Dust Storm in Arizona, May 17, 2016

Area Forecast Discussion
National Weather Service Tucson AZ
855 AM MST TUE MAY 17 2016

.SYNOPSIS...An upper level low pressure system will settle over
Arizona tonight then move slowly to the east through early Thursday.
This will result in cooler temperatures and a chance of showers and
thunderstorms later today through Wednesday night mainly north and
east of Tucson. Dry and warmer conditions will return for the latter
part of the weak then another upper level system will impact the
region this weekend into early next week.

&&

.DISCUSSION...We issued a Blowing Dust Advisory for the I-10
corridor east of Wilcox as wind and atmospheric stability conditions
will be very similar to yesterday.  The wind may be just a touch
lighter today however enough to potentially pose problems and also
some concern for the potential for strong gusts due to convective
cells that may form.

The various mesoscale models we use are pointing toward some
convection developing this afternoon across parts of Cochise,
Graham, Greenlee and southeast Pinal counties this afternoon. The
morning sounding, satellite imagery and look out the window supports
that we have a bit of moisture to play with so tweaked pops up just
a bit to slightly expand the coverage this afternoon.  While not
expecting much in the way of precipitation there is decent downdraft
potential with any cell that forms.

As the upper low settles overhead tonight the chance for convection
increases over the area tonight and Wednesday...primarily northern
and eastern areas.  Along with the convection will come relatively
cool temperatures with highs Wednesday 5-7 degrees cooler than
average.

The upper low moves off to the east Thursday taking the threat of
showers with it other than possibly over the White mountains.  A low
amplitude short wave ridge will move over the area in its wake
resulting in mostly clear and dry conditions with temperatures
rebounding to near average.

This weekend another deep upper low along the west coast will nudge
southward before slowly shifting east late in the weekend.  This
looks far enough north that the primary impact will be strong gusty
southwest winds and slightly cooler temperatures.  Beyond that the
broad trough looks to linger over the far west which should keep
this a bit more interesting well into next week.  Cerniglia

&&

.AVIATION...VALID THRU 18/12Z.
Scattered to broken cloud coverage 5-8k ft agl increasing to 7-10k
ft agl will continue through the forecast period for locations east
of Tucson including KDUG and KSAD. Meanwhile, from KTUS westward
mostly clear skies this morning will give way to scattered clouds 8-
11k ft agl. Expect scattered -TSRA/-SHRA mainly across the White
mountains NE of KSAD this afternoon. Surface winds becoming swly/wly
at 10-20 kts with gusts of 25-30 kts this afternoon, then tapering
off this evening.  Aviation discussion not updated for TAF
ammendments.

&&

.FIRE WEATHER....Expect scattered showers and thunderstorms mainly
across the White mountains and east of Benson this afternoon.  The
coverage of showers and thunderstorms will gradually increase across
much of southeast Arizona tonight and Wednesday.  The best chance of
wetting rains will be north and east of Tucson in the higher
elevations and especially in the White mountains.  Precipitation
chances will decrease Wednesday night, and enough moisture should
remain Thursday for a chance of showers and thunderstorms mainly
across the White mountains.  Dry conditions will then prevail area-
wide Friday into early next week.

Occasionally gusty afternoon winds will occur through Thursday due
to daytime heating.  This afternoon and Wednesday strong
outflow winds are possible near any convection that develops
due to the dry low level air mass in place.  Breezy to locally windy
conditions will return Friday and this weekend as a low pressure
system deepens northwest of the area.  Wind speeds may approach
critical levels for portions of the area as early as Friday, then
continuing through the weekend.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
    Blowing Dust Advisory 11 am through 7 pm for AZZ508, focused on
    I-10 east of Wilcox.

&&

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