380
FXUS65 KBOU 171004
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
404 AM MDT Fri May 17 2024

.KEY MESSAGES...

- Much warmer and drier today. There will be elevated fire weather
  conditions across northern Larimer and Weld Counties.

- Breezier Sunday into Monday with localized fire weather concerns
  possible depending on fuel conditions.

- Cooler, unsettled pattern with increasing precipitation chances
  across the region early next week.

&&

.SHORT TERM /Through tonight/...
Issued at 223 AM MDT Fri May 17 2024

Water vapor imagery shows a very dry airmass entering Colorado as
well as upper level ridging. Colorado will be under the right exit
region of a jet that moves over Wyoming today. This will lead to
strong subsidence and the vast majority of our forecast area will be
dry as a result. Some high resolution models indicate that very weak
instability in the late afternoon could lead to a few virga
showers. Some of these could create brief wind gusts and perhaps a
few rain showers could make it to the surface.

The strong subsidence aloft and downslope, westerly winds at the
surface will lead to very warm conditions across the urban corridor
and plains. Highs will reach well into the 80s and it is even
possible a location or two could reach 90 in the usual warm spots in
the South Platte River Valley. The record high for Denver is 91 and
that is out of reach.

The only minor weather concern today is elevated fire weather
conditions across northern Larimer and Weld Counties. Minimum
relative humidity will drop to as low as 12 percent there and wind
gusts could reach 25 mph. Across the rest of the plains, winds will
be too light to increase fire weather conditions.

&&

.LONG TERM /Saturday through Thursday/...
Issued at 333 AM MDT Fri May 17 2024

Cooler weather is expected Saturday behind a weak cold front. This
should keep highs in the 70s across most of the plains, though a
few of our warmer spots still could reach 80F. Main question for
Saturday is how much moisture lingers across the region behind the
front, and what that looks like for a PoP forecast. Pretty good
confidence that the high country (especially along/south of I-70)
sees typical afternoon showers and storms, with lower confidence
along/east of I-25. High resolution guidance supports at least
widely scattered convection across the plains by the late
afternoon hours which is reflected in the current grids.

Sunday should be warmer and drier as westerly flow aloft begins to
gradually strengthen ahead of a trough axis. The added downslope
component to the flow should usher out any lingering moisture with
the best chance of any showers/storms confined towards the Wyoming
border. Highs again should rebound into the upper 70s to low 80s
across the lower elevations.

Southwesterly flow aloft will increase Monday as the trough axis
approaches, with a lead shortwave expected to eject into the
Central Plains from Monday into Tuesday. A surface low is
generally expected to form across southern Colorado on Monday
afternoon and quickly shift east... with a strong cold front
expected behind it. There are still a few questions about the
timing and evolution of the primary shortwave (and the overall
synoptic pattern) which will ultimately influence the mesoscale
environment as well. While it`s a fairly low confidence forecast
period, the overall pattern does look quite favorable for
cooler/wetter weather across the forecast area.

Model guidance gradually diverges by mid/late next week. The mean
pattern would favor zonal flow with enough moisture embedded to
support isolated/scattered showers and storms, mainly across the
higher elevations. Temperatures in this period look to be near
normal.

&&

.AVIATION /06Z TAFS through 06Z Saturday/...
Issued at 1158 PM MDT Thu May 16 2024

VFR conditions through the TAF period. There will be healthy
drainage the rest of the night. Winds will become weak this
morning and into the early afternoon. The winds in the mid to late
afternoon will be very tricky, especially at DEN. There will be
periods of gusty westerly winds that mix down and some of the
westerly winds could reach around 20 knots. However, there is
expected to be plenty of periods of very light winds in the
afternoon as well.

During the evening, there will be westerly flow and not the usual
drainage winds at DEN and APA. A cold front will move through the
terminals between 08-11Z Saturday shifting winds to the NNE.

&&

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

&&

$$

SHORT TERM...Danielson
LONG TERM...Hiris
AVIATION...Danielson