Heat in Colorado, July 7 to 12, 2021

Area Forecast Discussion
National Weather Service Grand Junction CO
1145 AM MDT Wed Jul 7 2021

.SHORT TERM...(Today through Thursday)
Issued at 357 AM MDT Wed Jul 7 2021

High pressure remains centered over the Great Basin this morning,
with eastern Utah and western Colorado still under dry north to
northwest flow. The 00z Grand Junction sounding had a PWAT value of
just under 0.60 inches, which is over 0.30 inches lower than just 12
hours prior. This drying trend is expected to persist over the next
few days, limiting the potential for afternoon convection. Isolated
showers or storms will be possible this afternoon along the southern
Divide and eastern San Juans, which lie on the edge of some better
moisture. Otherwise, the region will remain under mostly clear
skies, allowing temperatures to climb. Highs this afternoon will be
at or above the century mark for the lower desert valleys of western
Colorado and eastern Utah, and are forecast to be another 3-5
degrees warmer tomorrow. Unfortunately, overnight lows for these
hottest areas will not offer much relief, bottoming out in the upper
60s to low 70s. As such, Excessive Heat Advisories for Eastern Utah
desert valleys go into effect today at noon, and portions of
northeast Utah, as well as the Grand and Paradox Valley, join at
noon tomorrow. These advisories remain in effect through Friday
evening. In addition to the heat, fire weather concerns make a
comeback as winds increase across northeast Utah and northwest
Colorado. Red Flag Warnings are in effect for these areas from noon
to 8PM tomorrow.

.LONG TERM...(Thursday night through Tuesday)
Issued at 357 AM MDT Wed Jul 7 2021

The ridge of high pressure will remain overhead through the end of
the week, with flow becoming more westerly late Thursday into
Friday. Moisture tires to sneak in under the ridge under Friday,
with forecast PWAT values looking to creep up once again into the
0.70-0.90 inch range, possibly higher over the Four Corners. Models
are in good agreement with regards to this moisture return, so
expect to see afternoon convection once again Friday and Saturday,
with the Central and Southern Divide most favored. Otherwise, the
Western Slope will remain dry and hot into the weekend. Lower desert
valleys can expect afternoon highs close to 100F to persist into the
next workweek. Overnight lows drop into the mid-60s after Friday, so
currently the Excessive Heat Advisories only run through Friday
evening. An upper level jet is expected to remain just north of the
area through Friday, which will keep gusty afternoon winds going
across northeastern Utah and northwestern Colorado. Relative
Humidities are expected to remain low, therefore critical fire
weather conditions are expected once again on Friday. Fire Weather
Watches are currently in effect from noon to 8PM Friday.

Early next week may see another increase in moisture, as forecast
PWAT values climb back up again Tuesday, thanks to a return to
westerly flow and some potential shortwaves moving through. This
being at the very end of the long term period, models are in a bit
of disagreement, but in general they do indicate the potential
return to increased storm activity.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1145 AM MDT Wed Jul 7 2021

VFR conditions will continue for the next 24 hours. Expect mostly
sunny skies this afternoon with diurnally driven cumulus across
the high terrain, particularly in the San Juans. Winds will
generally be light though a few gusts up to 20kt are possible.
Quiet weather follows overnight as typical drainage flows take
control under a mainly clear sky.

&&

.FIRE WEATHER...
Issued at 357 AM MDT Wed Jul 7 2021

High pressure shifts westward and will take position over the
Southwest during the period. As a result, the forecast area will
trend drier and warmer over the next several days. However, the high
becomes flattened by a disturbance passing north of the region
resulting in stronger gradient wind flow Thursday, but more so on
Friday. Latest guidance suggests that winds and relative humidity
will reach critical levels across northeast Utah and northwest
Colorado on Thursday. Red Flag Warnings have been issued for
Thursday from noon to 8PM for portions of northeast Utah and
northwest Colorado. A Fire Weather Watch remains in effect Friday
from noon to 8PM for the same areas, as winds and relative humidity
values are still forecast to reach critical levels.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning from noon to 8 PM MDT Thursday for COZ200-202.

     Fire Weather Watch from Friday afternoon through Friday evening
     for COZ200-202.

     Heat Advisory from noon Thursday to 8 PM MDT Friday for COZ006-
     020.

UT...Red Flag Warning from noon to 8 PM MDT Thursday for UTZ486.

     Fire Weather Watch from Friday afternoon through Friday evening
     for UTZ486.

     Heat Advisory from noon to 9 PM MDT Thursday for UTZ024.

     Heat Advisory until 8 PM MDT Friday for UTZ022-027-029.

&&

SHORT TERM...BGB
LONG TERM...TGJT
AVIATION...MDM
FIRE WEATHER...TGJT

Hazardous Weather Outlook
National Weather Service Grand Junction CO
524 AM MDT Wed Jul 7 2021

COZ001>014-017>023-UTZ022>025-027>029-081130-
Lower Yampa River Basin-Central Yampa River Basin-
Roan and Tavaputs Plateaus-Elkhead and Park Mountains-
Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor-
Central Colorado River Basin-Grand and Battlement Mesas-
Gore and Elk Mountains/Central Mountain Valleys-
Central Gunnison and Uncompahgre River Basin-
West Elk and Sawatch Mountains-Flat Tops-
Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide-
Northwest San Juan Mountains-Southwest San Juan Mountains-
Paradox Valley/Lower Dolores River-
Four Corners/Upper Dolores River-Animas River Basin-
San Juan River Basin-Southeast Utah-Eastern Uinta Mountains-
Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat-
La Sal and Abajo Mountains-Canyonlands/Natural Bridges-
524 AM MDT Wed Jul 7 2021

This hazardous weather outlook is for eastern Utah and western
Colorado.

.DAY ONE...Today and Tonight

Hot weather moves in today, with triple digit heat expected for
the lower desert valleys.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Hot temperatures continue through Friday reaching triple digits
for the lower valleys. Fire weather concerns also increase
Thursday and again Friday as gusty winds and low humidities occur
each afternoon.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.