A low pressure system is currently digging southward over the Western
U.S.,
bringing a cooler, less stable airmass towards Arizona. The system is
cutting off from the jet stream, which is currently located in Northern
Canada. Current forecasts indicate that the low pressure system will
stall
over the Southwest for the next few days, then slowly move eastward on
Sunday. However, cut-off lows tend to have more erratic
movement/development
than systems that are steered by the jet stream. Thus there has been
considerable inconsistency and uncertainty in the weather forecasts for
this
weekend.
What is certain however, is that we will see a cooling trend this
weekend.
Highs will be in the 60s today, dropping into the 50s on Friday and
Saturday. Overnight low temperatures will drop from the lower 40s
tomorrow
morning to around freezing on Sunday morning.
Current forecasts indicate that south to southwest winds will develop
today
through Friday, with sustained winds 10-25 mph, and higher gusts
possible.
The south wind will usher increased moisture into Arizona. This
moisture,
combined with lifting and cooler air aloft, will give rise a chance of
showers or thunderstorms this afternoon through Saturday (especially
over
Eastern Arizona and New Mexico).
Instability will be weak, but if thunderstorms form, moderate wind
shear
over Arizona will help organize them. Showers/thunderstorms that
develop
will move towards the north-northeast at around 20 mph, with gusty wind
and
small hail possible.
The best chance of showers will be Friday morning through early
afternoon.
C. James
--
This Prescott weather discussion is brought to you by the Meteorology
Department at Embry-Riddle Aeronautical University (ERAU). Beginning
Fall
2004, ERAU will begin offering a NEW degree program in applied
meteorology
at our state-of-the-art meteorological facility. Please spread the word
to
all potential qualified candidates for our program! For more
information,
refer to
http://www.erau.edu/pr/degrees/b-appliedmeteorology.html or
call
Dr. Mark Sinclair (928-777-3842).