747
FXUS65 KBOU 101120
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
520 AM MDT Sun Aug 10 2025

.KEY MESSAGES...

- Another round of strong to severe thunderstorms possible this
  afternoon across the urban corridor and eastern plains.

- Elevated fore conditions will continue over the higher terrain.

- Drier and warmer weather develops Monday through Wednesday.


&&

.UPDATE...
Issued at 300 AM MDT Sun Aug 10 2025

A weak upper level trough will move across the area later today thru
this evening.  At the sfc, sfc low pres will be over the Palmer
Divide with east to east southeast flow across the plains. There
will likely be a convergence zone along the El Paso-
Douglas/Elbert county line which will act as a focus for tstm
development by early aftn. Overall, MLCAPE looks to be lower than
yesterday with values in the 1500-2000 j/kg range. Shear profile
will still be favorable for a few svr storms from the Palmer
Divide across the east central plains. Further north, will
probably see tstms develop over the Cheyenne Ridge with some of
the activity move southeast across portions of Weld and Logan
counties by late aftn into the early evening hours. MLCAPE in this
area will be around 1000 j/kg so can`t rule out a svr storm or
two as well.

For this evening, there are varying solutions as to how much
additional tstm activity there will be where lingering instability
will exist, along portions of the I-25 Corridor eastward.  Overall
confidence is low so have kept precip chances mostly in the chc
category for now.

&&

.DISCUSSION /Through Saturday/...
Issued at 1250 PM MDT Sat Aug 9 2025

We finally got a reprieve from the blistering heat today, with
morning temperatures ranging from high 50s to low 60s across the
plains. The forecast area should stay below 90 degrees today: mid-
high 80s for the plains and low 60s to low 80s for the
mountains/valleys. Elevated to near critical fire weather conditions
are expected across the northern mountains and high valleys (see
Fire Weather Discussion). However, the main concern today is the
severe weather potential across the urban corridor and plains this
afternoon and evening.

The first round of storms will likely occur in the next hour or so.
Current radar imagery shows a well established Denver cyclone
just east/northeast of DIA, with the associated convergence zone
south of the cyclone and over the Palmer Divide. With continuous
moisture advection into the plains this morning from the E/SE
winds, there is a nice spread of mid 50s to low 60s dewpoint
temperatures. Hi-res guidance has MUCAPE between 1500-2500 J/kg,
EBWD >30 kts and steep mid-level lapse rates above 8 deg C/Km.
This environment would support multiple supercells capable of
producing 1-2" hail and damaging wind gusts up to 60 mph. The
tornado threat is low, but cannot rule out a brief one occurring,
especially along the DCVC. We expect storms to initiate off the
convergence zone on the Palmer Divide and travel east through the
late afternoon/evening. Another area of storm development will be
in northern/northeastern Colorado along a boundary along the
border between Wyoming, Nebraska, and Colorado. We will likely
have a watch out in the near future.

The second round of thunderstorms is expected for the urban corridor
and plains this evening and overnight. However, the severe threat
will be conditional. An upper level shortwave (currently in southern
Idaho) will enter the state tonight, forcing convective initiation
along the foothills/urban corridor and northern plains. With daytime
heating destabilizing the atmosphere, but no afternoon storms to
"use up" that energy, a few strong to potentially severe
thunderstorms are possible. Guidance is in good agreement of MLCAPE
values expected to be up to 2,000 J/kg, EBWD >40 kts and steep lapse
rates. Hail up to 2" will be the main threat again, along with
strong outflow wind gusts. Storms will travel east and could
continue to the early morning hours.

Another round of thunderstorms is expected for Sunday late morning
and early afternoon as the upper level shortwave travels across
the state. The severe threat will be dependent on how long the
overnight storms linger in our forecast area. Models are trending
towards instability building in the morning hours before
convective initiation starts around 11 AM/noon. MLCAPE values
could get up to 1500 J/kg and bulk shear between 30-40 kts. All
severe hazards will be possible, with large hail as the biggest
threat. However, if overnight storms linger past sunrise, initial
storm development could remain sub-severe along southern urban
corridor and Palmer Divide. Regardless of the severe threat, brief
moderate to heavy rain is expected with storms that develop. Due
to the multiple rounds of storms expected today combined with the
storms tomorrow, WPC has introduced a slight risk for excessive
rainfall for parts of Lincoln and Elbert counties. Although,
localized flooding issues are also possible across the eastern
plains.

Below normal temperatures are expected for Sunday and Monday, with
Sunday being our coolest day of the forecast period. Highs should be
in the mid-upper 70s across the plains. On Monday, flow aloft will
turn northerly behind the exiting shortwave, which will keep
temperatures in the low 80s. Scattered showers/thunderstorms are
also possible but should stay sub-severe.

By Tuesday, an upper level ridge will begin to rebuild over the
western United States, which will bring back warm and briefly dry
conditions. Highs are expected to reach mid-high 90s each day.

&&

.AVIATION /12Z TAFS through 12Z Monday/...
Issued at 515 AM MDT Sun Aug 10 2025

A cool front was approaching from the north and will allow for
winds to become northerly in the next few hours.  Winds by 18z
will shift to a more NE direction and then trend to easterly
by 21z. Still not sure about tstm development this aftn as initial
activity may stay to the south and southeast of the airports so
will keep prob30. Outflow boundaries may generate some activity
this evening thru 03z so have kept prob30 in until then.  Winds
this evening will depend on which direction ouflow boundaries
come in from.  For now have left them easterly and then going
more SE by 03z.

&&

.FIRE WEATHER...
Issued at 300 AM MDT Sun Aug 10 2025

Elevated fire conditions will continue over the higher terrain
today through Wednesday. However, winds will be relatively
light through the middle part of the week ahead.

&&

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

&&

$$

UPDATE...RPK
DISCUSSION.....Ideker
AVIATION...RPK
FIRE WEATHER...RPK