Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 210445

Area Forecast Discussion
National Weather Service Tucson AZ
945 PM MST Feb 20 2017

.SYNOPSIS...Dry conditions will prevail through Saturday. Expect
much warmer daytime temperatures Tuesday and Wednesday before
temperatures return to seasonal normals Thursday and Friday. A
slight chance of valley rain and higher elevation snow may then
occur early next week.


.DISCUSSION...Clear skies prevail at this time along with light
winds. Based on satellite trends as well as the 21/00Z NAM/GFS...
the inherited official forecast was updated to depict clear skies
the rest of tonight, and for most locales into Tuesday morning.
Perhaps some cirriform clouds will encroach upon the area from the
northwest Tuesday afternoon. Markedly warmer temperatures will occur
Tuesday, with forecast high temperatures to range about 10-15 degs
warmer versus temps that occurred this afternoon.

Please refer to the additional sections for further detail.


.AVIATION...Valid through 22/06Z.
Clear skies into Tuesday morning followed by a FEW or perhaps SCT
clouds above 25k ft AGL encroach upon the area from the northwest
Tuesday afternoon and evening. Surface wind will be variable in
direction mostly less than 12 kts into Tuesday evening. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions will prevail through Saturday
followed by a slight chance of valley rain and higher elevation snow
early next week. Much warmer temperatures will occur into Wednesday
followed high temperatures returning close to seasonal normals
Thursday and Friday. 20-foot winds will generally be less than 15
mph during much of the upcoming week, although occasional afternoon
gusts will occur.


.PREV DISCUSSION /245 PM MST/...Lingering moisture in the form of
mainly flat-topped cumulus is creating mostly sunny to partly cloudy
conditions this afternoon. Surface temperatures have rebounded
nicely compared to yesterday, with values around 6 to 12 degs warmer
than 24 hours ago. With the last storm system well to our east and
strong ridging building in behind it, a quick warm up will continue
into Tuesday and Wednesday. Daytime high temps should reach values
approximately 7 to 10 degs above normal each afternoon. Look for
mostly sunny skies on Tuesday with some increasing cloudiness from
the west/northwest Wednesday afternoon ahead of a weak disturbance.

There is now fairly good agreement with the track of the
aforementioned shortwave trough. It is expected to swing south out
of the Pac NW and through the Great Basin Wednesday night into
Thursday, with any appreciable moisture remaining north of the area.
However, a tight pressure gradient aloft will help to produce some
gusty west/northwest winds Thursday afternoon, especially near the
AZ/NM border. With the last couple runs of both the GFS and ECMWF
coming in dry, have opted to remove any mentionable PoPs from the
forecast in association with this system. Therefore, dry conditions
are forecast to continue into the upcoming weekend, with zonal flow
setting up Friday into Sunday and daytime temps hovering within a
few degrees either side of normal.

Sunday afternoon into next week, we`re still watching the potential
for another disturbance pushing through the region. However, with
only slightly improved model consensus between the GFS/ECMWF, no
major changes were made with regard to PoPs. It looks as if the bulk
of moisture will hold off until at least Monday. If nothing else, we
should still see another uptick in west/southwest winds, especially
Sunday afternoon.






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