Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 191739
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1139 AM MDT Wed Apr 19 2017

.SHORT TERM...(Today through Thursday night)
Issued at 318 AM MDT Wed Apr 19 2017

Latest observations indicate the cold front has passed Vernal,
Utah over the last few hours but hasn`t reached as far south as
the Grand Valley. This is fairly obvious due to a temperature of
49F in Vernal while Grand Junction is still at 62F (was just about
to send this AFD and noticed the temperature has dropped to 43F
in Craig while Meeker remains at 52F so the front is somewhere
between the two). Quite a difference. Plenty of returns can be
seen on the radar from about Nucla and Montrose northward while
sensors are reporting some light rain at the Nucla airport and
Meeker at this hour so some precipitation is reaching the ground.

For the remainder of the early morning hours, short range models
show the front continuing to drop to the southeast and will be
draped along the I-70 corridor around 6AM or so and then washing
out quickly a few hours after that as upper level support wanes.
Some showers will likely continue over the northern mountains and
Flat Tops through the early afternoon hours thanks to favorable
flow with maybe an inch or two of snow possible for the highest
elevations. Outside of those areas, expect clouds to start lifting
in the afternoon while high temperatures drop several degrees
from what was seen yesterday.

A quick transitory ridge will move over the region late tonight
but by Thursday morning it will have shifted to the east thanks
to the next weather system. As the next trough approaches, winds
are expected to increase yet again though the strongest winds
looks to be from the Uncompahgre Plateua southward. A weak pre-
frontal shortwave will likely kick off some very isolated showers
and a few storms from mid-morning onwards with an increase in
coverage from about 6PM onwards as the trough and cold front
become the focus for precipitation. The San Juans and areas south
look to stay relatively dry while areas north are favored in this
regime. Important to note that H7 temps drop to between -2 to -4F
late Thursday night with models highlighting some snow over the
northern mountains and Flat Tops. Amounts look to be in the 4 inch
range but any convection could put down an additional few inches
in a very short time. Later shifts will need to keep an eye on
this possibility.

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

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 18Z TAFS through 18Z Thursday afternoon)
Issued at 1139 AM MDT Wed Apr 19 2017

Scattered showers with a few embedded thunderstorms will continue
over the northern and central Continental Divide this afternoon.
A shower is possible at KASE early this afternoon which could
result in a brief period where CIGS fall below ILS breakpoints.
Otherwise, TAF sites will experience VFR conditions and CIGS above
ILS breakpoints through the next 24 hours.

&&

.FIRE WEATHER...
Issued at 318 AM MDT Wed Apr 19 2017

As another system moves in Thursday raising fire weather concerns.
Models indicate 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
continued uncertainty, a Fire Weather Watch remains in effect.
FMOs are encouraged 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.

&&

$$

SHORT TERM...TGR
LONG TERM...NL
AVIATION...NL
FIRE WEATHER...TGR



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