FXUS65 KGJT 192129

Area Forecast Discussion
National Weather Service Grand Junction CO
329 PM MDT Thu Jul 19 2018

.SHORT TERM...(Tonight through Friday night)
Issued at 329 PM MDT Thu Jul 19 2018

The center of high pressure aloft will shift southeast toward
northern Texas and allow subtropical moisture to increase
clockwise into the Four Corners throughout the day on Friday.
Convective indices for Friday are not screaming out with a huge
amount of support for widespread showers and thunderstorms, but
dewpoints will begin to rise and clouds will float in from the
south. Rains are most likely in SE Utah and SW Colorado on Friday...with
precipitation and any storms that develop moving from southwest to
northeast. It is likely that showers and thunderstorms which
develop across eastern Utah and western Colorado Friday will occur
later in the day. A shortwave moving south to north across eastern
Utah may allow rain showers and a few thunderstorms to continue
through the overnight hours Friday night.

.LONG TERM...(Saturday through Thursday)
Issued at 329 PM MDT Thu Jul 19 2018

Lapse rates increase late morning Saturday in correlation with
the shortwave trekking northward to initiate numerous showers and
thunderstorms across much of eastern Utah and western Colorado.
One inch plus precipitable water values will expand northward in
eastern Utah on Saturday, so there will be plenty of support for
convection throughout the day. Expect that convective activity
will be enhanced over high terrain but ultimately supported by
passing shortwaves.

A trough across the Pacific Northwest will drop the southern
fringe of an upper level jet across NE UT/NW CO on Sunday which
will help increase 0-6km bulk shear to about 15 to 30 kts. muCAPE
above 1000J/kg expands northward on Sunday, and shortwave timing
on Sunday looks to be later in the day across NE Utah and NW
Colorado, though this shortwave may drive convection across the
entirety of eastern UT and western CO.

High pressure begins to shift westward again early next week, but
forecast models are keeping decent moisture available across the
region. Dewpoints on MOS guidance do trend lower by next Tuesday..
out of values near 60 degrees (like on Sunday) to the mid 40s.
This may be identifying a decrease in showers and thunderstorms in
the valleys but continuing afternoon mountain showers and
thunderstorms each day next week.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1138 AM MDT Thu Jul 19 2018

High pressure will remain overhead today resulting in VFR
conditions for all TAF sites over the next 24 hours. Apart from
some gusts to 20-25 knots this afternoon, winds will remain light
and terrain driven. Isolated storms will be possible across the
higher terrain of SE UT/SW CO from 18Z-03Z. Moisture increases
from the south on Friday with clouds and the chance for showers
and storms increasing after 15Z Friday.




Back to Main Forecast Discussion Page