Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 202127

Area Forecast Discussion
National Weather Service Tucson AZ
227 PM MST Sun May 20 2018

.SYNOPSIS...A storm system will bring breezy conditions Monday with
a slight chance of thunderstorms over the White Mountains, then
breezy and slightly cooler temperatures on Tuesday. Wednesday through
the weekend temperatures will steadily grow warmer each day with
100+ highs expected across lower elevations Friday onward.


.DISCUSSION...The next storm system to affect our weather is
currently developing over northern California and it will continue to
deepen as it slowly settles to the southeast over southern California
by Monday evening. This will tighten the pressure gradient over the
region resulting in gusty winds Monday afternoon, especially over
higher elevations. It will also draw low to mid level moisture west
across New Mexico late tonight into early Monday bringing the
potential for isolated thunderstorms very close to our eastern
border. At this time is looks as though some low level moisture will
make it into the Gila Valley as far as Safford Monday morning then
quickly mix out with daytime heating. This scenario will kill the
chance for storms in our area with the possible exception of the
White Mountains where enough moisture may linger for a storm or two.
Anything that develops will quickly move to the northeast.

By late Tuesday the storm will weaken a bit and move northeast into
Nevada. Basically, another breezy day similar to Monday just without
the threat of moisture and high temperatures peaking 3-5 degrees
lower than today or Monday.

Wednesday into Thursday the storm quickly weakens and moves north
resulting in diminishing winds and near to or slightly warmer than
average temperatures.

Beyond that, the heat is on. Heights and thicknesses quickly rise as
a ridge builds north across the Southwest and Rocky Mountain states
Friday into the weekend. Temperatures will respond by rising
noticeably to 8-12 degrees warmer than average by Saturday, which
this time of year means highs 100+ degrees anywhere near or below
4000 ft in elevation. While not quite approaching record levels, it
will be a very hot holiday weekend with some locations possibly
seeing their hottest temperatures of the year thus far next weekend.


.AVIATION...Valid through 22/00Z
SKC tonight, with SCT-BKN high clouds at 20-25k ft AGL moving in
Monday morning and persisting into the afternoon. Surface wind
SLY/SWLY at 8-12 kts into the early evening, becoming light
overnight. Surface wind increasing during the mid-morning hours to
SLY 15-20 kts with gusts to 30 kts Monday afternoon. Aviation
discussion not updated for amended TAFs.


.FIRE WEATHER...A weather system passing north of the area will
bring breezy to locally windy conditions both Monday and Tuesday.
This in combination with low humidities will create critical fire
weather conditions in the White Mountains Monday, with isolated
areas of brief critical fire weather conditions across the rest of
Southeast Arizona. Therefore...A Red Flag Warning is in effect from
Noon MST Monday until 7 PM MST Monday evening for the northern
portions of Fire Weather Zone 153 including Northern Graham and
Northern Greenlee counties.

The system will also bring a slight chance of a dry thunderstorm
to the White Mountains Monday afternoon. Temperatures will remain
slightly above normal with little day to day variation in highs
through the middle of the week before a warming trend occurs the
second half of the week into next weekend.

There is a possibility some mid-level moisture will try to creep
into the area from the south and east late next weekend. This would
result in a possibility (albeit low confidence) of a dry storm
developing over the higher terrain along the Arizona/New Mexico
border next weekend.


Red Flag Warning from noon to 7 PM MST Monday for AZZ153.



FIRE WEATHER...Rasmussen

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