Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tucson Arizona
907 PM MST Wednesday may 6 2015
Synopsis...expect gusty winds through Friday as a strong low
pressure system approaches from the northwest. A cooling trend can
be anticipated Thursday through Saturday. There is a slight chance
of showers and thunderstorms across the White Mountains Saturday as
the system moves north of the area. Dry conditions with much warmer
temperatures will then prevail early next week.
Discussion...the upper pattern is defined by a developing upper
trough digging south along the West Coast...and a strong shortwave
moving into Nebraska/South Dakota resulting in severe weather across
the central portions of the country. For our neck of the Woods...all
is quiet. The latest satellite imagery indicated that the majority
of the cumulus clouds across the area this afternoon had dissipated.
It was a bit of a breezy day today as southwest winds began to pick
up in response to tightening pressure gradients ahead of that
deepening trough along the West Coast. Expect gusty southwest winds
again Thursday and especially Friday as this feature moves farther
south and eventually begins to lift into northern Arizona Saturday.
With the strong winds on Friday...critical fire weather conditions
may be present across the far southeast corner of the state.
However...minimum humidities are expected to be in the teens so
conditions will be brief and marginal at best.
Otherwise...current forecast looks to be on track and no updates are
necessary this evening.
Previous discussion...Arizona will remain in between weather systems
through late tomorrow as another one drops south along the interior
West Coast into Southern California by tomorrow morning. As the
system approaches...strong and gusty winds will continue through
this evening. The wind will be even stronger tomorrow. Models track
this system through northern Arizona Friday into Saturday. For
now...the best chance of rain will be across northern Arizona into
the White Mountains mainly on Saturday. Thereafter...a ridge of high
pressure was prognosticated to build over the area before another system
approaches the central California coast early next week. Daytime
temperatures will remain below normal this week.
Aviation...valid through 08/06z. Clear skies with a southerly
component to the overnight winds...generally below 10 kts through
07/15z. Stronger winds Thursday...with an earlier start...winds
starting to increase around 07/15z at kols...and 07/16z at ktus and
kdug. The strongest winds /15-25 kts with gusts to 35 kts/ are
expected in the late morning to early afternoon hours. Aviation
discussion not updated for taf amendments.
Fire weather...a low pressure system will strengthen northwest of
the area through Friday resulting in increased southwest winds each
day from the late morning through early evening hours. For the rest
of this afternoon and Thursday sustained 20 foot winds are expected
to be less than 20 miles per hour for the most part with min relative humidity levels roughly
15-20 percent. Friday...the winds will be a bit stronger over the southeast
part of the area with slightly lower min relative humidity levels which may result
in short periods where the weather component of red flag conditions
will be met over southern Cochise County...but then marginally so.
That along with moderate fuel conditions would produce
marginal...spotty and short duration red flag conditions overall.
Thus...there are no headlines planned at this time.
Other than that...a few showers and thunderstorms may occur across
the White Mountains Saturday as the low pressure system moves north
of the area. Expect less wind this weekend although some afternoon
gustiness will occur due to daytime heating.
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