Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 280400
Area Forecast Discussion
National Weather Service Tucson AZ
900 PM MST Thu Apr 27 2017
.SYNOPSIS...A storm system will generate strong gusty winds Friday
with somewhat weaker winds following on Saturday. Blowing dust
may be an issue, especially in the vicinity of Interstate 10 with
a few showers or thunderstorms are possible well northeast of
Tucson Friday. Cooler temperatures are forecast Saturday followed
by dry conditions and a warming trend next week.
.DISCUSSION...A rather significant shield of high clouds has
overspread the region and is helping to keep the temperatures up a
bit along the the light breeze that continues. I adjusted the
short term temp, dewpoint and sky grids just a bit as a result but
pretty much left the rest alone.
Overnight the mid-level gradient over the area gradually tightens
with winds aloft steadily increasing. This will allow winds to
ramp up fairly quickly Friday morning once this mixes out a bit.
Winds speeds by afternoon are expected to be similar to what we
experienced back on Tuesday and with the storm in fairly close
proximity the wind will be rather slow to ease up Friday evening.
Blowing dust and fire weather issues are the main concerns and
they are addressed well in the current forecasts, advisories and
warnings so no changes needed there. Breezy conditions will linger
into Saturday especially eastern areas so basically two more days
of hanging onto your hat.
.AVIATION...Valid through 29/00Z.
BKN-SCT clouds above 20k ft AGL then FEW-SCT clouds near 10k ft
BKN above 20k ft after 28/18Z. SFC wind will be W-SW 6-12 kts
through tonight then quickly increase to 20-30 kts with local
gusts in excess of 40 kts by Friday afternoon with local areas of
blowing dust. The winds will be slow to decrease Friday evening.
Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...Strong and gusty winds will continue to be a
concern the next couple of days. Strong winds are expected Friday,
similar to what we had on Tuesday with gusts in excess of 40 mph.
Humidity values will be a bit elevated, however given the very
dry fuels we will maintain the Red Flag Warning due to the
potential rapid fire spread in the light fuels despite the higher
The wind will remain somewhat elevated in speed Saturday across
eastern sections on the back side of an exiting system. Humidity
values will also lower significantly on Saturday, so critical fire
weather conditions will once again be a concern. A Fire Weather
Watch is in effect Saturday afternoon and early evening for
locations east of Tucson. The wind settles down next week, but
very dry conditions will remain in place with some afternoon
breeziness at times.
.PREV DISCUSSION...Winds are increasing over the next 36 hours as
a strong ridge amplifies off the west coast and a system digs
through the intermountain west and front range of the rockies.
Main concern continues to be wind, with a Red Flag Warning
tomorrow, and a Fire Weather Watch Saturday. We also have a Wind
Advisory Friday afternoon and a Blowing Dust Advisory for I-10
east of Tucson.
This next system is digging a littler further south than previous
systems as the ridge amplifies offshore. This will bring a decent
chance of showers or thunderstorms to mainly higher terrain areas
northeast of Tucson late Friday into Saturday (especially
mountains in northern Graham and Greenlee counties). Plenty of
cooler air behind a late April frontal passage Saturday with
daytime temperatures dropping from upper 80s to lower 90s tomorrow
to 70s on Saturday. Saturday night will be the coolest we`ve seen
in about 3 weeks, with 30s in valleys east and south of Tucson,
and 40s from Tucson westward. A few spots will probably freeze
Sunday morning in colder Cochise county valley locations.
The eastern flank of the ridge will start to assert itself into
our area early next week with a slow pattern shift. We still may
see a batch of gusty winds Tuesday and/or Wednesday with systems
digging sharply immediately downstream to our east, but not as
strong as this week. Otherwise dry and warmer.
As the slow and amplified pattern continues to gradually phase
across the CONUS next week, high pressure will bring hotter
temperatures the second half of the week. MOS numbers are not
handling the potential of the airmass very well. We may be
flirting with our first 100 at TIA by next Friday.
Wind Advisory from noon to 8 PM MST Friday for AZZ503>514.
Blowing Dust Advisory from noon to 8 PM MST Friday for AZZ508-
Red Flag Warning from 10 AM to 8 PM MST Friday for AZZ150>152.
Fire Weather Watch from Saturday afternoon through Saturday
evening for AZZ151-152.
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