Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 152107

Area Forecast Discussion
National Weather Service Tucson AZ
207 PM MST Wed Feb 15 2017

.SYNOPSIS...Gusty east winds today, otherwise dry and warmer
conditions the second half of the week. A stronger Pacific storm
system will bring a very good chance of valley rain, mountain
snow, cooler temperatures and gusty winds this weekend.


.DISCUSSION...Windy east and southeast winds today as expected,
but we should hold below advisory levels (and your mileage may
vary with some locations locally shielded or enhanced by
terrain). The low that passed through us yesterday is now near
southern Sonora and central Baja, serving to dirty up the base of
a developing ridge as it loses higher latitude support. We`ll see
a warming trend with the larger scale ridge, but the easterly
return flow will keep that from getting out of hand the next 2
days. Just a little above average for Mid February.

Still on track for a stronger, windier, wetter, and cooler system
to impact the area over the weekend. A complex northern Pacific
situation with 3 systems impacting national interests. The current
weather maker for the Pacific Northwest will push onshore over the
next 42 hours before shearing into the back flank of the mean
ridge position in southern Canada. Our storm system is currently
south of the storm hitting the Aleutians, with a significant
split from the eastern Pacific guiding it in our direction.
Confidence is increasing on track and timing with better signals
from ensemble and ensemble mean model output, as well as GFS/ECMWF
agreement. Best moisture and dynamics focusing on Saturday night
into Sunday morning, however strong upslope Saturday will see some
shower activity. Windy conditions as early as late Friday, but
strongest Saturday. Similar precip forecast with 1/3 to 3/4 of an
inch in valleys and 3/4 to 1.4 inches in mountains, with 5 to 12
inches of snow above 7000 feet.

Ridge building in from the west early next week for a dry warming
trend. Or a warm drying trend.


.AVIATION...Valid through 17/00Z.
Mostly clear. Windy surface winds out of the east and southeast,
12-20 kts and gusts of 25-30 kts thru 16/03Z. Winds diminishing
overnight with normal diurnal wind trends returning Thursday.

Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions are expected into Friday, followed by
a good chance of valley rain/mountain snow over the weekend as a
strong Pacific storm system moves across the region. Expect gusty
east to southeast 20-ft winds today, with gusty south to southwest
winds Friday afternoon, Saturday and Sunday. Otherwise, 20-foot
winds will generally be less than 15 mph.






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