Frogville´s Weather Service

Updated:  21-Apr-2026 3:30am 
  Clear Temperature: 63.6°F   -1.8°F/hr Humidity: 35% Dew Point: 35.4°F Wind: NE  1.6 mph Gust: 2.0 mph Barometer: 29.850 inHg   Steady Rain Today: 0.00 in UV Index: 0.0  None

102
FXUS65 KTWC 210823
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
123 AM MST Tue Apr 21 2026

.SYNOPSIS...Warm and dry into the weekend. Breezy conditions
are anticipated for the second half of the week into this
weekend, resulting in elevated to near critical fire weather
conditions east of Tucson Wednesday through the weekend.

&&

.DISCUSSION...The upper pattern is defined by a weak upper-low
moving east through central New Mexico and a strong upper-low
off the coast of the Pacific Northwest and northern California
with a low-center positioned near 40N/130W. Strong agreement
with the grand ensemble members of the GEFS, ECMWF and GEPS
tracking this upper low into NRN CA by 22/00Z this afternoon,
and then across the northern Great Basin Wednesday with a
followup shortwave again on Thursday. As this occurs, a strong
ridge of high pressure off the coast of British Columbia Canada
will force the development of a weak low south of itself near
35N/132W by 24/00Z Thursday afternoon. This results in a mean
open trough with westerly zonal flow along its base directed
into the Desert Southwest. This orientation is conducive for
progressive shortwaves to zip quickly by to our north in the
westerly flow aloft. As this pattern sets-up, models suggest a
couple of low-to-mid level disturbances move through southern
Arizona Wednesday and again Thursday. These features will be
dry, but will result in breezy WLY winds across Southeast
Arizona both days. Given the breezy westerly winds (20-foot west
winds 15 to 20 mph with gusts 30-35 mph) and the dry airmass
across the region (minimum RHs in the teens areawide), we can
expect to see elevated to near critical fire weather conditions,
with the most impactful day being Wednesday. The 21/00Z HREF
and REFS both have a probability 20-40 percent for reaching
critical fire weather conditions (RH20 mph) across portions of Fire Weather Zone 152
Wednesday.

The upper-low to our west eventually pushes into southern California
Saturday in response to a stronger upper-low undercutting the
ridge and moving into its place from the west. This will bring
stronger mid-level flow into the area, with breezy to windy
southwest to west winds across Southeast Arizona this weekend.
Although lower-level moisture will push into the CWA from the
west Saturday, areas from Tucson east may be slower to moisten
up, resulting in yet another day of near critical fire weather
conditions Saturday. Cooler temperatures and deeper lower-level
moisture associated with the upper low eventually move into
Southeast Arizona Sunday, increasing RHs and reducing the fire
weather threat.

&&

.AVIATION...Valid through 22/12Z. FEW-SCT mid-level clouds 10-15k
ft AGL BKN-OVC high clouds AOA 20k ft AGL through the valid period.
SFC winds under 10 kts and terrain driven through 21/18Z, then
SWLY/WLY 10-15 kts with occasional gusts to 20-25 kts into the
early evening. Otherwise, SFC winds remain under 10 kts and
terrain driven. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Warm and dry into the weekend. Minimum RHs will
generally be in the 10-20 percent areawide through Saturday,
then increase to 10-25 percent in the valleys and 25-35 percent
in mountains Sunday as weather disturbance moves into the area.
Passing systems to the north this week will keep Southeast
Arizona dry, with breezy west winds the second half of the week
into next weekend. There is a 20-40 percent probability that
areas Tucson eastward will reach elevated to near critical fire
weather conditions Wednesday, with elevated to near critical
conditions persisting through the Saturday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

Visit us on Facebook, X, YouTube, and at weather.gov/Tucson

NWS TWC Office Area Forecast Discussion