Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 112124
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
324 PM MDT Tue May 11 2021

.SHORT TERM...(Tonight through Wednesday night)
Issued at 257 PM MDT Tue May 11 2021

Satellite imagery and radar returns show an area of dissipating
scattered to broken clouds and isolated showers / storms over and
near the central / northern Colorado mountains.  Expect subsidence
under the northwest flow thanks to the ridge of high pressure
currently building over the western CONUS.  The remainder of the
short term forecast calls for clearing skies, warming temperatures,
and dry surface conditions.  Northwest flow aloft could promote a
few areas of breezy afternoon winds along while otherwise quiet
conditions prevail Wednesday.

Warming temperatures in the short term sit near to just below
normals across almost all of the CWA thanks to the ridge and
associated WAA.


.LONG TERM...(Thursday through Tuesday)
Issued at 257 PM MDT Tue May 11 2021

Ridging becomes a bit more shallow to start the long term period as
weak disturbances to our north flatten the ridge. As this occurs,
upper level flow remains westerly across our CWA. The thermal ridge,
however, will move overhead causing temperatures to continue
creeping upwards. By Friday, high temps will be 5 to 10 degrees
above normal across the region. As one would expect, dry conditions
will remain in place and with deeper mixing forecast, fire weather
concerns will start to increase. This trend will continue into the
weekend.

By Friday afternoon, a weak disturbance will move across, generally,
northern portions of the CWA and fire off a few showers/storms as it
moves through. This wave looks to pass through at peak heating and
with forecast CAPE values around 500 J/kg, there should be plenty of
energy to allow some convection. Unfortunately, with such a dry sub-
cloud layer in place, any precip that falls will evaporate before
hitting the ground.  The biggest result from any of these
showers/storms will be gusty outflow winds.

As the shortwave moves through, models continue to bring a trough
down from the PacNW and form a closed low by Saturday morning. By
late Saturday night, deterministic models show the low starting it`s
eastward move. The exact track varies a bit from model to model but
the end result keeps most of the CWA dry while northern Utah and the
Front Range get some precip. The low finally transitions into an
open wave by Monday evening and this looks to be the best chance for
any precip for the region. At the moment, precip looks to favor a
convergence zone that sets up over the northern half of the CWA.
Plenty of time for this solution to change and expect that it will.

The end result then, all areas will see increasing temperatures and
breezy afternoons and times of sun and clouds heading into the
weekend. Keep an eye on Monday evening (or thereabouts) for some
possible precip.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1136 AM MDT Tue May 11 2021

Low ceilings and visbilities will continue for KHDN, KEGE, KASE
and to a lesser extent KRIL through the afternoon hours. Some
light rain and snow and -TSRA remain in the forecast through 00Z
for those TAF sites mentioned above as a low pressure system
slowly moves eastward today. Conditions should slowly improve as
the afternoon wears on. For now, expect those same TAF sites to be
below ILS breakpoints and in the MVFR to IFR category. Other TAF
sites will remain VFR. After 00Z, skies will start clearing as
high pressure builds in. Some slight concern for morning fog
where most precip falls today but not nearly confident enough to
include in TAFs.


&&

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

$$

SHORT TERM...SS
LONG TERM...TGR
AVIATION...TGR


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