Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 181729
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1129 AM MDT Thu Jul 18 2019

.SHORT TERM...(Today through Friday)
Issued at 358 AM MDT Thu Jul 18 2019

Persistent westerly flow aloft will keep conditions dry across the
entirety of eastern Utah and western Colorado today with above
normal temperatures. Guidance continues to inexplicably keep high
temperatures on the cool side, so, similar to the previous
forecaster, kept temperatures near persistence today. Our much
missed upper air sounding at Grand Junction shows the mid and
upper levels of the atmosphere continuing to dry out with an
observed precipitable water of 0.43 inches with last night`s
sounding. Precipitable water values are projected to decrease by
another tenth of an inch or so by this evening. Far northwest
Colorado will remain on the outskirts of a jetstreak aloft which
will allow the breezy conditions to persist during the afternoon
and evening hours, so the current Red Flag Warning remains on
track. A mild night is on tap for tonight with near to slightly
above seasonal low temperatures under mostly clear skies.

Upper level flow will shift to the southwest on Friday as lower
heights dig into the Pacific Northwest and as the subtropical high
remains to the east. Conditions will remain dry, though moisture
will slowly trickle into the region from the south, generally in
the form of mid and high level clouds during the afternoon hours.
The gradient will remain tight across northwest Colorado, allowing
critical fire weather conditions to redevelop over Colorado Fire
Weather Zone 200. Therefore, a Red Flag Warning was issued with
this morning`s package. More on that in the Fire Weather
discussion below.

.LONG TERM...(Friday night through Wednesday)
Issued at 358 AM MDT Thu Jul 18 2019

Precipitable water time series for the Grand Junction area shows a
gradual uptick in PWATs beginning late Friday and continuing
through early next week as subtropical moisture is pulled into the
region from the south. The center of the subtropical high will be
positioned well to the east, though the lack of depth to the
Pacific trough will not allow for a steady influx of moisture
through the weekend. Even so, the increase in moisture will allow
for at least isolated convection, focused on the higher terrain
along the Divide, each afternoon and evening beginning Saturday.
The ridge axis becomes more prominent on Monday and into Tuesday,
allowing for moisture to more easily drift north. This will result
in better coverage of showers and thunderstorms across the
region. It is important to note that inconsistencies continue to
plague the extended models in regards to how much moisture will be
available...it all depends on how favorable the synoptic pattern
is. Regardless, a return to cooler and unsettled weather is likely
as we head into the latter half of July.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1128 AM MDT Thu Jul 18 2019

Expect VFR conditions for the next 24 hours with mostly clear
skies. Breezy conditions will occur at times this afternoon with
the stronger winds across northwest Colorado in the realm of 20 to
30 kts.

&&

.FIRE WEATHER...
Issued at 358 AM MDT Thu Jul 18 2019

Hot, dry and breezy conditions will continue through Friday as
high pressure builds over the area. A tighter wind gradient will
persist across northwest Colorado today and Friday, allowing
critical fire weather conditions to redevelop during the
afternoon and evening hours. Today`s Red Flag Warning for Colorado
Fire Weather Zone 200 remains on track and a separate Red Flag
Warning has been issued for Friday with this morning`s package.
Elsewhere, weaker winds will inhibit widespread critical fire
weather conditions. Moisture will gradually increase from the
south this weekend with rain chances increasing a bit each day
next week.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning until 8 PM MDT this evening for COZ200.

     Red Flag Warning from noon to 8 PM MDT Friday for COZ200.

UT...None.
&&

$$

SHORT TERM...MMS
LONG TERM...MMS
AVIATION...MDA
FIRE WEATHER...MMS



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