477
FXUS65 KBOU 150824
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
224 AM MDT Wed May 15 2024

.KEY MESSAGES...

- Cooler today, with some scattered afternoon thunderstorms, and
  local redevelopment of showers in the evening.

- Warmer and generally drier starting Thursday, with lesser but at
  least isolated daily afternoon showers/thunderstorm coverage,
  highest for the mountains.

- A return to more active weather early next week with a better
  chance for afternoon and evening showers and storms.

&&

.SHORT TERM /Through tonight/...
Issued at 140 AM MDT Wed May 15 2024

The region will be under the influence of upper-level troughing
today, with cooler temperatures as a result. Highs will be close
to 10 degrees below yesterday`s values for the lower elevations,
and around 5 degrees cooler in the high country. There will be a
few showers around extending along the northern tier of our
forecast area this morning, including both the mountains and
plains. Instability will be tapered today, but still sufficient
for isolated to scattered thunderstorms in the afternoon, most
numerous after 2 PM. Any thunderstorms today should remain sub-
severe, but may produce brief heavy rain and small hail.

Later this evening, a weak front associated with a secondary
fast-moving wave carrying a more southward trajectory will advect
slightly deeper moisture into the area, and inject more
northerly/northeasterly near-surface winds into the plains and
urban corridor. This will provide for a slight increase in
precipitation coverage for southwestern portions of our forecast
area, where shallow upslope flow will favor some local
enhancement (mostly the southern foothills/Palmer Divide and
adjacent parts of the Denver metro, and also Park County). Under
generally stable conditions it would largely come in the form of
more stratiform rain and some high elevation snow above ~9,500 ft.
Precipitation intensities shouldn`t be too high with this second
wave but a few tenths of an inch look likely for a few locations
when all is said and done, especially closer to the foothills.
Precipitation will taper off for most areas by midnight though a
few lingering showers will be possible overnight across southern
Park, Jefferson and Douglas Counties.

&&

.LONG TERM /Thursday through Tuesday/...
Issued at 140 AM MDT Wed May 15 2024

A departing trough along with convergent flow aloft will lead to
strong subsidence across norther Colorado on Thursday. The vast
majority of our forecast area will remain dry although a few showers
and weak storms could form over the higher terrain south of I-70.
Highs will warm to the 70s across the plains in what will be a
gorgeous weather day.

Zonal flow aloft will develop on Friday and Saturday as an upper
level ridge will influence the weather in Colorado. Subsident flow
along with downslope winds will lead to warm conditions. Highs
will warm well into the 80s across the plains on Friday with a
cold front early Saturday morning keeping highs slightly cooler
on Saturday. On Sunday, a return of downslope flow will result in
highs well above normal. The warm, dry, and breezy conditions
Friday through Sunday will create elevated fire weather conditions
across portions of the plains. The only area that may near Red
Flag Warning criteria is just south of the Cheyenne Ridge as winds
will be strongest there.

A trough will move over the western US during next work week and
will stall out. There will be southwesterly flow aloft with
numerous shortwave troughs that move across Colorado throughout
the week. These troughs will provide forcing for storms to form
most afternoons. Models do not show much moisture return to
eastern Colorado during the week but if moisture is better than
forecast, there will likely be severe thunderstorms.

&&

.AVIATION /06Z TAFS through 06Z Thursday/...
Issued at 1128 PM MDT Tue May 14 2024

Continue to favor drop in CIG heights after 09-10Z, with some
improvement and scattering mid to late morning ahead of the
development of scattered showers and thunderstorms in the
afternoon. This activity should hold off until 20Z at least,
possibly closer to 21Z, and convective bases will likely be lower
than previous days, around 040. Light drainage or variable winds
early this morning will transition to NNE or NE flow past sunrise,
strengthening some through the morning.

By Wed evening (00-02Z), thunderstorms should become less numerous
with a modest and temporary reduction in cloud cover, along with a
counter-clockwise rotation in winds back to light west or
southwest winds for the remainder of the evening and overnight
period. More stratiform rain showers should then begin to fill in
through the evening, most persistent across the foothills and
southwest metro, but likely impacting all Denver area terminals at
times for most of the evening with a return to lower CIG heights
in the 015-030 range.

&&

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

&&

$$

SHORT TERM...Rodriguez
LONG TERM...Danielson
AVIATION...Rodriguez