Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 230355

Area Forecast Discussion
National Weather Service Tucson AZ
854 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...A storm system well to the north over Utah was
generating a band of mid/high clouds pushing across Arizona attm
ahead of a trough axis to our west over southern California/western
Arizona. This band of clouds will move east of the forecast area
late tonight/early Thursday morning as the trough axis pushes east
of Arizona, with clear skies expected Thursday.

Otherwise, warm high temperatures were reported across southeast
Arizona this afternoon, with most readings 10-15 degrees above
seasonal averages. In fact, broke a record high temperature at
Bisbee-Douglas Airport today, with a new record of 82 degrees (old
record was 80 degree set in 1982).

However, the record warmth is over for at least the next 7 days, as a
trough develops over the west with cooler northwest flow aloft
across the area. High temperatures the next 7 days are expected to
vary from several degrees below normal to right around normal. For
more on the forecast please refer to the prev discussion section
below. The forecast appears to be in good shape. No updates.


.AVIATION...Valid through 23/23Z.
FEW-SCT clouds around 15k ft AGL and SCT-BKN clouds AOA 20k ft AGL
til 23/10Z. Clearing skies aft 23/10Z. SFC WND generally WLY/NWLY
at 8-13 kts thru 23/16Z. 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.


.PREV 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.





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