Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 251645
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1045 AM MDT Thu May 25 2017

.SHORT TERM...(Today through Friday)
Issued at 444 AM MDT Thu May 25 2017

Mild morning across the southern two-thirds of the forecast area
as increased cloud cover helping to hold heat in out ahead of sfc
cold front which has stalled along the Bookcliffs, just north of
Interstate 70. The front is expected to make another push
southward today, before finally stalling for good along the San
Juan Mountains this afternoon or early evening. Expect scattered
to numerous showers and thunderstorms north of the front, with
dry, breezy and warm conditions to the south. With the front
expected to stay north of the southern valleys, focus shifts
toward fire weather as fuels are critical in our Southwest
Colorado zones. Current red flag warnings look sufficient,
additional details below. These unsettled conditions will remain
in the forecast through Friday as we expect another wave to drop
south later Friday on into Saturday. That system will be packing a
little colder air, bringing the potential for more late May snow
for the northern and central mountains.

Back to todays weather, evening KGJT sounding had the old classic
inverted-V signature with very dry conditions. Any showers will
struggle to generate much in the way of measurable precipitation
until we can moisten up the lower levels. Priming of that layer
will take some time, so major concern with any convection today
will be strong outflow winds which could exceed 50 mph. Storms are
expected to become more efficient at producing wetting rains by
mid-afternoon, so anticipated a transition type of day with the
convection.

Temperatures will remain at or above normal for most areas, with
the exception of the far northern zones which will be a bit cooler
behind the southward progressing front. Cooler temps then expected
tonight and Friday for the majority of the forecast area.

.LONG TERM...(Friday night through Wednesday)
Issued at 444 AM MDT Thu May 25 2017

One last surge of cooler air is expected to drop south through the
area Friday night and Saturday with associated upper level support
driving another round of showers and thunderstorms. Some high
mountain snow is expected with this system, focused on our
northern and central mountains from Vail Pass north to the Park
and Gore Ranges near Steamboat Springs. H7 temps are forecast to
drop below freezing Friday night with models in good agreement.
With favorable orographics in addition to the passing support
aloft from weak wiggles in the flow, may be able to squeeze out a
few inches of wet snow across the Flat Tops and Park Range.

Heights climb up a notch Sunday and Monday with the western ridge
trying to slide east, but weakness on the back side of the ridge
will allow an upper low to drop southeast toward the Baja
California region by early next week. This system is expected to
close off over northern Mexico or southern Arizona, allowing it
to tap deeper moisture to the south. The moisture will work
northward Tuesday and Wednesday, bringing another increase in
showers across the area. Models are not in great agreement at this
point, thus running with the blended solutions will be a good
starting point as we have plenty of time to adjust as the finer
details get hammered out.

Temperatures will be jumping around a bit with warmest days
expected to be Sunday and Monday, followed by cooler conditions as
cloud cover and moisture levels increase Tuesday and Wednesday.

Plenty of outdoor activities will be found across our area this
weekend and residents and adventurists should be prepared for
showers and thunderstorms, along with cooler conditions. Some high
mountain snow is not out of the question and efforts to prepare
for this outcome are encouraged.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1045 AM MDT Thu May 25 2017

Scattered showers and isolated thunderstorms will persist across
much of eastern Utah and western Colorado through tonight as a
cold front works through the region. Showers will be most
numerous north of I-70 with gusty outflow winds and brief heavy
precipitation expected with the strongest storms. ILS cigs will be
common north of the front with VFR conds persisting across the
southern valleys.

&&

.FIRE WEATHER...
Issued at 444 AM MDT Thu May 25 2017

A cold front dropping south across western Colorado this morning
will stall north of the San Juan Mountains, with scattered
showers and a few thunderstorms expected along and north of the
front. Across the southern valleys, especially across Colorado
Fire Weather Zones 207 and 290, gusty southwest to west winds are
expected to develop this morning and continue through this
evening. With the front stalled to the north, expect temperatures
to remain above normal with relative humidity values dropping
below 15 percent for several hours. With winds in place, low
humidities and critical fuels, Red Flag Warnings are in effect
from noon through the early evening hours. North of the San
Juans, scattered to numerous showers are expected with a cooler
air mass in place, keeping relative humidity above the 15 percent
threshold.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning until 7 PM MDT this evening for COZ207-290.

UT...None.
&&

$$

SHORT TERM...JDC
LONG TERM...JDC
AVIATION...TGJT
FIRE WEATHER...JDC



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