Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus65 kgjt 232117 

Area forecast discussion
National Weather Service Grand Junction Colorado
317 PM MDT Mon Oct 23 2017

Short term...(tonight through Tuesday night)
issued at 133 PM MDT Mon Oct 23 2017

Mostly sunny skies and dry weather dominate the weather picture
over The Four Corners region this Monday afternoon as a shortwave
trough departs to the east in the Great Plains. Some stronger
northwest flow aloft remains in place over the northern Colorado
mountains with some of the higher Ridgetop observing sights
gusting over 30 mph. 500mb heights have already begun to rise
area-wide, leading to a warmer afternoon today. In fact,
temperatures have already climbed above the average of 64 at Grand
Junction Airport. Expect mostly clear skies overnight tonight as
any lingering cirrus drifts south and east of the area. A large
ridge of high pressure will drift toward the region from the Great
Basin on Tuesday, bringing a sunny and dry day with temperatures
running around 5 degrees above average. Morning valley inversions
should mix out before noon, with light northerly flow in the
afternoon over the western slope.

Long term...(wednesday through monday)
issued at 133 PM MDT Mon Oct 23 2017

The ridge of high pressure will flatten somewhat on Wednesday as
our next storm system makes its way into the Pacific northwest.
Expect another warm and mostly sunny day, with afternoon flow
turning a little more westerly. Some high clouds will spill
southward into eastern Utah and western Colorado by early Thursday
morning as a trough heads southward through the northern rockies.
Winds will also pick up in the higher terrain on Thursday
afternoon as the upper-level gradient tightens in the north.

Global models have not been in great agreement regarding the
placement and depth of the next trough over the past few days.
Fortunately, today's 12z forecast runs are not quite as disparate.
However...the GFS still remains the drier solution with the European model (ecmwf)
depicting a deeper trough over the central rockies, and thus more
precipitation across a larger area. Have opted to favor the GFS
in this forecast package, as the European model (ecmwf) has trended drier in each
of the past four forecast cycles. The official forecast package is
now mostly dry through the frontal passage on Thursday afternoon,
with only light precipitation forecast in the northern and
central mountains. 700mb temperatures support snow levels in the
8000-9000 foot range in the mountains on Thursday. Any lingering
precipitation should end by sunrise on Friday will be limited to
the higher terrain along the Continental Divide as the trough
heads east across the plains. Dry weather will return to the
western slope for the weekend before another system approaches
from the north on Monday afternoon and evening.


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1130 am MDT Mon Oct 23 2017

All taf sites will have ceilings above ils breakpoints and VFR
conditions through the next 24 hours. Winds will be light and
driven by surrounding terrain.


Gjt watches/warnings/advisories...

National Weather Service Glossary of Abbreviations