632
FXUS65 KBOU 172121
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
321 PM MDT Tue Jun 17 2025

.KEY MESSAGES...

- Severe storm threat with high winds and large hail will continue
  through 6 PM.

- Warm and dry conditions are expected Wednesday through the
  weekend.

- Strong signal for record breaking heat from Friday into the
  weekend, along with potential for critical fire weather
  conditions.

&&

.DISCUSSION /Through Tuesday/...
Issued at 302 PM MDT Tue Jun 17 2025

After quite an active night and morning, we have the last round
of strong/severe storms moving through the region for the next few
hours. So far, these thunderstorms have been producing hail up to
1.5", but only sub-severe wind gusts (up to 50 mph). We expect the
hail and wind threat to continue as storms travel east, but mainly
be confined to the northern/northeastern counties. SPC
mesoanalysis has a widespread SBCAPE of up to 2,000 J/Kg across
the northern plains, but the Palmer Divide and southeastern plains
are more stable due to early morning storms and overall lack of
sunshine. Model Skew-T from most recent CAMs indicate the
potential for 60 mph winds and large hail before the storms leave
our area a little after 6 PM.

This evening, there will be scattered lingering showers due to
residual moisture across the Front Range and adjacent plains.
With clearing skies overnight, relatively light winds and dew
point depressions close to zero, there could be fog across the
plains Wednesday morning. If this happens, the morning commute
would be impacted with low visibility.

A warming and drying trend will begin Wednesday afternoon as an
upper level ridge amplifies and travels east towards central
CONUS. With southwest flow aloft, warm and dry air will be
advected into the region. Temperatures should get up to the mid
80s across the plains on Wednesday. However, the main concern is
towards the end of the week, where guidance has consistently
trended towards 97+ degree max temperatures Thursday through
Saturday, with Friday being the warmest day. ECMWF and GEFS have
multiple members reaching over 100 degrees. But, there is still
some uncertainty if we will reach triple digits or not as the
ECMWF has trended down a little from yesterday. The record high
temperatures for the 20th and 21st are 99 degrees (set in 2017 and
2007 respectively), so there is a chance we could break the
record.

Another concern with the prolonged heat, is the fire weather
threat. With the drier air being advected into the region,
relative humidity values are expected to dip into the single
digits, especially on Friday and Saturday. With breezy wind gusts
possible towards the weekend, there could be elevated to critical
fire weather conditions. However, fuels still being green will
keep fire danger low. We will continue to monitor.

Guidance has continued to indicate an upper level trough
traversing the region at the beginning of the week. This will
bring more precipitation to the mountains and plains as well as a
brief cooldown.


&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1222 PM MDT Tue Jun 17 2025

Multiple rounds of showers/thunderstorms are expected to continue
through 22Z/23Z with VRB wind gusts up to 45kts and hail. There
is still a chance that gusts could reach severe thresholds of 50
kts. but it is unlikely (~20%). Lingering showers are possible
behind these storms, mainly between 23Z and 01Z. Winds should
return to drainage overnight with a gradual clearing of skies.

Tomorrow, there is a small chance (~20%) of FG mainly between
11Z-15Z bringing IFR conditions to DIA. Have kept it out of the
TAF for now due to the low probability. Outside of that, light
winds and VFR conditions are expected for the rest of the TAF
period.

&&

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

&&

$$

DISCUSSION...Ideker
AVIATION...Ideker