Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 192019
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
118 PM MST THU MAY 19 2016

.SYNOPSIS...Dry conditions and increasing temperatures are forecast
through the end of the week as weak high pressure builds across the
area. Low pressure will return this weekend resulting in breezy
conditions along with slightly cooler temperatures. Below normal
temperatures will persist through at least the middle of next.

&&

.DISCUSSION...
Dry air remains clearly evident on water vapor imagery this
afternoon as low pressure continues to slowly move into the central
plains. Across Arizona, some cu have developed in the mountains east
of Tucson although radar returns remain non-existent as of 19z. This
isn`t much of a surprise given surface dewpoints in the mid 30s and
temps in the low to mid 80s.

Forecast for the rest of tonight into tomorrow calls for quiet
weather and near normal temperatures as weak shortwave ridging moves
across the region. Looking ahead toward the weekend however, a dry
upper level trough is forecast to deepen across Nevada with a
tightening surface pressure gradient across Arizona Saturday and
especially Sunday. As is typical this time of year, this will result
in breezy/windy conditions (dust remains a possibility in the
normally dust-prone areas) along with the potential for elevated
fire weather concerns. Any precipitation associated with this low
pressure system will be displaced well north of the forecast area
and PoPs remain at or below climo.

The upper low will remain quasi stationary over Nevada through early
next week resulting in a prolonged period of southwesterly flow
aloft and slightly lower than normal heights. Afternoon breezes will
be common along with below normal temps although highs will still
top out near 90 each afternoon across the deserts. The low will
finally migrate eastward late next week although pwats will be well
under normal and thus precip chances should be slim. Main impacts
would likely be in the form of another round of late-spring winds.

&&

.AVIATION...VALID THRU 21/00Z.
Skies clearing aft 20/01z then a few-sct clouds 8-10k ft aft 20/19z
northern mountains.  Wind becoming variable less than 10 kts aft
20/02z then becoming SW 10-15 kts xcp to 20 kts west of KTUS Friday
afternoon.  Aviation discussion not updated for TAF ammendments.

&&

.FIRE WEATHER...
Breezy to locally windy conditions will develop Friday and continue
through this weekend into early next week as a low pressure system
deepens northwest of the area. Wind speeds will approach critical
levels for portions of the area generally from Tucson westward
Friday and Saturday, then shifting into eastern areas on Sunday.
Breezy winds to continue Monday and Tuesday but remaining below
critical thresholds. Minimum relative humidity values will generally
be in the 10 to 15 percent range for valley locations Friday through
Sunday and 20 to 25 percent across the mountains. Even lower minimum
relative humidity values early next week.

For Friday and Saturday some areas west of Sells in zone 150 will
approach and potentially exceed critical thresholds for an hour or
two but due to the marginal nature of the event both days and
marginal fuels in that region will hold off on any fire weather
headlines.

Then the focus will shift east Sunday onward to the southern
portions of zones 151 and 152 but again will hold off on any watches
at this time.  Cerniglia

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

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