978
FXUS65 KBOU 191133
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
433 AM MST Wed Nov 19 2025

.KEY MESSAGES...

- Quiet weather continues today.

- Still a considerable amount of uncertainty regarding the storm
  system for Thursday and Friday. Accumulating snow remains likely
  (60- 70%) across the Front Range mountains and foothills, and
  across the Palmer Divide. Only a slight chance (<20%) of snow
  for the Denver metro and plains.

- Dry and mild (slightly above normal temperatures) conditions
  return for the weekend.

&&

.UPDATE...
Issued at 421 AM MST Wed Nov 19 2025

Our brief quiet weather pattern will continue today, ahead of a
rather complex storm system Thursday/Friday.

For the third or fourth consecutive night, there is significant
spread across the overnight forecast guidance for the upcoming
storm system. While the overall synoptic details are
straightforward enough, few models have produce any sort of run to
run consistency and it`s difficult to put much faith in any
solution given the constant "windshield wiper" effect offered by
typically reliable forecasts.

However, there are still a few things that are slowly becoming
more clear. First, snow levels will likely be too high to see
accumulating snowfall across most of the lower elevations. Second,
there has been a gradual trend to keep the bulk of the moisture
east of the Front Range... meaning snowfall totals in the higher
elevations won`t be too impressive. Related to (2), there is also
better confidence in a soaking rainfall across the eastern half of
our CWA, where nearly every model produces >0.25" of rainfall.
This means that there may be a fairly sharp gradient of QPF across
the I-25 corridor, even if our current PoPs/QPF are still fairly
smooth. As we get into the window where more CAMs are available,
we`ll see if that helps or hurts our confidence level for this
afternoon`s forecast package.

&&

.DISCUSSION /Through Tuesday/...
Issued at 126 PM MST Tue Nov 18 2025

Upper level ridging will prevail over Colorado through Wednesday
ahead of an upper level low over Southern California and Desert
Southwest. This will continue to bring mild and dry conditions
across the area with highs in the 60s across northeast Colorado.
Flow aloft turns southerly as the upper level low tracks eastward.
This will increase moisture and cloud cover Thursday with
temperature cooling closer to normal. Depending on the track of
this system rain and snow showers may lift northward into the area
during the afternoon.

The main upper level low over the southwest part of the country
is ejected northeastward across the Desert Southwest and ends up
somewhere over eastern Colorado and/or Kansas. As it tracks
eastward, the system will be weakening. However, there is a good
amount of moisture with this system as precipitable water values
climb 200-300 percent of normal. The storm track still is
uncertain leading to a highly uncertain forecast across the area.
The latest trends seem to favor the eastern plains and the Palmer
Divide. For the mountains, with weak flow aloft (no orographic
lift) and the best synoptic lift well south and east, snowfall
amounts should be light. The most uncertain area is the northern
foothills and urban corridor where models vary from zero
precipitation to over an inch. Cold air stays bottled up well
north of us with 700mb temperatures - 1C to -4C over Colorado, so
most of the precipitation below 6000- 7000 feet is expected to
fall as rain. Only hope for snowfall across the lower elevation is
if the precipitation rate is intense enough to cool the air
column enough for snow. The coldest model, the NAM, shows isolated
locations of this occurring. Rain/snow comes to an end during the
day Friday as this weakening system shifts east of the region.

Mild and dry conditions are expected to return for the weekend
and early next week. The region will be between systems, the
exiting one from Thursday/Friday, and an upper level low over the
southwest part of the country. Models generally agree the next
system tracks well south of the area, across northern Mexico,
Arizona, and New Mexico. Only a small subset (~5-10%) of the
ensembles show this system tracking far enough north to bring
rain/snow to the northern half of Colorado, thus will keep the
forecast dry for the weekend and Monday. On Tuesday, we see a
shift in the weather pattern with ridging along the west coast and
northwest flow across Colorado. Too soon to pick out embedded
shortwaves in the flow aloft, but cooler temperatures seem to be a
good bet. Will also have a chance for snow in the mountains with
this type of setup being more favorable for snow.

&&

.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 421 AM MST Wed Nov 19 2025

VFR through the TAF period. Winds should remain light through the
period with a shift to the east or southeast later today. A
gradual increase in high cloud cover is expected but there are no
ceiling or visibility concerns at this time.

&&

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

&&

$$

UPDATE...Hiris
DISCUSSION...12
AVIATION...Hiris