Excessive Heat Warning 8, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
210 PM MST Tue Aug 11 2020

.SYNOPSIS...High pressure will push our above average heat to
near record levels the second half of the week. A modest moisture
increase will bring a few storms to the area, but still well below
average for mid August.

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.DISCUSSION...The main message for the rest of this week into early
next week will be the heat. Record or near record high temperatures
can be anticipate Thursday into the weekend. That said, the
Excessive Heat Watch has been upgraded to a Warning for Thursday
into Sunday. Might need to eventually extend this Excessive Heat
Warning into Monday if deeper moisture doesn't spread into the area
by Monday.

Recent models continued to show the ridge of high pressure aloft
strengthening overhead Thursday through the weekend as it builds
northward and becomes centered over the Great Basin region by
Monday. This northward shift in the center of the upper high will
allow deeper moisture pooled south of the International Border to
move into the region. The steering flow will also become more
favorable for supporting areawide thunderstorms as a deeper layer of
easterly winds develop with the upper high centered north of the
area. This advertised upswing in thunderstorm activity next week
should help lower high temperatures a few degrees as well.

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.AVIATION...Valid through 13/00Z.
Thru 12/08Z, SCT-BKN clouds at 10k-15k ft MSL east of a KOLS-KSAD
line, with FEW-SCT clouds at 10k-15k ft MSL elsewhere. Aft 12/08Z,
FEW-SCT clouds areawide at 10k-15k FT MSL. A slight chance of
-TSRA/-SHRA mainly south and southeast of KTUS in the vicinity of
KOLS and KALK thru 12/04Z. SFC wind generally less than 12 kts
through the forecast period, with NWLY winds in the afternoon and
early evening and SFC wind variable in direction at other times.
Aviation discussion not updated for TAF amendments.

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.FIRE WEATHER...There will be a slight chance of showers and
thunderstorms generally south and southeast of Tucson early this
evening. Otherwise, hot and dry weather will be the main theme
through the upcoming weekend, along with isolated shower and
thunderstorm chances. 20-foot winds will follow typical diurnal
patterns at less than 15 mph outside of any thunderstorm wind gusts.
Daytime humidity will generally be in the 15 to 25 percent range in
the valleys and 20 to 30 percent in the mountains with moderate to
good overnight recoveries.

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.TWC WATCHES/WARNINGS/ADVISORIES...
    Excessive Heat Warning from Thursday morning through Sunday
    evening for AZZ501>506-509.

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