Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 211612
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
910 AM MST Sat Jan 21 2017

.SYNOPSIS...Precipitation will decrease into this evening but gusty
winds will continue. Dry conditions will then prevail late tonight
into Sunday. A storm system moving north of the area will bring a
few showers Sunday night followed by more widespread valley rain and
mountain snow showers Monday and Monday night. Precipitation will
decrease Tuesday with dry conditions prevailing Wednesday into next
weekend.

&&

.DISCUSSION...Scattered showers now from the Tohono Nation eastward
with a decent west to east band from Picture Rocks east across the
Catalina mountains to Mt Graham where a few more inches of snow is
likely before tapering off through the day.  Speaking of snow,
looking at incoming photos and talking to folks looks like 12-24
inches across the higher peaks like Mt Lemmon and Mt Graham with
deeper drifts due to the strong winds last night. Also have some
wind damage noted atop Mt Lemmon and a few locations in the valley
areas due to the burst of strong winds last night.

Area washes are generally running with some running pretty good but
all expected to remain below bankfull and will settle back this
afternoon. The Flood Advisory for the Sabino creek was allowed to
expire as it has come down significantly although water will be
flowing pretty good through the day.

Updated the forecast package for the next 12 hours basically
clearing the precipitation out of here a little quicker from west to
east and removing it from this evening. Also trimmed the cloud cover
from west to east although with the sun poking through will allow
for cumulus clouds to spring up into the early afternoon. It will
remain windy eastern areas this afternoon so will leave the wind
advisory as is. For the winter storm warning that runs through noon,
with the current band of snow across the mountains will leave that
up until then and let it expire at that time as little is expected
later today.  Cerniglia

Remainder from previous discussion...Moisture is expected to
increase from northwest-to-southeast Sunday afternoon into Monday as
the aforementioned upper low pressure system moves southeastward
toward northern California. There is a slight chance of showers
Sunday afternoon west-to-north of Tucson, then perhaps as far
southeast as Tucson Sunday night. A chance of valley rain and
mountain snow exists Monday and especially Monday night. A slight
chance of valley rain/mountain snow continues mainly from Tucson
eastward Tuesday and Tuesday night.

A few snow showers may occur mainly across the White Mountains
Wednesday. Otherwise, a drying trend will commence by next
Wednesday, and markedly drier conditions will then prevail Thursday
into next Friday as high pressure aloft amplifies along the West
Coast.

High temps today will remain quite cool, and will average nearly 8-
15 degs or so below normal. A warming trend is on tap Sunday into
Monday, then much cooler temps will prevail Tuesday. Expect no
significant change in daytime temps Wednesday followed by high temps
returning closer to seasonal normals by next Friday.

&&

.AVIATION...Valid through 22/12Z.
Scattered to numerous -SHRA and higher terrain -SHSN early today
then isolated -SHRA and mountain -SHSN east of KTUS this afternoon.
Dry conditions area-wide tonight into Sunday morning. Expect local
MVFR conditions with mountains obscured into this afternoon due to
precipitation mainly well east of Tucson. Otherwise, cloud decks
mainly 3k-7k ft AGL today followed by decreasing clouds this evening
into tonight. Surface wind today mainly wly 12-25 kts with gusts of
25-40 kts. Surface wind diminishing to mostly less than 12 kts most
sections around 22/03Z and continuing into Sunday morning. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect scattered showers today to decrease into this
evening followed by dry conditions tonight into Sunday morning. A
slight chance of showers exists west-to-north of Tucson Sunday
afternoon and Sunday night, then scattered to numerous valley rain
and mountain snow showers will return Monday and Monday night.
Precipitation chances decrease again Tuesday with dry conditions
prevailing late Wednesday into next weekend. Gusty west winds will
occur today and again Monday afternoon. Otherwise, 20-foot winds
will mainly be terrain driven less than 15 mph.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
    Winter Storm Warning until noon MST today for AZZ510>515.

    Wind Advisory until noon MST today for AZZ503.

    Wind Advisory from noon today to 5 PM MST this afternoon for
      AZZ511>513.

    Wind Advisory until 5 PM MST this afternoon for AZZ507>509.

&&

$$

Cerniglia/Francis

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