Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
247 PM MST Mon Jul 19 2021

.SYNOPSIS...The weather pattern will remain favorable for scattered
showers and thunderstorms through midweek then an increase in
activity is expected late in the week. High temperatures will be
near or slightly below normal through the week.

&&

.DISCUSSION...Isolated thunderstorms producing locally heavy rain
have developed across the forecast area this afternoon and will
continue to do so into the evening. Much less activity than last
evening although there remains a flood threat with any of the
stronger or slower moving storms. PW values range from around 1.5
east to 2.0 inches west with fairly impressive CAPE to the east so
potential for a severe storm or two also exists east.

For much of the area tonight north and east of Tucson the storm
activity will diminish late this evening while to the south and west
there's a strong hint of an MCS type system moving NW out of Sonora
affecting this area late tonight early Tuesday morning. Grids
basically reflect that thought.

Tomorrow will be an average day and with the mid level flow oriented
more NE (vs east today) the Rim comes into play for our area. This
generally means storms south of Tucson headed west to southwest early
to mid afternoon then Rim activity headed Southwest late in the day
into the evening. Always a question as to how far they make it and
will be interesting to see if they get as far as Tucson. Tuesday
evening that may not happen. There is a similar setup for Wednesday
except a slightly more favorable environment with a better chance of
getting Tucson in the mix.

Then Thursday into the weekend an interesting pattern is looking to
evolve although models are all over the place with the details.
Basically a significant trough or wandering upper level low pressure
system will in near or over the area during this period. A lot of
uncertainty with this pattern. With the amount of moisture and
resultant instability that will likely be present, this could
provide for some interesting and potentially concerning (related to
flooding) periods Thursday into the weekend. We will have to wait and
see how this evolves with time.

&&

AVIATION...Valid through 21/00Z.
SCT-BKN clouds at 8k-12k ft MSL til 20/10Z then slowly diminishing
thereafter. ISOLD-SCT SHRA/TSRA persisting through the evening hours
KTUS north and east and through the night KTUS south and west. Wind
gusts to 45 kts possible near any TSRA along with MVFR conditions and
mountain obscurations. Otherwise, SFC wind generally less than 12
kts. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...A wet monsoon pattern will continue the next week,
resulting in scattered showers and thunderstorms, more numerous late
in the week. The storms will primarily be during the afternoon and
evening hours, but may also occur during the overnight and morning
hours as well. Primary concerns outside of the typical gusty winds is
the potential for flooding due to heavy rains. Afternoon
temperatures will remain below normal. Min RH values will be in the
27-37 percent range at the lower elevations, with higher values in
the mountains. 20-foot winds will generally be less than 15 mph when
not influenced by thunderstorms.

&&

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

Public...Cerniglia
Aviation...Cerniglia
Fire Weather....Cerniglia

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Special Weather Statement
National Weather Service Tucson AZ
323 PM MST Mon Jul 19 2021

AZZ509-510-192245-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-White
Mountains of Graham and Greenlee Counties including Hannagan Meadow-
323 PM MST Mon Jul 19 2021

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL GRAHAM AND CENTRAL
GREENLEE COUNTIES UNTIL 345 PM MST...

At 322 PM MST, Doppler radar was tracking a strong thunderstorm near
Clifton, moving northwest at 10 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Clifton, Morenci, Guthrie and Three Way.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy 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 3292 10927 3298 10959 3332 10929 3320 10904
      3308 10905
TIME...MOT...LOC 2222Z 121DEG 9KT 3300 10931

JRM