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Area forecast discussion 
National Weather Service Grand Junction Colorado
1100 am MDT Monday Oct 20 2014

Short term...(today through tuesday)
issued at 242 am MDT Monday Oct 20 2014

Clouds and showers have dissipated overnight giving way to mostly
clear skies. However...the low pressure...or open wave depending
on which model being looked at...remains to our south and will
allow some moisture to advect into the region. The end result will
be very similar to yesterday with showers and thunderstorms once
again favoring the San Juans and central mountains from noon
through evening hours. Plenty of sunny skies outside of this
precipitation with temperatures remaining warm though this changes tomorrow.

For this evening...thunderstorms will be limited mainly to the
Colorado southern and central mountains but in response to the trough
working into Nevada...strengthening southeast gradient winds across the
south will bring moisture advection with storms and showers
increasing in southeast Utah and SW Colorado by midnight and beyond.

Tuesday the NAM is deeper with the trough but all models begin to
lift the best forcing to the NE across Idaho. This would generally
limit showers in this forecast area but for the deep moisture over
the region. Precipitable water values rise to over 0.9 inches
which is impressive for late October. Showers will spread across
the forecast area with the best rainfall expected along south-
facing slopes. Cloudy skies will limit instability for isolated
embedded thunderstorms expected within widespread showers. Snow
levels remain high with 700mb temperatures at 5c or warmer. Still
convection will drive snow flakes lower to around 10kft but with
little survivable accumulation. Breezy southeast-SW winds expected with

Long term...(tuesday night through sunday)
issued at 242 am MDT Monday Oct 20 2014

The trough lifts NE through Wyoming-Montana with the entrance tail
of the 50kt jet dragging across the north overnight. This brings
cold advection and a surface front across the region overnight into
Wednesday morning for the best chance of showers and storms. Snow
level will drop to around 8500-9500ft overnight but rises again on
Wednesday. Drier air begins to work into NE Utah on Wednesday that
ends showers from west to east through the day. The last showers
end by midnight along the Continental Divide. Snow accumulations
of up to 6 inches are expected over the higher Colorado mountains with
clearing skies a cool night is expected Wednesday night.

Benign weather sets up Thursday and continues into the weekend as
high pressure builds in. The jet stream will take aim at the Pacific
northwest during the period and will shunt the ridge axis to the plains
while we stay under SW flow keeping temperatures above average. A deep
trough comes ashore Saturday and looks to move across the County Warning Area
Sunday bringing some precipitation for mainly the northern half of the area.
Ec and GFS in fairly good agreement but with this event so far expect some changes in the coming days.


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1100 am MDT Monday Oct 20 2014

Expect VFR conditions to continue at taf sites through the next 24
hours. However...there will be scattered showers and a few
thunderstorms over the central and southern mountains this
afternoon and evening. This activity will result in localized
mountain obscuration and gusty outflow winds. There is a 20 to 30
percent chance that this activity could impact taf sites late this
afternoon through 04z/tues...though flight rules should remain


Gjt watches/warnings/advisories...




Short term...tgr/Joe
long term...Joe/tgr layers

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