761 
FXUS65 KBOU 302056
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
256 PM MDT Fri Jun 30 2023

.SHORT TERM...(This evening through Saturday)
Issued at 250 PM MDT Fri Jun 30 2023

Water vapor shows a shortwave trough directly over our forecast 
area that is slowly moving eastward. This trough has helped to 
create scattered showers and storms. The main concern is Lincoln 
and Elbert Counties where moderate instability with CAPE up to 
1,500 j/kg along with moderate deep layer shear of 35-45 knots
exists. Strong to severe storms with large hail and damaging wind
gusts are the primary threat and there is a Severe Thunderstorm 
Watch there. There is another cluster of storms forming in the 
foothills to the west of Denver and they are moving into the 
western Denver suburbs. There are strong inflow winds out of the 
east and northeast that are fueling these storms. Earlier storms 
have made conditions quite cool in Denver which will limit the 
strength of the storms but the SPC mesoanalysis shows up to 1,000 
j/kg of mixed layer CAPE so marginally severe hail could form. The
Monument Hill AWOS is reporting a temperature of 68 F which means
that that area has destabilized after the earlier convection. 
Considering this, along with the strong northeast winds that favor
convection on the Palmer Divide, it appears likely that a line or
cluster of storms will move over the northern Palmer Divide. 
These storms could produce large hail and damaging winds. 

Otherwise, in the mountains, there are scattered storms that will
slowly dissipate by this evening. Across the plains to the north
and east of DIA, conditions are very stable which should limit
storm activity. Some showers are possible into the evening but
they should be light. 

If you are hoping for some great weather after a couple weeks of
heavy rain and storms seemingly every day, then I have some
wonderful news for you. The start of the holiday weekend will see
a good amount of sunshine with rather light winds. High
temperatures will be below normal with highs in the 70s to low 80s
across the I-25 corridor and plains. There may be a few very light
showers in the mountains and foothills but they won't amount to
much. 

.LONG TERM...(Saturday night through Friday)
Issued at 245 PM MDT Fri Jun 30 2023

...Summer warmth returns...some sparks for the Fourth of July...

We'll start this period under mostly dry conditions Saturday
night, with only an isolated shower or storm lingering early in
the evening near the higher terrain (mainly Park County). 

Sunday will feature warmer temperatures, but some moisture and
slight instability returns under the ridge. There may also be a
weak shortwave in west/northwest flow aloft, enough to support 
isolated to scattered storm coverage.  

The models are in good agreement that Monday will be mostly dry
with a subsident airmass under a flat ridge. It will also be our
warmest day of the period with downslope flow and further warm 
advection aloft. High temperatures may reach the lower 90s, a rare
occurrence on the plains this year. 

By Tuesday, the 4th of July, the GFS and GEFS are still a little 
faster for the upcoming shortwave, while the EC and EC ensembles 
are a little slower. That said, it looks like there's reasonable 
agreement we will have an increase in convection and shower/storm 
coverage just in time for the 4th of July afternoon and evening
activities. Even if the slower EC verifies, we'll have scattered 
and high based storms with gusty winds. If the faster GFS works 
out, then look for at least scattered coverage of stronger,
heavier rain producing storms.

Then cooler and unsettled weather is expected to settle in by
Wednesday, although storm coverage will be dependent on the amount
of instability and potential for another shortwave. Gradual
warming to closer to normal temperatures is then expected late in
the week. But there will still be a chance of storms each 
afternoon and evening.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1235 PM MDT Fri Jun 30 2023

Outflow winds have impacted DEN with strong gusts up to 37 knots
out of the east. These will weaken shortly. Another round of
showers and storms may come off the foothills and towards the
terminals later this afternoon. Since it is so cool and stable,
direct impacts from storms are not expected so VCTS was included
in the TAF but no TEMPO group. However, a direct impact is 
possible and lower visibility and ceilings and gusty winds could
occur. Later this evening, the showers and storms will come to an
end. Winds will be light tonight and tomorrow morning. Showers
should avoid the terminals tomorrow afternoon. 


&&

.HYDROLOGY...
Issued at 245 PM MDT Fri Jun 30 2023

Storms this afternoon could produce flash flooding in East
Troublesome and Cameron Peak burn areas due to heavy rainfall. 
These storms will dissipate this evening. 

There is no threat of flash flooding tomorrow. 

Airmass dries out for Saturday with only low chances for weak 
showers and thunderstorms. There will be an increase in storms for 
Sunday, though moisture doesn't look as impressive as with the 
previous systems we have seen. This is expected to keep the flash 
flood threat low, even in the burn scars.

Storms with heavier rain would be possible toward next Tuesday 
and Wednesday. 

&&

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

$$

SHORT TERM...Danielson
LONG TERM...Barjenbruch
AVIATION...Danielson
HYDROLOGY...Danielson/Barjenbruch