Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
300 AM MST Wed Aug 11 2021

.SYNOPSIS...Increased shower and thunderstorm activity will bring
temperatures a few degrees below average into the weekend. Some
storms will generate strong winds and heavy rain which will result
in continued flooding concerns and localized storm damage.

&&

.DISCUSSION...The weak low near west central Arizona was joined by
another mid level impulse rotating up from the south late last
night. Combine that with a synoptic scale upper level diffluent
pattern, elongated shear axis, continued moisture amounts well
above average, and well organized deep convective outflows and you
get the past 8 hours of widespread heavy rain and nearly
continuous lightning. Rainfall amounts between 2 and 4 inches over
a broad area from northeast Tucson to the foothills continues to
cause flash flooding issues as that water pushes downstream into
areas that saw between 1 and 2 inches for most of the rest of the
city. Watching the impressive outflow from the earlier convective
complex in Yuma County, and you get the feeling we have more to
watch for this morning as storms redevelop through the Tohono
O'Odham Nation.

All that can be said at this point is that we probably will be too
worked over to get something organized across our current active areas
by the time this afternoon rolls around, but high PoP / low QPF
isn't out of the question.

We should be able to recover to average thunderstorm chances
Thursday afternoon/evening before we see another major feature
enter our weather picture.

Remember 3 weeks ago when the high was well north of us and we
were wide open to the strong inverted trough that pushed straight
in from the east? It's starting to look that way again for this
weekend. Current ensembles show another direct hit for southeast
Arizona Saturday. With deep moisture in place, we'll likely be
seeing another couple of days with excessive rainfall chances this
weekend. Watch for enhanced severe thunderstorm chances ahead of
this system for Thursday and/or Friday.

&&

.AVIATION...Valid through 12/12Z.
Mostly SCT-BKN clouds 10-14k ft MSL. Isolated to scattered
SHRA/TSRA through the forecast period. Local MVFR conditions and
gusty winds with SHRA/TSRA. Outside of SHRA/TSRA, SFC winds will
be less than 10 kts following a normal diurnal flow of sly/sely
during the night/early morning and mainly wly/nwly late morning
through afternoon. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Ample moisture this week along with periodic
mid level disturbances will result in at least a mid grade monsoon
pattern. Given the higher levels of moisture and cloud coverage,
temperatures will be cooler this week. Strong, erratic winds and
locally heavy rainfall will be possible with any stronger storms
that develop. 20-foot winds will generally be less than 15 mph when
not influenced by thunderstorms.

&&

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

Meyer

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Special Weather Statement
National Weather Service Tucson AZ
224 PM MST Wed Aug 11 2021

AZZ503-507-513-112145-
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-
224 PM MST Wed Aug 11 2021

...A strong thunderstorm will impact portions of southeastern Santa
Cruz County through 245 PM MST...

At 222 PM MST, Doppler radar was tracking a strong thunderstorm near
Patagonia, or 18 miles northeast of Nogales, moving northeast at 10
mph.

HAZARD...Wind gusts up to 50 mph and half inch 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...
Elgin.

This includes Route 83 between mile markers 17 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

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 3138 11072 3152 11078 3162 11056 3142 11048
TIME...MOT...LOC 2122Z 239DEG 16KT 3149 11066

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

TRIPOLI