Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 201533

Area Forecast Discussion
National Weather Service Tucson AZ
833 AM MST Mon Mar 20 2017

.SYNOPSIS...Dry conditions with unseasonably warm daytime
temperatures will continue into the middle of the week. A storm
system will then bring a chance of showers Wednesday night
followed by cooler temperatures with lingering showers Thursday.
Expect dry conditions with a warming trend next Friday and

.DISCUSSION...Strong high pressure aloft continued across
southeast Arizona although it was starting to weaken slightly as a
large upper trof continued to take shape off the California coast.
According to morning plot data, 500mb heights were down around 30m
as the upper ridge axis had shifted east into New Mexico. 24hr
change charts at 8 am showed temps still running around 5 degrees
ahead of yesterday`s pace but as the day wears on, good mixing
should allow somewhat cooler air to mix down to the surface. All
that being said, the daily highs will stay very elevated and in
the low to mid 90s over the warmer deserts, especially portions of
Pima county. IR imagery showed some relatively thin high clouds
spreading through the southwest flow aloft and some of this
cloudiness will spread across southeast Arizona but overall skies
should be mostly sunny today. Expect some local afternoon
breeziness favoring the southwest to west. Forecasts look to be in
good shape and no updates are needed at this time.

.PREVIOUS DISCUSSION...A few mid-level cloud exists across
southeast Arizona this morning as a shallow outflow boundary
pushes WNW across the area. Highs today will be similar to what
occurred on Sunday. Cooler temperatures next Tuesday and Wednesday
as upper high pushes east while Pacific storm pushes into the
west coast. Locally gusty southwest winds Tuesday becoming more
widespread on Wednesday afternoon with strongest winds south and
east of Tucson. A few local may approach advisory criteria for a
few hours on Wednesday.

The Pacific storm will bring a chance of showers, possibly a few
thunderstorms to the area Wednesday night into Thursday morning.
Snow levels dropping down to around 7000 feet north to 8500 feet
south by Thursday morning with amounts generally less than 2" above
7500 feet. QPF values generally less than 0.25" which highest values
possible across Pinal and Graham counties. Turning much cooler on
Thursday with highs running 18-22 degrees cooler than today.

Dry and warmer Friday and Saturday as upper ridge builds across the
state. Another system possible on Sunday.

.AVIATION...Valid through 21/12Z.
Expect FEW-SCT clouds mainly above 15k ft AGL continuing into Monday
afternoon. Surface wind variable in direction less than 12 kts into
this morning, then surface wind swly/wly 8-15 kts with gusts to 20
kts Monday afternoon. Aviation discussion not updated for TAF

.FIRE WEATHER...Expect dry conditions into Wednesday. A Pacific
storm system will then bring a chance of showers to most sections
Wednesday night followed by a chance of showers mainly northeast of
Tucson Thursday. A few snow showers may occur across the White
Mountains northeast of Safford Thursday night. Dry conditions will
prevail Friday into next Sunday. 20-foot winds Monday and Tuesday
afternoons will be from the southwest to west at 5-15 mph with gusts
to 20 mph. 20-foot winds Wednesday afternoon and Wednesday night
will also be mainly from the southwest, but increase to 10-20 mph
with gusts to near 30 mph as the storm system moves into the area.
There will be some gusty west to northwest winds Thursday, then less
wind Friday into Saturday. Some breezy west winds are forecast to
return next Sunday.






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