Four Square Mile, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

755
FXUS65 KBOU 112147
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
347 PM MDT Fri Apr 11 2025

.KEY MESSAGES...

- Very warm and dry weather along with gusty winds will lead to critical
  fire weather conditions Saturday.

- Record high temperatures likely on Saturday.

- Cooler temperatures early next week, with scattered light
  showers Sunday afternoon and Sunday night. Mostly rain at lower
  elevations.

&&

.SHORT TERM /Through Saturday/...
Issued at 322 PM MDT Fri Apr 11 2025

The axis of an upper level ridge will move through northern Colorado
tonight. On Saturday, a jet stream will move over Wyoming and will
position Colorado under the right exit region of the jet. This will
lead to maximum compressional warming as the subsident flow will
combine with downslope, westerly winds in the low levels. The only
thing that may keep the temperature from hitting 90 in Denver will
be high level clouds and it does appear likely there will be high
level clouds. Therefore, the forecast high for Denver is 86 which
would break the daily record by 1 degree. If for some reason the
high clouds do not develop, some places may see the 90 degree
mark across the plains.

The main concern on Saturday will be the critical fire weather
conditions. The very warm and dry weather combined with gusty
westerly winds will lead to conditions where rapid fire spread is
possible. A Red Flag Warning was issued for the Denver metro,
foothills, South Park, Palmer Divide, and portions of the plains.
This is discussed further in the fire weather section below.

&&

.LONG TERM /Saturday night through Friday/...
Issued at 322 PM MDT Fri Apr 11 2025

Models have trended upward with the batch of showers coming over
with the back part of the upper trough Sunday night, possibly into
early Monday. Coincident with the QG lift, there`s a period of
decent orographic forcing in an unstable environment for the
mountains Sunday evening, so there could be a pretty good burst of
snow for a few hours. Temperatures will still be pretty warm with
a snow level likely dropping from 9000 to 8000 feet during this
time, so this will mainly affect the higher mountains. Impact will
still be limited due to the temperatures, but the overnight period
Sunday night could be troublesome over the higher passes. For
lower elevations, we`ll have cooler low level air with a decent
inversion, but the QG forced showers will move across during the
night. There are still some model runs showing this slow enough to
slop into Monday morning a bit, and if it`s cold enough we could
have snow on the plains around sunrise. Air temperatures should
still be above freezing with warm ground though, so we`re not
really concerned about any travel impacts below about 7,500 feet.

There continues to be some improvement in the model handling of
the flow just after that trough departs. There`s ridging with a
weak little trough coming through the developing ridge late
Tuesday. We`ll still likely be a little unstable and not dried out
yet, so low PoPs are in order, mostly for afternoon/evening
showers. Wednesday looks relatively dry and warmer under the
ridge.

There`s still a mess for the pattern at the end of the week. There
will be a low developing in the southwest. There are bigger
differences in the handling of the low moving across southern
Canada into the Great Lakes. Most solutions have this too far
north for much impact, but there is probably a cold front that
will drop south on the east side of the mountains. The EC ensemble
members have highs ranging anywhere from the lower to mid 70s down
into the 50s on Thursday and Friday because of this uncertainty.
The NBM is towards the warmer end of this range, which seems
reasonable. There may be some weak factors (mid level moisture
advection, low level upslope, deformation ahead of the developing
low) favoring some shower activity, again probably mostly
diurnal, for Thursday and Friday. But these may not pan out or be
strong enough to produce much. Low PoPs from the NBM are
sufficient, and may be too much.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1254 PM MDT Fri Apr 11 2025

VFR conditions throughout the TAF period. There will be light
winds today and then strong drainage tonight. The concern for this
forecast period will be winds on Saturday afternoon. There will
most likely be sporadic westerly gusts which could reach 25 knots.
However, there will be plenty of breaks in the westerly winds with
periods of light and variable winds during the afternoon.

&&

.FIRE WEATHER...
Issued at 322 PM MDT Fri Apr 11 2025

Relative humidity will be exceptionally low on Saturday as values
could be around 5-6 percent. There will be strengthening winds
with gusts up to 30 mph across the plains to the west of a line
from Limon to Fort Morgan and gusts up to 40 mph in the foothills
and South Park. This will lead to critical fire weather conditions
and a Red Flag Warning was issued for those locations. Fire
weather zones 246 and 247 were not included in the warning because
the fuels were marked "non-critical" yesterday after
precipitation has resulted in greenup.

Elevated to critical fire weather conditions are possible for
South Park on Sunday. With a cold front pushing in Sunday morning,
relative humidity values are expected to be above 20% across the
northern and central plains and around 15% across South Park.
There could be gusts up to 50 mph across the mountains and 35 mph
on the plains. Temperatures will be cooler with lighter winds in
the early part of the week, but it will be dry and warmer again by
Wednesday. There`s a chance of elevated to critical fire weather
conditions again late in the week, though humidities will likely
be higher than this week and the wind forecast is pretty
uncertain.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Saturday for COZ214>216-
238>244.

&&

$$

SHORT TERM...Danielson
LONG TERM...Gimmestad
AVIATION...Danielson
FIRE WEATHER...Danielson/Gimmestad