-- Discussion containing changed information from previous version are highlighted. --
290
FXUS65 KGJT 092152
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
352 PM MDT Sun Jun 9 2024

.KEY MESSAGES...

-- Changed Discussion --
- Afternoon terrain based thunderstorms and showers will
  continue Monday and Tuesday, favoring southern mountains and
  the Divide.

- Temperatures will cool slightly Monday, then inch upward by
  Wednesday, with highs nearly 15 degrees over normal expected
  Wednesday afternoon.

- Active weather returns late week with another system progged
  to arrive Friday, along with some temperature relief.
-- End Changed Discussion --

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
-- Changed Discussion --
Issued at 340 PM MDT Sun Jun 9 2024

Convection continues to bubble on the terrain this afternoon, thanks
to the cyclonic flow pinching off of the open wave hung up in
Baja/SOCAL. Storms are firing on mostly south facing aspects and
then drifting/shearing off to the northeast. Generous precipitable
water content and favorable CAPE are keeping things going.
Unfortunately, much of the rainfall is hanging up in the mountains
and rain gauges around populated portions of the region aren`t
showing much return on the measurable rainfall. A few hundredths
along the 550 corridor and a tenth of an inch around Ridgway have
been measured thus far. A frontal boundary traversing the northern
Rockies drags through Monday, with height rises in its wake
translating to a return of more dominant high pressure building in
the Great Basin. This should serve as a dampener across the northern
half of the CWA by Monday afternoon. Meanwhile down south, leeside
cyclogenesis on the northeastern plains of New Mexico will keep some
moisture and forcing available on our southern mountains Monday
afternoon. Storms will once again hug the terrain they form upon and
likely drift out over valleys and decay. Gusty winds and a few
downpours are possible. Forcing pulls off to the east Monday evening
and quiet overnight conditions will return once again. Cloud cover
and a shift to northwesterly flow on Monday should help knock down
temperatures a touch. Clearer skies up north will keep temperatures
around 5-10 degrees over expected normals, while down south
temperatures will shift closer to normal. This summer-like trend
doesn`t show much sign of easing up, but I will leave that talk to
the long term.
-- End Changed Discussion --

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
Issued at 340 PM MDT Sun Jun 9 2024

On Tuesday one system exits over the Southern Plains while another
sits off the coast of Southern California. This places our area
under a ridge with minimal forcing. The moisture does not fully
scour out so expected terrain-driven showers and storms in the
afternoon. The models favor the Divide for now, but would not be
surprised if the other ranges see increasing chances. The ridge
causes temperatures to gradually rise a few degrees each day. On
Wednesday the ridge pulls some drier air in from the west, but
this looks to be brief. Also, on Wednesday the ridge axis will
be directly overhead so this should be the warmest day of the
week. On Thursday the low pressure begins to move inland over
the Desert Southwest. As this occurs we start to see another
round of moisture advection. Thursday still looks warm, but
there may be enough moisture for some convection on the higher
terrain around the Four Corners. The chances for showers
continues overnight as the low approaches and forcing increases.
The models still agree that the low tracks over the area on
Friday, which will be the best shot for widespread showers and
storms. Temperatures also cool off closer to normal values. On
Saturday the system lifts out over the Plains leaving north-
northwest flow, and there may be enough moisture for high
terrain convection. Drier air ushers in on Sunday and
temperatures gradually rise again.
-- End Changed Discussion --

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1111 AM MDT Sun Jun 9 2024

Terrain based thunderstorms are forming and a few of these
storms may possibly make it into the valleys later this
afternoon. However confidence is very low so VCTS will continue
in the TAF for now. With these high based storms...gusty winds
will be the main threat to airfields. The precipitation looks to
become more organized over southwest Colorado tonight and into
Monday with a thicker cloud cover expected. However VFR looks to
prevail over the next 24 hours. Terrain obscuration over the
southern mountains is possible by sunrise on Monday.

&&

.HYDROLOGY...
-- Changed Discussion --
Issued at 337 AM MDT Sun Jun 9 3374

Looking across the board at hydrographs it looks like many
tributaries have reached or will reach the seasonal peak in the
next day or so with this water running down the mainstem rivers
through the week. Advisories continue for Gore Creek...with
water levels forecast to trend downward after todays
peak...possibly dropping below action levels by Tuesday. The
upper Roaring Fork...Duchesne and Eagle Rivers all are running
near bankfull as well but again trending downward over the next
few days. Most forecasts suggest the snowpack is dwindling with
falling trends continuing even with the strong warmup later in
the week. So this could be the end of the runoff for 2024...stay
tuned.
-- End Changed Discussion --

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...LTB
LONG TERM...KJS
AVIATION...TGJT
HYDROLOGY...15