000
FXUS65 KTWC 120420
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
920 PM MST Tue Dec 11 2018

.SYNOPSIS...Expect dry conditions across much of the area the rest
of the week along with a modest cooling trend. For late in the
weekend and early next week, there is a slight chance of showers
south and east of Tucson. However, temperatures will remain
relatively mild for this time of year.

&&

.DISCUSSION...Models remain in excellent agreement through
Wednesday as a weak closed low continues to move southeast. The
low will track across central Baja and into Sonora with little to
no impacts for southeast AZ. At this time, the forecast remains
dry. Some forecast model solutions do hint at a long shot chance
of a shower or sprinkle across the higher terrain around the
International Border along/east of Douglas. Otherwise, dry for the
rest of the area. Another dry system will pass to the northeast
of the area Wednesday night through Thursday and will usher in
cooler weather for Thursday.

&&

.AVIATION...Valid through 13/06Z.
Ceilings AOA FL150 (with patchy virga) will continue into evening
before clearing overnight. Anticipate more distinct westerly
winds Wednesday afternoon with some minor gustiness possible.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Anticipate a notable uptrend in winds on
Wednesday (favoring westerly directions) as the southern end of a
weather system brushes the area. Gusts gusts in the 15-25 mph
range will be common in the afternoon on the valley floors over
eastern portions of the forecast area with higher speeds at higher
terrain. Winds will remain elevated at ridgetops overnight
favoring northerly directions. However, critical thresholds are
not expected. Anticipate some lingering breezes on Thursday but
favoring northeast and easterly directions. Temperatures trend
downward on Wednesday and Thursday followed by a notable decrease
in humidities. Over the weekend and early next week, there will be
a couple of opportunities for light rain but confidence in the
occurrence of wetting rain is not high at this time. No strong
wind events are anticipated.

&&

.PREV DISCUSSION...A weak upper low centered over the Channel
Islands this afternoon will track southeastward the rest of the
day and overnight then weaken quite a bit during the the day
Wednesday as it moves over Sonora. Moisture with this system is
limited to the upper half of the troposphere. Also, with that
track the bulk of it will miss the forecast area. Thus, not
anticipating precip will reach the ground but instead just thick
high clouds with some patchy virga. There is an upstream system
helping to kick this one along. While it is a larger and stronger
system, it will mostly pass to the north and east of the forecast
area. But it will help push the clouds out for mostly clear skies
Wednesday and Thursday along with cooler temperatures. There will
be more noticeable winds as well with breezy to windy conditions
for higher terrain areas and in some foothill locations. Made some
minor upward adjustments to the wind speeds, but overall, no
changes in the short term.

An upper level ridge builds over the area Friday bringing warmer
daytime temperatures. This ridge moves east of the area on
Saturday as an upper level trof moves into the western CONUS.

Thereafter plenty of uncertainty on timing of potential southern
stream systems impacting the area late in the weekend into early
next week. At this time went with slight chance of valley rain and
high elevation snow showers.

&&

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

&&

$$

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NWS TWC Office Area Forecast Discussion