556
FXUS65 KBOU 130240
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
840 PM MDT Fri Jul 12 2024

.KEY MESSAGES...

- Heat wave through Sunday with temperatures reaching 100 to 105
  degrees across the urban corridor and plains. Important to take
  steps to limit outdoor activity, find ways to cool off, and stay
  hydrated as much as possible.

- A Heat Advisory is in effect today through 8 pm for the I-25
  corridor, expanding across all the plains for Saturday and
  Sunday.

- Slight heat relief possible by Monday, but more so by Tuesday
  and Wednesday. Increasing chance of showers and thunderstorms
  for that period.

&&

.UPDATE...
Issued at 833 PM MDT Fri Jul 12 2024

Forecast updates are minimal for this evening. A warm night is in
store with low temperatures well into the 60`s across the lower
elevations, and even near 70F along the base of the foothills
where downslope drainage winds will be more prevalent. Even the
high mountain valleys should struggle to fall below about 45
degrees tonight.

As mentioned below, we`ll have a slight increase in mid-level
moisture tomorrow which should support a little more high-based
afternoon convection, mainly in the mountains. Most of that
convection is unlikely to bring wetting rain, so dry lightning
will be a potential concern. However, instability still appears
too marginal to sustain anything more than an isolated threat, so
will hold off on fire weather headlines for our mountains for the
time being.

&&

.SHORT TERM /Through Saturday/...
Issued at 205 PM MDT Fri Jul 12 2024

Limited cumulus development on satellite this aftn.  There is still
some potential for isold high based activity mainly along and south
of I-70 over the higher terrain and across srn portions of Lincoln
county.  Radar also show a weak convergence boundary extending from
Lincoln county into ern Washington county and Logan county.  No
cumulus along this boundary but not impossible an isold storm or two
could develop along it, late this aftn or early this evening, where
sfc based cape is maximized over Logan, Phillips and Sedgwick
counties.

Overnight through Sat, the center of a large upper level high will
remain near the Four Corners area. Little change in 850-700 mb
temps expected on Sat with highs staying in the 100-105 range
across the plains. Record high at Denver is 100 on Sat, which
should be broken.

Meanwhile, there will be some increase in mid level moisture on Sat
as water vapor imagery does show moisture over Utah rotating around
the upper level high this aftn.  As a result, will see at least
widely sct high based shower/storms over the higher terrain Sat
aftn.  At lower elevations, with high T-TD spreads, could see isold
high based showers, with mainly virga, producing gusty outflow winds
across the I-25 Corridor as DCAPE values are decent.  Over the far
nern plains, sfc based CAPE is fcst to be from 500-1000 j/kg.  Thus
could see an isold strong storm or two if the cap can be broken by
late aftn.

&&

.LONG TERM /Saturday night through Friday/...
Issued at 205 PM MDT Fri Jul 12 2024

Record to near record heat is expected to continue on Sunday as
upper level high pressure dominates the Southern and Central
Rockies. Max temperatures across the plains are expected to range
between 100 and 105 degrees with 103 forecasted at DIA which would
set a new record for the date. The high county will be quite warm
as well with temperatures climbing above 80 in places such as
Breckenridge, Dillon and Grand Lake. There should be enough mid
level moisture around to produce isolated to scattered late
afternoon and evening showers and storms, mainly over the higher
terrain. Due to the lack of low level moisture, any showers and
storms that form will most likely produce sprinkles and gusty
winds. With the potential for dry lighting there may be some fire
weather concerns across portions of the CWA.

On Monday, the upper high is expected to weaken and flatten which
will allow an upper level disturbance and associated cool front to
move across Northeastern Colorado. Increased moisture behind the
front should allow for a better chance of showers and storms which
should result in somewhat cooler temperatures. Nevertheless,
temperatures should still be hot across the plains with high
ranging between 95 to 100 degrees.

On Tuesday, the models are showing the upper ridge retrograding
southwestward into Arizona in response to a potent shortwave moving
across the Northern Great Lakes. Consequently, the upper flow aloft
over Colorado should turn more northwesterly opening the door for
occasional upper level disturbances and cold fronts. This should
result in some relief in the heat along with higher precipitation
chances, especially along and east of the Continental Divide. By
Friday, temperatures may warm back up above 90 degrees on the
plains with decreased precipitation chances.

&&

.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 516 PM MDT Fri Jul 12 2024

Northeast winds will rotate clockwise to SSW drainage low tonight
near midnight, then turn generally north/northeast for Saturday
afternoon. VFR conditions will prevail for all terminals through
the TAF period. Mid-level cloud cover at/above 080 will be a
little more expansive tomorrow afternoon, but chance of any
showers is slim. Still, occasional outflow winds to around 25 kts
will be possible mid to late afternoon.

&&

.FIRE WEATHER...
Issued at 205 PM MDT Fri Jul 12 2024

Elevated fire danger will be in place across the plains
foothills and higher valleys on Saturday due to hot and
dry conditions along with low humidity levels. However,
winds will be relatively light in most areas.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM to 8 PM MDT Saturday for COZ038>040-
042>051.

Heat Advisory from 10 AM to 8 PM MDT Sunday for COZ038>040-
042>051.

&&

$$

UPDATE...Rodriguez
SHORT TERM...RPK
LONG TERM...JK
AVIATION...Rodriguez
FIRE WEATHER...RPK