782
FXUS65 KBOU 172337
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
537 PM MDT Fri Jul 17 2026

.KEY MESSAGES...

- Hot weather continues through Monday. The highest temperatures
  will occur Sunday and Monday, and a Heat Advisory has been
  issued for the Denver Metro/I-25 corridor from 10 AM Sunday
  through 9 PM Monday.

- Scattered afternoon/early evening storms in the mountains
  expected through Sunday with the plains remaining dry.

- Significant monsoonal moisture and cooler temperatures will
  arrive on Tuesday of next week. The thunderstorms that develop
  will be capable of producing locally heavy rainfall.

&&

.DISCUSSION /Through Friday/...
Issued at 141 PM MDT Fri Jul 17 2026

Visible satellite shows cumulus clouds growing upscale over the
mountains this afternoon. Meanwhile, there are fewer clouds over
the foothills and western I-25 corridor. Based on this satellite
signature and given a similar environment to yesterday, scattered
showers and storms are expected once again over the mountains but
the chance for showers and storms over the western I-25 corridor
is lower today. Storms over Clear Creek and Park Counties will be
capable of producing locally heavy rainfall. Given that some areas
in those counties received around 1.5" of rain yesterday, there
could be some localized minor flooding from some of these storms
today. A few storms will make their way into Jefferson and Douglas
Counties this evening but are not expected to produce much
rainfall there.

On Saturday, there will be slightly warmer temperatures aloft
with slightly less moisture in the low levels. As a result, there
will be less coverage of showers and storms over the higher
terrain with isolated coverage expected. Temperatures will be warm
again but not noteworthy for this time of year.

An upper level ridge will strengthen on Sunday and the easterly
flow within the low levels will decrease. With stable conditions
aloft, there will be plenty of sunshine across the plains. With
700 mb temperatures around 20 C, highs across the urban corridor
will be in the upper 90s to around 100. Downtown Denver, Fort
Collins, and Greeley will all have very hot temperatures on the
pavement and there will be no relief from the sunshine since
afternoon clouds will be limited. Considering that, along with the
HeatRisk being at level 3 for the majority of the urban corridor,
a Heat Advisory was issued.

On Sunday night, the axis of the low level thermal ridge will be
over northern Colorado. Low temperatures will be near record warm
with lows potentially staying above 70 across much of the Denver
metro. Given this, the decision was made to continue the Heat
Advisory through Sunday night.

The ridge aloft will be strongest on Monday and 700 mb
temperatures will warm to around 22 C. A warm start to the day
from the warm low temperatures, plenty of sunshine, and subsident
flow will lead to a very hot day across the I-25 corridor and
eastern plains. The GFS ensembles have a 50th percentile of 101 at
KDEN and the ECMWF ensembles have a 50th percentile of 100. It
seems reasonable that the KDEN ASOS reaches 100 and downtown
Denver could hit 102 or 103. Many other downtown areas will be
101-102. Therefore, the Heat Advisory continues through Monday and
will end Monday evening.

By late Monday, there will be a cold front that pushes into
northern Colorado. This will pool moisture along it and provide
forcing for storms over the higher terrain. Some of these storms
could produce heavy rainfall and it`s possible some move off the
higher terrain onto the adjacent plains during the evening.

The front will move to southeastern Colorado on Tuesday with east
or southeast winds over northeast Colorado. This will push ample
moisture into our forecast area and precipitable water values in
Denver will reach 1.25". Strong storms with heavy rainfall are
expected across the majority of our forecast area including the
I-25 corridor.

Precipitable water will increase further Wednesday and Thursday
and could be near the 99th percentile for any day in Denver`s
history. Scattered strong storms will again produce heavy
rainfall. This may end up being a period where flash flooding is a
concern and it`s possible there would be a need for Flood Watches.
Otherwise, temperatures will lower to near normal Wednesday and
Thursday.

&&

.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 537 PM MDT Fri Jul 17 2026

VFR will persist through the TAF period. Remnants of weak
convection to the southwest has pushed a boundary through KAPA,
and appears this could reach KDEN 01-02Z, but it is slowing so
only about a 50-60% confidence of a wind shift to more southerly
by then. Otherwise, winds will be more E-SE this evening before
winds comply to fairly normal patterns. That means SE-SSW at
KDEN and KAPA 03Z-13Z, then SW 13Z-15Z, VRB 15Z-17Z, and then
increasing E with gusts increasing to 15-20kts 18Z-24Z Saturday.
KBJC will see a more NW wind component during the 03Z-15Z period.

No storms or outflow potential will exist Saturday.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM Sunday to 9 PM MDT Monday for
COZ038>040-043.

&&

$$

DISCUSSION...Danielson
AVIATION...20

NWS BOU Office Area Forecast Discussion