Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 180908
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
308 AM MDT Mon Jun 18 2018

.SHORT TERM...(Today through Tuesday)
Issued at 308 AM MDT Mon Jun 18 2018

Drier air continues to punch into the region from the southwest
this early morning ahead of a strong upper level low pressure
system spinning over northern Nevada. Showers have just about
exited the region with a few lingering light showers over the
northern Park Range east of Steamboat Springs at this hour. Deeper
moisture that was over the region this weekend has also departed
to the Front Range with Precipitable Water values lowering to
between 0.3 and 0.5 inches on the western slope. All of those
words above to basically say, today is going to be a much drier
and warmer day compared to the weekend, with mostly sunny skies
and breezy conditions.

Critical fire weather conditions are likely across portions of
east-central Utah and west-central Colorado to northwest Colorado
as stronger winds aloft mix down to the surface. These winds are
the result of a tightened pressure gradient this afternoon as the
upper low lifts northeast into southern Idaho, with a 60 kt jet
rounding the base of the trough and laying over these areas.
Decided to issue a Red Flag Warning for today given the latest
guidance indicating a bit stronger winds. H5 winds will increase
up to 40 kts with H7 winds up to 20 kts, with good potential these
winds will mix down. Isolated thunderstorms are possible across
the eastern Uintas as this upper low lifts into southern Idaho
with enough remnant moisture remaining. Cannot completely rule it
out today. Winds will relax a bit on Tuesday as this upper low
tracks across the Northern Rockies along the Montana-Wyoming
border. The southern edge will clip the north and as it does,
expect isolated storms to form mainly across the northern
mountains Tuesday afternoon. There will also be an increase in
cloud cover for areas along and north of I-70 with breezy
conditions as this trough passes. Expecting the relative humidity
to remain elevated enough across the north to preclude critical
fire weather conditions on Tuesday. Temperatures will be near
normal through Tuesday.

.LONG TERM...(Tuesday night through Sunday)
Issued at 308 AM MDT Mon Jun 18 2018

Forecast models have become more consistent on the synoptic
pattern for the midweek timeframe features - a ridge over SoCal
and Baja CA, and a closed low meandering eastward on Wednesday and
allowing the high pressure to take a better hold across the
southwestern US. Models are indicating a trough brushing northern
UT and CO on Friday or early this weekend, with the EC a bit
faster than the GFS with this feature. There is no obvious
indication of critical fire weather problems mid to late in the
week, however conditions will be quite dry across the region
during what is already an moderate to extreme drought across Utah
and much of Colorado. The only chance for any precipitation looks
to be early next weekend with the passing trough and it will be
focused over northcentral CO mountains and limited. Temperatures
are anticipated to increase to near and a few degrees above
normal by the end of the week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 308 AM MDT Mon Jun 18 2018

VFR conditions will prevail over the next 24 hours with mostly
sunny skies across the region. Breezy conditions will occur late
morning into the afternoon as stronger southwest winds aloft mix
to the surface. An isolated storm or two is possible over the
eastern Uintas this afternoon as a disturbance moves from northern
Nevada into southern Idaho, but this should not have any impact on
TAF sites.

&&

.FIRE WEATHER...
Issued at 308 AM MDT Mon Jun 18 2018

A low pressure system over northern Nevada will shift slightly
north to southern Idaho this afternoon. This system will bring
breezy southwest winds and drier conditions over the area this
afternoon leading to critical fire weather conditions across
portions of east-central Utah and west-central to northwest
Colorado. Moisture will still hang on across the northern areas
even though winds will be breezier, with relative humidity staying
above critical thresholds. A Red Flag Warning has been issued for
Utah Fire Weather Zones 487 below 7000 feet and 490 below 8000
feet, and Colorado Fire Weather Zones 202, 203 and 290. Winds will
relax Tuesday and through the remainder of the week as this low
pressure system moves across the northern Rockies and departs the
region, with high pressure building in across the Great Basin.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning from 11 AM this morning to 8 PM MDT this
     evening for COZ202-203-290.

UT...Red Flag Warning from 11 AM this morning to 8 PM MDT this
     evening for UTZ487-490.

&&

$$

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


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