Area forecast discussion
National Weather Service Tucson Arizona
900 am MST sun may 19 2013
Synopsis...a broad upper level trough over the western US will hold
temperatures near normal levels through Tuesday. Then the trough
will gradually move east allowing for a warming trend from Wednesday
Onward with dry conditions through the week.
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Discussion...a broad upper level trough centered over the Rocky
Mountain states will very slowly drift east maintaining a dry northwest
flow across the region through Monday night. Low and middle level
thickness levels suggest highs near normal today through Tuesday
with generally normal diurnal winds that will have somewhat enhanced
speeds each afternoon.
As the initial low moves east a shortwave ridge will pass across the
region late Tuesday as a deep upper level low settles in along the
West Coast. This low Marks the beginning of a long wave trough
setting up along the West Coast that will linger into early the
following week. That setup will result in a dry SW flow setting up
over Arizona with the possibility of moisture spreading up into New
Mexico...and it will cause temperatures to jump to 4-8 degrees above
normal from Wednesday Onward. The thing that will need to be
watched with this setup is the potential for breezy/windy periods
(southwest winds) depending on the strength and depth of features
rotating around the base of the trough. While the wind won't be
strong enough to be a concern for the public in general it could
pose concerns for the fire fighting community. This is something
that can't be quantified this far out in time so stay tuned.
Cerniglia
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Aviation...sky clear through early Monday morning or 20/12z. Surface wind
this afternoon and early this evening westerly/northwesterly 10-18 kts with gusts
to near 25 kts...strongest wind east and south of ktus. Otherwise...
surface wind less than 10 kts. Aviation discussion not updated for
taf amendments.
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Fire weather...dry conditions will prevail through next Saturday.
Expect a gradual daily warming trend through Wednesday followed by a
continuation of above normal daytime temperatures Thursday through
Saturday. Daytime minimum relative humidities will generally be in
the single digits to lower teens with fair overnight recoveries.
Expect normal diurnal wind trends today through Wednesday...with
occasional gusts during the afternoon and early evening hours due to
strong daytime heating. Somewhat stronger southwest winds are
forecast to occur Thursday and Friday as a low pressure system
deepens northwest of the area.
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Twc watches/warnings/advisories...none.
&&
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