FXUS65 KTWC 052022

Area Forecast Discussion
National Weather Service Tucson AZ
122 PM MST Wed Oct 5 2022

.SYNOPSIS...A low pressure system will linger over northwest
Mexico and southern Arizona with a chance of showers and
thunderstorms through the coming weekend. Temperatures will
remain near or below average for early October.


.DISCUSSION...The low pressure is over New Mexico and will be
starting to transition to our southwest through the rest of the
day and into Thursday. This will dampen the chances for widespread
convection as the moisture and dynamics is not fully in place.
Yet, there is enough ingredients for several isolated
thunderstorms to develop which the latest 20z radar scan show
storms and showers in Santa Cruz County and in the White
Mountains. As the day progresses, more storms can develop in the
region due to better CAPE, surface heating, and moisture. PWATs
are hovering around an inch for the majority of the region.

Tomorrow and the weekend...Once the low pressure center moves to
the southwest of Arizona, hovering around Gulf of California, a
strong ridge will develop along the Pacific Coast. The low
pressure center will be in an ideal position to bring some
moisture from the tropics for daily afternoon thunderstorms. Even
though the moisture is on the low end, it is just enough to create
pesky showers and thunderstorms. CAMs are show Thursday afternoon
to be a day for scattered thunderstorms as the low tracks across
southeast Arizona. Another better day for storms will be Friday
and Saturday due to upper level dynamics and decent vorticity
advecting around the low. Thus, the ensemble models have show this
Rex Blocking pattern lasting through the weekend and into the new

Next week...Ensemble models are showing a longwave trough / lower
pressure coming down into western CONUS to drive out the moisture
starting sometime Wednesday. The ensemble model guidance moisture
trend dramatically drops from 1 inch to a whopping 0.7 inches!
Enough to turn the rain valve off for Southeast Arizona for the
middle of October. Although, there is still uncertainty on how
far south it will be to drive the remaining moisture to become
more of a westerly flow. Otherwise, daytime temperatures will
gradually trend downwards to follow near seasonal normals.


.AVIATION...Valid through 07/00Z.
SCT-BKN clouds at 7k-12k ft AGL through 06/06z and after 06/22z.
Otherwise, mostly FEW-SKC during the night time hours. ISOLD-SCT
TSRA/SHRA through 06/04z with brief MFR conditions and wind gusts
to 40+ kts possible with the TSRA. Increase chances for SCT
TSRA/SHRA developing after 06/18z through the end of the forecast
period. Outside of thunderstorm outflows, SFC wind generally less
than 12 kts, with higher gusts during the afternoon hours.
Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Isolated to scattered afternoon and evening showers
and thunderstorms are expected through the upcoming weekend. The
main threats will be strong and gusty outflow winds, isolated
areas of heavy rainfall and dangerous lightning. Outside of
thunderstorm outflow winds, 20-foot winds will remain less than 15
mph today, with some gusty east/southeast winds Friday and





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NWS TWC Office Area Forecast Discussion