Area Forecast Discussion
Issued by NWS Grand Junction, CO

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709
FXUS65 KGJT 190914
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
314 AM MDT Thu Apr 19 2018

.SHORT TERM...(Today through Friday)
Issued at 310 AM MDT Thu Apr 19 2018

A strong Pacific storm was moving into the Western Great Basin
early this morning and will move steadily east through the day.
The primary initial consequence of the approaching storm will be
steadily increasing winds starting about 9-10 AM this morning.
Wind speeds should reach a peak along the CO and UT border between
6 and 8 PM today. Models indicate moisture being drawn north from
NM this evening with an associated increase in precipitation
chances along the Continental Divide. The precip is well ahead of
the low center in the warm advection portion of the storm. Models
historically over predict this warm advection precipitation, but
have been consistent with it in the last few runs.

On Friday the upper low center is projected to travel from central
UT over SW and central CO. A trowal signature should help wrap
precipitation around the northern and western quadrants of the
storm Friday. This will shift the main focus of precipitation to
the northern third of western CO and eastern UT. The cold
advection will reach the forecast area which will lower snow
levels.

.LONG TERM...(Friday night through Wednesday)
Issued at 310 AM MDT Thu Apr 19 2018

By late Friday afternoon and into the evening hours this cyclone
will have fully tapped into the meat of the warm conveyor belt fed
by GoMex moisture. Theta transport vectors and humidity profiles
are showing the classic T-Bone steak pattern developing with the
left branch of the WCB arcing back into NE.Utah and NW.Colorado
Friday night. This area of moisture advection and dynamics from
the storm should lead to heavier precipitation potential in our
northern CWA through the early morning hours before the storm
refocuses on the Front Range and the Plains for Saturday. This
precip will occur during the coldest part of the storm and at night
so accumulations during this time could be the most impactful for
travel. Residual wrap around mositure will keep some shower
activity around for Saturday on our side of the hills with the
better chances right near the divide through sunset. Transitory
ridging sets up early Sunday into early Monday ahead of the next
Pacific trough aiming for the N.Rockies. This is just a brush by
but a cool front looks to sag into the northern CWA and may add
just enough lift to squeeze out some light precipitation across
the divide peaks going into Tuesday morning. The upstream system
pushing this storm through is 180 degrees out of phase along the
Left Coast by Wednesday leaving confidence well below par. As for
temperatures...Saturday may be a bit below normal but we should
warm to above normal for much of the extended forecast and mirrors
the CPC outlooks.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 310 AM MDT Thu Apr 19 2018

VFR conditions will prevail at all TAF sites through about 04z
this evening. South to southwest winds aloft and at the surface
will increase throughout the day and overnight. Widespread
mechanical and mountainwave turbulence is expected. Precipitation
will increase, mainly near the Continental Divide after 06z.

&&

.FIRE WEATHER...
Issued at 310 AM MDT Thu Apr 19 2018

Red Flag Warnings remain in effect today for most of Colorado as
gusty winds move back in along with dry humidities. Winds will
begin increasing after about 9 AM in many locations and continue
well into the evening. When Red Flag Warnings are in effect open
burning is highly discouraged as any fire starts will be difficult,
if not impossible, to control.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning from noon today to 9 PM MDT this evening for
     COZ200-202-203-207-290-292-294-295.

UT...None.
&&

$$

SHORT TERM...CC
LONG TERM...15
AVIATION...CC



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