195
FXUS65 KTWC 110931
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
231 AM MST Sat Oct 11 2025

.SYNOPSIS...Deep tropical moisture will remain over our area into
Monday. Shower and thunderstorm chances become more widespread today
through Monday. The prolonged period of rain will result in rises
across main stem rivers and a Flood Watch is in effect. Rain chances
diminish starting Tuesday with temperatures after today below normal
through the week.

&&

.DISCUSSION...Deep southerly flow early this morning with embedded
disturbances ahead of a mid level shortwave is resulting in
widespread showers with a few embedded thunderstorms primarily
across the western half of Arizona with activity extending into our
forecast area, especially across central and western Pima County and
Pinal Counties. Meanwhile, generally dry conditions prevail
currently from Tucson eastward. This precipitation we`re seeing in
the western deserts is mostly on the light side, with a few very
brief heavier downpours. Thus it`s not really impactful with MRMS 3
hour precip amounts mostly less than 0.20" with a couple of isolated
spots up to 0.40". CAMs do show this activity waning a bit for a
brief period this morning before expanding in coverage later this
morning and afternoon to include more of our forecast area.

Not much change in the latest forecast thinking for today through
Monday. In the larger picture, the forecast area remains under near
record to record levels of PWAT between now and Monday ranging
between about 1.2 to 1.7 inches (~200 to ~300 percent of normal).
With all the moisture in place, we just need some lifting mechanisms
to squeeze out precipitation and we`ll have that with the
approaching trough/lowering heights and some jet dynamics starting
today, plus the shearing mid level remnants of Tropical Storm
Raymond (now about 145 miles south of the tip of Baja) Sunday into
Monday. The most likely precipitation totals remain in the 1 to 3
inch range for today through Monday for much of southeast Arizona
with those values increasing to upwards of 3 to 4 inches along the
Int`l border from Nogales eastward and in the mountains. Lower end
QPF (25th percentile) is now around 0.2 to 1.5 inches with the 1
inch or greater amounts across Santa Cruz and Cochise Counties.
Higher end QPF (75th percentile) is generally 2 to 4+ inches. The
flood watch that is in effect continues to look good along with the
WPC slight risk of excessive rain areas today and Sunday, shifting
to locales east of Tucson Monday.

With a few breaks in the clouds today and temperatures near
seasonable levels, that will allow for some instability to develop.
HREF/CAMs show SBCAPE values around 500-1000 J/KG this afternoon
which should allow for embedded thunderstorm activity within braoder
showers that will increase in coverage this afternoon into the
evening hours.

Drier conditions will return to the forecast area starting Tuesday
with only slight chances of precipitation mainly across Graham and
Greenlee Counties with dry conditions area-wide by Wednesday.

Today will be the last day of near normal temperatures before an
extended stretch of below normal temperatures through the rest of
the forecast period as troughiness will continue.

&&

.AVIATION...Valid through 12/12Z.
Generally BKN-OVC clouds at 5K-8K ft AGL thru the forecast period,
along with scattered -SHRA/-TSRA. MVFR conditions are possible in
any brief SHRA/TSRA activity due to lower visibilities and ceilings.
SFC wind ELY/SELY at 6-12 kts, becoming SLY/SWLY at 8-14 kts aft
11/19Z with occasional gusts to 20-25 kts especially near any TSRA.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...High temperatures near normal today, then 3-9
degrees below normal through next week. Tropical moisture moving
northward through Mexico will result in widespread showers and
isolated thunderstorms through Monday. There will be the potential
for widespread rainfall totaling 1 to 3 inches across much of
southeast Arizona today through Monday. Drier conditions start to
move in Tuesday. Minimum RH values will be at least 25+ percent in
the valley`s, with values through Tuesday at 40+ percent. 20-foot
wind speeds will generally be 15 mph or less into the middle of next
week and gusts to 20-25 mph.

&&

.HYDROLOGY...Runoff from the rainfall this weekend into early
next week will bring rises, possibly 3 to 8 foot rises, to the main
stem rivers/creeks across southeast Arizona with main concerns being
the San Pedro river, Nogales wash/Santa Cruz river. The latest
forecast from the CBRFC depicts the San Pedro River at Palominas
(SPPA3) nearing action stage on Monday due to large runoff from the
basin in Sonora. Otherwise, the normally dry washes and low water
crossings will have water flowing through them.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flood Watch from noon MST today through Monday afternoon for
AZZ501>509-511>515.

&&

$$

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