Severe Thunderstorm Warning 99, NWS Denver/Boulder, CO

Area Forecast Discussion
National Weather Service Denver/Boulder CO
522 PM MDT Thu Jun 12 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms this afternoon and evening.
  Winds to 50 mph, brief heavy rain, and small hail will be the
  main threats for most of the area. A few storms could be severe
  over far northeast Colorado with strong winds and large hail.

- Chance of afternoon showers and thunderstorms continues Friday
  with a few severe thunderstorms possible over the eastern
  plains.

- Warming and drying trend this weekend with the chance for
  thunderstorms confined to the northeast plains.

&&

.DISCUSSION /Through Thursday/...
Issued at 219 PM MDT Thu Jun 12 2025

Another round of afternoon and evening showers and thunderstorms
will track across the area. The airmass over the higher terrain
and nearby plains is little more moist and unstable compared to
yesterday with mid 30s to mid 40s dew points and MLCAPE up of 300-
800 J/kg. This will result in mainly high-based showers and
thunderstorms with gusty outflow winds the main threat. Brief
heavy rain and small hail will also be possible. Southeast winds
over the eastern plains are advecting moisture into the area. Dew
points here are in the 50s with 60s nearby in Kansas and Nebraska.
MLCAPE in this area is 1000-2000 J/kg. Thus, some of the storms
over the northeast plains could become severe with large hail and
damaging winds. Models are in good agreement the northeast corner
of Colorado will see a round of storms this evening, 6 PM to 10
PM. To the west showers and thunderstorms will be ending during
the evening hours.

Water vapor satellite imagery showing drier air off to the west.
This drier will shift eastward for Friday. This will lead to fewer
and weaker showers and thunderstorms across the higher terrain
and nearby plains. Over eastern Colorado, southeast winds will
continue to bring moisture, with dew points in the 50s to lower
60s. It will be unstable again with MLCAPE of 1500-2500 J/kg.
Models vary how far west the best instability and moisture make
it. Most models keep it over far northeast Colorado, though the
NAM model has it as far west as Greeley and just east of DIA.
Outflow from thunderstorms tonight over Nebraska may help push the
southeast winds westward more than the models show.

For this weekend and Monday, ridging intensifies over the Central
and Southern Rockies, leading to warmer temperatures and drier
conditions. Most locations over northeast Colorado are expected to
top 90F degrees. With precipitable water falling below a half
inch along the Front Range and below a third inch over the higher
terrain, not expecting enough moisture for showers and
thunderstorms. Again, the best chance for storms will be over far
northeast Colorado where southeast winds may bring enough moisture
for thunderstorms, some of which could end up being severe.

For Tuesday, the latest model runs have been trending towards an
upper level trough pushing through the area and knocking down the
ridge. This will lead to cooler temperatures with highs in the 80s
across northeast Colorado. It may also bring enough moisture for
showers and thunderstorms, though not all models show this, but
enough do to mention showers and thunderstorms for Tuesday
afternoon and evening.

On Wednesday and Thursday, a flat upper level ridge will prevail
over Colorado. Wednesday's temperatures may stay below 90F over
the plains, but by Thursday temperatures are expected to heat up
into the 90s again. Some of the longer term models are showing
temperatures well into the 90s and nearing 100F towards next
Friday- Sunday (June 20th to 22nd). Drier air will be over the
area as well with little to no chance for showers and
thunderstorms, unless we see more moisture than expected.

&&

.AVIATION /00Z TAFS through 00Z Saturday/...
Issued at 518 PM MDT Thu Jun 12 2025

Another boundary was moving across DIA with WNW winds. May see
some gusts up to 25 mph for the next hour or so. After this
boundary exists the area winds may trend to more SW by 01z and
then more southerly by 03z. By 14z Fri winds will become light and
variable around 5 mph. By 19z, look for winds to become southeast
with a chc of gusty showers and tstms by 20Z.

&&

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

&&

DISCUSSION...Meier
AVIATION...RPK

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
933 AM MDT Thu Jun 12 2025

COZ030>051-131545-
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Grand and Summit Counties Below 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet-
Central and Southeast Park County-
Larimer County Below 6000 Feet/Northwest Weld County-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
Northeast Weld County-Central and South Weld County-Morgan County-
Central and East Adams and Arapahoe Counties-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County-
Southeast Elbert County Below 6000 Feet/South Lincoln County-
Logan County-Washington County-Sedgwick County-Phillips County-
933 AM MDT Thu Jun 12 2025

This hazardous weather outlook is for northeast and north central
Colorado.

.DAY ONE...Today and Tonight

Scattered showers and thunderstorms this afternoon will bring
gusty winds, with speeds reaching up to 50 mph. A few storms could
become severe with 60 mph winds. Over the northeast corner of
Colorado, one inch hail may occur with the severe thunderstorms as
well.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Scattered afternoon showers and thunderstorms are expected again
Friday. Some strong to severe storms will be possible over the
northeast plains Friday afternoon. For the weekend, the chance for
storms is limited to the northeastern plain. Where a severe storm
or two will be possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today and tonight.

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