Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 220905
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
305 AM MDT Tue May 22 2018

.SHORT TERM...(Today through Wednesday)
Issued at 304 AM MDT Tue May 22 2018

The area of low pressure remains to our west this morning and will
slowly shift to the north and open up as the day progresses.
There`s one little difference today that we`ve not seen over the
last few days: upper level support. An 80kt jet streak will round
the base of the low and move across our area today during max
heating which will create some divergence aloft. Simply put, more
widespread vertical motion is expected. Examination of forecast
Skew-Ts does show some steep lapse rates, MUCAPE close to 1300
J/kg, and DCAPE a bit above 900 J/kg. This all means that the
necessary ingredients are in place for some showers and storms
today with some being a bit stronger than seen recently. In fact,
SPC has placed an area of marginal risk for severe thunderstorms
over west central portions of the CWA...will be interesting to see
if the next update includes the same area as SPC forecasts can and
do change. That being said, as the low pressure and support moves
in, convection will fire down south first before spreading
northward through the afternoon and evening hours. The biggest
concerns will be gusty outflow winds though some small hail is
possible as mid- levels remain fairly dry from 18Z through 21Z
which is conducive to hail formation. Some heavier rainfall is
also expected. Convection will end by midnight though a few stray
showers here and there are possible.

Wednesday, the remnants of the open wave will have shifted to
Montana and Wyoming where another closed low will form. As all
support will have also shifted north, precipitation chances
decrease with the eastern Uintas looking favored for some showers,
maybe a quick storm, while the rest of the CWA stays dry.
Southwesterly flow will continue to usher in warmer temperatures
as highs inch upwards.

.LONG TERM...(Wednesday night through Monday)
Issued at 304 AM MDT Tue May 22 2018

Dry southwest flow aloft will continue Wednesday night following
the passage of the Great Basin trough to the north. A ridge will
develop over the Great Basin and slide east Thursday ahead of
another strong Pacific storm that will be approaching the
northern California coast. As this storm moves inland Friday and
Saturday, southwest winds at the surface and aloft will increase.
Sunday currently appears to be the day that winds will be strong
enough to combine with existing dry and warm conditions to raise
fire weather concerns.

The low center aloft wobbles over Utah through Sunday with its dry
slop planted over eastern UT and western CO and all its moisture
west of the low center. Through Monday, the GFS shows little
movement then finally it begins to move NE late Monday night.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 304 AM MDT Tue May 22 2018

VFR conditions will be the rule today though some showers and
thunderstorms may cause brief MVFR if they set up over, or close,
to TAF sites. All TAF sites will have a chance to see some
precipitation today though KTEX, KASE, and KEGE probably have the
best chances due to favorable orographics. Expect convection to
start firing at 18Z, give or take, reaching a maximum at 21Z that
will continue through 03Z. Small hail, brief, heavy downpours, and
gusty outflow winds will be possible near any showers or storms
that form.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...TGR
LONG TERM...CC
AVIATION...TGR



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