286
FXUS65 KBOU 281748
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1148 AM MDT Sun Apr 28 2024

.KEY MESSAGES...

- Not as cool today with a chance of showers and thunderstorms
  this afternoon and early evening. Alpine areas could see an
  additional 1 to 4 inches of snow.

- Warmer and drier conditions to start the week.

- Turning to cooler and possibly wetter Wednesday and Thursday.

&&

.UPDATE...
Issued at 1056 AM MDT Sun Apr 28 2024

Northwesterly winds are developing across most of the plains at this
time.  There was small batch of light rain showers over Urban
Corridor earlier this morning, but they dissipated now.  The
foothills and western half of the plains are receiving fairly decent
sun at this time.  There is more cloudiness elsewhere for the CWA.

Models are showing some lower end MLCAPE values for the CWA this
afternoon, with nothing much above 400 J/kg.  Soundings off ACCARS
are showing about that assuming it can get to 56 F at DIA this
afternoon.  The models are showing limited convection into the early
evening hours. Current pops aren`t too bad so will make minor
adjustments, especially early where there is no convection
currently.

&&

.SHORT TERM /Through tonight/...
Issued at 302 AM MDT Sun Apr 28 2024

The upper low this morning is presently over far northeast CO
this morning and will continue to lift northeast into central NE
by this afternoon. Lows clouds and maybe some patchy fog this
morning, but that should decrease after sunrise. The best chance
of showers this morning will be in the vicinity of the trough in
the far northeast plains, and in the mountains. The flow aloft
will remain northwesterly this afternoon with enough moisture and
instability to produce additional showers as well as some
thunderstorms. The HiRes models all indicate some decent cell
development, with sfc based CAPES of 250-600 j/kg and mid level
lapse rates over 8 C/KM. In addition, brisk northwest winds will
develop across the plains with gusts up 35 mph possible this
afternoon. For this evening, the models maintain some qpf through
this evening, then it tapers off overnight. High temperatures
today will be on the cool side, but 10-12 degrees warmer than
Saturday.

&&

.LONG TERM /Monday through Saturday/...
Issued at 302 AM MDT Sun Apr 28 2024

Weak upper level ridge to move across the Central Rockies Monday
bringing dry and mild conditions. High temperatures are expected
to top out around 70F across northeast Colorado. For Monday night,
a weak trough moving across Wyoming and jet will provide lift to
produce an area of rain and high mountain snow over southern
Wyoming and the north central Colorado mountains late Monday night
and early Tuesday morning. Westerly flow around the base of the
trough will produce a downslope flow east of the mountains,
bringing the precipitation to an end Tuesday morning. Expect
breezy conditions over the mountains and foothills Tuesday. It
will be another mild and dry day Tuesday with highs again around
70F degrees over northeast Colorado.

Upper level trough will track across the Northern and Central
Rockies Wednesday and Thursday. Model trends have been all over
the place with the track and strength of the system. The ECWMF had
been tracking slow, stronger, and farther south, until the 00Z
run, which is weaker and drier over Colorado. The GFS which was
the weaker model and showed this system staying farther north is
now the stronger and slower model. All said, confidence in the
forecast for Wednesday and Thursday is low. Temperatures should
trend cooler with the trough and cold front moving through the
region. Chances for precipitation and amounts are still very
unclear, so will go middle of the road with PoPs of 30-60 for
Wednesday and Thursday.

For Friday, northwest flow aloft will prevail behind the upper
level low east of Colorado. Temperatures begin to rebound Friday,
but should stay somewhat cool under the northwest flow with highs
in the lower to mid 60s over northeast Colorado. Current pattern
depicted by the GFS and ECMWF favor dry conditions for Friday,
though given the amount of uncertainty in the pattern prior to
Friday, will keep the 20-30 PoPs in the forecast from the NBM.

For the weekend, flow aloft will turn westerly for Saturday and
then southwesterly for Sunday. Temperatures will continue to warm
each day under this pattern with highs returning to the 70s over
northeast Colorado Sunday. Models show a weak trough passing north
of Colorado Saturday with a cold front dropping south across
Colorado, this help keep highs in the 60s. Can`t rule out isolated
to scattered storms behind the front this far out, so will roll
with low PoPs.

&&

.AVIATION /18Z TAFS through 18Z Monday/...
Issued at 1147 AM MDT Sun Apr 28 2024

Models have weak downsloping surface winds at DIA this afternoon.
Weak normal drainage wind patterns are expected overnight. Will
leave the "VCSH" in at this time, however the airmass needs to
warm up a bit to hit the convective temperature. If some showers
do develop, variable direction outflow winds gusts to 40 knots are
possible.

&&

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

&&

$$

UPDATE.......RJK
SHORT TERM...Cooper
LONG TERM....Meier
AVIATION...RJK