833
FXUS65 KBOU 300639
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1239 AM MDT Thu May 30 2024

.KEY MESSAGES...

- Scattered afternoon showers and thunderstorms Thursday-Friday. A
  few could be severe across the eastern plains.

- Warmer and drier beginning Saturday. Hottest temperatures so far
  this year likely Sunday into Monday.

&&

.UPDATE...
Issued at 849 PM MDT Wed May 29 2024

Storms have mostly weakened and moved out of northeast Colorado
with the exception of a line of thunderstorms moving east across
southwest ELbert and Lincoln county. An outflow boundary moves
westward across the Denver airport and Adams and Arapahoe
counties. Made some minor adjustments to the precipitation
probabilities to reflect the last of the showers/storms exiting to
the east.

&&

.SHORT TERM /Through Thursday/...
Issued at 239 PM MDT Wed May 29 2024

Ongoing scattered storms and showers should continue through this
evening. Weaker shear, instability, and lower dew points should keep
showers non-severe. Areas across the eastern plains to right of the
dryline align with SPC slight risk through this evening. Far east,
MLCAPE increases near 800-1000 J/kg and lapse rates between 7-
8C/km. There still a lack of favorable shear for thunderstorm
development but the threat of hail is high. Up to 2 inch hail
could occur from these severe storms along the eastern plains.
With cyclone development near DIA and robust outflow boundaries,
the threat of landspouts will occur through this evening mainly
for Morgan, Washington, Logan, eastern Adams, and eastern Arapahoe
counties.

Thursday, a cold front will arrive which will lead to lower
temperatures in the afternoon. Although conditions should become
stable after the front, daytime heating may lead to scattered storms
and showers along the Palmer Divide and adjacent plains. There is
low confidence in a severe threat of tornadoes but wind gusts up
to 60 mph and up to 1 inch hail will likely become the main
threat.

&&

.LONG TERM /Thursday night through Wednesday/...
Issued at 239 PM MDT Wed May 29 2024

Scattered thunderstorms are expected to continue into the evening
Thursday, mainly along and south of I-70. However, the NAM has
joined the GFS in showing isolated/scattered storms are able to
break the cap across northeast Colorado. Some of these storms are
expected to be strong to severe with ML CAPE to around 1000 J/kg.

For Friday, westerly flow aloft will increase as a trough passes
north of Colorado. Meanwhile at the surface, easterly winds will
transport moisture westward with dew points in the upper 40s to
lower 50s as far west as I-25. With dew points this high, ML CAPE
reaches 1000-1500 J/kg. Seems to be a good setup for strong to
severe storms due to good shear, moisture, and instability. One
limiting factor to severe storms will be low clouds Friday morning
and how long they persist. They could limit warming and result in
a capped airmass.

Southwest flow aloft will bring warmer and drier conditions to
much of the area Saturday. A dry line sets up over the eastern
plains Saturday. To the west of it, weak isolated high based
showers and storms are expected. To the east of the dry line,
strong to severe thunderstorms will again be possible.

For Sunday through Wednesday, models continue to advertise a
warmer and drier period even though upper level details are
somewhat uncertain. For Sunday, a lee side surface trough is
expected to develop under a westerly flow aloft. This will bring
gusty westerly downslope winds. Temperatures heat up along the
Front Range with the first 90 degree day possible. The eastern
plains may end up east of the lee side trough. Areas east of the
trough will see a chance for afternoon/evening thunderstorms.
Monday and Tuesday will remain mild and dry. Downslope flow
weakens, which should result in slightly cooler temperatures,
though highs are still expected to reach the mid to upper 80s over
northeast Colorado. Surprisingly good agreement among the models
for Wednesday. They show an upper level trough passing well north
of cold. A cold front associated with this system dives south
across Colorado Tuesday night bringing cooler and continued dry
air for Wednesday.

&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1235 AM MDT Thu May 30 2024

VFR through Thursday. Some uncertainty about details of a frontal
passage this morning, but it appears there will be a weak
northwest or north wind shift around 09-10z and then a stronger
north to northeast wind developing in the 12z-15z time range.
Scattered thunderstorms are expected 20z-02z with a couple of wind
shifts with gusts to 30 knots the most likely impact.

&&

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

&&

$$

UPDATE...Mensch
SHORT TERM...AD
LONG TERM...Meier
AVIATION...Gimmestad