Dense Fog Advisory 2, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
325 PM MST Fri Jan 29 2021

.SYNOPSIS...Another weather system will move across the area
tonight bringing more valley rain, mountain snow and strong winds.
This Pacific system will be warmer compared to the last one with
snow levels remaining mostly above 5,500 feet. Dry and warmer
weather can be anticipated early next week before the next weather
system impacts the region around Wednesday and Thursday.

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.DISCUSSION...Skies have cleared across the eastern half of the
forecast area which has allowed some of the stronger gradient
winds aloft to work down to the surface. Gusts have been in the 30
to 40 mph with locally higher gusts. Afternoon temperatures ended
up a few degrees warmer than forecast. On the precipitation side
of things, the approaching cold front was over far western Arizona
this afternoon with scattered showers mainly across Maricopa
county with a few isolated showers moving into far western Pima
county as of 3 pm. Cloud cover has been increasing in the past
couple of hours in advance of the cold front across central and
western Pima county as moisture from the Gulf of California is
advected north. Overall the system has slowed down versus what we
were looking at this time yesterday.

For the remainder of this afternoon into this evening. Scattered
showers and mountain snow showers will be moving across the area
with most of the activity done by midnight with few showers across
the eastern zones thru 5 am. Can't rule out a lightning strike or
two this evening. So a quick hitting storm.

This weekend: Cooler Saturday in the wake of tonights system,
then warmer Sunday to close out January that likely will end up
above normal temperature wise and below normal precipitation wise.

Monday and Tuesday: Much warmer to start February under upper
level ridge.

Wednesday and Thursday: The next Pacific weather system swings
across the area for a chance of valley rain and mountain snow.
As usual this far out there are timing difference in the ensemble
world. Thus few changes were made to the recommended forecast
initialization for both days.

&&

.AVIATION...Valid through 31/00Z.
Scattered SHRA is developing across western Pima County this
afternoon and will progress west to east across the forecast area
into the evening hours. Some embedded TSRA is possible this
afternoon, mainly over west/central Pima County. Cloud bases of 8-
12k ft MSL are likely, with brief MVFR conditions possible. SFC
winds SWLY 15-25 kts gusts to 40 kts into early evening, gradually
decreasing thereafter. Light and variable winds expected
tomorrow. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Another weather system moves west to east across the
region today resulting in valley rain and mountain snow primarily
during the afternoon and evening hours. 20-ft winds this afternoon
are southwesterly 15-25 mph, including occasional stronger gusts.
Precipitation amounts are expected to generally be on the lighter
side. Weather conditions dry out again by Saturday, with another
chance for wet weather toward Wednesday of next week.

&&

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

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