563
FXUS65 KGJT 172048
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
248 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 TUESDAY/...
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 /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1124 AM MDT Wed Jul 17 2024

Slightly drier conditions suggest a downturn in convective
coverage today and early radar and satellite trend concur.
Storms developing over ridges in the next few hours will take a
slow drift southward...some surviving into the adjacent valleys.
Confidence overall is low due to the lesser storm coverage but
forecast for now favors KTEX KDRO and KASE for a passing storm
with VCTS used elsewhere. Gusty winds continue to be the main
threat from the storms today and could exceed 40 mph under the
right conditions. Clearing tonight and VFR holds over the next
24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...MMS
AVIATION...TGJT