quite done with unsettled weather.

&&

.AVIATION...Valid through 30/12Z.
BKN-OVC clouds AOA 20k ft AGL through the period with the exception
of this afternoon when there will be a brief break in the high
clouds. SFC winds today increasing after 29/17Z becoming SWLY
12-20 kts with gusts to 30 kts through 30/03Z. Strongest winds
will be at KOLS and KDUG terminals. Thereafter through the end of
the TAF period winds will be less than 12 kts. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...
Warm through Saturday as an upper level ridge moves across the area.
Winds will increase on Friday to around 15 to 20 mph ahead of an
approaching storm system, which may overlap relative humidities of
10 to 15 percent in the lower elevations. Winds should become a
bit stronger on Saturday with speeds 20 to 25 mph and locally 30
mph in some spots, though moisture will be on the rise. Good
chances for widespread precipitation arrive with a cold front by
early Sunday and continuing through Monday, with possible
lingering showers Tuesday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from noon to 10 PM MST Saturday for AZZ501>515.

&&

$$

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NWS TWC Office Area Forecast Discussion