Forecast Discussion

Forecast Discussion for TWC NWS Office
FXUS65 KTWC 082128

Area Forecast Discussion
National Weather Service Tucson AZ
228 PM MST Mon Mar 8 2021

.SYNOPSIS...A storm system slowly moving in from the northwest
will bring gusty winds at times and a steady cooling trend through
the week. We may also see a few valley rain and mountain snow
showers, with best chances late Thursday into late Friday.


.DISCUSSION...Southeast Arizona is caught in between high pressure
south and east of our area, and a strong approaching weather
system currently just off the Pacific Northwest coast. As this
system slowly digs into the region, our winds will increase with
some gusty afternoons over the next several days. We don`t expect
them to be strong enough for wind headlines, but there are
definite fire weather concerns as outlined in the fire weather
section below.

The evolving split is rather deep with a good track bringing the
system into Arizona Friday. The high amplitude flow isn`t very
progressive with a building ridge through the Gulf of Mexico and
less higher latitude support as the system approaches from the
northwest the second half of the week. With slower timing we
should have enough of a fetch to bring in enough moisture for a
chance of valley rain and mountain snow showers by late Thursday
or Thursday night into Friday or Friday night. Precip amounts are
not expected to be significant, with valley locations looking to
stay under 1/3 of an inch at this point. Cool enough for snow
levels as low as 4500 feet, with 1 to 3 inches above 6000 feet.

Some clearing from the west next weekend as the low shears into
the front range of the Rockies and the central plains. However,
ensemble mean height anomalies suggest continued large scale
troughiness through the region at least the first half of next


.AVIATION...Valid through 10/00Z.
BKN-OVC clouds generally AOA 15K-18k ft MSL thru 09/18Z, then
clearing skies from west to east. SFC wind SLY/SWLY SFC at 8-18 kts
and gusts up to 25 kts (with the strongest wind east of Tucson) thru
09/02Z. Aft 09/02Z, diminishing wind and SFC wind less than 12 kts
between 09/04Z and 09/17Z. SFC wind increasing again aft 09/17Z,
and SWLY SFC wind at 15-25 kts and gusts to 25-35 kts by 09/20Z.
Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions are expected into the middle of this
week, with a slight chance of precipitation in the White Mountains
starting on Tuesday and then across the rest of southeast Arizona
Thursday night into Saturday. High temperatures will be 3-7 degrees
above normal Tuesday, with much colder temperatures overspreading
southeast Arizona Thursday through Saturday. Gusty 20-foot wind
speeds are expected Tuesday into Saturday.

Critical fire weather conditions are expected Tuesday south and east
of Tucson and therefore a Red Flag Warning has been issued for
portions of Santa Cruz and Graham counties and all of Cochise
county from 1 pm to 7 pm MST Tuesday for strong and gusty southwest
winds, low relative humidity values and a high fire danger. There
will be the possibility of localized critical fire weather
conditions being met during the afternoon and early evening hours in
areas south and east of Tucson again Wednesday, with borderline
conditions hanging on over Cochise County Thursday as the colder air
overspreads the area and higher RH values follow.


Red Flag Warning from 1 PM to 7 PM MST Tuesday for AZZ151-152-



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NWS TWC Office Area Forecast Discussion