Solomon, Arizona Weather Forecast Discussion

478
FXUS65 KTWC 181646
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
946 AM MST Thu Sep 18 2025
.SYNOPSIS...Moisture has moved into the region which will lead to
scattered showers and thunderstorms today through Friday with
diminished thunderstorm chances over the weekend. Temperatures near
to just below normal into the weekend before warmer and drier
weather returns next week.
&&
.KEY MESSAGES...
-Chances (30-50%) for isolated showers and storms first forming
 primarily on the high terrain before becoming scattered in the
 afternoon to evening hours. Localized instances of flash flooding
 possible.
-Chances (20-50%) for thundershowers continue into the evening and
 overnight hours with moderate to heavy rainfall possible at
 times.
&&
.UPDATE...Main forecast focus today into tonight is again on
isolated to scattered showers and thunderstorms with heavy rainfall
being the primary hazard. Although the most favorable area for
synoptic ascent associated with the remnant low of Mario is
mainly to our west, we will have plenty of moisture (PW 1.4" near
Tucson to 1.7" in far western Pima County) in place to support
heavy rainfall with any storms that develop. Modest instability
will help fuel storms as morning clouds gradually dissipate.
Anticipate isolated showers and storms to form first over the high
terrain areas in the early afternoon before becoming scattered.
This evening, current thinking is that synoptic scale forcing for
ascent could become a bit more favorable as a modest mid/upper
jet drifts into southeast Arizona. Better dynamics would support
thundershowers into the evening and overnight hours with moderate
to heavy rainfall at times.
&&
.PREV DISCUSSION... /issued 212 AM MST Thu Sep 18 2025/
Southeast Arizona is under mostly cloudy skies with a few weak
showers visible on radar. Aloft the upper level remnants of Mario
are just off the coast of southern California and high pressure is
centered over north central Mexico. Anomalous moisture is in place
with PWAT values 120-180 percent of normal from east to west
respectively. This moisture will be in place through tomorrow. The
low will move north and a little eastward through the day tomorrow
and Friday. This will lend upper level support to showers and
thunderstorms with the best synoptic scale support just to the west
in Yuma County and southern California. Today expect another round
of scattered showers and thunderstorms starting this afternoon and
continuing into the evening. The main threat will again be heavy
rainfall leading to localized areas of flash flooding. Some HREF
members keep convective activity going overnight thanks to the jet
that will be over the region. Right now this activity looks to be
favored over Pima County, then becoming more widespread as the sun
comes up Friday morning. Shower and thunderstorm activity then
continues into Friday afternoon. Event total rain looks to be
highest along the international border and in the Sky Islands with 2
day rain totals 1"-3" possible. Expect flowing washes and rivers
especially where soils become saturated leading to more runoff.
Temperatures will be a few degrees below normal thanks to the cloud
cover and moisture.
This weekend moisture begins to decrease, but will still be above
normal. However the area of high pressure currently to the south
moves northward and southeast Arizona loses its upper level support
for storms. As a result NBM PoPs are 10-20 percent both days mainly
over the higher terrain. Temperatures begin to increase becoming 2-3
degrees warmer than today and Friday.
Early next week the high keeps nudging northward, but ensembles also
bring a closed low south into southern California with another low
in the Great Plains and Midwest. This sets up an omega block over
the western U.S. For Arizona this will slowly dry us out with
temperatures climbing above normal. Lingering moisture will lead to
slight chance (15-20 percent) PoPs Monday with dry conditions
expected thereafter. Tucson could see triple digit highs by the
middle of next week.
&&
.AVIATION...Valid through 19/12Z.
BKN-OVC clouds 6k-10k ft AGL and BKN-OVC layer AOA 18k ft AGL thru
the valid period. Scattered TSRA possible after 18/19Z through the
evening. Some overnight convective activity will be possible, but
confidence is low on terminals being affected. With showers and
thunderstorms, expect locally heavy rainfall and erratic winds up to
35 kts. Other than thunderstorm driven winds, SFC winds will be from
the south southwest 5-10 kts in the afternoon and evening becoming
variable less than 7 kts at other times. Aviation discussion not
updated for TAF amendments.
&&
.FIRE WEATHER...Above normal moisture is in place leading to min
RH between 20-40 percent through the weekend. Expect scattered
shower and thunderstorm chances (30-60 pct chance) today and Friday,
then diminished thunderstorm chances this weekend. Heavy rainfall
will be the main threat. Dry conditions return next week. 20-foot
winds will be 8-12 mph with some afternoon/early evening gusts to
around 20 mph over the next week with normal diurnal patterns
through the weekend.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Update...DVS
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NWS TWC Office Area Forecast Discussion