Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Grand Junction Colorado
348 am MDT Monday Mar 30 2015

Short term...(today through tuesday)
issued at 347 am MDT Monday Mar 30 2015

Sunday evening's radiosonde observation analysis indicated a fairly Flat Ridge across
the northern rockies with dry air across eastern Utah/western Colorado. The 00z-
08z satellite water vapor loop showed an upper low west of Baja California
pushing moisture into AZ/nm...while a northestern Pacific trough directed
moisture into southwestern Canada and through the northern rockies ridge. A
smaller upper low was moving from central California into southern with some
high clouds into southeast Utah and SW Colorado. A few lightning strikes were
noted over the Sierra-Nevada mountains and near the center of this low
last evening.

More unseasonably warm and mostly dry weather is on tap today and
Tuesday. The Baja California low is forecast to move east across northern Mexico and
stay well south of our area. Models show the southern Nevada low moving to NE
Arizona by this evening...looking at the 300 mb vorticity field. This
disturbance and strong surface heating will likely result in isolated
to perhaps scattered showers and a few high-based thunderstorms
mainly over the San Juans this afternoon into early evening.

Isolated mountain showers or thunderstorms are possible again on Tuesday
as a trough in the northern stream approaches. Expect an uptick in
wind gusts Tuesday afternoon as 700 mb flow increases in pre-frontal
warming ahead of the trough.

Long term...(tuesday night through sunday)
issued at 347 am MDT Monday Mar 30 2015

The midrange models are in better agreement this morning as
compared to previous model runs...though the GFS still carries
more amplitude in its shortwave features than does the European model (ecmwf).
Timing with all the models is more consistent as the ridge over
the western U.S. Slides east of the area Tuesday. The two things to
highlight for this week are the windy...warm and dry conditions
expected Wednesday and Thursday...and the significantly cooler
temperatures...especially low temperatures...Friday and Saturday.

A stronger cold front and trough move from the pacnw into the
northern rockies and western Great Basin by Tuesday afternoon. The
fastest easterly push of this front will be along the
U.S./Canadian border where the low center moves quickly east. The
surface front trails behind and is expected to drag through the
forecast area Wednesday and Wednesday night. A second trough and more distinct
wave on the frontal band is projected by the GFS to move through
Thursday afternoon and night. Much colder low temperatures are expected Friday
and Sat mornings.

The European model (ecmwf) shows the upper ridge recovering over the western U.S.
Sat and sun...while the GFS hints at the ridge briefly than sends
another trough and cold front into the Great Basin Sat night and
Sunday.

&&

Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 347 am MDT Monday Mar 30 2015

VFR conditions will prevail at taf sites through Monday night.
Isolated showers and weak thunderstorms are are expected to form over
the southern mountains after 19z today with gusty outflow winds
possible to about 35 miles per hour. The expected coverage is not great
enough to mention in the ktex taf at this time. Daytime mixing
will result in locally gusty surface winds after 20z and diminishing
after sunset.

&&

Gjt watches/warnings/advisories...
Colorado...none.
Utah...none.
&&

$$

Short term...jad
long term...cirrocumulus
aviation...cirrocumulus

National Weather Service Glossary of Abbreviations