Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 220513
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1113 PM MDT SAT MAY 21 2016

.UPDATE...
Issued at 917 PM MDT Sat May 21 2016

Light rain being reported at Vernal underneath area of radar
returns in northeast Utah and northwest Colorado. Updated pops to
increase coverage and chances of showers across these areas as
NAM12 picking up on this very well. Seems to be some sort of
frontal feature hung up on the bookcliffs with the boundary
stretching from Moab to Craig, as evidenced by a wind shift to
northwest behind it and southwest winds in front of it. The jet
is riding on top of this front, causing some overrunning
precipitation in northeast Utah and northwest Colorado. Expect
showers to continue through 3 am before winding down as this
feature lifts northward.

UPDATE Issued at 804 PM MDT Sat May 21 2016

Winds have decreased substantially across much of the region with
the valleys seeing gusts in the 10s and 20s and mountains seeing
gusts in the 20s and 30s. Some higher gusts are still occurring in
the southeast Utah mountains with gusts peaking around 50 mph at
Abajo Peak. Winds should lessen as the sun sets and clouds
increase, therefore, have allowed the wind advisories to expire at
8 pm MDT.

&&

.SHORT TERM...(Tonight through Sunday night)
Issued at 229 PM MDT Sat May 21 2016

Large trough sprawled across the western US will remain nearly
stationary over the next 24 hours. Associated 110kt jet aloft will
remain centered over eastern Utah and northwest Colorado keeping
winds elevated through Sunday. Short term MOS guidance indicates
some decoupling in protected valleys tonight but wind guidance
remains near 5 to 15 mph sustained throughout the night. A subtle
cold front associated with the trough will brush the area late
tonight towards morning.

The low center that was to our west today will shift northeast
through Sunday. While strong southwest flow aloft will remain
stretched over the area through the day, it is expected to relax
somewhat. Breezy conditions will again develop at the surface Sun
afternoon, but winds will not expected to be near as strong as
the last couple of days. The far north, especially the Uinta
Mountains, will see a a better chance of showers and afternoon
thunderstorms, with isolated convection possible for the other
mountains. Otherwise, most of the area will remain dry. Cooler
temperatures are expected behind the cold front, with below normal
highs. Nighttime lows Sunday night will also be below normal and
quite a bit cooler than tonight`s.

.LONG TERM...(Monday through Saturday)
Issued at 229 PM MDT Sat May 21 2016

Additional low pressure energy over the Pacific Northwest will
keep a mean long wave trough over the western CONUS through the
period. The flow will remain from the southwest through midweek,
with typical springtime afternoon breezes. One embedded shortwave
passing on Tue will increase winds somewhat, and may bring a
slight chance of showers/afternoon thunderstorms mainly to the
northern portion.

Then a better defined low pressure system will break off from the
mean trough during the second half of the week. While forecast
details are still uncertain, this will result in a better chance
of showers and late day thunderstorms on Thu and Fri. Models
indicate conditions may remain unsettled into the weekend.

Look for a warming trend early in the work week, however temps are
still expected to stay below normal. Then temps should cool
midweek through Fri, with a possible rebound on Sat.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1100 PM MDT Sat May 21 2016

Vfr conditions will prevail the next 24 hours, but winds will be
a bit of an issue. Until sunrise surface winds will begin to
lessen at valley airports as surface winds decouple from upper
level winds. This should cause low level wind shear at most lower
elevation taf sites until about 14z. A cold front will drag
through the area through the day, but clouds will help prevent
surface winds from increasing as much as Saturday.

&&

.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&

$$

UPDATE...MDA
SHORT TERM...JAM/EH
LONG TERM...EH
AVIATION...CC



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