Freeze Warning 4, NWS Tucson, AZ

307 
WWUS75 KTWC 312052
NPWTWC

URGENT - WEATHER MESSAGE
National Weather Service Tucson AZ
152 PM MST Wed Oct 31 2018

AZZ508-509-011500-
/O.CON.KTWC.FZ.W.0004.181101T0900Z-181101T1500Z/
Eastern Cochise County below 5000 feet-Upper Gila River Valley-
Including the city of Willcox
152 PM MST Wed Oct 31 2018

...FREEZE WARNING REMAINS IN EFFECT FROM 2 AM TO 8 AM MST
THURSDAY...

* IMPACTS...These temperatures will damage sensitive crops and 
  vegetation that remain alive at this point in the season. 

* TEMPERATURES...Morning lows in the upper 20s to lower 30s.

* TIMING...Approaching freezing by 2 AM MST in some locations, 
  with coldest temperatures between 5 AM and 7 AM. 

* For a detailed view of the hazard area...visit 
  weather.gov/Tucson and click on the Detailed Hazards Icon 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Freeze Warning means sub-freezing temperatures are expected.
These temperatures will kill sensitive crops and vegetation.
Cover them...if possible...with cloth sheets or blankets to
protect them from freezing.

&&

$$

Cerniglia
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751 
WWUS75 KTWC 011502
NPWTWC

URGENT - WEATHER MESSAGE
National Weather Service Tucson AZ
802 AM MST Thu Nov 1 2018

AZZ508-509-011615-
/O.EXP.KTWC.FZ.W.0004.000000T0000Z-181101T1500Z/
Eastern Cochise County below 5000 feet-Upper Gila River Valley-
Including the city of Willcox
802 AM MST Thu Nov 1 2018

...FREEZE WARNING HAS EXPIRED...

Temperatures have warmed into the mid to upper 30s in the Sulphur
Springs Valley and will continue to warm through the morning
hours. Therefore, the Freeze Warning has been allowed to expire. 

$$

Zell

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Area Forecast Discussion
National Weather Service Tucson AZ
940 PM MST Tue Oct 30 2018

.SYNOPSIS...Scattered showers and isolated thunderstorms east of
Tucson this evening becoming isolated rain and snow showers mainly
near the White Mountains late tonight into Wednesday morning. Dry
conditions will then persist into early next week. Expect gusty
winds Wednesday afternoon east of Tucson. Cooler temperatures will
also occur, with freezing temperatures in colder eastern valleys
Wednesday night. A gradual warmup will prevail later this week.

&&

.DISCUSSION...A band of showers and thunderstorms was occurring at
this time from near Clifton westward to near Safford, then further
west into far eastern Pinal County. Other isolated showers were
moving northeastward across north central and northeast Cochise
County. Most rain gauge amounts have been under one tenth of an
inch.

The ongoing showers with isolated thunderstorms have been generally
further south to southwest versus several numerical weather model
solutions, including high resolution models. Otherwise, IR satellite
imagery and surface observations depicted mostly clear skies west of
Tucson with partly cloudy skies elsewhere.

At any rate, based primarily on satellite imagery and surface
observations, and to a lesser extent on HRRR solutions, the official
forecast was modified earlier this evening to depict isolated to
scattered showers and isolated thunderstorms through 09Z Wednesday
(2 AM MST Wednesday) generally east of a Mount Graham to Douglas
line.

Isolated to scattered rain/snow showers are then forecast to occur
late tonight into Wednesday morning mainly across the White
Mountains. These showers will prevail ahead of a mid/upper trough
axis currently from eastern Utah southwestward into northern
Arizona. This mid/upper trough axis is progged via the 31/00Z GFS to
move eastward into western New Mexico around midday Wednesday. As
such, precip-free conditions will return area-wide Wednesday
afternoon. Gusty northwest winds will also occur Wednesday
afternoon, especially favoring the northwest wind-prone Upper Gila
River Valley that includes Safford. Decreasing clouds eastern
sections Wednesday followed by clear skies area-wide Wednesday night
with light winds.

The combination of light winds and a very dry regime should produce
somewhat widespread freezing temperatures at least for a few hours
in the colder eastern valleys. Would not be surprised to see a
Freeze Warning issued with subsequent forecast, especially favoring
the Sulphur Springs as noted in the Previous Discussion section. Dry
conditions to prevail Thursday into early next week.

Please refer to the additional sections for further information.

&&

.AVIATION...Valid through 01/06Z.
Isolated to scattered -SHRA and isolated -TSRA mainly KSAD-KDUG
eastward until 09Z Wednesday, then isolated -SHRA/-SHSN mainly White
Mountains northeast of KSAD late tonight into Wednesday. Precip
ending by Wednesday afternoon. Otherwise, clear skies to few clouds
above 20k ft AGL KTUS vicinity westward. East of KTUS scattered to
broken clouds generally 6k-10k ft AGL becoming clear skies by
Wednesday evening. Surface wind Wednesday afternoon 8-18 kts with
gusts 25-30 kts. Strongest speeds east of KTUS favoring KSAD/KDUG.
Surface wind variable in direction mainly less than 12 kts other
times. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Isolated to scattered showers mostly across the
White Mountains late tonight into Wednesday morning. Dry conditions
will then prevail Wednesday afternoon into early next week. Gusty
northwest winds to occur Wednesday afternoon east of Tucson. 20-foot
wind gusts should approach 25-30 mph at times. Thereafter, 20-foot
winds will be mainly terrain driven under 15 mph.

&&

.PREV DISCUSSION /308 PM MST/...By mid-day Wednesday the system over
New Mexico continues to shift southeast into the southern plains,
while a highly amplified ridge of high pressure over the eastern
Pacific Ocean begins to edge eastward into the western United
States. This will turn the upper level flow to the northwest across
the area, ushering in cooler air across the region. With this cooler
air, daytime temperatures on Wednesday will be 5-8 degrees below
normal. Freezing or near freezing conditions are expected in some
isolated locations east of Tucson Wednesday night/Thursday morning,
primarily in the Sulphur Springs Valley from near Willcox southward
to north of Douglas. While wind speeds will lower considerably
across most of the forecast area on Wednesday, gusty winds will
persist in the upper Gila River Valley which will be oriented with
the northwest flow pattern.

The ridge of high pressure over the eastern Pacific Ocean continues
to slowly move eastward late in the week and over the upcoming
weekend. However, the ridge stays centered off the central/northern
California coast through the period. This puts Arizona on the front
side of the ridge, with periods of high clouds and daytime high
temperatures warming back up above normal levels.

&&

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

&&

Francis
PREVIOUS DISCUSSION...Zell

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