Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 170903

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
303 AM MDT Mon Apr 17 2017

.SHORT TERM...(Today through Tuesday)
Issued at 237 AM MDT Mon Apr 17 2017

An area of low pressure will be moving over the northern Rockies
today causing widespread precipitation for the Pacific northwest
reaching Idaho and Montana later today. This low pressure will
put an end to our zonal flow as upper level winds shift to the
southwest allowing temperatures to climb thanks to warm air
advection. Winds will also start to increase as the gradient
tightens somewhat so another afternoon of some gusty winds is
expected with lighter winds down south and higher winds up north.
These winds, along with low humidities, have increased fire
weather concerns. These concerns will be discussed below in the
fire weather section. For today then, expect some high clouds,
gusty winds in the afternoon, and a bump in high temperatures.

On Tuesday, a jet streak will approach from the southwest and will
support a cold front at the surface. A few showers are possible
for extreme northeastern Utah during the day Tuesday though most
of the CWA will remain dry. Clouds will increase in the afternoon
from the northwest to southeast ahead of the front. If cross-
sections are to be believed, cloud heights will drop to between 10
to 15K feet, somewhat lower that seen over the weekend. Thickness
values and lowering heights indicate the front moving through
Tuesday evening and having moved through all of western Colorado by
Wednesday morning. As the greatest quasi- geostrophic forcing
remains to our west and then shifts north, frontal passage will
bring more showery precipitation than pronounced rainfall. Despite
that, can`t rule out some heavier showers and a few rumbles of
thunder along the front Tuesday evening.

.LONG TERM...(Tuesday night through Sunday)
Issued at 255 PM MDT Sun Apr 16 2017

The focus of the storm will remain across Wyoming but most
locations should see some short duration frontal precipitation
Tuesday night into early Wednesday as the cold front passes. Snow
levels will drop Tuesday night to around 9000 feet with the best
chance for moderate accumulations by late Wednesday over the
higher elevations across the north, with only light accumulations
expected in the central and southern mountains. After a brief
respite, another Pacific storm system will move across the area
later Thursday into Saturday with another round of valley rain and
higher elevation snow. This storm system appears to be slightly
colder than the mid-week system.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 237 AM MDT Mon Apr 17 2017

Clouds will be on the increase today but shouldn`t pose any
threats to aviation as they will remain well above ILS
breakpoints. Some gusty winds of 15 to 25 mph will occur this
afternoon and die down between 01-02Z.


Issued at 237 AM MDT Mon Apr 17 2017

Dry conditions remain in place across much of the CWA and the area
of low pressure well to our north will cause some gusty winds this
afternoon. Gusts of 25 mph or greater are expected for much of CO
fire weather zones 200 and 202 but with fuel still not critical
will not issue any fire weather highlights. Even so, if doing any
open burning today, take extra care.

On Tuesday, an approaching cold front with upper level jet support
will approach western Colorado. Forecast soundings indicate deep
mixing will allow winds and wind gusts to reach 20 to 25 mph if
not higher for CO fire zones 290 and 292 where fuels are critical.
Will issue a fire weather watch for Tuesday from 19Z to 01Z to
account for these conditions. Important to mention that much of
UT fire zone 490 will also see these same conditions but fuels, at
this time, are not critical so will hold off issuing anything for
that area.


CO...Fire Weather Watch from Tuesday afternoon through Tuesday
     evening for COZ290-292.



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