National Weather Service Forecast Discussion

Thornton Weather Forecast   
Today's Forecast Story   
379
FXUS65 KBOU 260221
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
821 PM MDT Tue Mar 25 2025

.KEY MESSAGES...

- Mostly dry weather Wednesday through Friday, with above normal
  temperatures.

- Cooler with a chance of precipitation Friday night into early
  next week.

&&

.UPDATE...
Issued at 748 PM MDT Tue Mar 25 2025

It`s a fairly calm night across the forecast area this evening.
One may even suggest it feels like spring! Waves of weak
boundaries associated with passing virga showers over Larimer and
Weld Counties have been sliding across portions of the northern
plains, washing out as they move over the airfields at KDEN. Once
these dissipate in the next hour or two, diurnal winds are
expected to resume for the overnight hours. Aside from adding in
current observations, no significant changes were made to the
current forecast.

&&

.SHORT TERM /Through Wednesday/...
Issued at 245 PM MDT Tue Mar 25 2025

North and northwesterly winds are blowing across most of the plains
early this afternoon. Current temperatures are mostly in the mid
to upper 60s over the plains at this time. Convective cloudiness
continues to develop over the mountains north of I-70, the
foothills and most of the plains.

Models keep upper ridging over the CWA tonight and on Wednesday with
benign synoptic scale energy expected. Will decrease what little
cloudiness I have early this evening after sunset. Model cross
sections show it to be pretty dry overnight and on Wednesday.
Normal diurnal wind patterns are expected tonight and on
Wednesday with fairly weak speeds. Temperatures on Wednesday look
to be 2 to 4 C warmer than today`s highs.

&&

.LONG TERM /Wednesday night through Tuesday/...
Issued at 245 PM MDT Tue Mar 25 2025

The main weather feature will be above normal warmth Thursday and
Friday. Upper ridging and weak flow aloft is expected Wednesday
night into Friday morning. Southwesterly flow aloft is progged on
Friday. A weakening upper trough will get into the CWA late Friday
night. The QG omega fields indicate benign synoptic scale energy
into Friday morning, then weak upward vertical velocity is progged
the rest of the Friday and Friday night. The low level pressure
and wind fields show fairly weak drainage winds Wednesday night,
then Thursday`s winds will be dominated by southwest and westerly
flow but not significantly strong. There will be a mix of normal
drainage winds and downsloping Thursday night. More downsloping on
Friday.

For moisture, there are limited amounts in the mid and upper levels
Wednesday night into Friday.  Moisture increases Friday afternoon
and night with the weakening trough.  There looks to be enough
moisture along with the weak lift for some 30-60% pops for much of
the CWA Friday evening, decreasing overnight.  The plains will have
mostly rain showers as temperatures stay pretty warm overnight.   Snow
fall amounts do not look significant in the mountains.

For temperatures, highs on Thursday and Friday are close to 20
degrees F above seasonal normals for the plains with mid 70s to
lower 80s both days. Those type readings could set new record
highs in some places, especially on Thursday where Denver`s
record is 78 F.

For the later days, Saturday through Tuesday, there is fairly
strong west-southwesterly flow aloft on Saturday with an upper
trough progged to move across Colorado Saturday night into Sunday
morning. Strong upward motion is indicated Saturday night into
Sunday morning on the QG Omega fields. Now the GFS looks to be
the strongest with this feature. Consistency has not been good
between the models or between the model runs. Models show a
decent colder airmass to move into the plains and foothills on
Saturday. Now, the QPF fields have pretty decent measurable
precipitation for much of the CWA Saturday afternoon into Sunday
midday. Snowfall in the mountains could be significant enough to
warrant highlights eventually. The plains should turn to all snow
by sometime Saturday evening, however the bunt of the precipitation
will likely fall as rain. It is still a ways away and the
consistency of the models has not been great. Monday and Tuesday
could be somewhat unsettle with the models showing weak, broad
upper troughing and strong flow aloft. For temperatures, readings
look to be around seasonal normals Saturday, Monday and Tuesday,
with Sunday the coolest day.

&&

.AVIATION /00Z TAFS through 00Z Thursday/...
Issued at 547 PM MDT Tue Mar 25 2025

VFR conditions expected through the TAF period. A weak outflow
from NW to SE moving virga showers over central Weld County is
currently battling the diurnal SE winds to bring E to NE winds to
KDEN. These are expected to return to the SE once the showers move
away, in the next few hours. Once this happens, winds will return
to the typical diurnal pattern, shifting to the S near midnight
(6-7Z). For tomorrow, winds are expected to make a turn "around
the clock" through the morning, making their way to the east at
all TAF sites between 21-23Z.

&&

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

&&

$$

UPDATE...Bonner
SHORT TERM...rjk
LONG TERM....rjk
AVIATION...Bonner

NWS BOU Office Area Forecast Discussion