FXUS65 KTWC 272048
Area Forecast Discussion
National Weather Service Tucson AZ
148 PM MST Sat Feb 27 2021
.SYNOPSIS...Expect brisk winds, patchy blowing dust and cooler
temperatures in southeast Arizona Sunday. There is also a slight
chance of snow showers in the White Mountains. After a chilly
Sunday night, expect a mild Monday and further warming Tuesday.
.DISCUSSION...Satellite imagery shows thick cirrus streaming
across the southeast corner of Arizona, but otherwise sunny
Our next weather maker will be quickly moving south across the
Great Basin into Arizona. As a result, a much colder airmass will
settle into the area Sunday, but not a lot of moisture. There may
be a few snow showers along the Rim, but most of southeast
Arizona will remain dry. Winds will be the big story, shifting
from the southwest to the northwest and becoming gusty. These
winds could certainly produce areas of blowing dust, especially
given the dry February. With increased confidence in windy
conditions and continued low humidities, the Fire Weather Watch
was converted to a Red Flag Warning for areas generally south and
east of Tucson. See Fire Weather section for more details.
Cool overnight lows are forecast Sunday night. It looks increasingly
likely that east winds will develop some time early Monday, but
there is still some uncertainty if they will develop early enough
to keep the air stirred up and prevent some areas from getting too
cold Sunday night. At the very least, locations in the Tucson
Metro area that are sheltered from east winds will likely see
freezing temperatures by Monday morning. NBM guidance continued to
show a 50 percent probability of readings dropping down to 32
degrees or lower at Tucson Airport.
Under abundant sunshine, temperatures should rebound to near
seasonal levels Monday afternoon with even warmer temperatures
expected Tuesday ahead of our next weather system. While
differences still exist, there is increasing consensus among
ensemble members and operational models regarding that midweek
weather system. Models are honing in on a late Wednesday into
Thursday time frame for rain and mountain snow showers.
Probabilities of receiving measurable precipitation range from 20
to 40 percent in most areas Wednesday night with 50 percent
chances near the Rim.
.AVIATION...Valid through 29/00Z.
FEW-SCT clouds AOA 20k ft MSL thru 28/00Z, then clear skies thru
Sunday morning. After 28/19Z FEW-SCT clouds AOA 15k ft MSL.
WLY/NWLY SFC wind at 8-13 kts with gusts up to 22 kts until 28/02Z
then becoming light and variable. Wind becoming W/NWly 15-25 kts
with gusts around 35 kts after 28/19z. Aviation discussion not
updated for TAF amendments.
.FIRE WEATHER...Critical fire weather conditions are forecast
Sunday afternoon into Sunday evening generally east/southeast of a
line from Patagonia Lake to Fort Thomas to Clifton. Therefore, a Red
Flag Warning is now in effect from Noon through 7 pm Sunday. ERCs
below about 6,000 ft are currently at levels typical of mid April
with a High Fire Danger Rating forecast. West to Northwesterly 20-
foot winds of 20-30 mph with gusts around 40 mph (higher over high
terrain) are expected Sunday afternoon into the early evening hours
with Min RH levels of 7-13 percent. Further north over Fire Zone 153
there is a chance of a few snow showers over the higher peaks of the
Breezy easterly winds are expected Monday with dry conditions
continuing. The next chance for precipitation should hold off until
Wednesday or Thursday as a system is forecast to pass across the
Red Flag Warning from noon to 7 PM MST Sunday for AZZ151-152-154.
Aviation and Fire Weather Forecaster...Cerniglia
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson