Scientific Forecaster Discussion
fxus65 ktwc 291635
Area forecast discussion
National Weather Service Tucson Arizona
935 am MST Mon may 29 2017
Synopsis...there is a chance of afternoon and evening thunderstorms
east of Tucson into Thursday. Hotter than usual temperatures through
Tuesday will trend closer to seasonal normals Wednesday and
Thursday. Expect dry conditions with another warming trend next
Discussion...mostly sunny skies with a few cirriform clouds moving
across Southeast Arizona at this time. Dewpoints at lower elevations
valid 16z were generally in the 20s. However, dewpoints had risen
into the 40s from northern Cochise County northward into the White
Mountains. 29/12z ktwc sounding total precip water value of 0.31
inch was just 0.05 inch higher versus 24 hours ago. 29/12z upper air
plots depicted a ridge axis extending from central California
northward into British Columbia. Meanwhile, a weak southern branch
of the jet extended from near 30n/130w eastward across northern Baja
California and into Southeast Arizona, and light westerly flow
prevailed above 500 mb.
Surface wind speeds east of Tucson at this time are not as strong as
projected to be 24 hours ago. However, the dewpoint increase
especially near the New Mexico border and further northwest into the
upper Gila River valley including Safford arrived as advertised.
Have noted that the 29/12z univ. Of Arizona WRF-NAM depicts precip echoes
to develop by early this afternoon generally from Mount Graham
southwest of Safford southeastward to the northern portion of the
Chiricahua Mountains. These potential showers and thunderstorms are
depicted to move eastward later this afternoon, with the bulk of
this activity to be east of this forecast area this evening. The
29/12z nam12 is similar with this scenario.
Thus, see no reason to adjust the inherited official forecast that
depicts at least a slight chance of showers and thunderstorms this
afternoon generally east of a Mount Graham to Douglas line.
Otherwise, partly cloudy skies should prevail east of Tucson this
afternoon with mostly sunny skies from Tucson westward into the
western deserts. High temperatures this afternoon will mostly be a
couple of degrees or so warmer versus Sunday, and in turn will
average about 2-5 degrees above normal.
Please refer to the additional sections for further detail.
Aviation...valid thru 30/12z.
Expect scattered -tsra/-shra to develop by 21z from near ksad
southeastward to north of kdug. Expect any -tsra/-shra to be east of
the Arizona/nm border by 30/03z. Otherwise, few-broken clouds above 20k ft
above ground level ktus vicinity westward, and few-scattered clouds around 8k-12k ft above ground level
east of ktus. Surface wind variable in direction mostly less than 12
kts, although gusts to near 40 kts vicinity thunderstorms and rain. Aviation
discussion not updated for taf amendments.
Fire weather...increased moisture will bring a chance of mainly
afternoon and evening thunderstorms east of Tucson through Thursday.
Expect gusty and erratic winds due to thunderstorm outflows. Dry
conditions will prevail area wide Friday into Sunday.
Previous discussion /345 am MST/...surface dewpoints across SW New
Mexico early this morning are up 17 to 30 degrees versus 24 hours
ago. This moisture will continue to push west today under easterly
low-mid level flow into Graham, Greenlee and Cochise counties. This
will lead to a chance of mainly mountain thunderstorms east of
Tucson. With the low levels rather dry, the main threat from these
storms will be lightning and strong gusty outflow winds that may
produce localized areas of blowing dust. The outflow winds will also
push moisture further west overnight into Tuesday with the mountains
around Tucson getting into some action Tuesday afternoon/evening.
Negatively tilted upper level trof will move into the state on
Wednesday and be east of the area by Friday. Enough moisture across
the eastern areas for a continued chance for afternoon/evening
activity mainly near the mountains. Dry areawide next weekend.
A few degrees warmer today with similar high temperatures tomorrow.
High temperatures to close out may (wed) and start June (thu/fri)
will be at or slightly below normal. Highs next weekend similar to
Climate...the forecast high of 101 degrees today at Tucson
International Airport, if achieved, would be the warmest Memorial
Day since 2000 when the temperature reached 108 degrees. The hottest
high temperature in may for Tucson was recorded 107 years ago today
when the Mercury hit a blistering hot 111 degrees.