Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 261748

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1148 AM MDT Wed Jul 26 2017

.SHORT TERM...(Today through Thursday)
Issued at 242 AM MDT Wed Jul 26 2017

Convection continued during the night along an elongated vort
lobe from northern Grand County in eastern UT to Routt County in
western CO. Expect this convection to weaken and decrease during
the morning hours as the vort lobe should weaken and lose its
identity. Also some convection persisted in west-central CO
associated with a disturbance embedded in the flow just south of
the vort lobe, and this activity should exit our CWA by sunrise.

As the already elongated upper high extending from NM to AR is
expected to further elongate westward, our CWA will be under a
more westerly flow aloft today and Thursday which will suppress
the flow of subtropical moisture for our area. However, the flow
aloft over eastern UT and western CO should be relatively light
which should allow residual moisture to remain over our CWA.
Models indicate PWATs to be around an inch or a little higher
today across our CWA, with little change on Thursday. So still
expect at least scattered showers and thunderstorms through
Thursday mainly in the afternoon and evening hours, with locally
heavy rain possible. However, since any heavy rainfall should be
only localized, no FFA should be needed today or Thursday.

.LONG TERM...(Thursday night through Tuesday)
Issued at 242 AM MDT Wed Jul 26 2017

Strong high pressure should be over the region Friday and
Saturday with models indicating main concentration of diurnal
showers and thunderstorms for our CWA to be over SE UT and
W-Central/SW CO, favoring mountains. This appears to be similar to
the situation experienced over our CWA last weekend. However,
models are indicating a little seepage of subtropical moisture
back into the southern portion of our CWA on Saturday.

GFS and EC then surge subtropical moisture northward into our area
beginning Saturday night, continuing through Monday. The models
then decrease the subtropical moisture some on Tuesday, though
each model has a different reason for the decrease. So, not a lot
of confidence for significant changes on Tuesday. Lowered the max
temperatures at least several degrees for many locations and
raised the min temperatures from blended model solution starting
Saturday night. If this monsoonal surge still looks to be on
track for later shifts, then later shifts should take a look at
the temperatures that will be input to our grids from the blended
models, as they will likely need to be adjusted back to something
similar as what was done during this shift.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1121 AM MDT Wed Jul 26 2017

VFR conditions will prevail early this afternoon. Low clouds
associated with morning showers have scattered out and afternoon
convection has commenced. Later today, a few showers and
thunderstorms may affect some higher altitude terminals, however
coverage is expected to be less than on Tuesday afternoon.
Mountains near terminals may be obscured by any precipitation
and/or low cloud early this evening.




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