Damaging Winds in Arizona, July 24, 2024

Area Forecast Discussion
National Weather Service Tucson AZ
216 PM MST Wed Jul 24 2024

.UPDATE...The Storm Prediction Center has issued a Severe
Thunderstorm Watch until 9 PM MST for portions of Southeast
Arizona including Pima, southeast Pinal, Graham and Santa Cruz
counties.

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.SYNOPSIS...
Daily chances for showers and thunderstorms are expected through
this week into this weekend with the main threats being strong gusty
winds and heavy rainfall.

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.PREV DISCUSSION... /issued 151 PM MST Wed Jul 24 2024/

It's shaping up to be an active afternoon and evening across
southeast Arizona as our area is under a favorable flow pattern
with the necessary moisture to result in showers and
thunderstorms. With the high to our northwest, we've got 10-15 kts
of mid level NE steering flow to help push convective development
now over the White Mountains into the lower elevations later this
afternoon into this evening. Latest SPC RAP mesoanalysis shows
MLCAPE of 500-1500 J/KG with 1500 J/KG of DCAPE to support strong
winds. Moisture levels east of Tucson aren't quite as high with
PWAT values at or just above 1 inch, so SBCAPE values are in the
250-500 J/KG across much of Cochise COunty. Outside of the
convection coming off the White Mountains, latest visible
satellite shows a cumulus field developing across much of the
area, so additional showers and thunderstorms are expected in
advance of the push from the White Mountains. SPC has most of
Pima, Pinal and Santa Cruz Counties in a slight risk for severe
thunderstorms. The gusty outflow winds may result in areas of
blowing dust, thus a Blowing Dust Advisory remains in effect from
4 PM to 11 PM. Additionally, flash flooding is a threat,
especially from Tucson westward into the T.O. nation where deeper
moisture is in place as PWAT values are 1.3"-1.7" west of Tucson.
Convective activity will tend to wind down later this evening.

A very similar flow pattern is in place for Thursday and the
HREF/CAMs are showing an active day, especially for
Graham/Greenlee/Cochise County which may not get hit as hard today
to work the atmosphere over. Confidence is a bit lower from Tucson
westward since the atmosphere may be more worked over in these
locales, especially if today turns out to be a big day. SPC has
already outlined our area in a marginal risk for severe
thunderstorms for Thursday and that looks good.

The mid/upper level high will start to wobble a bit more to the
south Friday which will turn the flow more northerly. Deep moisture
levels remain in place with PWAT values ranging from 1.25" to 1.75"
across the region to continue our active monsoon period. As the high
continues to nudge south and east this weekend, that will tend to
push the best chances for showers and thunderstorms from Tucson
south and eastward. By early to mid next week, the high will shift
into New Mexico that will shift out flow pattern to come more from
the east to southeast. Some indications of an inverted trough early
next week as well that could help ramp up activity as well.

Temperatures during the forecast period will be about 3 to 6 degrees
above normal.

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.AVIATION...Valid through 26/00Z.
SCT-BKN clouds AOA 8-10K FT MSL until 25/06Z then again aft 25/18Z.
Another round of scattered to numerous SHRA/TSRA expected to develop
and impact much of the forecast area moving from the NE of the fcst
area to SW now thru 25/11Z then again 25/20Z thru the end of the
period. Strong winds to 50-60 kts possible near TSRA. Outside of
TSRA, surface winds will generally be easterly/southeasterly and
remain under 10 kts. Aviation discussion not updated for TAF
amendments.

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.FIRE WEATHER...
Scattered afternoon and evening showers and thunderstorms with day
to day variability on which areas will see the best chance of
rainfall. Today through Friday is looking particularly active at
this time, with each day having the threat of heavy rain, localized
flash flooding and strong gusty winds. Minimum relative humidities
will be 20 to 30 percent in most lower elevation locations and 25 to
40 percent in mountain areas. Away from thunderstorms, 20-foot winds
will generally be 15 mph or less, with afternoon/early evening gusts
to 20-25 mph and light winds overnight.

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.TWC WATCHES/WARNINGS/ADVISORIES...
Severe Thunderstorm Watch until 9 PM MST for
AZZ501>507-509>511-513>515. (This includes Pima, southeast Pinal,
Graham and Santa Cruz counties)

Blowing Dust Advisory until 11 PM MST this evening for
AZZ502-504-505.

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