Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 260325
Area Forecast Discussion
National Weather Service Tucson AZ
825 PM MST Sat Mar 25 2017
.SYNOPSIS...Expect dry conditions with mild daytime temperatures
and some gusty afternoon winds through Monday. A low pressure system
will then bring cooler temperatures and a chance of showers Tuesday
and Wednesday. Dry and warmer Thursday before the next system
provides another chance of showers and cooler temperatures Friday
into next Saturday.
.DISCUSSION...Upper level speed max (26/00Z KTWC sounding and upper
level plots depicted 70-90 kt speeds between 300-200 mb) was
bringing mostly cloudy to cloudy skies to southeast Arizona at this
time. The 25/18Z GFS depicted this system quite nicely. The bulk of
these clouds based on this solution and per satellite trends (clear
skies or mostly clear skies upstream across southern California
presently) should move east of this forecast area by around 26/09Z
The official forecast was updated for increased cloud cover this
evening versus the previous forecast, then a trend toward mostly
clear skies or even clear skies later tonight and by daybreak
Sunday. Surface winds will continue to diminish as well during the
next few hours.
Please refer to the additional sections for further detail.
.AVIATION...Valid through 27/06Z.
Broken to overcast clouds above 20k ft AGL followed by clearing
skies after 26/06Z. Clear skies to scattered clouds above 20k ft AGL
Sunday and Sunday evening. Surface wind diminishing to less than 10
kts most sections by 26/08Z and continuing into Sunday morning.
Surface wind wly/nwly 10-16 kts with gusts near 20 kts Sunday
afternoon and Sunday evening. The strongest speeds will be east of
KTUS. Aviation discussion not updated for TAF amendments.
.FIRE WEATHER...A series of weather systems will bring gusty winds
at times over the next 7 days. The strongest winds are expected
Monday and Tuesday afternoons and next Friday. Otherwise, expect dry
conditions through Monday followed by a chance of showers mainly
north and east of Tucson periodically from Monday night through next
.PREV DISCUSSION /235 PM MST/...The upper pattern is defined by a
closed upper low over MO, a trough moving through the Great Basin,
and a longwave ridge of high pressure in the Eastern Pacific.
Southeast Arizona resides on the southern periphery of the trough,
with the latest satellite imagery indicating the wedge of high
clouds have since moved east into New Mexico.
The main impact of this system will be breezy conditions, especially
to the southeast of Tucson. These winds, in combination with the dry
airmass already in place will result in very localized and brief
critical fire weather conditions late this afternoon. This is a very
borderline situation, so we currently do not have a Red Flag Warning
Otherwise, Southeast Arizona will be impacted by a few weather
systems over the next week. The first system will move through
northern Arizona Tuesday and Wednesday, bringing with it a chance of
light valley rain to our forecast area, and even a few inches of
mountain snow to higher elevations of the White Mountains. The
majority of the GEFS member plumes for QPF indicate this system will
generally bring less than a tenth inch of rain to Tucson, with
slightly higher amounts farther NE (less than a quarter inch in
The second system will move into the area Friday into Saturday.
Still some differences between the GFS and ECMWF on the strength and
duration of this feature. The 25/12Z GFS is much more bullish with
this system, and the 25/12Z ECMWF run, which had been more
progressive, has now come more in line with the GFS solution. This
system is stronger and colder than the first system. The main impact
will be strong gusty winds Friday along with a chance of showers
Friday and Saturday.
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