785
FXUS65 KBOU 310545
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1145 PM MDT Thu May 30 2024

.KEY MESSAGES...

- Severe storms shifting slowly south and east overnight, slowly
  diminishing.

- A few severe storms possible across the plains and I-25 Corridor
  Friday, with the best chance being Denver and southward.

- Warmer and drier beginning Saturday, with a couple strong to
  severe storms still possible on the plains.

- Hottest temperatures of the year Sunday into early next week.

&&

.UPDATE...
Issued at 1144 PM MDT Thu May 30 2024

Well that was impressive. We popped off the instability that
pushed back to the Front Range this evening in a big way, with
severe storms and unfortunately a lot of damage for north and east
portions of metro Denver.

That severe threat is shifting off to the east and southeast, but
will continue for the next couple hours before slowly fading as
energy gets used up. However, still can`t rule out some overnight
redevelopment over the northeast plains with the next arriving
surge and cold front.

&&

.SHORT TERM /Through Friday/...
Issued at 250 PM MDT Thu May 30 2024

GOES-18 Water Vapor imagery displays dry air throughout northeast
Colorado. Although storms may struggle to begin, scattered showers
and storms are expected through tonight especially south of I-70
across the plains. Areas north of I-76 will be drier this afternoon.
Winds aloft remain light as westerly flow continues. Models favor a
surface low developing late this evening near the Colorado Kansas
border. CAMs, especially the HRRR, have shown a line of
thunderstorms pushing eastward starting from Weld to Yuma county
near midnight tonight. MUCAPE values between 700-900 J/kg amongst
guidance seems to favor this outcome thus this forecast update
adjusted PoPs tonight for lingering showers and storms until
Friday morning. There some uncertainty about the severe potential
of these overnight showers and storms but it is possible these
storms could produce small hail, wind gusts up to 45 mph, and
brief heavy rainfall. If there is enough low level moisture, a
few spots of fog could occur along I-76 Friday morning. Model
soundings have shown light northeast winds to support this
outcome. By Friday afternoon, another round of scattered showers
and storms are possible along the foothills, urban corridor and
plains with the threat of severe storms mainly east of I-25.

&&

.LONG TERM /Friday night through Thursday/...
Issued at 250 PM MDT Thu May 30 2024

Strong to severe thunderstorms will remain possible into Friday
evening as storms progress eastward across the plains. Best chance
for the showers and storms will be along and south of I-70. It`s
still unclear how stable/capped it will be across northern
Colorado.

On Saturday, the airmass begins to dry out and warm up along the
Front Range. There will be enough moisture and instability for
high based showers and storms. Gusty outflow winds will be the
main threat with this activity. A dry line/lee trough sets up over
eastern Colorado. To the east of it, dew points will reach the
50s with ML CAPE of 1000-2000 J/kg. This combined with increasing
shear will likely produce a few severe thunderstorms over the
eastern (perhaps far eastern) Colorado.

First taste of summer arrives Sunday. An upper level trough
moving across the Northern/Central Rockies will increase the
westerly flow aloft and also cause a lee side trough/dry line to
form over far eastern Colorado. This will lead to gusty downslope
west winds for Sunday. Temperatures will warm to around 90F across
northeast Colorado. The wave passing north of Colorado, could
produce a few high based showers/storms over northern Colorado.
The best chance for convection will be over far northeast Colorado
where better moisture will be possible.

For Monday and Tuesday, flat ridging in the westerly flow aloft
is expected to keep temperatures warm, in the mid 80s to lower
90s. The airmass is looking too dry for showers or storms. On
Tuesday, models are coming into better agreement showing a closed
low tracking across the Northern Plains. This will cause flow
aloft to turn northwesterly and bring a cold front late Tuesday.
Still expect a warm day Tuesday with dry conditions.

For Wednesday and Thursday, an upper level ridge builds somewhere
over the western half of the country. Models are still unclear
where the ridge will set up. Expect warm conditions to continue
Wednesday and Thursday though slight cooling may occur behind
Tuesday`s cold front. Chances for showers and storms continue to
be low, with the vast majority of the ensemble members showing dry
conditions continuing through Thursday. One of the outliers
happens to the 12Z GFS. It shows some subtropical moisture moving
northward late next week. Can`t rule this out, though this seems
to be a stretch given what the other models show.

&&

.AVIATION /06Z TAFS through 06Z Saturday/...
Issued at 1144 PM MDT Thu May 30 2024

Storms are moving out of KDEN and KAPA area, with some clearing
post-storm expected. Post storm winds should turn more southeast
and then southerly, with partial clearing. A weak front is
expected to move in early Friday morning in the 11Z-12z timeframe,
perhaps a little later than earlier indicated. Confidence is
increasing for stratus considering more low level moisture, so
we`ll likely have (60-70% chance) MVFR ceilings for several
hours, and a low chance (20-30%) they could last into the
afternoon before gradually breaking up. Scattered showers/storms
are possible in the late afternoon and evening, but coverage
may very well be limited by low level stability.

&&

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

&&

$$

UPDATE...Barjenbruch
SHORT TERM...AD
LONG TERM...Meier
AVIATION...Barjenbruch