Severe Thunderstorm Warning 52, NWS Tucson, AZ

543 
WWUS55 KTWC 202159
SVSTWC

Severe Weather Statement
National Weather Service Tucson AZ
259 PM MST Thu Aug 20 2020

AZC003-023-202230-
/O.CON.KTWC.SV.W.0052.000000T0000Z-200820T2230Z/
Cochise-Santa Cruz-
259 PM MST Thu Aug 20 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 330 PM MST
FOR SOUTHWESTERN COCHISE AND EAST CENTRAL SANTA CRUZ COUNTIES...

At 257 PM MST, a severe thunderstorm was located near Fort Huachuca,
or 12 miles west of Sierra Vista, moving south at 15 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Sierra Vista, Huachuca City, Fort Huachuca, Parker Canyon Lake and
Ramsey Canyon Preserve.

This includes the following highways...
 Route 83 between mile markers 3 and 7.
 Route 92 near mile marker 328.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3160 11053 3166 11038 3145 11025 3139 11043
TIME...MOT...LOC 2157Z 008DEG 11KT 3153 11043 

HAIL...1.00IN
WIND...60MPH
 
$$

184 
WWUS55 KTWC 202209
SVSTWC

Severe Weather Statement
National Weather Service Tucson AZ
309 PM MST Thu Aug 20 2020

AZC003-023-202219-
/O.CAN.KTWC.SV.W.0052.000000T0000Z-200820T2230Z/
Cochise-Santa Cruz-
309 PM MST Thu Aug 20 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN COCHISE AND EAST
CENTRAL SANTA CRUZ COUNTIES IS CANCELLED...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning has
been cancelled.

LAT...LON 3160 11053 3166 11038 3145 11025 3139 11043
TIME...MOT...LOC 2204Z 329DEG 14KT 3149 11040 

$$

Area Forecast Discussion
National Weather Service Tucson AZ
935 AM MST Thu Aug 20 2020

.SYNOPSIS...Expect storm coverage and chances to increase today
into the weekend. High temperatures will moderate through the
weekend, but will still be 2-5 degrees above normal. Next week
storm chances decrease and temperatures climb back up to near
record levels.

&&

.DISCUSSION...Ongoing gulf surge, thanks to Hurricane Genevieve,
has increased moisture values across southern Arizona, especially
from Tucson west. Latest GOES PW imagery showed values from 0.90"
near the AZ/NM border to 1.2" over western Pima county, with
values up to 1.40" across Yuma county. The 12z Tucson sounding had
a PW value of 1.49" which is backed up by GPS PW at that time.
However, since release and looking at the GPS PW trace, the value
over Tucson is down to around 1.25". On the upper air charts, the
500 mb high was located over northeast Arizona with easterly mid-
level winds over the area but not as strong as previous days.

As we have been advertising all week, it will be an active day
thanks to the increased moisture. Afternoon action will be mainly
focused northeast of Tucson across Graham/Greenlee counties and
also southeast of Tucson across Santa Cruz county and the southern
half of Cochise county. East-northeast steering flow will
eventually bring storms into eastern Pima county this evening as
storms fire up along outflow boundaries. SPC has most of the area
under marginal risk of severe storms for strong gusty winds.
Localized heavy rain also a threat. Based on above thinking I
will be updating the forecast to increase PoPs northeast of
Safford and also across Santa Cruz and the southern half of
Cochise county this afternoon.

With the increasing moisture, high temperatures will be cooler and
below excessive heat criteria.

Details on the remainder of the forecast can be found in the
previous discussion section below.

