Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
955 AM MST Tue Jul 27 2021

.SYNOPSIS...Isolated to scattered storms are expected today and
tomorrow before a more active weather period begins Thursday into
the weekend. High temperatures will run near to a few degrees below
seasonal normals.

&&

.DISCUSSION...Will likely see an upswing in showers and
thunderstorms this afternoon and evening as a weak disturbance
provides the upper-level support for triggering storms today.
Otherwise, a more pronounced upper low will approach the region
Thursday signaling a more significant upswing in activity Thursday
afternoon into the weekend. Please refer to the previous discussion
in this product for more details.

&&

.AVIATION...Valid through 28/18Z.
FEW/SCT clouds 15k-20k ft AGL through the morning with FEW/SCT
clouds around 8k-12k ft AGL by the afternoon. Isolated to scattered
SHRA/TSRA with +TSRA possible from KTUS south to KOLS. Gusty outflow
winds are likely with KTUS possibly seeing late afternoon gusty
outflows from the south/southwest. Gusts to 35kts+ possible. Storm
activity will gradually diminish around sunset. Aviation discussion
not updated for TAF amendments.

&&

.FIRE WEATHER....Isolated to scattered showers and thunderstorms
will be possible each afternoon and evening through Wednesday.
Precipitation chances then increase going into the upcoming
weekend. Gusty, erratic winds and locally heavy rainfall will
accompany any storms that develop. High temperatures will be near
to slightly below normal through Friday, lowering to below normal
levels this weekend. 20-foot winds will generally be less than 15
mph when not influenced by thunderstorms.

&&

.PREV DISCUSSION.../issued 231 AM MST Tue July 27 2021/
For today and Wednesday, a ridge will center slightly eastward over
the central Great Plains today allowing flow over southern Arizona
to shift more southeasterly throughout the day. Low to mid-grade
monsoon moisture remains in place over southeast Arizona with PWAT
values of 0.9-1.6 inches from east to west respectively. Yesterday
was a fairly slow day but we are expecting an increase in coverage
of convection today with the addition of upper level support in the
form of a weak impulse rotating around the high. The morning should
remain quiet with showers and storms expected to begin to pop
between noon and 2 PM. Best chances for storms start near the border
over Santa Cruz and southern Pima counties and then spread northward
across much of Pima County into southern Pinal County through this
evening. Activity will remain more isolated in nature across the
remainder of the area. Gusty, outflow winds will be likely along
with isolated flooding issues possible. Wednesday shows hints of a
slightly slower day before the ramp up Thursday into the weekend.
Temps will continue to warm today and tomorrow, reaching back up to
seasonal normals.

For Thursday through Monday...as mentioned above, we are expecting
the next active period to begin Thursday as an easterly wave moves
through northern Mexico into southern Arizona Friday into Saturday.
Moisture surge begins to work into the area Thursday allowing for
higher precipitation chances and a higher threat for flash flooding
which will continue for the remainder of the period. Unfortunately,
the "down" days we see earlier in the week won't be quite long
enough to significantly dry out area washes and streams which are
still running from last weekend. Continue to monitor the forecast,
especially if you have outdoor plans late this week into the weekend.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

Prev Discussion...Guillet
Aviation...Michael
Fire Weather....Michael

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Special Weather Statement
National Weather Service Tucson AZ
156 PM MST Tue Jul 27 2021

AZZ503-507-513-272145-
Upper San Pedro River Valley including Sierra
Vista/Benson-Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Upper Santa Cruz River and Altar
Valleys including Nogales-
156 PM MST Tue Jul 27 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN COCHISE AND
SOUTHEASTERN SANTA CRUZ COUNTIES UNTIL 245 PM MST...

At 156 PM MST, Doppler radar was tracking a strong thunderstorm 7
miles west of Parker Canyon Lake, or 20 miles west of Sierra Vista,
moving west at 15 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Patagonia, Parker Canyon Lake, Fort Huachuca and Canelo.

LAT...LON 3155 11043 3135 11047 3143 11085 3164 11077
TIME...MOT...LOC 2056Z 103DEG 14KT 3147 11058

AH