Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 230357
Area Forecast Discussion
National Weather Service Tucson AZ
857 PM MST FRI JUL 22 2016
.SYNOPSIS...Isolated to scattered thunderstorms will occur mainly
east to south of Tucson Saturday. Increased moisture will then
provide scattered thunderstorms across much of the area starting
Sunday and continuing during the upcoming week. Expect well above
normal temperatures again Saturday followed by a moderation in
daytime temperatures next week.
.DISCUSSION...A small cluster of thunderstorms existed over the
eastern portion of Pinal County from near Oracle northward to just
east of Dudleyville at this time. These thunderstorms were decreasing
in intensity during the past 15-30 minutes. Meanwhile, cloud tops
were cooling fairly rapidly associated with a MCS over northeast
Sonora during the past hour. This system has generated several
lightning strikes during the past 15-30 minutes just south of
The 23/02Z HRRR suggests that showers/tstms will move into far
southeast Cochise County during about the next hour, then showers/
tstms will continue moving westward into Santa Cruz County and
perhaps eastern Pima County including the Tucson metro area by
daybreak Saturday. The composite reflectivity signatures as per this
HRRR solution suggests that a remnant MCV may be near the Tucson
metro area, perhaps south of the metro area, around 23/13Z. This
solution does merit some credibility given satellite trends.
At any rate, the official forecast will be updated to include
isolated to scattered showers/tstms the rest of tonight from Tucson
eastward/southward to the New Mexico/International borders. Precip-
free conditions should occur across western/central Pima County.
Believe that the bulk of any showers/tstms should end around sunrise
Saturday or shortly thereafter.
Please refer to the additional sections for further detail.
.AVIATION...VALID THRU 24/06Z.
Isolated -TSRA north of KTUS mostly ending around 23/08Z. Expect
scattered -TSRA/-SHRA initially vicinity of KDUG moving westward
later tonight. This activity may reach KOLS but is not expected to
reach KTUS. However, forecast confidence is low regarding the
westward extent of these -TSRA/-SHRA, which should then end around
12Z-14Z Saturday. Isolated to scattered -TSRA/-SHRA to return mainly
east to south of KTUS Saturday afternoon/evening. Brief wind gusts to
near 40 kts and MVFR conditions with the stronger TSRA. Aviation
discussion not updated for TAF amendments.
.FIRE WEATHER...Isolated to scattered thunderstorms mainly east to
south of Tucson Saturday. Greater coverage of thunderstorms will
then occur starting Sunday and continue into the upcoming week. 20
foot winds will generally be light and diurnally driven outside of
.PREV DISCUSSION /211 PM MST/...As expected convection is slow to get
going this afternoon thanks to a slightly drier air mass. PWs holding
just over an inch in the Tucson area with less to the east and a bit
more to the west. Thus expecting mainly isolated convection through
the evening before it dies off. Its been a slow climb temperature-
wise and we still have 3 degrees to go to reach the record at Tucson.
However we are currently sitting at 104 so the potential is still
there with about 3 hours of heating potential left.
For Saturday, expecting similar conditions to this afternoon with
limited moisture and hot temperatures. Convection will be fairly
isolated and primarily affecting the Whites and the mountains south
and well east of Tucson.
Saturday night it looks as though we should get a lower level surge
of moisture which will kick up the dewpoints. Will need to watch for
convection continuing well into the night near our southern border as
As a result of the increase in moisture the threat of showers
increases Sunday afternoon when compared to today and Saturday along
with about 4-5 degrees of cooling of afternoon high temperatures
although with higher dewpoints it likely won`t feel all that much
Looking at cross sections and model soundings the moisture increases
in amount and depth Sunday night which will set us up for a more
active week next week with Monday and Tuesday potentially being the
more active days with PWs generally in the 1.5-1.75" range. At that
point will have to play it day by day for any more detail. During
that time the afternoon high temperatures should settle back closer
to average thanks in part to the clouds and precipitation.
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