333
FXUS65 KBOU 141929
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
129 PM MDT Fri Jun 14 2024

.KEY MESSAGES...

- Numerous thunderstorms and a greater severe storm threat this
  afternoon

- A return to hot and mainly dry weather this weekend into early
  next week.

- Snowmelt producing minor impacts from high streams. Gradually
  diminishing flows next week.

&&

.SHORT TERM /Through Saturday/...
Issued at 123 PM MDT Fri Jun 14 2024

A strong short wave trough will continue to provide lift for
showers and thunderstorms through this evening. The wave will then
move across eastern Colorado tonight and be east of the state for
Saturday. Showers and thunderstorms will track east across
Colorado this afternoon and early evening. With temperatures in
the lower 80s and dew point in the lower 60s, MLCAPE has climbed
to 2000 J/kg over the eastern plains. There may be just enough
shear for a couple supercell thunderstorms to form. However with
large scale ascent, expect storms to organize into a line as they
track east across the plains. Hail slightly larger than 2 inches
in diameter and wind gusts to 75 mph will be possible with the
stronger storms. Can`t rule out a brief tornado over the northeast
plains where there is stronger low level winds (better shear).
The strong/severe storms will be east of the area by mid evening,
however a second round of showers and weak thunderstorms is
expected this evening as the trough tracks across the state.

For Saturday, weak ridging in the westerly flow aloft will follow
today`s system. Temperatures warm back up into the lower 90s.
MLCAPE reaches 500 J/kg. Moisture decreases with dew points
falling into the 30s during the afternoon. We end up with just
enough moisture and instability for high-based showers and
possibly a few weak thunderstorms during the afternoon. Gusty
outflow winds will be the main impact from the showers and storms.
Any rainfall will light.
&&

.LONG TERM /Saturday night through Friday/...
Issued at 123 PM MDT Fri Jun 14 2024

Sunday will be the hotter day of the weekend as the mid-level
thermal ridge approaches the region. Much drier air aloft is also
expected, with increasing southwesterly flow aloft. There would
still be a slim chance of a couple of weak/high-based showers in
the afternoon but the continued drying should limit those chances.
High temperatures in this pattern should reach the mid 90s,
though recent GFS/ECM MOS products give highs closer to 100F. A
few models try to push in a weak front into the northeastern
plains - perhaps aided by a weak Denver cyclone - that could keep
temperatures a bit cooler across the Denver metro and adjacent
plains.

The heat is expected to continue into Monday. Deterministic and
ensemble models are in good agreement with the dry/southwesterly
flow pattern continuing. GFS/ECM 700mb temperatures are roughly
1-2C warmer than Sunday (near 20-21C), and while ensembles are
(unsurprisingly) a bit cooler, those temperatures still lie near
the 90-99th percentile of the CSFR climatology. Forecast highs
will again be short of record (100F) but should still rise into
the mid/upper 90s across most of the plains. Another frontal push
may keep temperatures a bit cooler than forecast but confidence
regarding if/where that front tracks is low.

An approaching trough axis should bring relief from the heat by
Tuesday and Wednesday with the axis of the thermal ridge shunted
off into the Great Plains. Though widespread precipitation isn`t
expected, the increase in moisture should allow for at least
scattered showers and storms while high temperatures remain closer
to normal values.

Forecast solutions diverge towards the end of next week. The
general pattern looks well forecast, with ridging rebuilding
across the eastern U.S. with a series of shortwaves tracking
across the northern Rockies. There are differences in the
timing/location of these waves and with the strength of the
ridging to our east, but the pattern favors above normal
temperatures returning by late week.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1121 AM MDT Fri Jun 14 2024

Still on track for thunderstorms to track across northeast
Colorado this afternoon. For DEN, the best chance for storms looks
to be in the 21-23Z window. Gusty outflow winds, hail, and heavy
rain will be possible with the stronger storms. A second round of
showers and weak thunderstorms will be possible 02-06Z.

Saturday will begin with mostly clear skies. Isolated/scattered high
based gusty showers are expected to form after 20Z. Outflow winds
from the showers will likely produce a wind shift or two after 21Z
Saturday.

&&

.FIRE WEATHER...
Issued at 123 PM MDT Fri Jun 14 2024

Elevated to critical fire weather conditions are possible Sunday
and Monday with well above normal temperatures and drying humidity
values. Increasing flow aloft will lead to gusty winds, especially
across the high country on both days, with lighter speeds across
the plains. Main question is just how dry we`ll get. Models
attempt to push a weak surface cold front or two into the
northeast plains on Sunday and/or Monday, with dew points
remaining in the 50s north of the front. There are also additional
uncertainties regarding fuels status across our forecast area.
RAWS-based ERC/Fuel Moisture charts suggest that the recent warm
spells have dried things out, but are generally near or just below
normal.

&&

.HYDROLOGY...
Issued at 123 PM MDT Fri Jun 14 2024

Precipitable water values of 1 to 1.5(in) and dew points around
60F degrees will provide ample moisture for thunderstorms to
produce heavy rainfall. Where storms remain station or track over
the same area, flooding will be possible.

Elevated flows continue in the mountain streams, with Flood
Advisories remaining in effect for the streams above Granby and
Grand Lake. Remain alert of the dangers of water that is running
high and cold. Flows are expected to gradually decrease next week
as the peak snowmelt is passing by.

&&

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

&&

$$

SHORT TERM...Meier
LONG TERM...Hiris
AVIATION...Meier
FIRE WEATHER...Hiris
HYDROLOGY...Meier