Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 251111
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
410 AM MST WED MAY 25 2016

.SYNOPSIS...Breezy to windy conditions will occur this afternoon as
a low pressure system approaches from the west. Expect cooler
temperatures Thursday behind this system, then a warming trend will
prevail Friday into early next week.

&&

.DISCUSSION...IR/water vapor satellite imagery depicted a cyclonic
circulation representing a mid/upper level low centered just
southwest of Point Conception, California at this time. Meanwhile,
clear skies with light east-to-southeast surface winds prevailed
ahead of this system across southeast Arizona. The upper low will
move slowly eastward across southern California today. A tightening
mid-level gradient over this forecast area will produce breezy to
windy conditions this afternoon and early this evening.

Based on the various 25/00Z models, opted to issue a Wind Advisory
from noon today to 7 PM MST this evening for locales south-to-
southeast of Tucson. Please refer to AWIPS product PHXNPWTWC
/WMO Header WWUS75 KTWC/ for additional information. Have also
included patchy blowing dust this afternoon and evening for the
lower elevations of central/eastern Cochise County.

Critical fire weather conditions are also forecast to occur from
noon today to 7 PM MST this evening for much of southeast Arizona.
Please refer to the Fire Weather section in this Discussion and
AWIPS product PHXRFWTWC /WMO Header WWUS85 KTWC/ for additional
information. Have noted that the 25/00Z GFS/ECMWF/CMC were somewhat
slower with the newd migration of the upper low tonight into
northern Arizona versus previous solutions. Thus, although wind
speeds at lower elevations should diminish quickly around or shortly
after sunset, gusty winds may continue tonight across higher
elevations.

The upper low is progged to be centered over north-central Arizona
by daybreak Thursday, then move newd into eastern Colorado around
daybreak Friday. The GFS/ECMWF/NAM show the potential for some high-
based thunderstorms mainly along the Mogollon Rim northward Thursday
afternoon. The NAM/ECMWF also suggest the potential for some high-
based thunderstorms Friday afternoon across the White mountains.

However, the GFS was markedly drier versus the NAM/ECMWF regarding
Friday afternoon. For this forecast issuance, have maintained precip-
free conditions across all of southeast Arizona Thur-Fri with the
belief that any measurable precip will remain north of the area.
This scenario is subject to revision, however, with subsequent
forecasts.

At any rate, markedly less wind will occur by Friday and continue at
least into early next week given a loose mid-level gradient progged
across the area. A baggy upper trough is depicted via the GFS/ECMWF
to be over the swrn CONUS this weekend and early next week. Have
noted that the ECMWF even depicted a weak closed upper low to be
centered over the area Monday. Still appears that any measurable
precip Monday will remain north of this forecast area.

A slight chance of showers/tstms may then encroach upon far eastern
sections Tuesday. Again, have continued with precip-free conditions
Tue, but this scenario is also subject to revision with subsequent
forecasts. Thereafter, GFS/ECMWF were quite similar with the
amplification of an upper high over the swrn CONUS next Wed. This
pattern will translate into dry conditions.

High temps today will generally be a couple of degs lower versus
Tue, then another 4-8 degs or so of cooling is on tap Thur. A
warming trend will then occur Fri-Sat followed by minor daily temp
changes Sun-Tue. More significant warming may occur by next Wed, but
this is just beyond the scope of this forecast package.

&&

.AVIATION...VALID THRU 26/12Z.
Mostly clear skies will prevail through at least Thursday morning.
Light sfc winds will become SW 15-25 kts and gusts 30-40 kts this
afternoon, with the strongest winds along the international border.
Wind easing to 10 kts or less this evening except remaining gusty
over higher terrain. Aviation discussion not updated for TAF
ammendments.

&&

.FIRE WEATHER...A Red Flag Warning is in effect from noon today to
7 PM MST this evening for zones 151 and 152, and now also includes
eastern zone 150. The expansion into 150 is due to an increase in
forecast winds for this area and basically includes the eastern half
of the Tohono O`Odham Nation eastward. West of there winds will be a
bit lighter and there is generally a lack of a decent grass load.

An upper level low just west of Los Angeles will shift east across
the state through early Thursday. As the low approaches winds will
increase this afternoon resulting in the Red Flag conditions for
much of the area. Isolated spots in fire weather zone 153 may
briefly reach criteria, but these conditions are not expected to be
widespread enough for a warning at this time. That said, this area
(east of Safford from Duncan northward) will have Haines 6
conditions late this afternoon and early this evening.

Winds are expected to settle down this evening across the valleys
but will remain elevated across the higher terrain as the low
continues to approach. Then during the day Thursday the low will be
centered just north of the Whites allowing for a lighter west wind
and a small threat of high based mostly dry thunderstorms over the
White mountains.

Friday the winds will be much lighter. However, there is still a
small threat of mostly dry thunderstorms over the White mountains
during the afternoon hours. Then dry and slightly cooler than normal
conditions are expected this weekend and early next week with
lighter, more typical diurnal winds.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
    Red Flag Warning from noon today to 7 PM MST this evening
      for AZZ151-152.

    Wind Advisory from noon today to 7 PM MST this evening for
      AZZ507-508-512-513.

&&

$$

DISCUSSION...Francis
AVIATION/FIRE WEATHER...Cerniglia

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