Severe Thunderstorm Warning 129, NWS Tucson, AZ

018 
WWUS55 KTWC 091657
SVSTWC

Severe Weather Statement
National Weather Service Tucson AZ
957 AM MST Mon Dec 9 2019

AZC019-021-091715-
/O.CON.KTWC.SV.W.0129.000000T0000Z-191209T1715Z/
Pima-Pinal-
957 AM MST Mon Dec 9 2019

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 AM MST
FOR NORTH CENTRAL PIMA AND SOUTH CENTRAL PINAL COUNTIES...

At 956 AM MST, severe thunderstorms were located along a line
extending from near Picacho Peak State Park to 9 miles southwest of
Avra Valley, moving east at 20 mph.

HAZARD...60 mph wind gusts and large hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Marana, Avra Valley, Picacho Peak State Park, Picture Rocks, Red Rock
and Silver Bell.

This includes the following highways...
 Interstate 10 between mile markers 218 and 241.
 Route 79 between mile markers 102 and 108.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3277 11101 3234 11118 3232 11158 3267 11142
TIME...MOT...LOC 1656Z 250DEG 18KT 3265 11131 3236 11144 

HAIL...0.88IN
WIND...60MPH
 
$$

Meyer

437 
WWUS55 KTWC 091713
SVSTWC

Severe Weather Statement
National Weather Service Tucson AZ
1013 AM MST Mon Dec 9 2019

AZC019-021-091721-
/O.EXP.KTWC.SV.W.0129.000000T0000Z-191209T1715Z/
Pima-Pinal-
1013 AM MST Mon Dec 9 2019

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL PIMA AND SOUTH
CENTRAL PINAL COUNTIES WILL EXPIRE AT 1015 AM MST...
            
The storms which prompted the warning have weakened below severe 
limits and are now moving eastward away from I-10. Heavy rain and 
wind gusts to 40 mph are still possible with these thunderstorms.

LAT...LON 3277 11101 3234 11118 3232 11158 3267 11142
TIME...MOT...LOC 1711Z 251DEG 17KT 3267 11126 3238 11139 

$$

Meyer

Area Forecast Discussion
National Weather Service Tucson AZ
330 AM MST Mon Dec 9 2019

.SYNOPSIS...Expect periods of rain, higher elevation snow, and
isolated thunderstorms into this afternoon. Precipitation ending
east of Tucson this evening, then dry conditions Tuesday into next
weekend. Much cooler temperatures today and cold temperatures
tonight before a strong warming trend occurs later this week.

&&

.DISCUSSION...Scattered showers and embedded thunderstorms were
occurring mainly across eastern Pima County, eastern Santa Cruz
County and about the western half of Cochise County at this time.
Otherwise, cloudy skies were noted across southeast Arizona early
this morning. The precipitation is ahead of a closed upper low
centered over southern California. The upper low will move
southeastward and be generally centered near the International
border and just southwest of Nogales AZ late this afternoon.

Expect periods of rain into this afternoon as the upper low
approaches the area. For this forecast issuance, the Storm
Prediction Center Convective Outlook was used to delineate where
isolated thunderstorms should prevail into this afternoon. The area
essentially excludes portions of western Pima County and south
central Pinal County from thunderstorm potential. Any thunderstorms
late this afternoon and early this evening should then occur
basically east of a Clifton to Sierra Vista line. Otherwise,
isolated to scattered showers from Tucson eastward this evening,
then any measurable precipitation should be east of this forecast by
midnight tonight.

For this forecast issuance, WPC guidance was heavily used for liquid
amounts into this evening. Based on these amounts, which match
various high resolution models such as the HRRR and the Univ of AZ
WRF-NAM and WRF-GFS quite, the heaviest liquid amounts should favor
a band from near Kitt Peak northeastward across the Tucson metro
area, and further northeast into southern Graham County. As such,
the heaviest liquid amounts favor the Catalina/Rincon Mountains near
Tucson, and the Pinaleno Mountains including Mount Graham. Based on
camera reports and RAWS temperatures, snow levels as of this writing
generally range from about 8000-8500 feet. Snow levels will
gradually fall during the next several hours, and are forecast to be
around 7000-7500 feet this afternoon.

