636
FXUS65 KBOU 270629
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1229 AM MDT Fri Sep 27 2024

.KEY MESSAGES...

- Warm and dry for the foreseeable future with very limited
  chances of precipitation.

- Record highs possible Sunday and Monday.

- Front to bring slightly cooler conditions Monday night into
  Tuesday.

- Periods of elevated to critical fire weather conditions possible
  next week.

&&

.UPDATE...
Issued at 859 PM MDT Thu Sep 26 2024

A warm almost-summer night is underway. We`re seeing a few mid
level clouds and have adjusted the sky cover up a bit for that.
While no precipitation is still expected, it`s not entirely
impossible we see a little virga before morning. The partly cloudy
skies will act to keep us warm, as will a "cold" front arriving
from the north which will only aid mixing. Thus, we`ve bumped up
temperatures a couple degrees in most areas, and we could be
looking at low temperatures close to record warm minimums - to
compliment our record highs today.

&&

.SHORT TERM /Through Friday/...
Issued at 238 PM MDT Thu Sep 26 2024

Current observations show a new record high temperature has been set
for Denver this afternoon. The previous record of 90F (set in 2010),
will be replaced with today`s 91F as another day of above normal
temperatures continues for northern Colorado.

After today`s record breaking temperatures and some scattered cloud
coverage expected to return to the forecast area overnight, low
temperatures will be a few degrees warmer than last night. Overnight
lows will range from 8-18F above normal across the CWA. A weak cold
front is expected to slide south across the forecast area just
before sunrise Friday morning. Northerly winds are expected to
increase from north to south beginning around 2-3AM. The HREF Grand
Ensemble shows probabilities ranging from 20-50% of wind gusts
greater than 35 mph, mainly for the northeastern corner of the state
from Weld County east, and southern Lincoln County. Probabilities
diminish quickly for anything greater than 40mph. Gusty conditions
should diminish by around 9AM. Warm and dry conditions are expected
behind the front with high temperatures dropping slightly from
today`s as northerly flow aloft returns and today`s slightly
flattened 500 mb ridge rebuilds over the southwest. CAMs indicate
potential for an isolated high-based shower over the high country
tomorrow afternoon. Left enough PoPs in the grids to account for
this. If anything were to form, it would likely be a passing virga
shower, with forecast soundings indicating enough DCAPE values to
support potential for an associated gusty outflow.

&&

.LONG TERM /Friday night through Thursday/...
Issued at 238 PM MDT Thu Sep 26 2024

This weekend`s weather will be dominated by upper-level ridging
and, after Friday`s brief reprieve, daytime temperatures will
rebound into the upper 80`s to locally even low 90`s for the lower
elevations, peaking on Sunday. A few locations could approach
daily records Sunday if hotter solutions verify. Clouds will be
hard to come by, with ample sun and relatively light winds both
days. A few northerly gusts could exceed 20 mph Sunday afternoon
in the eastern plains, but speeds will not be sufficient to carry
more than an elevated fire weather threat.

A dry cold front will descend into northern Colorado on Monday,
generally between late morning and late afternoon, associated with
a broad upper-level trough well to our north. Monday`s high
temperature forecast for many plains/urban corridor locations
carries very high uncertainty at this time, given continued
differences in the progged timing of the front. The latest
guidance has, for the most part, delayed its arrival, with our
northern tier of counties best positioned for an early enough
onset to result in much cooler highs (e.g. in the 70`s). For the
Denver area, there`s potential for the front to hold off just
enough past peak heating to allow highs to climb back into the
90`s and thus again approach or exceed daily records. Regardless,
expect some fluctuation in the temperature forecast for Monday
until guidance comes into better agreement on frontal progression.
The other consideration will be the increase of northerly winds
in the afternoon, which could lead to more widespread fire weather
concerns across the plains as humidity values in the teens
linger. With limited if any moisture behind the front,
temperatures will cool efficiently overnight, and some of the high
mountain valleys look to fall below the freezing mark.

Tuesday will see cooler temperatures following the front with
highs down into the 70`s for the bulk of our plains and urban
corridor, with ample sunshine making for a pleasant Fall day.
We`ll return to mostly zonal flow aloft Tuesday onward, with
ensemble guidance suggesting an increased influence from
rebuilding high pressure and the return of a subsident pattern.
As such, expect anomalously warm and dry conditions to prevail
with highs into the 80`s returning by Wednesday. There could be
pockets of near-critical or critical fire weather conditions
across some of the higher elevations and foothills during this
period, where the westerly afternoon breeze will be strongest.

&&

.AVIATION /06Z TAFS through 06Z Saturday/...
Issued at 1228 AM MDT Fri Sep 27 2024

VFR through Friday. Some variability of the wind direction is
expected until a weak cold front moves through 10z-12z, then
northerly winds are expected through the afternoon. There may be
an hour or two with gusts to around 20 knots behind the front.

&&

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

&&

$$

UPDATE...Barjenbruch
SHORT TERM...Bonner
LONG TERM...Rodriguez
AVIATION...Gimmestad