Bisbee Junction, Arizona Weather Forecast Discussion

632
FXUS65 KTWC 191539
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
839 AM MST Fri Sep 19 2025
.SYNOPSIS...Ample moisture across the region will result in
generally scattered showers and thunderstorms today with
diminishing thunderstorm chances over the weekend. Temperatures
near to just below normal into the weekend before warmer and drier
weather returns next week.
&&
.UPDATE...Partly cloudy skies this morning across southeast Arizona
with just a few showers over Graham County with the bulk of the
stronger showers and thunderstorms further north across Gila County
and points north from there. With considerable moisture in place
(PWAT`s 1.1 inches east to 1.6 inches west), moderate instability
developing (MLCAPE 500 to 1000 J/KG) and 25-30 kts of 0-6km shear,
we expect scattered showers and thunderstorms to develop early this
afternoon mainly from the Tucson area eastward. Dynamics aren`t
quite as favorable as yesterday but certainly enough to aid in
convective development as storms move from west to east today. Main
concerns will be isolated flash flooding threat where storms back-
build and secondary threat for gusty winds to around 40 mph. Current
forecast is in good shape. No updates this morning.
&&
.DISCUSSION...The upper pattern this morning is defined by a
weakening upper low rotating NE through central California within
a larger scale NE-SW oriented trough extending off the California
coastline...and a strong subtropical high centered along the SE
Sonora/SW Chihuahua Mexico border. Decent deformation in the mid
and upper-level flow came through last evening resulting in
widespread showers and thunderstorms across the CWA. Although we
wont see the same level of dynamic support again today, there is
decent SW flow in the 500 mb flow this morning extending into SW
and south-central Arizona. This will result in some shear across
Southeast Arizona with the 19/03Z SPC SREF indicating a 50-90%
chance of 30+ kts 0-6km BRN shear slowly moving across SE AZ late
this morning into the afternoon...pushing into SW NM by 00Z this
afternoon. This isn`t overly impressive, but it should be enough
to help support more organized/sustained convection this afternoon.
Still plenty of deep moisture residing across the lower deserts
of SW AZ. The latest GOES TPW imagery indicated values around
1.65 inches across central and western Pima county, to 1.35 inches
around the Tucson Metro, lowering to 1.10-1.25 inches east of
Tucson. Although we can expect some moisture advection eastward
today, the threat of heavier rainfall will remain closer to the
moisture source. The 19/00Z HREF ensemble probability matched mean
3-hr QPF has a probability above 50% for rainfall in excess of an
inch across far SE Pima/E Santa Cruz far SW Cochise county
between 21Z and 00Z.
I would expect thunderstorms to fire off during the mid-morning
hours over the higher terrain of SE Pinal/central and eastern
Pima and Santa Cruz county and move ENE fairly rapidly in the
stronger mid-level flow. These storms will begin to expand E and SE
of Tucson through the afternoon. The main hazard from these
storms will initially be the potential for heavy downpours/
isolated flash-flooding from Tucson south and south-southeast
with the hazard becoming more of a strong thunderstorm outflow/
blowing dust concern across Cochise and southern Graham and
Greenlee counties during the afternoon.
Otherwise, I feel confident in the evolution of the upper pattern
through the weekend, but things really get iffy next week. The
models bring the upper low off the CA coastline this morning SE
toward southern California by Monday afternoon. As this happens,
it latches onto a plume of deeper moisture, advecting it across
our neck of the woods Sunday into Monday. Both the ECMWF and GEFS
ensemble members then indicate some reflection of a tropical
system moving up along the Baja next week...with the more
aggressive GEFS bringing it closer to the Gulf of California than
the much farther west-solution of the ECMWF. At this juncture,
the operational GFS looks wonky to me as I would expect a
stronger ridge to develop across NW Mexico (more like the drier
operational ECMWF). In any event, it bears watching for now.
&&
.AVIATION...Valid through 20/12Z. SCT-BKN clouds 6k-10k ft AGL
and SCT-BKN layer AOA 18k ft AGL thru the valid period. Scattered
TSRA developing late this morning, expanding E and SE into the
afternoon. Gusty and erratic winds to around 35 kts possible near
thunderstorms, especially to the southeast and east of Tucson
(near KALK/KDUG/KSAD) this afternoon. Outside of thunderstorms,
SFC winds SLY less than 7 kts this morning, becoming WLY 8-12 kts
in the afternoon. 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 generally
scattered shower and thunderstorm chances (30-60 pct chance)
today, 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.
&&
$$
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NWS TWC Office Area Forecast Discussion