Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 271602

Area Forecast Discussion
National Weather Service Tucson AZ
902 AM MST Thu Oct 27 2016

.SYNOPSIS...Strong high pressure will result in dry conditions with
well above normal daytime temperatures through the weekend. A
trough through western states should bring a moderate cooling
trend next week, with temperatures falling closer to seasonal
averages by the middle of the week.


.DISCUSSION...Water vapor imagery shows an expansive ridge that is
centered over southern Sonora Mexico this morning, with the ridge
axis extending north into the entire western half of the nation.
Meanwhile, a Pacific system is currently making its way toward the
Pacific Northwest. Also, Hurricane Seymour, which is generally about
850 miles west of the southern tip of the Baja Peninsula is expected
to weaken to a Tropical Storm later today. Southwest flow on the
western flank of the ridge with continue to pull mostly high level
moisture from the eastern Pacific northward today.

Current IR satellite imagery shows plenty of mid and high level
cloudiness across the eastern Pacific waters, much of California and
into western parts of Arizona. For Arizona, most of this cloudiness
is thin high cirrus clouds, so this cloud cover should not hinder
our chances of seeing afternoon high temperatures in the upper 90s
today, which will easily break record temps, especially at Tucson
where the record for today is 94 degrees, set back in 1937.

I already made some adjustments to the short term temp forecast to
reflect the most recent trends.


.AVIATION...Valid through 28/18Z.
VFR with patches of cirrus level cloud through the period.
Surface wind generally ely/sely at 5-15 kts with occasional gusts
to around 20 kts, diminishing below 10 kts after 27/22Z. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions will prevail into early next week.
Expect occasionally gusty east to southeast winds to around 20 mph
most of today. 20-foot winds will then be terrain driven
generally less than 15 mph into early next week.


.PREV DISCUSSION...A system shearing into northern portions of the
ridge will bring increasing clouds for our area over the next 36 to
48 hours, however lower level moisture will struggle. We`ll be lucky
to see sprinkles from this system Friday night. Meanwhile
temperatures will remain well above average through the weekend.

Some signs of a pattern change are appearing in the eastern Pacific
as hints of a split flow develop. Our first hope for more seasonable
weather is showing up on most GEFS plumes members as well as the
operational ECMWF (with no significant signals in ensemble mean and
spread comparisons for now). So we`ll continue to trend cooler by
the middle of next week while increasing our chance of mainly
mountain showers next Wednesday. A light dusting of snow at the very
highest mountain peaks (above 9000 feet) is not out of the question
at this point, but we`re still a ways out.






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