Fort Grant, Arizona Weather Forecast Discussion

917
FXUS65 KTWC 210816
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
116 AM MST Sun Sep 21 2025
.SYNOPSIS...Ample moisture across the region will result in
isolated to scattered showers and thunderstorms each day through
the middle of next week, with potentially strong storms impacting
Southeast Arizona late next week. Temperatures near normal this
weekend, warming to near the century mark by the middle of the
week.
&&
.DISCUSSION...The upper pattern this morning is defined by high
amplitude trough of low pressure off the central California
coastline and a subtropical high centered over the central Gulf of
California and southern Sonora Mexico. The GOES precipitable
water imagery this morning again indicated slightly drier values
across Southeast Arizona compared to 24-hours ago, with readings
generally above an inch to the west of a line from Douglas to
Willcox to Kearny. The deepest moisture (PWAT values between 1.10
and 1.45 inches) were generally west of a NW-SE oriented line from
Tombstone to Tucson to Florence.
The upper-low off the coast of central California this morning
will move slowly SE over the next 24 to 36 hours to a location
just south of the California Bight. As this evolves, we begin to
see an amplification in the flow around both this feature and the
subtropical high to our south. This will result in a decent
diffluent flow developing aloft across Southeast Arizona this
afternoon, then shifting into SW New Mexico early this evening.
Given this lifting mechanism and the ample moisture still residing
across the area, I would expect an uptick in thunderstorm
development/activity today. Expect scattered thunderstorms to
develop across SW Cochise, Santa Cruz and eastern Pima county this
afternoon, expanding east across the rest of Cochise, southern
Graham and southern Greenlee counties into the late afternoon and
early evening.
Otherwise, as a strong vort-lobe rounds the base of the upper low
Monday into Tuesday, we see the upper-low drift northward into
central California through Thursday afternoon, then ESE into
western Arizona Friday. In fact, there is strong agreement with
this solution among the 21/00Z GEFS and ECMWF ensemble members.
Experience suggests that this track would result in widespread
strong-to-severe storms across Southeast Arizona Friday as we
experience strong lift associated with the diffluent flow ahead
of the approaching low. In addition, strong entrainment of drier
air along the southern periphery of the upper low into the mid-
levels of developing thunderstorms storms across SE AZ will result
in an elevated potential for damaging outflow winds. Confidence
is still low-to-moderate at this point with regards to the
strength and timing to firmly message this scenario at this
juncture, especially given how rapidly the ensemble members
diverge next weekend. It is something we need to keep a close
eye-on the next few days though, for sure.
&&
.AVIATION...Valid through 22/12Z. SCT-BKN 12k-15k ft AGL east of
Tucson through 20/19Z with SKC conditions east of KTUS...then
SCT-BKN clouds 6k-10k ft AGL BKN 12k-15k ft AGL thru the valid
period. Scattered -TSRA this afternoon into the early evening
with gusty and erratic winds to around 35 kts possible near
thunderstorms. Outside of thunderstorms, SFC winds generally
less than 12 kts, favoring WLY direction during the afternoon
hours and ELY/SELY overnight and morning hours. Aviation discussion
not updated for TAF amendments.
&&
.FIRE WEATHER...Ample moisture across the region will result in
isolated to scattered showers and thunderstorms each day through
the middle of next week, with potentially strong storms impacting
Southeast Arizona late next week. Minimum RH values between 20-40
percent through Monday, lowering to 20-30 percent by the middle of
the week. 20-foot winds will be westerly 8-12 mph with some
afternoon/early evening gusts to around 20 mph. Breezy southwest
winds 10 to 20 mph will be possible Thursday and Friday of next
week.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
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NWS TWC Office Area Forecast Discussion