Given this analysis, have opted to issue a Winter Weather Advisory
until 5 pm MST this afternoon above 7000 feet for the Galiuro and
Pinaleno Mountains (including Mount Graham), and the Catalina and
Rincon Mountains near Tucson. Expect snow accumulations mostly
ranging from 6-11 inches, although higher amounts may ultimately
occur at the highest peaks.

The mid/upper trough axis is progged by early Tuesday morning to
extend from the Texas Panhandle southwestward into central Chihuahua
Mexico. With the expectation of only very gradually clearing skies,
fog formation should be somewhat limited. Dry conditions will then
prevail Tuesday into next weekend as high pressure aloft builds west
of the southern California/northern Baja California region. Although
the models depict a shortwave trough will move eastward across the
Four Corners region Wednesday night, any measurable precip
associated with this system will occur well north of this area. The
09/00Z models generally agree that the aforementioned upper high
will be shunted southward this weekend as another low amplitude
trough moves across the Four Corners region. Any measurable precip
with this system will also remain north of this forecast area.

Much cooler temperatures will occur today given the expected clouds
and precipitation. A hard freeze should occur tonight in colder
eastern and southern valleys. A brief freeze is possible in outlying
areas around the Tucson metro area and foothills locations as well.
A warming trend will occur Tuesday into Wednesday followed by minor
cooling on Thursday. Warmer daytime temperatures will resume Friday
into Saturday followed by a few degrees of cooling next Sunday.

&&

.AVIATION...Valid through 10/12Z.
BKN-OVC clouds 6k-10k ft MSL through this evening then clouds will
slowly start to thin out. Expect periods of light to moderate rain
into this afternoon before moving east of the area this evening.
Some -TSRA will be possible into the afternoon at all terminals. In
rain MVFR ceilings and visbys will be likely. Winds will be variable
less than 8 kts through the morning becoming southwesterly to
northwesterly at 7-12 kts this afternoon and evening. Near showers
or thunderstorms winds could gust to 30 kts. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Minimal fire weather concerns. A weather system is
expected to impact the area this morning through tonight with a
chance of valley rain and mountain snow, with the heaviest amounts
across the higher elevations. Dry conditions return Tuesday and
continue into the weekend. 20-ft winds will generally remain less
than 15 mph through the forecast period.

&&

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

&&

DISCUSSION...Francis
AVIATION...Hardin
FIRE WEATHER...Hardin

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Special Weather Statement
National Weather Service Tucson AZ
814 AM MST Mon Dec 9 2019

AZZ502-503-515-091600-
Tohono O'odham Nation including Sells-Upper Santa Cruz River and
Altar Valleys including Nogales-Baboquivari Mountains including Kitt
Peak-
814 AM MST Mon Dec 9 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL PIMA COUNTY UNTIL
900 AM MST...

At 812 AM MST, Doppler radar was tracking a strong thunderstorm 10
miles southwest of Kitt Peak, or 15 miles southeast of Sells, moving
northeast at 20 mph.

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

Locations impacted include...
Topawa, San Miguel, Kitt Peak, Ali Chukson, Vamori, Choulic,
Coldfields, Fresnal Canyon, Pan Tak, South Komelik, Itak and Ali
Molina.

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.

&&

LAT...LON 3158 11183 3166 11209 3209 11159 3178 11129
TIME...MOT...LOC 1512Z 238DEG 18KT 3181 11165

Special Weather Statement
National Weather Service Tucson AZ
916 AM MST Mon Dec 9 2019

AZZ502-504-505-091700-
Tohono O'odham Nation including Sells-Tucson Metro Area including
Tucson/Green Valley/Marana/Vail-South Central Pinal County including
Eloy/Picacho Peak State Park-
916 AM MST Mon Dec 9 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL PIMA AND SOUTH
CENTRAL PINAL COUNTIES UNTIL 1000 AM MST...

At 914 AM MST, Doppler radar was tracking strong thunderstorms along
a line extending from near Picacho Peak State Park to 13 miles
northwest of San Isidro. Movement was northeast at 20 to 25 mph.

Half inch hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Marana, Avra Valley, Picacho, Picacho Peak State Park, Red Rock,
Queens Well and Silver Bell.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with these storms, and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3283 11103 3218 11145 3213 11185 3271 11150
TIME...MOT...LOC 1614Z 245DEG 18KT 3268 11139 3218 11181

Meyer