Wildfire in Arizona, May 12 to 24, 2018

Area Forecast Discussion
National Weather Service Tucson AZ
930 AM MST Sat May 12 2018

.SYNOPSIS...Expect breezy to windy conditions with near normal
daytime temperatures this weekend. A gradual daily warming trend
will then occur Monday through Thursday with above normal
temperatures continuing next Friday. Generally lighter winds Monday
through Wednesday before stronger winds return late next week.

&&

.DISCUSSION...Clear skies prevail across southeast Arizona at this
time. Surface winds at lower elevations valid 9 am MST were from the
south to southwest at 10-20 mph with gusts near 30 mph. Surface temps
at lower elevations valid 9 am MST ranged from the mid 70s-lower
80s, and these temps were about 2-6 degrees lower versus 24 hours
ago. A very dry regime was also depicted via the 12/12Z KTWC, with a
total precip water value of 0.37 inch.

12/12Z upper air plots depicted an Omega pattern over the eastern
Pacific and western CONUS. A 553 dm low was centered over northeast
Nevada; a north-to-south ridge axis was further west and near 135W;
and a trough axis was even further west near 155W. Moderate to
strong southwesterly to westerly flow above 850 mb prevailed across
southeast Arizona.

Sunny skies will occur across this forecast area today. A tight mid-
level pressure gradient around the southeast periphery of the upper
low centered over northeast Nevada and across the area will result
in gusty south to west winds into this evening. A Wind Advisory is
in effect from 11 am to 8 pm MST this evening for much of southeast
Arizona (excluding western Pima County). Patchy blowing dust may
occur due to the gusty winds. High temperatures this afternoon will
be about 5-10 degrees cooler versus 24 hours ago, but these expected
high temps will still be quite close to normal for May 12. Winds
will diminish most locales later this evening with the loss of
daytime heating.

There are no updates planned at this time. Please refer to the
additional sections for further detail.

&&

.AVIATION...Valid through 13/18Z.
Clear skies thru tonight then a few clouds at 10k-15k ft AGL and a
few clouds above 20k ft AGL Sunday morning. Surface wind this
afternoon and evening sly to wly 15-30 kts with gusts near 40 kts.
Surface wind late tonight and early Sunday morning sely/sly 5-10
kts. Surface wind toward end of valid period sly/swly 10-20 kts with
gusts near 25 kts. Aviation Discussion not updated for amended TAFs.

&&

.FIRE WEATHER...A Red Flag Warning is in effect for much of
southeast Arizona (western Pima County excluded) from 11 am this
morning to 8 pm MST this evening. The combination of strong and
gusty mainly southwest winds, low relative humidity and a high fire
danger will create critical fire conditions.

Expect gusty mainly southwest winds again Sunday afternoon. Although
critical fire conditions are not expected to widespread nor long-
lived, the potential exists for at least a few locales to briefly
achieve Red Flag criteria Sunday afternoon. Somewhat less wind
should then prevail into the middle of the upcoming week before
stronger winds to return next Thursday and Friday.

Otherwise, daytime temperatures will be near seasonal normals this
weekend then warming to about 5-10 degrees above normal during the
latter part of the upcoming week.

&&

.PREV DISCUSSION /330 AM MST/...Rather warm May morning thanks to
gusty winds across the area. Temperatures at 3 am were mostly in the
60s and 70s. These gusty winds will continue throughout the weekend.
Although wind speeds will not be as strong as Friday still strong
enough for a wind advisory to be issued across much of the area.
Fire weather concerns are addressed in the fire weather section
below.

The gusty winds are associated with a quasi-stationary upper level
low over northern Nevada. This feature will gradually weaken this
weekend into early next week with daytime highs will be right normal.

Upper level ridging builds over the area middle part of next week
resulting in daytime highs warming back up and less wind.

Gusty winds return end of next week as another upper level trof
moves into the desert southwest.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Red Flag Warning from 11 AM this morning to 8 PM MST this
  evening for AZZ150>153.

 Wind Advisory from 11 AM this morning to 8 PM MST this evening
  for AZZ502>515.

&&

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