737
FXUS65 KBOU 111713
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1113 AM MDT Tue Jun 11 2024

.KEY MESSAGES...

- Fewer storms today, mainly south of I-70 with an outside chance
  of wind gusts to 60 mph and 1 inch hail.

- Snowmelt producing minor impacts from high streams, mainly in
  Grand County.

- Above normal temperatures and dry weather are expected
  Wednesday and Thursday.

- Slightly cooler conditions will arrive Friday and Saturday with
  scattered showers and storms. Some of these storms could be
  strong to severe along the plains with heavy rain.

&&

.UPDATE...
Issued at 1111 AM MDT Tue Jun 11 2024

The last of a Stratus deck is dissipating over the northeast
corner at this time. There is some convective cloudiness
developing in the mountains south of I-70. The water vapor
pictures are showing some drying moving across the CWA this
morning. Temperatures have warmed in the 70s over most of the
plains. Winds are weak over the plains and foothills with some
southwest to northwesterlies over the high mountains gusting into
the 20-30 mph range.

Not a bunch to change on the GFE grids this update. With some
warning aloft progged through the day, convection should be
somewhat curtailed, especially over the northern CWA. The best
instability is still expected over the southern half of the CWA
this afternoon and evening. The consensus with the various models
has the highest CAPE values over the southern half of the forecast
area along with the model reflectivity. Will leave some 10-30%
pops going, mostly over the southern half of the CWA.

&&

.SHORT TERM /Through tonight/...
Issued at 424 AM MDT Tue Jun 11 2024

Drier air aloft is spreading across our area from northwest to
southeast this morning. However, plenty of low level moisture
remains, and we`re seeing a patch of low clouds and fog developing
across much of northeastern Colorado with the clearing of the high
clouds and a light northeast wind. So far, it looks like it`s
mostly off the ground. It will probably continue to expand in
size, but the air closer to the foothills is a bit drier so we`re
not sure how much there will be along and west of I-25. Whatever
we do get should be pretty shallow and dissipate by about 9 am.

With the early clearing, there shouldn`t be much impact on today`s
high temperatures. The thunderstorm threat will be determined by
two things. First, continued slight warming and drying aloft,
capping convection over the northern mountains and northern border
areas. Second, the amount that the low level moisture will be able
to mix out. Conditions will be most favorable for storms in the
mountains southwest of Denver, and developing or drifting onto the
plains south of I-70 by evening. But there could still be enough
moisture for storms to eventually develop a bit further north than
that, especially in the foothills west of Denver and then drifting
over the city. So we`ll keep some low PoPs for that area as well.
There may still be enough moisture to create capes in the 1000-1200
J/kg range with temperatures in the 80s and dew points in the
lower 50s, and there`s a little more shear today, so while the
storms won`t be well organized, there`s still a chance of
marginally severe hail and maybe wind in the strongest storms.

Skies should pretty well tonight behind the convective clouds.
Lows will only be slightly warmer despite decent warming aloft.

&&

.LONG TERM /Wednesday through Monday/...
Issued at 424 AM MDT Tue Jun 11 2024

An upper level high pressure system sits in the Four Corners
Wednesday. This pattern will likely lead to strong subsidence thus
limiting thunderstorm development through Thursday night. Cross
sections indicate weak zonal flow aloft and low relative humidities
throughout the 500-700mb layer. Given these conditions, partly sunny
skies are expected both Wednesday and Thursday. Above normal
temperatures will occur across the region both Wednesday and
Thursday; near-record highs could occur along the eastern plains.
CAMs suggests there is enough instability in southern Wyoming to
bring isolated chances to the plains late Wednesday night into
Thursday morning. This seems to align with the next frontal system
developing on the Colorado/Wyoming/Nebraska border but overall,
seems to bring no relief to the heat.

By early Friday morning, the upper high located in the Four Corners
begins to breakdown as the next trough axis sweeps through the
Rockies by Friday afternoon. Model guidance seems to be in agreement
with scattered to numerous showers and storms along the mountains
and foothills then spreading to lower elevations by Friday evening.
QPF fields generally fall between 0.15-0.45 across northeastern
Colorado with the highest amounts for the northeast corner. Model
soundings keep higher MLCAPE values between 800-1200 J/kg and
supportive mid level rates between 7-8 C/km for the eastern plains
which may lead to strong or severe storms late Friday afternoon
through Friday night.

This weekend, the next chances of precipitation remain limited as
another upper level high develops south of the CWA. Above normal
temperatures return by Sunday afternoon. Ensembles display upper
90s across the plains early next week.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1101 AM MDT Tue Jun 11 2024

Fairly weak normal diurnal wind trends should continue this
afternoon and early early with normal drainage patterns expected
tonight. There doesn`t look to be any ceiling issues through the
period. Concerning convection, many of the models keep it out of
DIA later today, however a couple are showing the potential of
some -TSRA around the area with decent CAPE values and surface dew
points staying around 50 F or higher through the afternoon. Will
put a VCTS in the DIA TAF late in the day.

&&

.HYDROLOGY...
Issued at 424 AM MDT Tue Jun 11 2024

Heavy rainfall is possible with the stronger storms today, but
storm motion will be a bit faster so the flood threat looks to be
low. Little or no thunderstorm activity is expected near the
recent burn scars.

Elevated flows continue across the upper Colorado River basin.
Remain cognizant of the dangers of these cold flows, and be aware
of any Flood Advisories and Warnings. Flow may increase late this
week as warmer temperatures and scattered showers return to the
area.

&&

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

&&

$$

UPDATE.......RJK
SHORT TERM...Gimmestad
LONG TERM....AD
AVIATION.....RJK
HYDROLOGY....Gimmestad/AD