Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 242102
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
202 PM MST Wed May 24 2017

.SYNOPSIS...High pressure aloft currently over Arizona and
responsible for the May heat will slide to our south and east
tonight. Thursday and Friday will see us between low pressure
developing north of the area and high pressure shifting southward.
As a result, expect gusty winds and several degrees of cooling.
Strengthening high pressure this weekend will again push
temperatures above average into early next week. A bit of moisture
may result in a few showers and thunderstorms near the New Mexico
border early next week.

&&

.DISCUSSION...The peak of the May heat is this afternoon across the
region with temperatures topping out in the lower 100`s for the
deserts and in the mid to upper 90`s for the valleys south and east
of Tucson. As the ridge responsible for this heat flattens and
pushes off to the east-southeast, it will be replaced by west to
southwest flow aloft Thursday and Friday. Given that there will be
troughiness across the Great Basin, the gradient will tighten across
our area resulting in breezy to windy conditions both Thursday and
Friday afternoon. Winds will likely stay below advisory thresholds
but it will be close for eastern areas. Otherwise, expect areas of
blowing dust mainly near the Willcox Playa with temperatures
dropping back down to seasonal normals by Friday. Red Flag Warnings
are also in effect for much of Southeast Arizona Thursday and
Friday. See fire weather discussion below for more information.

Fairly quiet weather this weekend as broad ridging aloft moves back
in. Temperatures will remain a couple of degrees below normal on
Saturday with a few degrees of warming to seasonable levels on
Sunday. With a much weaker gradient, just expect a few afternoon
breezes.

Heading into Memorial Day and beyond, we`re going to be getting into
a bit more of an interesting weather pattern. The ridge across the
west will be quite dirty with lower to mid level flow becoming more
easterly to southeasterly advecting some moisture into the region,
especially east of Tucson. This pattern has the potential for some
thunderstorms with some dry lightning concerns as well. The 12Z
ECMWF/GFS and GEFS ensemble are now in better agreement keeping the
bulk of the increased moisture across Greenlee, Eastern Graham and
Eastern Cochise Counties. Current forecast trends are handling this
well with mentionable PoPs near the New Mexico border Monday through
Wednesday.

&&

.AVIATION...Valid thru 25/23Z.
SKC conditions thru 25/01Z, then FEW clouds around 15k ft AGL and
FEW-SCT clouds AOA 20k ft AGL. WLY SFC wind at 12-17 kts thru 25/03Z
then SFC wind generally less than 10 kts til 25/13Z. Increasing SFC
wind aft 25/13Z, with SWLY SFC wind at 17-24 kts and gusts to 30-35
kts by 25/18Z. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...A Red Flag Warning is in effect from 11 am to 8 pm
MST Thursday for much of southeast Arizona except Fire Weather Zone
150. A Red Flag Warning is also in effect from 10 am to 8 pm MST
Friday for portions of Fire Weather Zones 151 and 152, mainly south-
to-southeast of Tucson. The combination of strong and gusty winds,
low relative humidity values and a very high fire danger will create
critical fire weather conditions.

Less wind will then occur Saturday into early next week. An increase
in mid level moisture may produce a few showers and thunderstorms in
areas east of Tucson early next week. However, significant wetting
rain seems unlikely.

&&


&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 8 PM MST Thursday for AZZ151>153.

Red Flag Warning from 10 AM to 8 PM MST Friday  for AZZ151-152.

&&

$$


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