Sierra Vista, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

369
FXUS65 KTWC 201517
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
817 AM MST Sun Jul 20 2025

.SYNOPSIS...Chance of showers and thunderstorms each day through
Tuesday then drying out for most of southeast Arizona. High
temperatures generally blow normal through Tuesday then heating up
into next weekend.

&&

.UPDATE...A well defined MCV developed early this morning from the
remnants of the overnight convection in Sonora. This is currently
located about 50 miles southeast of Nogales and moving towards the
NW. Latest KEMX radar imagery shows some light shower activity just
out ahead of the MCV in SW Cochise and Santa Cruz Counties with the
radar returns more indicative of virga elsewhere. Meanwhile,
considerable cloudiness this morning for just about all of southeast
Arizona with the exception of right along the NM border where there
is some partial clearing. The HRRR has caught onto the MCV and is
better handling today`s scenario which will be that of the MCV
continuing its push to the NW with plenty of clouds near and ahead
of the MCV. In terms of convective development today, the clouds
will result in delayed storm development. We`ll be focused primarily
on Cochise and Santa Cruz County once skies clear for some shower
and thunderstorm development. However, lingering subsidence on the
backside of the MCV and limited instability should result in another
lower grade monsoon day overall. Temperatures will struggle to warm
to the forecast highs if clouds persist long enough as well. This is
something we`ll continue to monitor. No forecast updates at this
time. See previous discussion below for additional information.

&&

.DISCUSSION...The 20/00z 500 mb plot placed an upper low over srn
California and an upper high over Oklahoma. This placed southern
Arizona under southerly flow aloft between these two features
with satellite showing considerable cloud cover over the area with
230 am radar showing a band of mainly light showers/sprinkles
over SW Cochise county and ern Santa Cruz county moves slowly to
the NW. South across the border there were additional showers and
storms associated with decaying MCS.

Concerns for today.
1) Latest UofA CAMs and HRRR have isolated to widely scattered
light showers/sprinkles continuing through the morning hours as
they push to the NW.
2) How long the current cloud cover hangs around will certainly
impact possible development of storms this afternoon, and
3) Does an MCV emerge from the decaying MCS east of Hermosillo
and lift north toward the area under the southerly flow aloft.

The forecast today has slight (10-20%) chance of showers this
morning with (20-50%) chance of showers this afternoon into this
evening. If we get some got sun this afternoon, any storms that
develop with be capable of brief heavy rain with PWATs up to
1.25", especially across Santa Cruz and Cochise counties where
they will have the best chances to see more sun than elsewhere.

Tonight into the overnight hours: Potential to see a repeat of
this morning with considerable debris clouds and embedded light
showers during the overnight hours.

Little change from the previous discussion on the upcoming week
ahead.

Monday & Tuesday: Increasing chances for showers and
thunderstorms as an inverted trof pushes into southeast Arizona.

Wednesday thru Saturday: Temperatures warming to above normal
with widespread moderate HeatRisk by Friday. Decreasing
precipitation chances mainly focused to the south and east of
Tucson along the International/AZ/NM borders. Ensemble guidance is
in agreement that moisture will start to get shunted out of the
Desert Southwest by the middle of next week. Latest guidance from
the Climate Prediction Center suggests above normal temperatures
and below normal precipitation can be expected in the extended
period.

&&

.AVIATION...Valid through 21/12Z.
BKN-SCT 8k-11k ft with layers above to 25k ft. ISOLD -SHRA thru
20/18z moving to the NW. During this time the considerable debris
cloud cover will slowly decrease in coverage. A few -TSRA dvlpg
aft 20/19z mainly S and SE of KTUS or where there was more sun
than clouds. Gusty and erratic winds up to 35 kts with any storm.
Otherwise, surface winds mainly under 12 kts. Aviation discussion
not updated for TAF amendments.

&&

.FIRE WEATHER...Below normal high temperatures through Tuesday
then heating up into next weekend. Generally a low grade monsoon
pattern with day-to-day variability in thunderstorm coverage.
Afternoon winds will remain westerly from 10-15 mph, with
occasional gusts at or above 25 mph. Afternoon RH values in the
low lying areas will be 17-25% this weekend. In the higher
terrain, RH will be around 30 to 50%.

&&

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

&&

$$

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