Severe Thunderstorm Warning 53, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
212 PM MST Fri Jul 5 2024

.SYNOPSIS...Excessive heat with temperatures expected to approach
record levels in some locations. With high pressure building in
from the northwest, daytime temperatures will be trending hotter
into next week. Shower and thunderstorm chances will mainly be
confined south and east of Tucson into early next week as drier
air overspreads much of Arizona from the north.

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.DISCUSSION...Our main story is going to turn to the heat over the
next several days with strong high pressure driving near record
heat as the monsoon temporarily dips into lower grade activity.

Overall another down day with thunderstorm coverage. Moisture at
the surface continues to ebb and flow as we see periodic
relatively shallow input from the south. Precipitable water values
are trending down, now below 1 inch in Graham, Greenlee and Pinal
counties, up to 1.2 inches near the border and 1.5 inches south
of the border. Isolated initiation mainly near the mountains in
the early afternoon, with a few wandering into valleys south of
Tucson. A good day for isolated pulse severe. They shouldn't last
much past sunset.

Overall that will be the trend over the next several days, however
don't expect our corner of the state to scour all of the moisture
out. Some days will be busier than others, but in general not much
activity expected north of Tucson.

As high pressure builds in from the northwest and we see lower
levels of moisture, heights and thicknesses will support near
record heat for areas from Tucson into the lower deserts. Right
now we just have an excessive heat warning through Tuesday for all
but Santa Cruz and Cochise counties. Ultimately it may even be
extended another day or two if we don't see much moisture return
by mid week.

Ensemble means continue to suggest the high center will
eventually reconsolidate into a more favorable position by the
middle of next week and into the following weekend. Keeping an eye
on the tropics as TS Aletta off the southwest Mexican coast has
been quick to hit a rough patch as expected and has been
downgraded to a depression. No real impact expected for our area.

Height anomalies suggest a strong easterly wave across central
Mexico exiting into the Pacific later next week. That, along with
a more favorable synoptic pattern should get deeper moisture back
into at least our corner of the state.

&&

.AVIATION...Valid through 07/00Z.
SCT-BKN clouds at 7k-10k ft AGL and ISOLD-SCT TSRA/SHRA mainly
south and east of KTUS. MVFR conditions near TSRA, with mountain
obscurations and gusts to 40+ kts. Aft 06/03Z, gradual clearing
with ISOLD -TSRA returning after 06/20Z. Other than TSRA
outflows, SFC wind less than 12 kts favoring a WLY/NWLY direction
during the afternoon/early evening hours and variable in direction
at other times. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...There will be the daily chance for isolated to
scattered showers and thunderstorms mainly from Tucson south and
east into early next week. High pressure aloft will build to our
northwest through the weekend into early next week, which will
result in hot conditions. With the hotter temperatures and some of
the deeper moisture getting pushed to the south and east of the
region, min RH values will lower into the 10-18% range across the
lower elevations and 15-30% in the higher elevations into the middle
of next week. Hot high temperature are expected through early next
week, with highs 109-114 degrees from Tucson westward and up to
110 in the Gila River Valley. Excessive Heat will be an issue
during this time frame. Outside of any thunderstorm outflow winds,
20-foot winds will generally be 15 mph or less each afternoon
with occasional gusts to 20-25 mph through the weekend. Early next
week there will be the potential for more elevated wind speeds in
the 15- 20 mph range, especially east of Tucson.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM MST Monday for AZZ501-502-
504>506-509.

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