Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 191741

Area Forecast Discussion
National Weather Service Grand Junction CO
1141 AM MDT Sat May 19 2018

.SHORT TERM...(Today through Sunday)
Issued at 252 AM MDT Sat May 19 2018

Another unsettled day in store as mid-level circulation will
remain over the area and interact with some minor instability and
CAPE firing off some convection, similar to yesterday. However,
available CAPE looks to be a bit higher and very short range
models are picking up on better coverage this afternoon.
Convection will begin around 11am and increase through the early
afternoon. All higher terrain in eastern Utah and western Colorado
looks susceptible to some convection though the northern valleys
do look favored for the strongest. Plenty of virga can be
expected but some of the stronger, more persistent, cells will
allow some rainfall to reach the ground. Gusty outflow winds can
also be expected from these cells. The higher elevations of the
central mountains, and to a lesser extent the San Juans, may also
see a few inches of snowfall but this will be above tree line and
shouldn`t pose much of a threat to any roads. Outside of the
higher elevations, scattered to occasional broken skies can be
expected which will keep temperatures a few degrees cooler than

As far as the synoptic scale is concerned, a deep trough will be
found from the Gulf of Alaska reaching down as far as Mexico. Some
ridging will be found over the northern Plains while another
trough will be situated over the Ohio River Valley. The trough to
our west will move little into Sunday but little wiggles in the
flow will allow another day of convection on Sunday. The GFS is a
bit more robust with this convection as opposed to the NAM but
both models do highlight some QPF over the region. Valleys will
see times of sun and clouds while the higher terrain remain
favored. Flow will also become southwesterly which will cause
temperatures to warm-up some.

.LONG TERM...(Sunday night through Friday)
Issued at 252 AM MDT Sat May 19 2018

Upper level low over southern Nevada will sit nearly stationary
through Tuesday driving deep southerly flow across much of eastern
Utah and western Colorado. Enough moisture will be in place to
trigger diurnally driven showers and thunderstorms over the
mountains with a few valley leftovers into the early evening
hours. The low fills and lifts northeast across Idaho and
northwest Wyoming with the remnants arriving over Montana late
Wednesday night. This will drive much drier weather into the area
on Wednesday. As the system kicks arrives over Montana, broad
trough will swing southeastward Thursday and Friday. This is
expected to drive a cold front through with an uptick on
convection once again as we close out the work week. Temperatures
will be running withing 5 degree of normal for most of the
forecast area through the extended period.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1141 AM MDT Sat May 19 2018

VFR conditions are expected to prevail at the airports through the
period. The only challenge is the diurnal and orographically
driven convection that has already taken off. Uncertainty
continues around whether any of the storms will move over airports
such as KASE, KEGE and KTEX. They should be at least in the
vicinity at KASE and KEGE. Due to lower instability near KTEX only
mentioned VCSH there. Dry low levels will support gusty outflow
winds which will have to be monitored for short term amendments.




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