Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 291619
Area Forecast Discussion
National Weather Service Tucson AZ
919 AM MST FRI JUL 29 2016
.SYNOPSIS...A good monsoon pattern will remain in place through at
least the middle of next week. Beginning this afternoon daily rounds
of showers and thunderstorms are expected with the potential for
strong winds, blowing dust and locally heavy rains. Above normal
temperatures will continue today with cooler temperatures moving in
this weekend and continuing into early next week.
.DISCUSSION...Its looking like it should be a rather interesting
afternoon and evening. The atmosphere is nicely primed as indicated
on the morning sounding and looking at the forecast soundings it
should remain so with a nice increase in DCape this afternoon thanks
to heating. Looking at the H2O vapor imagery this morning along with
upper level flow and vorticity advection it looks like we have a
wiggle in the flow over central AZ that will drift south, thus
thinking we shouldn`t have as much inhibition as we did yesterday.
Taking all that into account, looking at a variety of HIRES models
and coordination with PSR, decided to ramp things up a bit this
afternoon and evening. I raised pops for basically the NW 2/3rds of
the forecast area and tweaked the areas of blowing dust. Also in the
mix split those grids into 3hr chunks for better temporary resolution.
Again in coordination with PSR, this looks like there is good
potential for blowing dust along the I-10 corridor NW of Tucson and
also across western Pima county later today. With that thought in
mind, a long lead time blowing dust advisory will be issued for the
afternoon and evening hours north and west of Tucson. It will take
awhile for things to settle down this evening. I updated the grids
for the first 18 hours and left the remainder alone for now.
Remainder from previous discussion...A fairly active monsoon pattern
is expected to continue this weekend into next week with the mid
level ridge axis remaining just north of our area with generally
easterly flow aloft. Moisture is expected to increase this weekend
setting the stage for a potentially prolonged active period,
especially as an inverted trough may aid storm development Sunday
into Monday. Meanwhile, given the deep moisture across the region,
we`ll begin to transition to greater flash flooding threat as well. A
fairly typical monsoon pattern for early August is then expected for
much of next week. Temperatures will cool off to below normal values
by Sunday and continue through much of next week.
.AVIATION...Valid through 30/12Z.
Expect an increase in areal coverage of -SHRA and -TSRA versus Thu
which was a down day. Thunderstorms dvlpg over the higher terrain
will move generally W into the valleys. Mostly VFR conditions thru
pd except for psbl MVFR in/around -SHRA/-TSRA. Winds generally 10
kts or less except brief gusts to 50 mph psbl with stronger TSRA with
local IFR conditions in blowing dust north and west of Tucson 29/21z
thru 30/03z. Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...After a down day on Thursday, today is expected to
be much more active with isolated to scattered thunderstorms this
afternoon and evening primarily zones 153, the northern part of 152
and much of 151 and 150. The biggest threat from these storms later
today will be very strong outflow winds with blowing dust. The rest
of the forecast period will see a continued threat for isolated to
scattered showers and thunderstorms along with slight cooler daytime
temperatures. Significant winds are not expected except in the
vicinity of thunderstorms.
Blowing Dust Advisory from 2 PM this afternoon to 8 PM MST this
evening for AZZ502-504-505.
Blowing Dust Advisory from 5 PM this afternoon to 8 PM MST this
evening for AZZ501.
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