Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 231610
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
Issued by National Weather Service PHOENIX AZ
910 AM MST Tue Jan 23 2018

.SYNOPSIS...Another cold one this morning with lows near freezing
in the deserts and well below freezing south and east of Tucson.
High pressure starts a strong warming trend today, with dry
conditions and breezy winds at times. The trend will be
interrupted briefly Friday with a several degrees of cooling
before resuming this weekend.

&&

.DISCUSSION...
At 830am this morning, an upper level high pressure ridge was
building into the desert southwest; 12z plot data showed the ridge
axis situated to our west with dry northwest flow aloft into
southeast Arizona. IR imagery this morning showed clear skies area-
wide. Winds this morning were rather light, favoring the east to
northeast. A baggy upper trof sagging to the southeast of Tucson
combined with higher pressure to the north will allow for a somewhat
stronger northeast low level wind to develop during the day, but
winds should stay locally breezy for the most part. With 500mb
heights remaining below 570dm and high pressure aloft still situated
well off to the west, temperatures today will be slow to climb with
the warmer central to western deserts remaining in the mid 60s to
near 70s. Overall, we are looking at benign weather today into the
middle of the week. No changes are planned to the forecast at this
time.

.PREVIOUS DISCUSSION...High pressure will build over the intermountain
west during the next 36 hours with SE AZ temperatures responding
by jumping back to average today and then several degrees above
average Wednesday. After another chilly morning, lows will begin
to moderate as well, recovering to near or a little above seasonal
normals. A breezy easterly return flow developing this morning
from New Mexico will assist the warming trend in many valley
locations with downslope flow.

A glancing blow from a system passing north of our area will bring
a few breezes and several degrees of cooling Friday before a
stronger ridge brings daytime highs around 10 to 14 degrees above
average over the weekend (this could mean an 80 for TIA Sunday or
Monday).

&&

.AVIATION...Valid thru 24/18Z.
Clear skies thru much of the period as high pressure aloft builds
into the area from the west. SFC wind SELY to NELY at less than 12
kts through this evening, some increase in wind from the east during
the morning Wed as surface gradients tighten somewhat. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Dry conditions will prevail over the next week.
Light, easterly 20-ft winds occur through mid-week, though speeds
should increase to around 15 mph Wednesday afternoon. Elevated
westerly to southwesterly winds may return Thursday and perhaps
Friday.

&&

.CLIMATE...Based on temperatures to date and the 7 day forecast,
it looks like Tucson is headed for top 5 warmest January on
record. This would be the fourth straight month with top 5 warmest
ranking.

&&

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

&&

$$

Meyer/Carpenter

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