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National Weather Service Grand Junction Colorado
428 am MDT sun Apr 19 2015

Short term...(today through monday)
issued at 425 am MDT sun Apr 19 2015

Clearing skies late tonight helped fog to form in the Colorado River
valley...with patchy dense fog near Rifle. Have issued a dense fog
advisory until 10 am MDT for the Colorado River valley and Interstate 70
from Delaware beque to Silt.

500 mb hand analysis at 00z showed a welcome kicker wave dropping into
the northern High Plains with a well defined tropopause fold showing up in
in water vapor as well. The stagnant low was located over east
central Colorado at 00z and satellite trends suggest it is finally
beginning to push east late this evening with the better height
falls over southern Kansas. There is a thin line of well defined
moisture wrapping around the back side extending from the park to
the Elk Mountains. This will keep snow pinned up against The Divide
through the early morning hours but dendritic layers will be drying
out and ascent shifting east as the northern trough swings into the
eastern Dakotas by sunrise. Boundary layer remains moist and will
help form stratus and fog through middle morning in several valleys but
so far any dense fog appears very localized. A warmup can be
expected the next few days as we push this low out of the
region. This warm-up will be tempered by increasing northwest flow
aloft...a result of the current northern stream trough deepening over
the western Great Lakes. Highs will stay below normal into early
week as a result with lows flirting with freezing in the Cortez
region. Instability this afternoon combined with residual moisture
leads to isolated showers developing over the northern and eastern
terrain today with a rumble of thunder more likely in the south. A
progressive wave moves through Wyoming toward northern Colorado late
tonight and across the region early Monday. Cross sections show
moisture staying mainly above mountain top level with the lift
better organized to the northeast of our County Warning Area. However the northerly
orographics favor some light snow over the northern mountain ranges
to highest probability of precipitation there and low confidence elsewhere.

Long term...(monday night through saturday)
issued at 425 am MDT sun Apr 19 2015

By Monday evening the main upper low will be over the Great Lakes
with the last weak shortwave trough sliding through the area
Monday the northwest flow left in the low's wake. Moisture
content decreases incrementally with some showers expected along
the Continental Divide and an old frontal boundary backing up
against the Front Range and Continental Divide through Tuesday.

Tuesday and Wednesday should be relatively dry as a transitory ridge moves
over the area...through the old frontal boundary should still act
as a focus for showers near the Continental Divide. The next big
trough will move onshore over Southern California Wednesday night and the midrange
models carry it fairly quickly east-northeast and into The Four Corners
region by Thursday night. The low moves overhead Friday and Sat and have
gone with more cloud cover and a high chance of precipitation through
both days. The storm appears cold enough for another bout of
mountain snow Friday night and Sat.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 425 am MDT sun Apr 19 2015

As low pressure continues moving east today the remaining
scattered snow showers over the eastern Utah and western Colorado mts will
also gradually decrease today through tonight. Mountain
obscurations will continue but become less widespread tonight.

Patchy fog this morning in most valleys will bring occasional
MVFR visibilities and ceilings to kgjt...kmtj and kase...while kril will
have IFR/LIFR ceilings and visibilities in dense fog until about 16z.


Gjt watches/warnings/advisories...
Colorado...dense fog advisory until 10 am MDT this morning for coz007.



Short term...15
long term...cirrocumulus

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