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Area forecast discussion 
National Weather Service Grand Junction Colorado
1033 am MDT Thursday Oct 30 2014

Short term...(today through friday)
issued at 405 am MDT Thursday Oct 30 2014

The ridge axis over the Great Basin will shift overhead during the
day causing temperatures to rise well above normal this afternoon.
With the exception of patches of middle and high clouds...skies will
be sunny with relatively light terrain driven winds.

No surprises in the first part of the forecast tonight into
Friday as models have been consistently amplifying the ridge over
The Rockies tonight...then shifting it into the High Plains on
Friday. This subtle shift will be due to a rather
strong...elongated trough arriving to the left coast of the Continental U.S..
the anti cyclonic center of the ridge was hand analyzed at 00z
near the Arizona/nm and Mexico border. As the ridge builds and
translates east this circulation shifts to the lower Rio Grand
Valley. 305k Theta surface show moisture surging northward out of
this region on the back side of the circulation. Ample moisture
will be focused in the western Gulf due to a cold front currently
settling into this region. The nose of this moisture moves into
the 4 corners by late Friday but will only be noticeable by an
increase in high level cloudiness toward sunset. Temperatures
during this period will remain above normal.

Long term...(friday night through tuesday)
issued at 405 am MDT Thursday Oct 30 2014

Significant height falls to our west will result in a
strengthening southerly middle level jet. This in turn leads to more
robust moisture advection over eastern Utah and western Colorado
this weekend. Precipitable water increases to near 0.65 12z Saturday...which
for late October is at least 150 percent of normal. Large scale
ascent is initially lacking with qg forcing focused over the
eastern Great Basin. However orographics and moist upglide will
eventually lead to showers breaking out over the southern
mountains and adjacent foothill valleys during the early morning
hours. The qg forcing lifts northeast of our County Warning Area but increasing
instability in the afternoon will cause showers to spread
northward...with the terrain still favored. An uptick in winds
will definitely be felt on Saturday as the instability aids in
mixing down the stronger middle level winds. This mixing looks to add
some dry air into the picture and models are leaning toward a
downtrend in quantitative precipitation forecast during the afternoon in response. However...
confidence in this scenario was wavering with precipitable water as high as it
is. So for now will stay with going forecast. Temperatures remain
above normal during these periods as well.

A cold front associated with this system is prognosticated to plow
through the region Saturday night into Sunday with the GFS more
progressive than the European model (ecmwf). Snow levels are indicated to fall to
near 7500 with frontal passage and the higher elevations may see snow
accumulations near 6 inches in some areas. Both models generate a
split in the flow eventually cutting off a low over the Desert
Southwest. Showers should continue off and on in the col between
the northern flow and the southern low on Monday before drying
arrives Tuesday. Quiet weather continues into Wednesday as a ridge
of high pressure redevelops over the west. Expect markedly cooler
temperatures in the wake of frontal passage Sunday and Monday with warmer
temperatures at midweek.


Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1030 am MDT Thursday Oct 30 2014

VFR conditions under mostly clear skies and light winds will
prevail the next 24 hours.


Gjt watches/warnings/advisories...


long term...15/nl

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