Area Forecast Discussion
Issued by NWS Tucson, AZ

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792
FXUS65 KTWC 120424
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
924 PM MST Mon Dec 11 2017

.SYNOPSIS...Plenty of cloud cover thanks to a low pressure system
sitting over Baja California. This low will sit to our south into
Thursday with clouds and potentially a few sprinkles at times near
the Mexico border. Then mostly clear and dry through next weekend
with above average temperatures continuing.

&&

.DISCUSSION...Cloud cover continues to slowly lower tonight as a
weakness in the flow at the base of the ridge is sitting just
south of the border. Cloud layers above 15k ft AGL on the 00Z KTWC
sounding, however subcloud layers still pretty dry. Precipitable
water around 1/4 of an inch, and surface dewpoints in the teens to
lower 20s. So, not much in the way of precip hitting the ground
anywhere. If you`re tall enough you might feel a few sprinkles. We
tweaked the cloud cover up a bit earlier, otherwise no additional
updates. Please see below for additional details.

&&

.AVIATION...Valid thru 13/06Z.
BKN-OVC cigs above 12k ft AGL. --SHRA possible near mountains as
low pressure remains nearly stationary near the Gulf of
California. Winds will favor the east/southeast tonight with an
increase in winds forecast after 15Z Tuesday. Expect easterly
winds in the 15-25kt range at all sites mid morning through late
afternoon. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Very dry air in place in lower levels and at the
surface should preclude much in the way of showers across the area
as low pressure remains nearly stationary south of the border.
Easterly winds will increase during the day on Tuesday but
critical thresholds should not be realized. Outside of Tuesday,
expect typical diurnal winds across the area.

&&

.PREV DISCUSSION...Considerable cloudiness continued across the
area in association with a weak upper low over the Baja Spur this
afternoon. Models track this low across Sonora, Mexico tonight
through late Wednesday. Light showers or sprinkles will be
possible south of Tucson, especially in the vicinity of the upper
low near the International Border. Otherwise, daytime temperatures
will remain above average this week. Models hint at another
system approaching Baja and northern Mexico late in the weekend.
Similar scenario as the upper low passing through tonight into
Wednesday.

&&

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

&&

$$

Meyer

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