Hilltop Arizona Weather Forecast Discussion

838
FXUS65 KTWC 072215
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
315 PM MST Tue Oct 7 2025
.SYNOPSIS...Moisture moves into the region mid-week bringing
increasing cloud cover and isolated to scattered shower and
thunderstorm chances Wednesday through Friday. Then more
widespread chances for showers arrive this weekend. Temperatures
transition from above normal through mid-week to below normal by
the end of the weekend.
&&
.DISCUSSION...Sunny to partly cloudy skies across the area with
PWATs starting to slowly increase.  On the synoptic front, the
area is on the western edge of sub-tropical high, an upper level
trof was moving out of the Gulf of Alaska toward PacNW, and
Hurricane Priscilla was located about 215 miles SSW of the
southern tip of Baja CA. Then further SE of Priscilla near
Guatemala is Invest 90E which may become next tropical storm to
form over the next several days.
Tomorrow through Friday, the increase in PWATs will bring a chance
of showers and thunderstorms to the portions of the area. Highs
remaining on the rather warm side for October. The western edge of
the upper high to our east will keep the deep tropical moisture
from Priscilla across western and northern Arizona as upper level
trof deepens over the PacNW.
This weekend into early next: Potential for a significant rain and
flooding event for the area as the dynamics from a pair of
Pacific trofs passing thru the state works on anomalously high
PWATS (over 200% or normal) with the help from Invest 90E. There
is still some uncertainty on the evolution, timing and amount of
rain that will occur. Some of the ensemble members from the GEFS
and EPS have some ridiculous storm totals. Current forecast storm
total QPF for Sat thru Tue has 1" to 3" in the valleys and 3" to
6" in the mountains. Again these numbers will change over the next
several days. With the rain and cloud cover, high temperatures
will cool to several degrees below normal and still may be too
warm.
&&
.AVIATION...Valid through 09/00Z.
FEW-SCT 9k-12k ft AGL. SFC winds terrain driven less than 10 kts
with lcl gusts to 20 kts thru 08/03z. Thereafter SFC winds E/SE
6-12 kts with lcly higher gusts. Aviation discussion not updated
for TAF amendments.
&&
.FIRE WEATHER...Minimum relative humidities in the 10-20 percent
range today, then quickly rising Wednesday onwards as moisture
moves in. Winds become southeasterly Wednesday through Friday.
Strongest southeasterly winds likely in the Gila River Valley
where 15-20 mph winds and gusts to 30 mph are forecast. Isolated
to scattered shower chances from Wednesday through Friday, then
increasing chances for wetting rain arrives this weekend.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
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NWS TWC Office Area Forecast Discussion