Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
902 AM MST Tue Oct 5 2021

.SYNOPSIS...
A weather system will pass across Arizona today bringing rounds
of showers and storms to the area. Best chances will be mainly
north and east of Tucson. Isolated strong storms will be possible
this afternoon and evening accompanied by strong winds, hail, and
brief downpours. A period of dry weather Wednesday and most of
Thursday before the next weather system brings isolated shower
chances to southeast Arizona Thursday night and Friday.

&&

.DISCUSSION...Our low is behaving about as expected this morning;
becoming an open wave as it shears into the front side of the
digging west coast trough. The remnants will push into southern
Utah by tonight. Our best moisture and dynamics couplets continue
to look like areas north and east of Tucson. It's really a toss-up
on whether we have an environment that will include Tucson in the
stronger storms this afternoon, or whether we're overcome by the
dry slot wrapping into the southeast flank of the low with any
significant dynamics north and east. Latest NBM output still has a
sharp PoP gradient with 30 percent chances around the metro area,
but based on short range meso trends that may be overly generous.

Please see the previous discussion for additional forecast
details.

&&

.AVIATION...Valid through 06/12Z.
SCT-BKN clouds at 10k-14k ft MSL and SCT-BKN layered clouds above.
Expect scattered SHRA with a few embedded -TSRA through the early
morning hours. Then this afternoon and evening expect stronger
scattered TSRA/SHRA mainly from Tucson eastward. Local and brief
MVFR conditions, mountaintop obscurations, and wind gusts to 40 kts
possible near the stronger TSRA. Otherwise, SFC wind less than 12
kts and favoring a SLY/SELY direction this morning then SWLY/WLY
thereafter. Aviation not updated for TAF amendments.

&&

.FIRE WEATHER...
Multiple rounds of showers and storms are expected through
tonight across southeast Arizona, beginning to clear from west to
east this evening. Dry conditions will follow for Wednesday and
much of Thursday before chances for isolated showers move back in
Thursday night and Friday. Periods of breezy, southwesterly
surface winds are expected today and again Thursday/Friday with
speeds of 10-15 mph gusting up to 20-25 mph. Temperatures will
remain within a few degrees of normal through Friday before
dropping several degrees this weekend.

&&

.PREV DISCUSSION... /issued 247 AM MST Tue Oct 5 2021/

Today...Radar returns continue to indicate showers with a few
embedded lightning strikes moving south to north across Pima and
southeast Pinal counties early this morning ahead of an
approaching low pressure system. The low is clearly visible on
water vapor imagery this morning spinning just off the coast of
southern California and is expected to continue on the
northeasterly track today into tonight, weakening as it moves
onshore and across Arizona. After this initial round of showers
pushes north of the area over the next 2-3 hours, the next round
is expected to move across Cochise, Graham, and Greenlee counties
through the early afternoon. This round should again be mostly
light shower activity with some embedded lightning strikes
possible. Stronger storms are expected this afternoon as the
environment destabilizes mainly from Tucson eastward where the
best moisture and shear profiles will be present. Discrete cells
could become strong to severe early this afternoon with more
organized activity possible mid to late this afternoon through
this evening. Strong winds and hail will be possible with these
storms. PWAT values remain between 1"-1.4" today which would
support brief heavy downpours and localized flooding issues,
especially with training cells and in flood-prone areas. Overall,
the lower elevations could see a few tenths of an inch or less
over the next 24 hours and the higher elevations potentially up to
0.5" to 1" of total rainfall. Storm chances will shift eastward
this evening and out of the area by 10 PM- 12AM.

Wednesday through Monday...Dry conditions are expected Wednesday
and Thursday as southeast Arizona remains between ridging to the
south and large-scale troughing to the northwest. A couple of
shortwaves will work through the mean flow to our north later
this week which could bring in some breezes and low end chances
for rain Thursday night and Friday. Dry weather and cooler
temperatures will follow for the weekend with max temps dropping
several degrees below normal. The next system to keep an eye on
will be a deepening trough over much of the western U.S Monday
through mid next week with potential to bring us some wind and
the coldest temps we have seen so far this season.

&&

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

Public...Guillet/Meyer
Aviation...Hardin
Fire Weather....Guillet

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Special Weather Statement
National Weather Service Tucson AZ
1241 PM MST Tue Oct 5 2021

AZZ507-508-511>513-052030-
Upper San Pedro River Valley including Sierra
Vista/Benson-Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Chiricahua Mountains including
Chiricahua National Monument-Eastern Cochise County Below 5000 Feet
including Douglas/Willcox-Galiuro and Pinaleno Mountains including
Mount Graham-
1241 PM MST Tue Oct 5 2021

...A strong thunderstorm will impact portions of northwestern Cochise
County through 130 PM MST...

At 1240 PM MST, Doppler radar was tracking a strong thunderstorm over
Dragoon, or 16 miles east of Benson, moving northeast at 20 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Willcox, Dragoon, Pearce-Sunsites, Cochise and Texas Canyon.

This includes the following highways...
 Interstate 10 between mile markers 311 and 342.
 Route 186 between mile markers 327 and 336.
 Route 191 between mile markers 54 and 66.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3189 10997 3194 11021 3227 11017 3229 10964
TIME...MOT...LOC 1940Z 202DEG 16KT 3200 11004

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

Meyer