Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 190320
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
920 PM MDT Tue Apr 18 2017

.UPDATE...
Issued at 919 PM MDT Tue Apr 18 2017

Critical fire weather conditions have eased up this evening as
relative humidity values climb back above 15 percent in the lower
valleys. Still expect periods of gusty winds through late tonight
as we see the cold front to our northwest push across the area.
Convection along the front will help to mix stronger gusts (up to
45 mph) down to the surface. Showers will also be on the increase,
become slightly more efficient at producing rain as the evening
wears on. Will be adjusting pop and wind grids to fit trends for
the next few hours. Front clears the forecast area Wednesday
morning with showers lingering across the north.

&&

.SHORT TERM...(Tonight through Wednesday night)
Issued at 402 PM MDT Tue Apr 18 2017

A weak shortwave on the nose of an easterly oriented jet streak
will drive a weak cool front across northeast Utah early this
evening. Convergence along the front combined with mid and high
level upward dynamic forcing will bring numerous showers and
embedded thunderstorms to the eastern Uinta mountains, eastern
Uinta Basin and portions of northwest Colorado this evening. The
shortwave pushes to the divide late tonight driving the cool front
to the I-70 corridor. In response, showers will overspread
northwest and central Colorado with little or no chance for
precipitation in the south.

Scattered showers will linger along Colorado`s northern and
central Divide mountains Wednesday. Despite partial clearing,
afternoon highs will be cooler on Wednesday, especially north of
the stalled front in the vicinity of the I-70 corridor. A shallow
transient ridge forms over the region Wednesday night while drying
continues. Overnight lows will be colder but do not pose a threat
of freezing temperatures in the lower valleys.

.LONG TERM...(Thursday through Tuesday)
Issued at 402 PM MDT Tue Apr 18 2017

Temperatures moderate and winds pick up from the southwest again
on Thursday ahead of the next Pacific system. Moisture running
out ahead of this storm is expected to generate scattered showers
and thunderstorms over the mountains during the afternoon. Shower
activity increases Thursday night as the negatively tilted trough
moves overhead and drives a cold front southeastward across the
forecast area. Precipitation becomes likely over the northern and
portions of the central Colorado mountains Thursday night and will
continue on Friday in the northwest flow on the backside of the
system. Models indicated this will be a pretty cold system and
snow becomes a concern, especially for the Elkhead and Park
Mountains and Flat Tops. Latest guidance suggests from 4 to 8
inches are possible above 8500 feet with snow possible down to
mountain bases Friday morning. Activity in the valleys and
southern mountains will be more scattered in nature with little
chance of precipitation for the Four Corners region.

Ridging and drying in store this weekend which will allow
temperatures to recover from below normal Friday, to well above
normal Sunday. Models showed a couple of weak transient
disturbances will pass to the north of the forecast area bringing
a slight chance for showers along the northern borders of Utah and
Colorado early next week along with breezy afternoon winds.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 919 PM MDT Tue Apr 18 2017

A cold front will pass through the region between 06z and 18z with
gusty winds and showers expected along and behind the front. Wind
gusts to 50 kts will be possible near showers with speeds quickly
diminishing after the front moves through. Showers linger over the
northern and central mountains in western Colorado trough
Wednesday afternoon with clearing and calming weather moving in
after 00Z/THU. ILS cigs are expected at most sites as the front
moves through with local MVFR cigs near showers. Ceilings lift
back above ILS thresholds by midday Wednesday at all but KASE and
KEGE, where clouds are expected to linger through the afternoon.

&&

.FIRE WEATHER...
Issued at 919 PM MDT Tue Apr 18 2017

Expect breezy, pre-frontal winds winds through this evening.
Relative humidity values have improved with critical fire weather
conditions easing a bit. Do have one active fire of note east of
Buford, CO. which we are picking up on the non-operational and
still preliminary GOES 16 satellite imagery. Social media posts on
our sites show some of the hotter pixels that were picked up.

Wednesday will see improved fire weather conditions with lighter
winds, but things fall apart again on Thursday as another system
approaches from the west. Models indicated southwest winds will
strengthen as dew points fall during the day. However, both GFS
and ECMWF models indicated some shower activity, mainly over the
mountains Thursday afternoon which may result in slightly higher
dew points. Given uncertainty, will issue a Fire Weather Watch for
the same areas listed previously. FMO`s are encourage to assess
fuels before Thursday for possible inclusion in future fire
weather highlights.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Fire Weather Watch from Thursday afternoon through Thursday
     evening for COZ203-207-290-292.

UT...None.
&&

$$

UPDATE...JDC
SHORT TERM...NL
LONG TERM...NL
AVIATION...JDC
FIRE WEATHER...NL/JDC



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