673
FXUS65 KBOU 111024
AFDBOU

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

.KEY MESSAGES...

- Fewer storms today, mainly south of I-70. A marginally severe
  storm is still possible.

- 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.

&&

.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 /12Z TAFS through 12Z Wednesday/...
Issued at 424 AM MDT Tue Jun 11 2024

A brief period of ceilings between 500 and 1500 feet is possible
over the north part of the Denver area this morning between 12z
and 15z, including KDEN and KBJC, with the threat higher (60%
chance) at KDEN. Visibilities are expected to remain above 3
miles. There is a lower chance (20%) that the clouds could push
all the way south to KAPA. Otherwise, VFR conditions are expected
through tonight. Isolated thunderstorms are expected in the
Denver area between 22z-02z, with a slight chance (20%) of wind
gusts to 30 knots.

&&

.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.

&&

$$

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