FXUS65 KBOU 031109

AFDBOU



Area Forecast Discussion

National Weather Service Denver/Boulder CO

509 AM MDT Thu Jul 3 2025



.KEY MESSAGES...



- Increased thunderstorm activity over the mountains this

  afternoon with a slight chance of thunderstorms over the plains

  tonight.

 

- A chance of thunderstorms and normal temperatures are expected 

  for the Fourth of July and Independence Day weekend. 



&&



.UPDATE...

Issued at 245 AM MDT Thu Jul 3 2025



Moisture will increase over the higher terrain today ahead of a 

weak upper level trough. Will see a gradual increase in 

shower/tstm development, over the higher terrain, by early to mid

aftn which will continue thru the early evening hours. Across the

plains it will be dry and windy thru the aftn.



For late tonight into Fri, the weak upper level trough will move 

across the area.  This feature will be over the mtns by 12z and then 

move across the far nern plains by 18z.  Latest data suggests there 

could be scattered showers and a few tstms in the morning across the 

plains with some potential for a few stronger storms over the far 

nern plains thru 18z.



Once this feature exits the area, its not clear how much 

redevelopment there will be in the aftn into the early evening 

hours.  There will be some mid level cooling in the aftn which could 

lead to some additional tstms behind the main trough but overall 

confidence is low at this point.  



&&



.DISCUSSION /Through Wednesday/...

Issued at 238 PM MDT Wed Jul 2 2025



Few changes to the forecast at this time, as weak convection

should be limited to the mountains today. South to southeast

steering winds should preclude anything drifting further east.

With CAPEs looking to be in the 400-800 J/kg range, threats should

be limited to subsevere gusty winds.



Mid level moisture will increase from the southwest on Thursday,

while low level moisture will increase from the southeast. This

will set the stage for a more active day, but the plains airmass

will likely remain capped most of the day. The strength of the

convection will still be limited by warm air aloft, but the

mountains should eventually see pretty good coverage of weak

convection, with a threat of gusty winds. On the plains, the storm

threat will likely wait until some combination of outflow from the

mountains, or more likely the shortwave aloft that will bring some

lift in the evening, and possibly lingering overnight in the

northeast corner. There could be up to 1000 J/kg of CAPE for the

plains in the evening, but with little shear, the threats are

mainly subsevere wind gusts, and possibly localized heavy rain if

there gets to be some organization to slow moving storms.



The timing of the shortwave Thursday night sets up an interesting

pattern for the Fourth of July. We'll likely have convection

exiting in the early morning hours, and drying northwest flow

aloft by afternoon. There will also be some cooling aloft though,

enough to allow for another round of convection in the slightly

cooler and drier airmass. We're hanging on to scattered

afternoon/early evening PoPs, but if the drying is enough there

may be less activity or a quicker end. In any event, it doesn't

look like a particularly active day in terms of coverage or 

intensity.



For the weekend and beyond, there are just subtle day to day

changes as we'll be under a mean ridge with a couple of shortwaves

moving over the top of it. There's enough variety in the low and

mid level moisture in the models to make it hard to pin down

details, though there is some tendency towards a little more

thunderstorm activity Sunday and Monday and then warming and

drying after that as the mean ridge strengthens. Overall, fairly

typical early July weather with lower elevation highs mostly in

the lower to mid 90s for an extended period and some threat of

storms each day.



&&



.AVIATION /12Z TAFS through 12Z Friday/...

Issued at 504 AM MDT Thu Jul 3 2025



Winds were light south early this morning and may go light and

variable by 14z. By 17z winds will be SE and stay that general

direction thru the aftn. By 03z winds will become more southerly.

Late tonight, sct showers may develop after 10z with ceilings

lowering to 8000 ft or so. Winds may become north or northwest 

by 10z if showers do develop.



&&



.BOU WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



UPDATE...RPK

DISCUSSION...Gimmestad

AVIATION...RPK