Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
254 PM MST Wed Aug 18 2021

.SYNOPSIS...Strong storms around this afternoon and evening, with
best coverage north and east of Tucson. Some storms will generate
extremely heavy rain. Thursday through the weekend will see a
drying trend with little to no thunderstorm activity. As this
happens, temperatures will climb back above late August averages
by Saturday. Conditions will again become favorable for storms
early next week.

&&

.DISCUSSION...A strong trough digging into the Great Basin is
lifting a mid level disturbance up from the southwest this
afternoon. Still plenty of moisture across southwest to central
portions of the state to generate a lot of strong convection north
of us across Maricopa and Gila counties. We've struggled a bit in
SE AZ with a mid level dry slot wrapping up from the southwest on
the eastern flank of the disturbance. It's shearing out pretty
quickly but still could be in a position to give us some storms
late this afternoon and early evening. If not, then we will
probably need to wait until next week before we see storms again.

Still on track for storm chances to drop off the table Thursday
into the weekend as a dry westerly flow kicks in behind the
trough. Mid level drying will deepen and eat away at our moisture
profile from the top down. The westerlies should even be deep
enough to limit storms across most of Sonora for a few days. We
should maintain enough lower level moisture for some afternoon cu
fields. Temperatures will jump back up to seasonal normals, and
probably a few degrees above over the weekend. Tucson will flirt
with adding another 100 degree day or two.

Ultimately we should be back in business by next Monday or Tuesday
with the ridge rebuilding across the southern plains into our
area, and the associated high center consolidating to our east.

&&

.AVIATION...Valid through 20/00Z.
SCT -SHRA/TSRA this evening, diminishing overnight. Clouds will
be SCT- BKN 6k- 11k ft MSL with ocnl MVFR conds in SHRA/TSRA.
Partial clearing overnight. Strong erratic outflows with storms,
otherwise sfc winds 10 kts or less. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...A chance of thunderstorms this evening, then a
drying trend with near zero storm chances Thursday through the
weekend. Even with the drying, some surface moisture will remain
and min RH values should remain above critical levels with good
overnight recoveries. 20-foot winds will generally be less than 15
mph when not influenced by thunderstorms.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 8 PM MST this evening for AZZ505-506-
509>511.

&&

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Special Weather Statement
National Weather Service Tucson AZ
810 PM MST Wed Aug 18 2021

AZZ509-510-190400-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-White
Mountains of Graham and Greenlee Counties including Hannagan Meadow-
810 PM MST Wed Aug 18 2021

...A strong thunderstorm will impact portions of central Greenlee
County through 900 PM MST...

At 810 PM MST, Doppler radar was tracking a strong thunderstorm near
Clifton, moving northeast at 25 mph.

HAZARD...Wind gusts up to 50 mph and penny 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...
Clifton, Morenci, York, Three Way and Guthrie.

This includes the following highways...
 Route 75 between mile markers 396 and 398.
 Route 78 between mile markers 155 and 174.
 Route 191 between mile markers 152 and 163.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

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.

&&

LAT...LON 3290 10931 3299 10941 3320 10905 3296 10905
TIME...MOT...LOC 0310Z 238DEG 21KT 3296 10931

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

JRM