Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 211944
Area Forecast Discussion
National Weather Service Tucson AZ
1244 PM MST THU JUL 21 2016
.SYNOPSIS...Hotter and drier conditions are expected Friday into
Sunday with some record high temperatures likely to fall. There will
be just enough moisture around for a few storms near the Mexico and
New Mexico border each of those afternoons. Then moisture will
increase across much of the area early next week for an increase in
storms and somewhat cooler afternoon temperatures.
.DISCUSSION...Convection kicking off across the higher terrain early
this afternoon with individual cells drifting to the NNW. The
convection will continue to develop and expand in coverage through
the afternoon with locally gusty winds with some blowing dust being
the biggest concern. There will be some decent rainers but with
slowly diminishing PWs less of a threat outside of training echoes.
All this activity will die off this evening much like yesterday as
there isn`t any larger scale forcing to keep things going.
Then Friday and Saturday drier air invades the region which is
currently on our door step looking at the water vapor loop. The
overall result of this will be a reduction in the convection and
resultant cloud cover with much of it being limited to our eastern
and southern border areas. The other affect of this will be to allow
afternoon temperatures to increase the next few days peaking Friday
and Saturday afternoons about 10 degrees above average and at or
slightly above records for several locations. I tweaked pops down a
bit a few areas and added a degree to the high temperature to many
areas on Saturday.
On Sunday lower level thickness values begin to drop back with
moisture beginning to increase from the south. This is basically
beginning to occur thanks to a nudge from the tropics but at this
time believe the main push of moisture will be Sunday night into
Monday. So for now only made minor adjustments to the pops Sunday and
went with about 5 degrees of cooling for the afternoon when compared
For Monday onward nudged pops upward with the current trend in the
models and introduced chance of storms to the western deserts
throughout the week. May need to adjust them up further early in the
week but will wait a bit and see how this begins to unfold. I also
nudged afternoon high temperatures down a couple of degrees but there
is potential to nudge them down further one or two of those days
depending on the moisture surge. Still have a decent amount of
discrepancy in the lower level thickness forecast in the models with
the ECMWF being on the cooler side.
.AVIATION...VALID THRU 23/00.
Scattered showers and thunderstorms will develop through at least
03Z with impacts to terminals including gusty winds, heavy rainfall,
and the potential for reductions in visibility. In general VFR
conditions will be prevalent throughout, unless a storm develops
directly over the airport. Cloud bases will hover around 8 or 9
thousand feet. Storm chances will drop quickly after 03Z. Aviation
discussion not updated for TAF amendments.
.FIRE WEATHER...Daily rounds of showers/thunderstorms will
linger into the weekend with coverage waning Saturday and Sunday.
A greater chance of storms will move into the area early next week.
Outside of gusty thunderstorm outflows, 20-foot winds will be
terrain driven and mostly less than 15 mph.
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