326
FXUS65 KBOU 270957
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
357 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 and Wednesday.

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

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

&&

.SHORT TERM /Through Tonight/...
Issued at 357 AM MDT Fri Sep 27 2024

A weak cold front is dropping through the Denver area at this
hour. It will bring a puff of north winds, mainly this morning,
and 5-10 degrees of cooling for the plains today, with little
change in the mountains. There`s a pocket of shallow mid level
moisture/instability that`s stuck in light flow aloft over central
and eastern Colorado. This will gradually fade today, but then
will be reinforced by diurnal convection over the mountains this
afternoon. We`ll probably just have a few sprinkles if anything
over the central mountains, but there is a small chance of a
thunderstorm or two.

All of this is handled pretty well in the going forecast. We did
make some changes for more cloud cover especially this morning.

&&

.LONG TERM /Saturday through Thursday/...
Issued at 357 AM MDT Fri Sep 27 2024

The strong ridge aloft that is currently over New Mexico will drift
northward this weekend and will be over Colorado for the majority of
the time. Strong subsident flow will lead to dry conditions with
plenty of sunshine. The story will be the heat as temperatures will
be near records or will surpass record highs. Saturday will be
the slightly cooler day of the two days with highs in the upper
80s across the plains. Since surface winds will be out of the
southeast across the plains, the slight upslope component will
likely keep most areas from hitting 90 F. That won`t be the case
on Sunday as lee cyclogenesis over eastern Montana and western
North dakota will develop south-southwesterly winds across the
plains. This will add a downslope component to the wind and with
compressional warming, highs will likely reach the low 90s across
a good portion of the urban corridor and plains. The high was
bumped up 1 F in Denver with a forecast of 91 F. This would be
within a degree of the record high of 92 and tying or breaking the
record could happen.

A trough will move to the north of Colorado on Monday extending
as far south as Wyoming. This will not bring precipitation to
Colorado but it will bring a cold front. The timing of this front
will be crucial to the forecast but models are not in good
agreement about the timing. The GFS and its ensembles have the
vast majority of members bringing the cold front through late in
the afternoon. Therefore, the majority of members forecast a high
in the low 90s across the plains. The ECMWF is more evenly split
between the front arriving in the morning or in the afternoon. The
ensembles have clustered around a high either in the low 70s in
Denver or a high in the upper 80s to low 90s. Cold fronts always
seem to arrive sooner rather than later around here and there`s no
reason that shouldn`t happen again. The forecast high
temperatures were left in the middle with highs in the low 80s
across the plains since there isn`t much confidence in the cold
front timing. If the cold front is slower, Denver may see a high
approaching the record of 91. Another concern is if the cold
front is slower to move through then there is potential for
elevated to critical fire weather conditions. The cold front will
have wind gusts of 40 mph behind it and minimum relative humidity
could be in the teens if highs are near 90.

There is better confidence that Tuesday will be the coolest day of
the extended. A surface high pressure system over Kansas and
Nebraska will create southeasterly winds across the plains. This
will keep a cooler, post-frontal airmass in our forecast area.

The slightly cooler temperatures will not last for long. Strong
ridging aloft will develop over Colorado late Tuesday and into
Wednesday. Westerly, downslope winds are expected throughout the
troposphere which will lead to peak compressional warming on
Wednesday. Ensembles have a relatively low temperatures spread
with the majority being in the upper 80s to low 90s across the
plains. This could easily end up setting the record for latest 90
degree reading in Denver`s history as the current latest one is
October 1st.

It is possible another cold front moves through on Thursday but
confidence in any aspect of the forecast is rather low from Thursday
onward.

&&

.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.

&&

$$

SHORT TERM...Gimmestad
LONG TERM...Danielson
AVIATION...Gimmestad