Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 221657
Area Forecast Discussion
National Weather Service Tucson AZ
952 AM MST SAT OCT 22 2016
.SYNOPSIS...Above normal daytime temperatures will continue this
weekend and into next week. There is a slight chance of showers and
thunderstorms mainly along the International border this afternoon.
A trough of low pressure moving into the western states will then
bring a better chance of showers and thunderstorms to the area
Sunday through Tuesday. Dry conditions return late Tuesday through
Thursday, with another slight chance of showers on Friday.
.DISCUSSION...latest models continued to suggest a chance of showers
or thunderstorms developing later this afternoon near the
International border. Otherwise, dry elsewhere today. Rain chances
will increase tomorrow into early in the work week as deeper
moisture advects into the area. Current forecast looked on track, so
no updates this afternoon.
.AVIATION...Valid through 23/18Z.
Clear skies/SKC conditions are expected thru 22/20z, then FEW-SCT
clouds at 10-14k ft agl. There will be a slight chance of -TSRA/-
SHRA aft 22/20z, continuing thru rest of the forecast period.
Outside of any thunderstorm wind gusts, surface wind will be less
than 12 kts. Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...There will be a slight chance of showers and
thunderstorms starting this afternoon and continuing into Sunday
night. A chance of showers and thunderstorms then exists Monday and
Monday night, with a few lingering showers early Tuesday in the
White Mountains. Dry conditions will prevail late Tuesday into
Friday. Another system will then bring a chance of showers and
thunderstorms late Friday into next weekend. Above normal daytime
temperatures are expected through Friday, with 20-foot winds less
than 15 mph.
.CLIMATE...Friday was the 15th consecutive day of at least 90 degrees
recorded at Tucson International Airport for October 2016. This is
the seventh longest period of 90 degrees or warmer for any October
on record (dating to 1894). The current official forecast indicates
that 90 degrees or warmer should also occur Today and Sunday. If
this happens, there will be 17 consecutive days this month of at
least 90 degrees recorded at Tucson International Airport. This 17
consecutive day period would be the sixth longest on record for
.PREV DISCUSSION...The 22/06z runs of the NAM and GFS as well as the
22/00z U of A WRFGFS develop some precip across the CWA late this
afternoon and evening.
Day 1 SPC outlook has a small portion of the SE AZ in the general
thunderstorm risk today as well. Assuming that the disturbance from
Sonora will provide some additional upper level support for
convection this afternoon as it moves into the state, have continued
a slight chance of showers and thunderstorms this afternoon mainly
along the Int`l border areas.
We should see dry conditions tonight into early Sunday as the ridge
axis slides eastward and a trough deepens off the Pac NW coast. This
will induce upper level SWLY flow, pulling an additional batch of
mid and high level moisture across Arizona. As such, a slight chance
of showers exists Sunday into Monday morning as things moisten up
from the top down. A shortwave in the flow will then provide
enhanced dynamics for chance category showers and few thunderstorms
on Monday afternoon. This disturbance exits quickly toward the
northeast Monday night, with enough lingering moisture to justify a
slight chance of showers east of Tucson on Tuesday.
Robust ridging is progged to develop across the western CONUS mid-
week, with dry conditions occuring Tuesday night into Thursday. NWP
model solutions diverge thereafter with regard to another
approaching disturbance. The GFS presents a wet solution while the
ECMWF keeps things dry. Initial thinking is that unsettled weather
of some kind will occur late next week into next weekend. Confidence
is currently very low with regard to the timing and the evolution of
this system. As such, introduced some low-end slight chance PoPs on
Friday, with single digit PoPs in the forecast for Saturday.
No break in the October warmth today with a few spots near record
highs again. Expect above normal daytime temperatures to continue
through the forecast period, despite some modest cooling on Monday
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson