Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
1033 AM MST Thu Jul 22 2021

.SYNOPSIS...An approaching weather system from the east will bring
widespread showers and thunderstorms to the area later today through
Saturday night. Locally heavy rainfall combined with a saturated
ground from recent rains may result in flash flooding and flooding
during this period. Improving weather can be anticipated late
Sunday, although elevated flows in area washes and streams will
still be possible. Thereafter, a decrease in daily shower and
thunderstorm activity can be expected early next week. High
temperatures will be near normal with the exception of Friday
through the weekend when below average readings can be expected.

&&

.DISCUSSION...Morning 500 mb upper air plot showed an upper high
near the 4 corners region with an upper low just east of the
Texas Big Bend. This upper low feature is well defined on the GOES
16 Water Vapor imagery. Infrared satellite imagery showed mainly
thin high clouds moving across the area. Will see plenty of
sunshine this afternoon with scattered showers and thunderstorms
developing mainly S/SW of Tucson, over the mountains near Tucson,
and across the White mountains. Storms will be moving to the west
southwest with localized severe storms and heavy rainers along
with areas of blowing dust. Storms on the rim will propagate to
the SW this evening bringing another round of strong storms and
heavy rain. This is the beginning of a multi-day heavy rain threat
for the area associated with the approaching upper low mentioned
above. A flash flood watch will go into effect at 6 pm this
evening and continue into Saturday night. More in the afternoon
discussion.

&&

.AVIATION...Valid through 23/12Z.
SCT-BKN clouds at 8k-12k ft MSL much of the period. Scattered to
numerous SHRA/TSRA developing this afternoon and evening. Expect
brief MVFR CIGS/VSBYS and mountain obscurations around TSRA along
with gusty outflow winds, potentially in excess of 45 kts with the
strongest storms. Otherwise, SFC wind generally less than 12 kts
following diurnal trends. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Monsoon continues to be active into this weekend
with scattered to numerous showers and thunderstorms. In particular,
this afternoon through Saturday looks extremely active with heavy
rainfall and flooding issues anticipated. While in this pattern,
showers and storms will be possible at all hours of the day and
overnight. Storms will also be capable of producing very gusty winds
in excess of 35 mph and numerous lightning strikes. Daytime
temperatures will remain below normal. 20-foot winds will generally
be less than 15 mph when not influenced by thunderstorms. Daytime RH
mainly above 25 percent into next Monday, with very good overnight
recoveries.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Flash Flood Watch from 6 PM MST this evening through Saturday
  evening for AZZ501>515.

&&

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Special Weather Statement
National Weather Service Tucson AZ
104 PM MST Thu Jul 22 2021

AZZ503-507-513-222030-
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-
104 PM MST Thu Jul 22 2021

...SIGNIFICANT WEATHER ADVISORY FOR EASTERN SANTA CRUZ COUNTY UNTIL
130 PM MST...

At 104 PM MST, Doppler radar was tracking a strong thunderstorm 9
miles southeast of Patagonia, or 21 miles northeast of Nogales,
moving west at 10 mph.

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

Locations impacted include...
Nogales, Patagonia, Sonoita, Elgin, Nogales International Airport,
Patagonia Lake State Park, Kino Springs, Canelo, Lochiel and Madera
Canyon.

LAT...LON 3172 11091 3169 11049 3133 11048 3133 11091
TIME...MOT...LOC 2004Z 090DEG 9KT 3148 11061

RH