280 
FXUS65 KBOU 301819
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1119 AM MST Tue Nov 30 2021

.UPDATE...
Issued at 1111 AM MST Tue Nov 30 2021

High clouds are starting to spread into the state from the north
on the edge of the mass of moisture covering the northwest U.S.  
These clouds are thin at first, but there's a lot of them and
they'll eventually get thicker as the warm advection aloft
continues through this evening. This will also create a window of
opportunity for an amplified mountain wave this evening. We'll
need to add some more cloud cover to the forecast, but it
shouldn't thicken enough to impact this afternoon's highs much,
maybe a little cooling towards the end of the day. We'll also need
to raise the highs over the northeast corner where it's looking
like it will get almost as warm as Denver this afternoon.

&&

.SHORT TERM...(Today and tonight)
Issued at 425 AM MST Tue Nov 30 2021

Cloudiness and warm downslope winds have kept low temperatures a 
few degrees warmer than expected in much of the lower foothills 
and adjacent plains this morning. Moderate synoptic subsidence 
will set back in this morning behind the passing shortwave and 
persist through Tuesday night. A weak front will move over the 
plains early this morning, bringing some breezy northerly winds 
and slight cooling, but will likely wash out by noon. There is 
some cooler air aloft as well, models are showing 700 mb 
temperatures briefly below 0 C Tuesday morning, but then rise 
quickly back to around 5 C by Tuesday afternoon. So temperatures 
will likely still remain well above normal, with highs in the mid 
50s to low 60s across the plains and upper 30s to lower 50s in the
high country. There may be elevated fire danger in South Park in 
the afternoon due to peak gusts around 25 mph with humidity down 
to 15 to 20 percent. Critical conditions are not expected. 

Cross-sections indicate another weak mountain wave starting to 
develop by the late afternoon. There will be enhanced subsidence 
beneath the right exit region of a jet in the north-northwesterly 
flow aloft, and about 50 knots of flow just over the ridgetop 
Tuesday evening into the night. Expect breezy conditions in the 
Front Range mountains and higher foothills, with widespread gusts 
up to around 45 mph and gusts up to 60 mph over the higher peaks. 
Low temperatures Tuesday night should be pretty similar to those 
tonight, in the teens and 20s in the high country and 20s and 30s 
across the plains, colder in the usual cold pools and warmer in 
the foothills and adjacent plains due to moderate downslope 
warming.

.LONG TERM...(Wednesday through Monday)
Issued at 425 AM MST Tue Nov 30 2021
 
Warm and dry weather continues...

A flat upper level ridge will quickly build back across the area
for Wednesday and Thursday. This will bring a return of
unseasonably warm temperatures, with highs pushing 70F across most
of the plains on Wednesday, and record/near record temperatures
for Thursday. The record high for Denver is 73 on December 1st, 
and 74 on the 2nd (Thursday). The latter seems more achievable 
with light downslope, continued warm advection, sunny skies, and 
shallower inversions to start the day. 

By Friday, the overall pattern changes little, but a weak cold
front will be pushing across the plains offering up some cooling.
Temperatures will still be well above normal with highs close to 
60F across the plains. Saturday should feature similar 
temperatures and a continuation of dry weather. The dry weather 
will remain in place Sunday and Monday with some warming expected 
under downslope/lee troughing.

There is actually reasonable agreement that a weak trough will 
finally move into the area toward next Tuesday. However, it looks 
like this will be a weak or splitting system so don't expect much
more than some light snow, with the best chance of that over the 
mountains. 

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1111 AM MST Tue Nov 30 2021


VFR through tonight. There's some uncertainty about wind direction
late this afternoon as southerly winds may become briefly north or
northeast between 22z and 02z. If this happens, speeds will be
less than 8 knots. Normal S/W drainage winds will resume this
evening.

&&

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

$$

UPDATE...Gimmestad
SHORT TERM...EJD
LONG TERM...Barjenbruch
AVIATION...Gimmestad