Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 222148

Area Forecast Discussion
National Weather Service Tucson AZ
245 PM MST Wed Feb 22 2017

.SYNOPSIS...Dry conditions will prevail through Saturday. A weather
system passing by to the north on Thursday will bring much cooler
temperatures to the area Thursday and Friday. A brief warmup on
Saturday before a fast moving system pushes across the area on
Sunday. A stronger Pacific storm will bring a chance of valley rain
and mountain snow to the area on Monday and Tuesday along with below
normal temperatures.


.DISCUSSION...High pressure aloft not only brought warm temperatures
this afternoon to southeast Arizona, it also kept the cloud cover
across wrn and nrn AZ. A few spots will end up close to record highs
for today. The above mentioned cloud cover will move across the area
tonight in advance of a quick moving shortwave that will pass by to
our north over the next 24 hours. Can`t rule out a few flakes across
the White mountains overnight.

This system will bring much cooler daytime temperatures along with
gusty winds on Thursday. Highs are forecast to be 10-17 degrees
cooler than today. Check fire weather section for any fire weather
critical areas that are possible tomorrow afternoon. With a colder
air mass across the area overnight lows Friday morning will get
quite chilly with the usual cold spots getting down into the mid to
upper 20s. Remaining cool on Friday then warmer Saturday under zonal
flow aloft.

Made some changes to the Sunday forecast as both 12z GFS/ECMWF are
swinging a fast moving short wave across the state. This system is
supported by the 12z ensembles. Thus went ahead and lowered highs
about 7-10 degrees from previous forecast and also introduced low
end pops for the mountains from Tucson NE.

Models still on track on moving a stronger, colder, wetter Pacific
upper trof across the area early next week. Below normal high
temperatures during the first half of next week.


.AVIATION...Valid through 23/23Z.
Clear skies thru 23/02Z, then FEW clouds around 15k ft AGL and SCT-
BKN clouds AOA 20k ft AGL til 23/10Z. Clear skies again aft 23/10Z.
SFC WND generally WLY/NWLY at 8-13 kts with some gusts to near 22
kts thru 23/03Z. Between 23/03Z and 23/16Z, light SFC WND less than
10 kts. Aft 23/16Z, SFC WND increasing with WLY/NWLY wind at 13-22
kts and gusts to 22-30 kts, with the strongest wind east of KTUS in
the vicinity of KDUG, KALK and KSAD. Aviation discussion not updated
for TAF amendments.


.FIRE WEATHER...A weather system passing to the north will result in
breezy conditions Thursday, along with cooler temperatures Thursday
and Friday as daytime temperatures fall below normal. Wind speeds
and relative humidity values will approach critical fire weather
thresholds Thursday afternoon for a couple of hours over portions of
Cochise and Graham counties. However, both the observed and forecast
fire danger class are only in the moderate category. Therefore, will
hold off on any watch/warning product as fire danger needs to be in
the high category (or higher).

Warmer conditions are expected Saturday as daytime temperatures
rebound to near normal. Lighter winds are also expected Saturday. A
stronger system will then approach the region on Sunday resulting in
cooler temperatures and breezy conditions. This system will then
move across the state on Monday and Tuesday, resulting in a chance
of valley rain and mountain snow, as well as breezy to windy
conditions and cooler temperatures. Dry and warmer conditions are
expected behind this system in the Wednesday through Friday time
frame of next week.





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