&&

.AVIATION...Valid through 21/12Z.
FEW-SCT clouds 10k-15k ft MSL through much of the period. Clouds
occasionally BKN with with ISOLD-SCT TSRA/SHRA this afternoon and
evening. Sfc wind gusts 40 kts with strongest TSRA along with MVFR
CIGS/VSBYS and mountain obscurations. Otherwise, sfc winds light E
to SE this morning becoming SW to NW this afternoon 10-14 kts with a
few higher gusts. Winds become light again late in the evening.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Isolated to scattered afternoon and evening showers
and thunderstorms into early next week. 20-foot winds will generally
remain less than 15 mph outside of any thunderstorm gusts which
could reach upwards of 40 mph. Daytime minimum relative humidity
generally 15-25 pct in the valleys today becoming 25 to 30 percent
Friday through Sunday along with good overnight recoveries

&&

.PREV DISCUSSION...Friday into the weekend storm chances continue with
the best chances Friday along the international border and the White
Mountains. Saturday storm coverage will increase to include most
of southeast Arizona and will likely be the day when the heaviest
rainfall is possible thanks to higher PWAT values and a more moist
surface profile. Saturday night models are hinting at some nighttime
storm activity for areas west of Tucson, so have included this in
the PoP forecast. Sunday expect similar coverage but with lesser
chances in the eastern portion of the CWA as drier air begins to
make its way into the area. Temperatures will be about 2-5 degrees
above normal during this time period with Saturday seeing the
"coolest" temperatures. The NBM gives about a 30 percent chance
that Tucson will see a high less than 100 on Saturday.

Next week drier air moves in but there will still be a little
residual moisture leftover for a slight chance of showers and
thunderstorms mainly in central/western Pima County and the White
Mountains each day. Temperatures will also increase again with a
return to near record levels.

&&

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

&&

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Special Weather Statement
National Weather Service Tucson AZ
116 PM MST Thu Aug 20 2020

AZZ509-510-202045-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-White
Mountains of Graham and Greenlee Counties including Hannagan Meadow-
116 PM MST Thu Aug 20 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN GREENLEE COUNTY
UNTIL 145 PM MST...

At 115 PM MST, Doppler radar was tracking a strong thunderstorm 10
miles south of Blue, or 24 miles north of Mule Creek, moving
southwest at 10 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

This storm will remain over mainly remote areas of northeastern
Greenlee County.

LAT...LON 3333 10936 3358 10916 3354 10904 3331 10905
      3330 10904 3329 10904 3323 10905
TIME...MOT...LOC 2015Z 035DEG 10KT 3345 10911

RH

Special Weather Statement
National Weather Service Tucson AZ
217 PM MST Thu Aug 20 2020

AZZ503-513-202145-
Dragoon/Mule/Huachuca and Santa Rita Mountains including
Bisbee/Canelo Hills/Madera Canyon-Upper Santa Cruz River and Altar
Valleys including Nogales-
217 PM MST Thu Aug 20 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN SANTA CRUZ COUNTY
UNTIL 245 PM MST...

At 217 PM MST, Doppler radar was tracking a strong thunderstorm 9
miles east of Nogales International Airport, or 15 miles east of
Nogales, moving west at 10 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

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

LAT...LON 3156 11086 3151 11059 3134 11058 3133 11059
      3134 11087
TIME...MOT...LOC 2117Z 091DEG 8KT 3141 11068

RH

Special Weather Statement
National Weather Service Tucson AZ
220 PM MST Thu Aug 20 2020

AZZ509-510-202215-
Upper Gila River and Aravaipa Valleys including Clifton/Safford-White
Mountains of Graham and Greenlee Counties including Hannagan Meadow-
220 PM MST Thu Aug 20 2020

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL GRAHAM AND CENTRAL
GREENLEE COUNTIES UNTIL 315 PM MST...

At 220 PM MST, Doppler radar was tracking a strong thunderstorm 11
miles northwest of Morenci, or 13 miles northwest of Clifton, moving
south at 25 mph.

Wind gusts up to 50 mph will be possible with this storm.

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

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.

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 3335 10959 3326 10911 3285 10919 3300 10978
TIME...MOT...LOC 2120Z 357DEG 20KT 3320 10940