Area Forecast Discussion
Issued by NWS Tucson, AZ

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430
FXUS65 KTWC 270452
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
952 PM MST Sun Feb 26 2017

.SYNOPSIS...A strong weather system will bring gusty winds along
with a good chance of valley rain and mountain snow showers Monday
night into Tuesday. Below average daytime temperatures will continue
into Tuesday, then dry conditions with a strong warming trend
Wednesday into next weekend.

&&

.DISCUSSION...The upper pattern is defined by recently departed
weak shortwave just to the east of SE Arizona in New Mexico,
zonal flow across our neck of the woods into the eastern Pacific,
and an upper low moving south from the Pacific Northwest. A rather
moist plume in the zonal flow that will phase with the descending
upper low from the Pacific Northwest the next 24-48 hours, resulting
in a decent shot from valley rain and mountain snow late Monday and
Tuesday.

Some blowing dust issues in northeastern Cochise county along I-10
near San Simon due to the wind and land use issues today. This area
may be problematic the next couple of days with a breezy southwest
surface flow Monday afternoon, and stronger winds initially from the
SW in the the morning becoming northwest in the afternoon. The
night shift may need to consider issuing another blowing dust
advisory near the San Simon area Monday afternoon for the potential
for blowing dust reducing visibilities along the interstate.

Otherwise, we are in a bit of a break before we begin to see the
impacts of this next system tomorrow evening. Current forecast is on
track with no updates necessary.

&&

.PREV DISCUSSION...
We`re still on track for a stronger and wetter system late Monday
into Tuesday. The low off the Pacific coast is gaining some higher
latitude support from the storm over the Pacific Northwest as they
phase together. A cool, wet and efficient system will result as it
develops over the next 48 hours. Best chance of valley rain and
mountain snow for our corner of the state will be Monday evening
through mid day Tuesday. Total valley rainfall amounts between .1
and .5 inches with precip equivalent in the mountains around .4 to
1.2 inches. Trajectories put lower values across far southern
areas with higher amounts on higher terrain slopes with southern
exposure from Tucson northward. 6 to 10 inches of snow above 6500
feet with isolated higher amounts above 8000 feet. 12 inches not
out of the question for highest elevations around Mt Graham as
well as southern portions of the White Mtns of northern Graham and
Greenlee counties.

Strong gusty winds with low end advisory levels possible ahead of
the front on Tuesday. Tricky overnight low forecast Tuesday
morning with winds and cloud cover making for a much narrower and
atypical diurnal trend.

A broad based low amplitude ridge takes control the second half of
next week into next weekend. Below average temperatures Tuesday
will jump to around 10 degrees above average by the weekend. A
pattern change will likely keep us dry beyond this period as well.

&&

.AVIATION...Valid through 28/06Z.
Few to scattered mid-clouds around 10-15 kft AGL with broken high
clouds above 20 kft AGL persisting thru Monday afternoon. Scattered
low clouds 6-8 kft AGL along with scattered to broken mid-high
clouds increasing in coverage from west to east in the afternoon and
early evening with isolated valley -shra and mountain -shsn
possible Monday evening. Surface wind will continue to diminish this
evening to below 12 kts, but increase again after 27/18Z. Expect
sly/swly surface wind of 14-22 kts and gusts up to 28 kts by 27/21Z.
The strongest speeds will be across far southeast Arizona. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Dry conditions will occur late this evening into
early Monday afternoon. A Pacific weather system will then bring a
slight chance of showers Monday afternoon, followed by a good chance
of valley rain and mountain snow showers Monday night into Tuesday.
Dry conditions will return Tuesday night and continue into next
Saturday. Gusty winds can be expected Monday afternoon and Monday
night, with even stronger winds on Tuesday, before less wind occurs
Wednesday. Expect occasionally gusty east winds Thursday and Friday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...

Winter Weather Advisory from 6 PM Monday to 5 PM MST Tuesday for
AZZ510-511-514.

&&

$$

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