FXUS65 KTWC 121641
Area Forecast Discussion
National Weather Service Tucson AZ
941 AM MST Sun Jul 12 2020
.SYNOPSIS...Another day or two of very hot conditions are expected
before temperatures begin ease back toward normal levels. There is
enough moisture around for isolated to scattered thunderstorms to
continue through Monday the diminishing a bit Tuesday. The
thunderstorm coverage should increase again later next week.
.DISCUSSION...Yesterday, late afternoon and evening, turned out to
be much more active than I and some of the CAMs thought. So what`s
in store for today?
First, it`s going to be a very hot July day with record to near
record high temperatures under strong high pressure aloft
centered over e-central AZ. Excessive Heat Warning remains in
effect for most of the forecast area today. Will address
continuing the warning on Monday in the afternoon discussion.
Second, abundant sunshine prevails this morning across the area
under easterly flow aloft. PW was down a bit from 24 hours ago,
with values ranging from 0.80" near AZ/NM border to 1.3" across
western Pima county. 12z Tucson sounding was rather similar to 24
hours ago. Storms developing over the White mountains and from
Mt. Graham south to the Huachucas later this afternoon, moving to
the west with outflow interactions developing storms at the lower
elevations that will continue into the early evening hours.
Will address the remainder of the forecast in the afternoon
.AVIATION...Valid through 13/12Z.
SKC to FEW 10-14k ft MSL becoming SCT-BKN 10-14k ft MSL this
afternoon/evening SCT-BKN 10-14k ft MSL. Isolated to scattered
SHRA/TSRA develop in the afternoon, favoring the higher terrain
and south of KTUS. Outside of TSRA outflows, light and variable
surface winds settle WLY/NWLY 8-12 kts with gusts around 20- 25
kts during the afternoon. Aviation discussion not updated for TAF
.FIRE WEATHER...With monsoonal flow in place, expect isolated to
scattered showers and thunderstorms each afternoon/evening through
the forecast period. The pattern becomes slightly less favorable on
Tuesday/Wednesday keeping storms to areas mainly southeast of Tucson
and over the White Mountains. Activity looks to ramp back up later in
the week. Temperatures reach near or above record levels today and
Monday, easing back closer to more normal levels thereafter. Relative
humidities hold close to average through the week with generally
good overnight recoveries. 20-ft winds generally remain less than 15
mph with afternoon gusts, although Monday will be breezier across the
Upper Gila River Valley. Also, any afternoon/evening thunderstorms
will capable of gusts of 45+ mph.
Excessive Heat Warning until 8 PM MST Monday for AZZ501>509-515.
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