Weather Service Report

FXUS65 KGJT 200951

Area Forecast Discussion
National Weather Service Grand Junction CO
351 AM MDT Sat Oct 20 2018

.SHORT TERM...(Today through Sunday)
Issued at 351 AM MDT Sat Oct 20 2018

High pressure centered over the Central Rockies will bring more
dry and warmer weather to Eastern Utah and Western Colorado today.
Expect light winds and plenty of fall sun across the board with
temperatures warming to near seasonal norms by this afternoon.

The ridge axis will shift east tonight allowing high clouds to
spread northeast through the Four Corners and across much of
western Colorado by early Sunday morning. The increase in high
cloud cover will help to moderate overnight lows in most areas to
bring a break from the colder mornings of late. 

Moisture will steadily increase through the day on Sunday with an
upper low strengthening off the central coast of California. This
low will eventually drive eastward into the Great Basin to bring 
more unsettled weather into the area by early next week. Cannot
rule out a few stray showers on Sunday across the higher terrain
with focus across eastern Utah, but potential remains low at this
time. Temperatures on Sunday will continue to nudge up, 
approaching 70 in the lower valleys. 

.LONG TERM...(Sunday night through Friday)
Issued at 351 AM MDT Sat Oct 20 2018

On Sunday night the models are in fair agreement that a vorticity 
maximum will round the base of the main trough over the Great Basin. 
The forcing for ascent is not relatively strong, but steeper 
midlevel lapse rates above increasing low-level moisture from the 
Gulf should contribute to some instability. The main forcing appears
to coincide with peak heating in the afternoon so showers and 
thunderstorms chances increase into the day Monday. Given the warm
south-southwesterly flow snow levels should be above 10,000 ft 
although may lower to 8500 ft Monday night with the nocturnal 
cooling as well as within any convection. The more favored areas 
for precipitation on Monday seem to be southeast Utah, southwest 
and central Colorado. 

The models are also advertising another shortwave rounding the
base of the main trough during the day Tuesday. Expect scattered
to widespread precipitation with modest lift moving over the
forecast area. Although there are some spatial-temporal 
difference with this wave so placement and timing could change. 
Given the current timing the amount instability could be limited 
by cloud cover and lapse rate contamination, but the moisture 
looks to be more robust. On Wednesday the favored upslope in the 
westerly flow should ring out the residual moisture in the form of
isolated to scattered showers mainly in the higher elevations. 
The quick moving trough arrives Friday bringing another round of 
precipitation along the divide.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 351 AM MDT Sat Oct 20 2018

VFR conditions expected at all sites through Sunday morning with
light winds and mostly clear skies. 





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