Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 270416

Area Forecast Discussion
National Weather Service Tucson AZ
915 PM MST Sun Mar 26 2017

.SYNOPSIS...Expect dry conditions with mild temperatures again
Monday. A low pressure system will then bring a chance of showers
Monday night into Wednesday mainly northeast of Tucson. Cooler
temperatures will also occur Tuesday followed by a warming trend
Wednesday into Thursday. The next system will bring another chance
of showers and cooler temperatures Friday into next weekend.


.DISCUSSION...IR satellite imagery and surface observations depict
mostly clear skies with some thin cirriform clouds across southeast
Arizona at this time. Meanwhile, a band of somewhat thicker mid and
high-level clouds were further upstream, and extended from southern
California northeastward into northern Arizona. These clouds were
ahead of a shortwave trough that was approaching the California

Expect clear skies or mostly clear skies the rest of tonight, then
some mid-level and mainly high-level clouds are forecast to increase
across the area Monday as the shortwave trough digs southeastward
into southern California and eventually into Arizona. High
temperatures Monday will be a few degrees warmer versus this
afternoon. However, some gusty southwest to west afternoon winds
will occur, with winds turning more northwesterly Monday evening.

Quick glance at the 27/00Z GFS then depicts a 552 dm closed low to
be centered over the Four Corners region early Tuesday. This upper
low is then progged to move slowly eastward into northern New Mexico
Tuesday afternoon. There appears to be enough moisture with this
system to merit a chance of snow showers across the White Mountains
late Monday night, and at least a slight chance of showers as far
west as Tucson on Tuesday as per the official forecast.

However, the 27/00Z NAM and the GFS suggests that measurable precip
will be confined mainly northeast of Safford. Will defer to
subsequent shifts to refine our precip forecast accordingly.

There are no updates to the first forecast period, or for the rest
of tonight. Please refer to the additional sections for further


.AVIATION...Valid through 28/00Z.
Expect a FEW clouds above 20k ft AGL the rest of tonight, then a FEW-
SCT clouds around 10k-15k ft AGL and SCT-BKN clouds above 20k ft AGL
Monday into Monday evening. Isolated -SHRA/-SHSN may occur across
the White Mountains NE of KSAD Monday evening. Surface wind mostly
less than 12 kts into Monday morning, then surface wind swly to nwly
12-20 kts with gusts near 25 kts Monday afternoon and Monday
evening. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Expect low humidities, mild daytime temperatures
and breezy conditions Monday, especially in Cochise county where
near critical fire weather conditions will be possible Monday
afternoon. A low pressure system will then bring cooler temperatures
and a chance of showers late Monday and Tuesday, especially to areas
northeast of Tucson. Farther south in southern fire weather zones
151 and 152, windy conditions and low humidities will result in
brief and localized critical fire weather conditions Tuesday.  It
will be dry and warmer Thursday before the next system results in
another chance of showers and cooler temperatures Friday into next


.PREV DISCUSSION /237 PM MST/...A storm system will begin to
approach the region on Monday, with the flow turning southwest ahead
of this system. This will lead to a few degrees of warming on Monday
along with breezy conditions, especially east of Tucson. The models
have been trending to a more northeast solution/track with this
system through the Four Corners region, which will result in highest
precipitation chances northeast/east of Tucson over Graham and
Greenlee counties Monday night through Tuesday night. However, there
will still be a slight chance of showers as far west as Tucson
during the day Tuesday. The highest elevations in the White
Mountains, such as Hannagan Meadow, could pick up 1-2 inches of
snowfall. This system will result in cooler temperatures area-wide
on Tuesday, with below normal temperatures.

Short wave ridging will transition across the area Wednesday and
Thursday, with near normal daytime temperatures on Wednesday and
temperatures warming to 5-8 degrees above normal Thursday.

Another storm system is then expected to move into the region
Friday, lingering into early Sunday. This system is progged to be
stronger than the one moving through the region early this week.
Again, the models have been trending to a more northeast track with
the system. However, with decent height falls, stronger dynamics and
a little more moisture to work with, there will be a chance of
showers over portions of Graham and Greenlee counties, with a slight
chance south and west of this area. There will be a fairly sharp
gradient as far as precipitation goes with this system, so if it
continues to trend further east with the track, precipitation
chances across southeast Arizona will be greatly diminished. Breezy
conditions are expected on Thursday as the system approaches the
region, with breezy to windy conditions Friday. Also expect cooler
temperatures Saturday and Sunday.





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