Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 241636
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
936 AM MST Sat Feb 24 2018

.SYNOPSIS...A cool and dry weekend ahead, with a brief warming
trend early in the new week. A stronger winter storm system
later Tuesday into Wednesday will bring a good chance of valley
rain and mountain snow. Dry and warmer to end the week.

&&

.DISCUSSION...The tail end of a system brought some cloudiness and
light showers to east-central Arizona last night. Recent satellite
imagery continued to show some lingering cloudiness, but expect this
to clear as the system track farther away this afternoon. The
current forecast was handling the trends well, so no updates
necessary this morning. Please refer to the additional sections for
more details.

&&

.AVIATION...Valid thru 25/12Z.
SCT-BKN clouds at 5k-8k ft AGL rapidly decreasing from west to east
with SKC conditions by this afternoon. SFC wind NWLY 8-15 kts this
morning weakening to less than 12 kts by midday. Less wind will
occur this evening into Sunday morning. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Dry conditions will prevail through Monday night.
The next storm system will bring scattered valley rain and mountain
snow showers Tuesday into Wednesday. Dry conditions will return next
Thursday and Friday. Expect gusty west to southwest 20-ft winds
Monday and Tuesday afternoons. Elevated northwest winds will occur
on Wednesday. Otherwise, winds will generally be terrain driven at
less than 15 mph through next Friday.

&&

.PREV DISCUSSION...A weather system moving through northern Arizona
brought us a few snow showers in the mountains early this morning,
but not much in the way of accumulations. The storm will quickly
lift into the northern plains today leaving cool and dry conditions
in it`s wake. Another system digging into the mean trough position
over western states will push quickly through on a trajectory that
keeps it north of our area tonight into Sunday morning.

Our busy pattern will continue to keep much of the west open to
storm systems with a mean trough position across the region
sandwiched between persistent ridges north of Hawaii upstream and
near southeastern states downstream.

We`re still on track for a strong winter storm system to dig
southward into southern California Monday night into Tuesday before
moving across Arizona Tuesday night through Wednesday. Best period
for valley rain and mountain snow is shaping up to be Tuesday night
into early Wednesday morning from Tucson westward, and Wednesday
morning into Wednesday afternoon east of Tucson.
There are still some timing issues, and if the system slows up a bit
it will have time to tap into a little more moisture as it pushes
through our area. Confidence continues to increase based on current
analysis, identification and progression of the large scale pattern
and operational / ensemble mean model agreement.
Snow levels may reach valley floors east of Tucson on Wednesday
morning, but some drying should already be underway.

&&

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

&&

$$

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