Flash Flood Warning 18, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
343 PM MST Fri Jul 31 2020

.SYNOPSIS...Strong high pressure aloft through the weekend will
provide very hot daytime temperatures, with record or near record
highs through Saturday. A side effect is that thunderstorm
development will be very limited again today. Isolated to scattered
thunderstorms return over the weekend to parts of the area, although
hotter than normal temperatures will continue.

&&

.DISCUSSION...Mostly clear skies across much of southeast Arizona,
though FEW-SCT cu and cb were developing across the White Mountains
and along the International border. As such, a few showers and
thunderstorms have popped up, mainly across Santa Cruz and Cochise
Counties. With strong winds aloft, many of the cloud tops are being
sheared off toward the south. Expect this to be the story into this
evening with most convection ending with the daytime heating. Could
have a few gusty outflows associated with the stronger storms.
Otherwise, it was very hot as expected this afternoon with
temperatures encroaching on record levels and the Excessive Heat
Warning remaining in effect. As of 31/22Z, KTUS had reached a high
of 110, which is only 1 degree shy of the record of 111 set in 1986.

Looking to this weekend we should have a slight uptick in showers
and thunderstorms compared to today, but the areas of activity
should generally remain similar. This translates to isolated to
scattered showers and thunderstorms along the International border
and areas mainly east and northeast of Tucson, particularly the
higher terrain. A high pressure ridge will also dominate the
southwestern CONUS so expect very hot temperatures to continue
through the weekend as well.

We should have a bit of a downturn Monday and Tuesday with regard to
convection, but temperatures will remain slightly above normal into
next week as the upper pattern is fairly stagnant. The ridge slides
slightly eastward by the middle of next week which should allow some
additional moisture to move into the area for PWAT values
approaching 1.25"-1.5". We should also have another day or two of
increased rain chances, which currently includes most of southeast
Arizona and the Tucson metro Wednesday and Thursday. Temperatures
will still remain a few degrees above average through next week
despite this increase in convective potential.

&&

.AVIATION...Valid through 02/00Z.
Isolated to scattered -TSRA/-SHRA mainly east to south of KTUS this
evening, then isolated -SHRA mostly near the ern AZ/wrn New Mexico
state line late tonight and early Saturday morning. Scattered
-TSRA/-SHRA mainly east to south of KTUS Saturday afternoon. Brief
tstm gusts to near 40 kts may occur at times. Otherwise, mainly SKC
west of KTUS, and FEW-occasionally BKN clouds around 10k-15k ft MSL.
Surface wind variable in direction mainly under 12 kts into Saturday
morning, then surface wind nwly 8-16 kts with gusts of 20-25 kts
Saturday afternoon. The strongest speeds should occur across the
Upper Gila River Valley and especially near KSAD. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect isolated to scattered mainly afternoon and
evening thunderstorms favoring locations east to south of Tucson
through around Tuesday. A further westward coverage of thunderstorms
to include much of the area may occur next Wednesday and Thursday.
At this time, appears isolated to scattered thunderstorms next
Friday will remain east of Tucson. 20-foot winds will generally
follow typical diurnal patterns at less than 15 mph apart from
thunderstorm wind gusts. High temperatures will be 5 to 10 degrees
above normal through at least Saturday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...

Excessive Heat Warning in effect until 8 PM MST Saturday for
AZZ501>506-509.

&&

Carpenter/BF

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Special Weather Statement
National Weather Service Tucson AZ
318 PM MST Fri Jul 31 2020

AZZ503-513-312300-
Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Upper Santa Cruz River and Altar
Valleys including Nogales-
318 PM MST Fri Jul 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN SANTA CRUZ COUNTY
UNTIL 400 PM MST...

At 317 PM MST, Doppler radar was tracking a strong thunderstorm near
Patagonia, or 15 miles northeast of Nogales, moving southwest at 10
mph.

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

Locations impacted include...
Nogales, Patagonia, Nogales International Airport, Patagonia Lake
State Park and Kino Springs.

LAT...LON 3137 11097 3159 11078 3151 11059 3133 11066
      3133 11088
TIME...MOT...LOC 2217Z 026DEG 9KT 3149 11073

BF

Special Weather Statement
National Weather Service Tucson AZ
627 PM MST Fri Jul 31 2020

AZZ504-514-010215-
Santa Catalina and Rincon Mountains including Mount
Lemmon/Summerhaven-Tucson Metro Area including Tucson/Green
Valley/Marana/Vail-
627 PM MST Fri Jul 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN PIMA COUNTY UNTIL
715 PM MST...

At 626 PM MST, Doppler radar was tracking a strong thunderstorm
across the eastern portions of the Tucson Metro Area near Davis-
Monthan Air Force Base, moving southwest at 25 mph.

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

Locations impacted include...
Tucson, Davis-Monthan Air Force Base, Tanque Verde, Sabino Canyon
Recreation Area, Catalina Foothills, Tucson International Airport,
Summit, Saguaro National Park East, Rita Ranch and Seven Falls.

LAT...LON 3203 11075 3208 11096 3245 11084 3241 11066
TIME...MOT...LOC 0126Z 031DEG 20KT 3221 11082