Area Forecast Discussion
Issued by NWS Grand Junction, CO

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669
FXUS65 KGJT 250448
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1048 PM MDT Tue Apr 24 2018

.SHORT TERM...(Tonight through Wednesday night)
Issued at 350 PM MDT Tue Apr 24 2018

A shortwave trough rotating slowly southeastward on the flanks of
the low centered over the northern Plains will sustain showers
over the central and southern Divide mountains early this evening.
Expect this activity to diminish within an hour or two after
sunset as cooling temperatures and subsidence stabilize the
atmosphere. Skies clear from northwest to southeast during the
remainder of the night with colder overnight lows. Dry northwest
flow aloft sets up over the area Wednesday and Wednesday night
resulting in quiet weather across the region. Temperatures will
moderate on Wednesday with highs expected to climb to around 5
degrees above normal at most locations.

.LONG TERM...(Thursday through Tuesday)
Issued at 350 PM MDT Tue Apr 24 2018

A shortwave in the northwest flow will brush the northern portion
of the Continental Divide on Thursday bringing a slight chance for
light showers over the Elkhead and Park Mountains. This activity
diminishes Thursday night as subsidence and cooling take over as
temperatures fall and a low off the West Coast moves the ridge
overhead.

As the closed western low moves toward northern California on
Friday, the ridge axis is forced east of the Divide and moisture
begins to track northward from the Mexican Plateau into eastern
Arizona and western New Mexico. GFS continued to be most
progressive in delivering moisture to southern Colorado Friday
afternoon while the NAM, ECMWF and Canadian suggest moisture won`t
arrive until later.

Models were marginally closer in agreement with this closed low,
but significant differences still exist. Experience suggests the
GFS progression of the vertically stacked system is too fast and
therefore preferred the ECMWF solution. The EC moves the closed
low very slowly from northern California across the northwestern
Great Basin and into the northern Intermountain region this
weekend, where it lingers on Monday. On Tuesday, the low splits
with the northern branch over the southern Canadian plains, and
the southern circulation developing over southern California. This
evolution results in showers holding off until Saturday morning,
then continuing off and on through the night into Sunday before
diminishing Sunday night. Unsettled weather redevelops Monday and
Tuesday as moisture is carried northward ahead of the developing
low over southern California.

Temperatures during the period will range from 5 to 10 degrees
above normal for most locations through the weekend before cooling
to near normal Monday and Tuesday of next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1046 PM MDT Tue Apr 24 2018

High pressure building over the region will bring VFR conditions
to all sites through Wednesday evening. A weak cold front is
expected to move south through the area late Wednesday night with
winds shifting to the north.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

$$

SHORT TERM...NL
LONG TERM...NL
AVIATION...JDC



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