Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
234 AM MST Sun Jul 18 2021

.SYNOPSIS...After a decrease in shower and thunderstorm activity on
Saturday, there will be an upswing in thunderstorms today. This
increase in shower and thunderstorm activity will continue through
most of this coming work week. High temperatures will generally
remain at or slightly below normal readings.

&&

.DISCUSSION...There was a decrease in thunderstorm activity on
Saturday but that will change today into this coming work week. An
upper low spinning off the coast of central Baja will lift northward
today as the upper high shifts to a position over the Four Corners.
This upper low should provide some upper-level support for more
widespread coverage in showers and thunderstorms this afternoon and
evening. Although the airmass over SE AZ had undergone some drying
in the past 24 hours, moisture remained adequate enough for locally
heavy rainfall. That said, WPC upgraded the excessive rainfall
outlook to a slight risk category for today. The latest HRRR and
HREF target mainly Santa Cruz into Cochise, southern Graham and
southern Greenlee counties with the heaviest rainfall amounts by
late this evening. Beyond today, the concern for heavy rainfall will
continue through the week as the upper high becomes established over
the Four Corners region. Eventually, a few more of the larger washes
and mainstem rivers could experience significant flows by next
weekend.

&&

.AVIATION...Valid through 19/12Z.
FEW-SCT clouds at 8k-12k ft MSL and BKN-OVC clouds AOA 20k ft MSL
thru 18/17Z, then SCT-BKN clouds at 8k-12k ft MSL til 19/05Z. Slowly
diminishing clouds aft 19/05Z. ISOLD -SHRA/-TSRA thru 18/17Z, then
SCT-NMRS SHRA/TSRA developing and persisting through the evening
hours tonight before diminishing. 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...There will be a good chance of showers and
thunderstorms across most of southeast Arizona the next week. Gusty
outflow winds will be the primary concern with the daily storms. 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 and follow normal diurnal trends when
not influenced by thunderstorms.

&&

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

&&

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Special Weather Statement
National Weather Service Tucson AZ
619 AM MST Sun Jul 18 2021

AZZ503-507-513-181400-
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-
619 AM MST Sun Jul 18 2021

...SIGNIFICANT WEATHER ADVISORY FOR SANTA CRUZ COUNTY UNTIL 700 AM
MST...

At 617 AM MST, Doppler radar was tracking a cluster of strong
thunderstorm near Elgin and Nogales, moving west at 5 mph.

Locally heavy rainfall and winds in excess of 40 mph will be
possible with these storms.

Locations impacted include...
Nogales, Tubac, Rio Rico, Patagonia, Sonoita, Elgin, Patagonia Lake
State Park, Nogales International Airport, Tumacacori, Amado, Kino
Springs, Pena Blanca Lake, Canelo and Lochiel.

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.

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 11122 3172 11106 3167 11048 3133 11052
      3133 11108
TIME...MOT...LOC 1317Z 067DEG 6KT 3156 11058