594
FXUS65 KGJT 180529
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1129 PM MDT Wed Jul 17 2024

.KEY MESSAGES...

- Temperatures are expected to remain a few degrees above normal
  with daily thunderstorm chances through the remainder of the
  week with a slight drying trend possible over the weekend.

- Threats from thunderstorms will mainly be from gusty outflow
  winds though a few storms will be capable of producing smaller
  hail and moderate to heavy rainfall rates. Overall flooding
  threats remain low.

- The combination of high based storms, gusty outflow winds and
  lightning will keep also keep a threat of new wildfire starts
  in the picture.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 248 PM MDT Wed Jul 17 2024

The storm mode has changed this afternoon with less shear and
slightly drier conditions in place. The best coverage remains
over the San Juans where slow moving storm or training storms
could lead to excess runoff through sunset but the probability
of this is low. Similar conditions are expected Thursday though
slightly higher PWAT will begin to creep into the 4 Corners
region...westward moving Gulf of Mexico moisture in the wake of
the lee side frontal passage and deep upslope flow. Storms
should initialize on the higher terrain by mid-day as usual and
migrate southeastward to adjacent valleys...with the southern
valleys favored thanks to the better moisture profile. The HRRR
attm is more bullish in keeping nocturnal convection into
Thursday night which makes sense as we advect in additional
moisture trapped under the main circulation aloft. This is an
outlier solution attm so pops remain fairly light and will keep
an eye on this trend. Temperatures will be fairly static with
highs continuing to run several degrees above normal.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 248 PM MDT Wed Jul 17 2024

Mostly a rinse and repeat forecast through the long term period as
we just keep watching the area of high pressure waver back and forth
across the Great Basin. On Friday the ridge will be centered over
southern Arizona as an embedded shortwave associated with the parent
trough dominating Hudson Bay brushes the Continental Divide. This
will result in an uptick in shower and thunderstorm activity as
PWATs continue to trend 110 to 140 percent of normal. Saturday will
be more of the same, although storm coverage will gradually taper
off across eastern Utah and more-so focus along the Divide into the
evening hours. As we head into the weekend odds begin to favor a
trend towards drier weather as the ridge of high pressure amplifies
farther north into the Intermountain West. Certainly won`t lock in a
dry and benign forecast by any means as unsettled weather continues
just to our east as the trough stays trapped over the eastern CONUS.
As this regime continues PWATs will gradually begin to trend down
but aren`t anticipated to drop below normal until early next week.
Regardless, pesky low level moisture paired with daytime heating
and orographics will be sufficient to fuel at least scattered
convection each afternoon into the new work week. But, as we
transition a bit each day, the potential for heavy rain will become
less likely as we shift more towards the threat of gusty outflow
winds. As we head into Tuesday the ridge looks to slowly de-amplify
as a trough of low pressure dives south from the Gulf of Alaska.

Temperatures will remain largely stagnant through the period as we
don`t see any notable shift in the synoptic pattern. This translates
to continued hot temperatures with highs trending near to slightly
above normal. Overnight lows each night will generally be mild for
mid July.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1117 PM MDT Wed Jul 17 2024

A thunderstorm south of KTEX will diminish to a shower over the
next few hours as it tracks southeast over the higher terrain.
Otherwise expect mostly VFR conditions across the region through
the TAF period with light terrain driven winds. The exception
will be thunderstorms between 18Z and about 02Z impacting KASE,
KGUC, KTEX and KDRO with brief periods of MVFR and gusty outflow
winds. Included vicinity thunderstorms at these TAF sites
through the afternoon.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...None.
UT...None.

&&

$$

SHORT TERM...15
LONG TERM...MMS
AVIATION...DB