National Weather Service Forecast Discussion

000
FXUS65 KBOU 010308
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
908 PM MDT Sun May 31 2020

.UPDATE...
Issued at 908 PM MDT Sun May 31 2020

Shower activity across northeast Colorado is almost over for the
evening, but a couple more showers are still moving out of the
mountains. Activity should be completely dissipated by midnight,
with decreasing clouds after that. Changes to the evening forecast
package have been minimal.

&&

.SHORT TERM...(This evening through Monday)
Issued at 141 PM MDT Sun May 31 2020

Convection has started over the higher terrain with upper flow
pushing storms to the east/northeast. Dewpoints are sitting slightly
lower than yesterday with values in the mid to upper 40s with low
50s across the far northeastern plains counties. Current ACARS
soundings show less of a CAP in place at this time than yesterday so
development will be easier than yesterday. However, models continue
to indicate a drier low level with lower PW values overall. Model
soundings continue to indicate high DCAPE values that would bring
higher chances of strong gusty winds with a few isolated strong
storms possible. Storms will push eastward through the evening
before dissipating after midnight. High cloud and downsloping will
allow for more mild overnight lows in the upper 50s to lower 60s.

For Monday, the ridge continues to break down and push eastward as
an upper trough deepens offshore of CA. Towards the surface a strong
lee side trough will build through the day maintaining a weak
easterly flow across the plains. This will help to create some
convergence against the foothills with increasing moisture and lift
provided by a disorganized disturbance embedded in southwest flow
aloft. Convection will once again start over the higher terrain with
some cells making their way onto the plains into the evening
hours. CAPE values range from 400 to 1200 j/kg with the higher
values further south. PW values continue to decrease with the main
threats from storms being gusty winds, light to moderate rain and
lightning with some possibly producing small hail. Temperatures
will continue to increase with low-90s being a high possibility
for the Denver Metro and surrounding areas.

.LONG TERM...(Monday night through Sunday)
Issued at 141 PM MDT Sun May 31 2020

Much of the upcoming week will be characterized by temperatures
well above normal for this time of year, and fairly typical rounds
of afternoon and evening showers and thunderstorms. The bulk of
the showers will remain over the mountains and adjacent plains
with only isolated coverage at best further east on the plains. Temperatures
through the week will be in the upper 80s to around 90 on the plains
and 60s and 70s in the mountains.

For Tuesday, broad high pressure aloft will be over the central and
southern plains states with a light southwest flow aloft over
Colorado. 700mb temperatures will remain close to +14c with little
change in temperatures. Moisture mainly in the middle and upper
levels with rather dry low levels. Expect mainly brief rain and
gusty winds with the storms. Flow is weak aloft with weak shear
profile so severe storms not expected.

By Late Tuesday and Wednesday the flow aloft will shift more
westerly and increase a bit as fast moving trof will speed across
the northern high plains states. There will be a weak front
associated with this trof which will move through the plains late
Tuesday night. However, looks like only a few degrees cooling at
best with little impact on Colorado weather. The flow aloft is
stronger Wednesday but moisture looks on the scanty side. Similar
situation on Thursday then a possibly better chance of showers by
later Friday as the upper low which had been off Southern
California coast pushes inland. Based on the GFS, the low will
rapidly weaken and lift northeast towards Colorado late Friday.
Expect higher coverage of storms with this feature if GFS timing
is correct. However, European and Canadian solutions are much
slower ejecting the low until Saturday which could mean a delay of
moisture push and showers until Saturday afternoon/evening. Will
at least have scattered pops for both Friday and Saturday for now.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 908 PM MDT Sun May 31 2020

Wind shifts from southerly to northeasterly should be the primary
aviation impacts overnight. Winds are currently out of the south-
southwest, but radar data is showing an outflow boundary moving in
from the northeast which should arrive before 10 pm. After a
couple hours of northeast winds, drainage southerlies should
return overnight. Mid and high level clouds will continue through
much of the night, but mostly clear skies should return by
sunrise. Monday will be a repeat of today, with afternoon showers
and thunderstorms expected to develop after 3 pm.

&&

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

$$

UPDATE...Dankers
SHORT TERM...Bowen
LONG TERM...Entrekin
AVIATION...Dankers

NWS BOU Office Area Forecast Discussion