Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 231641
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1041 AM MDT Wed May 23 2018

.SHORT TERM...(Today through Thursday)
Issued at 225 AM MDT Wed May 23 2018

Much drier air is entering the region from the southwest,
evident on the low and mid level water vapor channel, as the
upper low responsible for the active stormy weather the past few
days lifts to the north and into the northern Rockies. Meanwhile,
the Front Range from eastern New Mexico to eastern Colorado is
dealing with an active stormy night/early morning as convection
refuses to go to sleep for the night. Enough moisture and
instability will remain up north to trigger afternoon thunderstorm
development today. Thinking the coverage will be a little more
robust than the models are depicting with areas along the
bookcliffs north of I-70 to the Wyoming border being the focus for
convective activity. Models also tend to be too quick to dry
things out as these upper lows move out of the region. A trailing
shortwave disturbance will also move through northeast Utah and
northwest Colorado, with a 80 kt upper level jet, which will act
as a trigger for convective activity. Expecting higher terrain to
be favored although a few storms could drift across the northwest
Colorado valleys as the shortwave moves through. Anticipate gusty
outflow winds to be the main concerns with storms as the low
levels still remain dry, with little in the way of wetting rains.
Mostly sunny skies will be the rule south of I-70 with some
convective buildups possible over the higher terrain; better
chances exists up north. Afternoon temperatures will climb to a
few degrees above normal with a noticably warmer day than
yesterday due to the lack of overcast skies and less shower
activity.

The ridge of high pressure continues to build across the Front
Range and central High Plains on Thursday as yet another trough
of low pressure makes its appearance on the west coast. This will
continue southwest flow across the region with temperatures making
a bigger jump well into the 80s for most lower valleys, with highs
approaching low 90s for some portions of southeast Utah. Dry
conditions look to dominate the western slope with a slight chance
of thunderstorms over the northern mountains closer to the Wyoming
border (eastern Uintas and Elkheads/northern Park range).

.LONG TERM...(Thursday night through Tuesday)
Issued at 225 AM MDT Wed May 23 2018

The blocky pattern will remain in place across the Lower 48
through the extended period with the stronger jet stream located
well to the north. Ridging will become well established over the
Rockies by Thursday night and will really slow the next upstream
system which may not bring any precipitation until late in the
weekend or not at all depending on which model ultimately
verifies. Warm and dry southerly flow will lead to a high
probability of well above temperatures Friday into Saturday with
only a slightly lower probability going into Sunday for the same
reason as above. The storm will move into the Great Basin by early
Sunday and then basically stall due to the downstream block, a
relatively common theme late this Spring. So as rain falls back to
the West, windy conditions will develop over our CWA this weekend
and this will exacerbate critical fire weather conditions where
fuels have not greened up or retained much moisture. QG structure
of the system centered near the UT/NV border remains well out of
phase with the GFS taking on a more E-W configuration and the EURO
more N-S and compact. Still little confidence going past Saturday
but the general theme would be slight cooling by Sunday into
early next week as the thermal ridge is pushed more into the High
Plains. The probability of precipitation during this time is
likely higher near the Wyoming border and close to zero near the
New Mexico border. Don`t shoot the messenger.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1041 AM MDT Wed May 23 2018

Isolated to scattered showers and thunderstorms are expected to
develop over the northern mountains early this afternoon then,
once formed, will continue through 02Z this evening. This activity
poses little threat to TAF sites, though KVEL and KHDN may
experience brief and unpredictable outflow winds from storms over
higher terrain in the vicinity. Otherwise, VFR conditions will
continue through the next 24 hours with CIGS above ILS breakpoints
at all TAF sites.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...None.
UT...None.

&&

$$

SHORT TERM...MDA
LONG TERM...15
AVIATION...NL


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