754
FXUS65 KBOU 050311
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
911 PM MDT Tue Jun 4 2024

.KEY MESSAGES...

- Summer heat through the rest of this week, with a few 90 degree
  readings over the plains, with Friday the hottest day.

- Increasing chances for showers and thunderstorms this weekend
  into early next week, along with slightly cooler temperatures.

&&

.UPDATE...
Issued at 904 PM MDT Tue Jun 4 2024

Little change needed at this hour. We lowered tonight`s lows a
couple of degrees with the clearing and dry air. Also bumped up
wind speeds tomorrow afternoon a little as guidance is showing a
fairly widespread 15g25 mph over the northern part of the plains.

&&

.SHORT TERM /Through Wednesday/...
Issued at 145 PM MDT Tue Jun 4 2024

The west to north winds over the CWA at still gusting to  40 mph
in the mountains and over the eastern 2/3rds of the plains.
Current temperatures are in the mid 70s to lower 80s over the
plains and lower foothills, with 50s and 60s in the alpine areas.

Models show northwesterly flow aloft tonight to weaken as an upper
ridge pushes in from the west on Wednesday. There is little synoptic
scale energy for the CWA tonight or Wednesday. the low level winds
are mainly downsloping on Wednesday. Cross sections show a bit of
a mountain wave set up later tonight into Wednesday morning.
Moisture is lacking on Wednesday as is CAPE. Thickness grids show
Wednesday highs 4-6 C warmer than today`s, with Denver`s high
expected to get above 90 F for the first time this year.

&&

.LONG TERM /Wednesday night through Tuesday/...
Issued at 130 PM MDT Tue Jun 4 2024

A broad upper ridge will remain in place across the Western U.S.
through the end of the work week, leading to continued warm and
dry conditions across the forecast area.

Thursday should be a little cooler than Wednesday, following the
passage of a weak cold front Wednesday night. Still, robust
daytime heating should warm temperatures back into the upper 80s
across most of the lower elevations, with low to mid 80s also
possible in the high valleys.

The axis of the mid-level thermal ridge should be centered over
southern Colorado on Friday, with a shift to modest downslope flow
across the region. Mid-level temperatures are expected to be a
few degC warmer than Thursday and a return to the 90s looks likely
for the plains. How quickly we warm up will likely depend on how
much (if any) cloud cover develops as better moisture advects into
the region. The increasing moisture will also lead to increasing
PoPs, mainly across the higher elevations.

Moisture should continue to increase across the region this
weekend, with ensemble guidance suggesting PWATs near 125-175% of
normal (normalized anomalies near 1-3 sigma). A series of weak
shortwaves should traverse the edge of the retreating ridge in
this period, and scattered/likely PoPs are in the grids on
Saturday and Sunday.

Perhaps the most intriguing day of the forecast period is Monday.
The GFS and ECMWF both hint at a stronger shortwave/cold front
pushing across the region Sunday night or Monday, with deep
moisture/upslope flow behind the front. However, these
deterministic solutions are well on the cold/wet side of their
respective ensembles, and the majority of guidance keeps
temperatures in the 70s to low 80s.

Beyond that timeframe, guidance generally tries to rebuild the
ridge across the region with a gradual trend towards warmer/drier
weather.

&&

.AVIATION /06Z TAFS through 06Z Thursday/...
Issued at 904 PM MDT Tue Jun 4 2024

VFR through Wednesday. Winds will shift to southwest/west by 06z.
West winds at 10-15 knots will develop around 16z, becoming
northwest with gusts up to 25 knots after 18z.

&&

.HYDROLOGY...
Issued at 130 PM MDT Tue Jun 4 2024

The remaining mountain snowpack will continue to quickly melt off
the next several days as temperatures increase across the region.
Hydrologic forecasts continue to show elevated flows across the
Colorado/Fraser rivers in Grand county, with a few sites forecast
to reach action stage by Friday.

Meanwhile, the threat of burn area flash flooding will gradually
increase this weekend into early next week as a moist airmass
advects into the region. Confidence is low for any given day, but
something worth watching as we get closer to the weekend.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Gimmestad
SHORT TERM...RJK
LONG TERM....Hiris
AVIATION...Gimmestad
HYDROLOGY....Hiris