Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 151031

Area Forecast Discussion
National Weather Service Tucson AZ
331 AM MST Sun Dec 15 2019

.SYNOPSIS...A weather system passing north of the area will bring
a couple rain and snow showers to the White Mountains from this
evening through early Monday morning. For the rest of southeastern
Arizona, expect cooler and drier weather today. Much cooler
conditions are expected for the first part of the upcoming week
with cold morning low temperatures. Slightly warmer temperatures
return Wednesday and Thursday with even warmer temperatures by
Friday and Saturday.


.DISCUSSION...A shortwave will swing through Arizona through Monday
with the best energy staying well north of SE AZ. A few high
elevation snow showers and valley rain showers will be possible
later this evening and into early Monday morning across the White
Mountains. Otherwise, dry across the remaining areas with slightly
cooler condiitons and breezy winds east of Tucson.

As the system passes to the east, a much cooler airmass will
settle into SE AZ. Tucson will struggle to get out of the 50s on
Monday. Additionally, expect a chilly start each morning from
Monday through Wednesday. Forecast guidance has been trending
lower over the past several shifts and near freezing temperatures
are likely across the Tucson Metro area Monday morning with even
colder temperatures expected Tuesday morning. We will likely see
areas of freezing temperatures across the Metro with KTUS flirting
close to the freezing mark. Some of the coldest locations along
washes and favored drainages could dip around the upper 20s to
around 30 degrees. We will have to watch this, as an eventual
Freeze Watch/Warning may be necessary. The temperature forecast
will be a little tricky, since another southeasterly/easterly wind
will set up Tuesday and Wednesday morning. Can`t help but bring
up that sneaky freeze the Metro saw back on October 31st. At least
this time guidance certainly suggests freezing temperatures, thus
the more confident messaging. Temperatures will remain cool most
of the week with only a slow moderating trend. However by Friday,
warming increases with temperatures well into the 60s Friday for
the lower deserts and possibly 70s Saturday. For areas south and
east of Tucson, expect upper 50s to lower 60s Friday and lower to
middle 60s on Saturday.

We are sure quite a few people are interested in the longer range
forecast for Christmas, so here is a quick little blurb. Longer
range ensemble guidance is suggesting a storm system for the
holiday time frame. At this time, it appears to be a closed low
type storm system, which are always tricky to forecast as they
meander around off the SoCal or Baja coastline. Nonetheless, its
on the radar and we will be watching it closely for any potential


.AVIATION...Valid through 16/12Z.
FEW-SCT 10-15k ft and SCT-BKN AOA 20k ft MSL until 16/05z then
becoming SKC. Surface winds SLY/SELY 4-10 kts becoming WLY/SWLY 10-
18 kts with higher gusts this afternoon, especially east of KTUS.
Wind easing to W-SW 5-9 kts after 16/03Z.  Aviation discussion not
updated for TAF amendments.


.FIRE WEATHER...A weather system moving across the Four Corners
region will generate breezy winds today, especially east of Tucson.
This system will also result in a slight chance of sprinkles or
flurries in the White Mountains. Dry conditions area wide next week,
but with cooler temperatures. Locally gusty east winds are expected
Tuesday and Wednesday of next week.





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