Area Forecast Discussion
Issued by NWS Tucson, AZ

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048
FXUS65 KTWC 250350
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
850 PM MST Tue Apr 24 2018

.SYNOPSIS...Dry conditions with unseasonably warm daytime
temperatures through midweek. Increased moisture will then bring
isolated to scattered showers and thunderstorms mainly east of
Tucson Friday into Saturday. Dry conditions to return Sunday.

&&

.DISCUSSION...IR satellite imagery indicates broken cirrus over much
of southeast Arizona this evening. The cloud cover is associated
with an upper disturbance positioned over northern Baja. This weak
system will pass generally south of the area into Wednesday, with a
few virga showers possible along the Int`l border, especially during
the morning hours. Ridging will then set up into Thursday, with
deeper moisture feeding into the state from the southeast. This
moisture combined with very warm temperatures will then create the
potential for showers and thunderstorms Friday into Saturday. The
near term trends look good and no changes to the forecast are needed
this evening. Please see the remaining sections for additional
information.

&&

.AVIATION...Valid through 26/06Z.
SCT-BKN cirrus clouds through the period, thickening overnight in
the mid-levels around 15k ft AGL. Surface wind variable in direction
less than 10 kts into Wednesday morning. Wind becoming WLY/NWLY 8-12
kts Wednesday afternoon with a few gusts near 20 kts. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Light winds and dry conditions remain through the
beginning of Thursday, when an approaching weather system brings a
slight chance of thunderstorms over the White Mountains in the late
afternoon/evening. Unsettled weather becomes more expansive on
Friday as thunderstorms potentially develop from Tucson eastward.
The primary concern will be dry thunderstorms capable of starting
fires and producing strong outflow winds, especially in the higher
terrain where development is more likely. Similar conditions persist
into Saturday as well. Dry weather returns for Sunday and beyond,
but 20-ft winds strengthen reaching 15-25 mph each afternoon through
Tuesday.

&&

.PREV DISCUSSION...A weak disturbance near Baja will spread more
high clouds across the area during the next 24 hours. Otherwise, a
ridge of high pressure will provide the area with warm and dry
conditions the next few days. Thereafter, models were in good
agreement with spreading mid-level moisture into the eastern one-
half of Arizona by Friday and Saturday. This moisture increase will
bring isolated to scattered showers and thunderstorms to southeast
Arizona Friday and more so Saturday, especially in the mountains and
east of Tucson. A low pressure system entering the Pacific Northwest
will shunt this moisture east of the area Sunday with rain chances
ending. A secondary system will enter the Desert Southwest on Monday
bringing strong and gusty winds as early as Sunday afternoon and
evening. This system will also result in slightly cooler daytime
temperatures early next week.

&&

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

&&

$$

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