Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 291602
Area Forecast Discussion
National Weather Service Tucson AZ
900 AM MST Wed Mar 29 2017
.SYNOPSIS...Warmer today and Thursday under building high pressure
aloft. The next system will bring another chance of showers mainly
northeast of Tucson Friday through Sunday, along with strong and
gusty winds on Friday. A return to cooler temperatures Friday and
Saturday, then near normal early next week.
.DISCUSSION...12z 500 mb chart placed upper low over Texas Panhandle
with back edge of wrap around moisture across northern Greenlee
county. Moderate pressure gradient still exists over the area for
gusty NW breezes this afternoon. Warmer under abundant sunshine with
highs running 6-10 degrees warmer than Tuesday. Details for the
remainder of the forecast can be found in the previous discussion
.AVIATION...Valid through 30/12Z.
SKC areawide. Sfc wind less than 10 kts thru 29/18Z. Aft 29/18Z,
NWLY sfc wind at 8-16 kts, with the strongest wind in the upper Gila
River valley near KSAD. Aviation discussion not updated for TAF
.FIRE WEATHER...Afternoon breezes will continue today and
Thursday along with warmer temperatures. Another weather system will
then move in late Friday with gusty winds. Red flag conditions
possible Friday afternoon across far southern fire weather zone 152.
This system will also bring a chance of showers mainly northeast of
Tucson Friday through Sunday.
.PREV DISCUSSION...Shortwave ridging will crest across the area
tonight into early Thursday ahead of another stronger trough that
will impact the area Friday into the weekend. With the southwesterly
flow on Thursday, temperatures will be even warmer with highs
running about 6 to 9 degrees above normal. Expect just a few
afternoon breezes on Thursday as the pressure gradient starts to
tighten ahead of the next system.
The 00Z models are in pretty good agreement with the next trough
that will deepen into an upper low and track from the Great Basin on
Thursday towards the Four Corners region on Friday and then slowly
dropping south and east Saturday and Sunday across New Mexico. A
surface cold front will move through the area during the morning on
Friday, though perhaps into the early afternoon across far eastern
areas. Most of the deterministic guidance along with the SREF/GEFS
keeps the frontal passage dry but the ECMWF remains insistent on a
light QPF along the front as it draws in some moisture from the Gulf
of California. Have opted to keep most of the forecast area below
mentionable PoP thresholds except for Graham and Greenlee County but
future shifts will need to continue to monitor. Otherwise, with the
upper low to our north and an enhanced pressure gradient expect
breezy to windy conditions Friday afternoon, with the strongest
winds east of Tucson potentially exceeding advisory thresholds.
Temperatures will be cooler area-wide Friday with highs about 10 to
15 degrees colder than Thursday.
Some wrap around moisture is expected mainly northeast of Tucson on
Saturday and with a potential disturbance on the backside of the
upper low, some showers are possible once again for Graham and
Greenlee Counties. Most of the moisture should be off to our east on
Sunday but this will depend on just how fast the upper low moves
away from the area. Regardless, expect another cool day to start
April on Saturday with temperatures moderating on Sunday to near
normal as ridging starts to build in from the west. Thereafter, the
active pattern continues with another trough likely by late Monday
or Tuesday. Limited moisture again with the expected trajectory to
our north but winds could be on the breezy to windy side Monday and
Tuesday. Still plenty of time to iron out those details.
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