Scientific Forecaster Discussion
fxus65 ktwc 251530
Area forecast discussion
National Weather Service Tucson Arizona
830 am MST Thu may 25 2017
Synopsis...a trough of low pressure will bring breezy to windy
conditions with a modest cooling trend into Friday. Less wind
will occur this weekend and warmer temperatures will return early
next. Some increase in moisture will provide a few showers and
thunderstorms, mainly east of Tucson, for Memorial Day into next
Discussion...the main story today will be the strong winds as we
are caught between the subtropical ridge to our south and
troughiness across the Great Basin. 12z ktwc sounding shows winds of
30 kts just a few thousand feet above the surface which is already
mixing down early this morning per area observations. Winds will
remain just below advisory levels this afternoon but certainly
enough for fire weather concerns with red flag warnings in effect.
Meanwhile, just a few mid and high level clouds across the area in
the west to southwesterly flow aloft but no real impact on our
sensible weather other than possibly a little virga this morning
over Cochise County.
Gusty winds will remain with US on Friday as well across the entire
area as we remain in a very similar flow pattern. However,
temperatures will drop about 5 to 8 degrees compared to this
afternoon. Slightly below normal temperatures continue on Saturday,
then return to seasonal normals Sunday with more typical afternoon
breezes as the gradient slackens with ridging moving in. Early next
week still looks interesting as the lower to mid level flow becomes
more easterly to southerly as a mid level low undercuts the ridge.
This will transport more moisture into the region, especially east
of Tucson and may result in a few mainly dry thunderstorms Monday
through Wednesday east of Tucson.
Aviation...valid thru 26/18z.
Expect scattered-broken clouds mostly above 15k ft above ground level this morning followed
by clearing skies from west-to-east. Wind speeds increasing to
swly/wly 12-25 kts with gusts to near 35 kts in the afternoon, then
gradually decreasing overnight. Strongest speeds will be east of
ktus. Aviation discussion not updated for taf amendments.
Fire weather...a red flag warning is in effect from 11 am to 8 PM
MST today for much of Southeast Arizona except fire weather zone
150. A red flag warning is also in effect from 10 am to 8 PM MST
Friday for portions of fire weather zones 151 and 152, mainly
south- to-southeast of Tucson. The combination of strong and gusty
winds, low relative humidity values and a very high fire danger
will create critical fire weather conditions.
Less wind will prevail Saturday into early next week. Some increase
in moisture will result in a slight chance of mainly afternoon and
evening thunderstorms near higher terrain Memorial Day into next
Wednesday. Dry lightning will be possible.
red flag warning from 11 am this morning to 8 PM MST this
evening for azz151>153.
Red flag warning from 10 am to 8 PM MST Friday for azz151-152.