Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 142137

Area Forecast Discussion
National Weather Service Tucson AZ
237 PM MST Sat Jan 14 2017

.SYNOPSIS...A low pressure system will bring good chance of
showers and thunderstorms this afternoon and evening, with periods
of valley rain and mountain snow this weekend into early Monday.
Cooler temperatures. A few showers near the mountains early next
week, then another storm system will impact the area later next


.DISCUSSION...Showers and thunderstorms continue to develop across
SE AZ, with our low spinning near the norther Gulf of CA at 2PM
MST. Northeast quadrant of the low is increasingly active and will
continue to generate showers with embedded thunderstorms as it
tracks across northern Sonora and Southeast Arizona over the next
18 to 24 hours. This means we`re still looking at most favorable
period for precip to last through Sunday morning. Snow levels are
still currently above 8000 feet, but will fall through the
evening and overnight hours to around 5500-6500 feet by sunrise
Sunday (lowest levels will be further south, closer to the track
of the low). A Winter Weather Advisory above 6500 feet is in
effect until 11 AM Sunday, with 5 to 10 inches of snow above 7000
feet and 1 to 4 inches between 6000 and 7000 feet.

Wrap around from this low as it exits into southern New Mexico
will keep a chance of showers going Sunday, then a weaker impulse
carves into the back side of the trough and continues a few
showers Sunday night into Monday night or Tuesday morning.

Much cooler over the next few days, with daytime temperatures
around 10 degrees below average through Monday or Tuesday. With
the moisture and cloud cover, overnight lows will be above average
this weekend, then near average for mid January behind the partial
clearing early in the new week.

A stronger and colder system is expected to impact the entire
region the second half of next week.

The pattern amplifies the second half of the week with a stronger
lower latitude split. An impulse dropping through the region
Thursday night will set the table for a stronger and colder storm
system Friday night into Saturday. Snow levels possibly falling to
valley floors east and south of Tucson Saturday morning.


.AVIATION...Valid through 16/00Z.
Increasing clouds and showers with widespread coverage after
15/02Z. Isolated TSRA embedded in showers at times. This will
result in MVFR conditions at times, and potentially brief IFR
conditions. Higher terrain will be obscured with SHSN. Gusty
southerly winds this afternoon and early evening, then generally
less than 12 kts. Aviation discussion not updated for TAF


.FIRE WEATHER...A low pressure system will bring increasing shower
chances today with a few thunderstorms, then a good chance of
valley rain and mountain snow through Sunday. Some showers will
linger into Monday. Dry conditions are then expected Tuesday and
Wednesday before another storm system brings more precipitation
the second half of next week. Outside of some elevated southerly
20-foot winds at 10-20 mph today, 20-foot winds will be terrain
driven and generally less than 15 mph through Wednesday of next


Winter Weather Advisory until 11 AM MST Sunday for AZZ510>514.




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