878
FXUS65 KBOU 071849
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1249 PM MDT Mon Jul 7 2025

.KEY MESSAGES...

- Scattered afternoon/evening thunderstorms today, most numerous
  over the eastern plains.

- Some strong to severe storms are possible with large hail and
  damaging wind gusts, mainly across the eastern plains.

- Hot temperatures expected Wednesday with the upper 90s expected
  across the plains. It is possible the hot temperatures extend
  into Thursday.

&&

.UPDATE...
Issued at 300 AM MDT Mon Jul 7 2025

Upper level ridging begins to intensify over the region today
(continuing through Wednesday). With warming temperatures aloft
and slight drying, thunderstorm activity is expected to decrease
across the higher terrain and also along the I-25 urban corridor
today. There still should be enough moisture and instability this
afternoon for high-based thunderstorms. As the storms progress
eastward, storms encounter an increasingly unstable and more moist
airmass. Storms are expected to intensify with a few becoming
severe with large hail and winds to 60 mph. A shortwave trough
moves southeast across the Northern Plains today. This is expected
to produce a line of thunderstorms across Nebraska, which may
clip northeast Colorado as the line dives southeast. Storms are
expected to shift east of the area early this evening with the
area storm free around sunset.

&&

.DISCUSSION /Through Sunday/...
Issued at 238 PM MDT Sun Jul 6 2025

Satellite and radar show two main areas of convection this
afternoon. One area is along a boundary that has setup from near
Woodrow in western Washington County across to Kiowa. There are
good levels of instability feeding these storms with mixed-layer
CAPE around 1,500 j/kg. Strong updrafts have formed along this
boundary as a result. The issue these storms are currently having
with reaching severe limits is the lack of deep layer shear.
Surface to 6 km shear values are around 25 knots so storms may
struggle to maintain updrafts long enough to produce severe hail
although a report or two of 1" hail is possible. However, severe
wind gusts will be possible out of these storms throughout the
afternoon and evening given steep lapse rates and downdraft CAPE
around 1,700-1,800 j/kg. The other area of storms is along and
just south of the Cheyenne Ridge. This area will have the
potential for storms to congeal into a line as it heads east from
around Cheyenne, WY. As it heads further east, the instability
will increase with mixed-layer CAPE around 2,000 j/kg over the
far northeast corner of Colorado. It is expected that these storms
will produce damaging wind gusts up to 70 mph. A Severe
Thunderstorm Watch has been issued for areas along and east of
I-25 until 8pm tonight. Denver County was withheld from this watch
as dew points have dropped to the low 40 there and instability is
lower than other areas.

Some model guidance is showing that storms could continue into the
overnight hours tonight across the eastern plains. That threat
will depend on how much instability the storms this afternoon and
evening "use up." If there are fewer storms this afternoon and
evening, scattered coverage of storms could occur after midnight.
However, it is more likely that only a stray storm or two forms.

Better moisture will stay in place over the eastern plains on
Monday with dew point values in the low 60s from Akron and
eastward. With steep lapse rates, most unstable CAPE values are
forecast to exceed 3,000 j/kg in the northeast corner of Colorado.
This is ample instability for strong to severe storms to form. The
uncertainty with Monday`s forecast will come from the amount of
shear and what boundaries are left behind from overnight
convection. A weak shortwave aloft will enhance deep layer shear
with values around 35 knots across the far northeast corner. These
factors will lead to the development of an MCS that could produce
severe wind gusts up to 70 mph mainly east of a line from Fort
Morgan to Limon. SPC has an enhanced risk of severe weather and it
seems reasonable for the far northeast corner. The Denver metro
and I-25 corridor will mostly likely avoid much of the severe
weather assuming the best moisture stays further east.

The axis of an upper level ridge will move northeastward into
Colorado on Tuesday. This will increase temperatures aloft and
will decrease the chance for storms. However, enough lingering
moisture could produce an isolated storm near the Cheyenne Ridge.
High temperatures will begin to warm up to the mid 90s across the
plains.

Wednesday is still on track to be the warmest day of the upcoming
week as the best subsidence and warmest air aloft will be overhead
that day. Temperature forecasts still have Denver flirting with
100 degrees. With the NBM and ECMWF MOS mean forecasting a high of
98, the forecast was left at that number. However, Denver does
have a chance of reaching the record daily high temperature of 100
degrees. A Heat Advisory may be needed especially if it appears
cloud cover will be minimal.

Models have converged on a trough moving through our forecast area
on Thursday but this may only reduce the heat by 2-4 degrees from
Wednesday. A cold front moves through Thursday night with much
cooler conditions on Friday.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1217 PM MDT Mon Jul 7 2025

VFR conditions expected through the TAF period. Isolated/scattered
afternoon thunderstorms are expected to develop this afternoon
with the best coverage east of DEN. Strong outflow winds
producing wind shifts will be the main threat with gusts up to 40
knots possible if a storm were to move over the terminal. High
resolution models are beginning to converge on a solution that
takes a strong outflow from storms over the eastern plains
through all three terminals around 00-01Z with easterly winds
with gusts up to 35 knots. Therefore, the PROB30 was extended to
01Z this evening.

There will be much drier conditions on Tuesday and no storms are
expected to make a direct impact on the terminals. However, the
steep lapse rates and large DCAPE will allow storms to create
gusty winds and outflow boundaries. Therefore, a PROB30 was once
again included since a chance of an outflow boundary coming
through is at roughly 20-30%.

&&

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

&&

$$

UPDATE...Meier
DISCUSSION...Danielson
AVIATION...Danielson