Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 211725

Area Forecast Discussion
National Weather Service Tucson AZ
1025 AM MST FRI OCT 21 2016

.SYNOPSIS...Dry conditions will continue into Saturday morning.
Increasing moisture will then move northward across the area later
Saturday into early next week. This will result in a slight chance
of showers Saturday afternoon into Sunday night. Somewhat deeper
moisture will provide scattered showers and thunderstorms Monday.
Expect dry conditions to return during the middle and latter part of
the upcoming week.


.DISCUSSION...Wind speeds have decreased to generally less than 10
kts/12 mph/ across much of southeast Arizona at this time. The
exception was near the Tucson metro area, or more specifically
mostly across the southern/eastern portion of the Tucson metro area,
where wind speeds to near 20 mph were ongoing. Winds will diminish
to mostly less than 10 mph area-wide this afternoon.

Otherwise, clear skies will likely continue through tonight as any
mid/upper level moisture of significance remains south of this
forecast area. High temps this afternoon are forecast to be about
6-10 degs or so above seasonal normals.

Please refer to the additional sections for further detail.


.AVIATION...Valid through 22/18Z.
SKC through tonight then a FEW to perhaps SCT clouds mainly above
12k ft AGL toward the end of the valid period. Surface wind ely/sely
to 20 kts mainly in the vicinity of KTUS through about 20Z today.
Otherwise, surface wind mostly less that 10 kts with an ely/sely
component. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions through Saturday morning followed
by a slight chance of showers Saturday afternoon through Sunday
night. A better chance of showers and thunderstorms will prevail
Monday, then a drying trend will start Tuesday. There should be
enough lingering moisture for a few showers east of Tucson Tuesday
followed by dry conditions area-wide Tuesday night into Thursday.
Otherwise, expect above normal daytime temperatures and normal
terrain driven winds generally under 15 mph this weekend into next


.CLIMATE...Today will likely mark the 15th consecutive day of at
least 90 degrees recorded at Tucson International Airport for
October 2016. If achieved, this would tie for the seventh longest
period of 90 degrees or warmer for any October on record (dating to
1894). The current official forecast indicates that 90 degrees or
warmer should also occur Saturday and Sunday. If this happens, there
will be 17 consecutive days this month of at least 90 degrees
recorded at Tucson International Airport. This 17 consecutive day
period would be the sixth longest on record.


.PREV DISCUSSION /230 AM MST/...Gusty east to southeast winds will
persist across portions of southeast Arizona through the mid/late
morning hours before slackening off this afternoon as the surface
pressure gradient weakens. Otherwise, expect clear skies and well
above normal temperatures today with afternoon highs topping out 6-
10 degrees above seasonal averages. Not expecting record levels
although a few locales may be with a degree or two of their record
highs this afternoon.

The models indicate the upper high currently situated to our west
will shift eastward into southern Texas by early Saturday and over
the northern Gulf of Mexico on Sunday as a trough pushes into the
Pacific Northwest. As the high shifts eastward, moisture to our
south will work its way northward into the back side of the ridge in
advance of the developing west coast trough. This will lead to a
slight chance of showers and thunderstorms starting Saturday
afternoon and evening, mainly south/southeast of Tucson along the
international border. Although moisture will continue to increase
during the day Sunday, not a lot in the way of forcing or dynamics
to work with, so again the best precipitation chances are expected
to be from Tucson south/southeast.

There will be increasing chances for more widespread precipitation
Sunday night as the trough approaches the state from the west and
especially Monday/Monday night as the trough axis shifts across the
state. By Monday night, expect shower/thunderstorm chances to mainly
be from Tucson eastward. The forecast area will then rapidly dry out
from west to east on Tuesday as high pressure aloft builds in from
the southwest. However, there may be enough lingering moisture for a
slight chance of showers over far northeastern portions of the area,
roughly from Safford northeast into the White Mountains. Tuesday`s
high temperatures will be the `coolest` over the next 7 days, with
valley locations generally in the lower to mid 80s, which is still 2-
4 degrees above normal.

High pressure will then strengthen over the desert southwest and
northern Mexico in the latter periods of the forecast, in the
Wednesday through Friday time frame. This will lead to dry and
warmer conditions areawide. Afternoon high temperatures are expected
to top out in the upper 80s to near 90 degrees across the Tucson
metro area over this period.





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