Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 270429
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
930 PM MST Fri May 26 2017

.SYNOPSIS...A warming trend with less wind can be expected into
Monday. An increase in moisture will result in a slight chance of
showers and thunderstorms, mainly in the higher terrain east of
Tucson, from Memorial Day through next Friday.

&&

.DISCUSSION...Winds continued to diminish late this evening. Allowed
the Red Flag warning for the fire weather community expire on time
this evening with the winds diminishing and humidity values on the
increase. Otherwise, the overall forecast looked on track so no
updates necessary this evening. Please refer to the additional
sections for more details.

&&

.AVIATION...Valid thru 28/00Z.
Generally SKC conditions through the period, with some high clouds
AOA 20k ft AGL. Diminishing SFC wind through 27/10Z. Aft 27/18Z,
swly/wly SFC wind at 8-15 kts, with the strongest wind speeds in the
vicinity of KDUG and KALK. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Less wind will prevail this weekend and next week.
An increase in moisture will result in a slight chance of afternoon
and evening showers and thunderstorms mainly east of Tucson Monday
through next Friday. Expect erratic and gusty outflow winds with
thunderstorms that do develop.

&&

.PREV DISCUSSION...Clear skies and gusty winds continue across
southeast Arizona this afternoon, with the strongest winds (so far)
over Santa Cruz and Cochise counties. Expect elevated winds to
continue into the evening hours tonight before slowly diminishing.
Therefore, a Red Flag Warning remains in the effect through 8 pm MST
this evening for portions of Fire Weather Zones 151 and 152.

A ridge of high pressure will then build across the western United
States late in the weekend into the middle of next week. This will
result in warmer temperatures and less wind. Temperatures will peak
on Monday, with highs in the valley locations of southern Arizona
generally ranging from the mid 90s to the lower 100`s (Tucson will
be right around the century mark). By early to mid next week, the
ridge becomes highly amplified, with the high centered to our north
over the Great Basin. Weaknesses in the flow under this ridge will
allow moisture to push westward into the southern Arizona Monday
through Wednesday of next week. The bulk of this moisture will
remain east of the Tucson Metro area across Cochise, Graham and
Greenlee counties. The latest model runs are not quite as robust
with this moisture (versus 24 hours ago). Therefore, low end slight
chance pops exist for most of the eastern valleys of Cochise and
Graham counties, with a little higher chances in the mountains of
those counties. The highest precipitation chances will be in the
White Mountains/northern half of Graham county where chance to good
chance pops exist Monday through Wednesday of next week.

Forecast confidence is low in the latter periods of the extended
forecast late next week. Not only are the operational GFS and ECMWF
quite different during the Thursday/Friday time frame of next week,
the latest GFS solution differs completely from its prior runs. In
general, the ECMWF has a weak trough to our west with a continued
moisture seep across eastern areas, while the GFS develops a weak
closed low off the southern California coast and shifts this feature
(with a fairly decent Pacific moisture feed) across the state. At
this time, have stuck close to the inherited forecast of slight
chance pops across eastern areas and nearly steady daytime
temperatures.

&&

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

&&

$$

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