Johnstown, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

966
FXUS65 KBOU 021640
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1040 AM MDT Wed Apr 2 2025

.KEY MESSAGES...

- Mountain snow diminishing this morning. Scattered light mountain
  showers this afternoon and tonight.

- Windy on the northeast plains today. A slight chance of snow
  showers on the plains with little to no accumulation.

- Another round of precipitation Thursday and again from Friday
  afternoon through Saturday morning. Metro Denver should see some
  snow with a mix of rain and snow across the plains.

- The best chance for accumulating snow will be from the Front
  Range Mountains/foothills into the Palmer Divide. Travel impacts
  are possible.

&&

.UPDATE...
Issued at 1010 AM MDT Wed Apr 2 2025

Northwest winds have strengthened across the far northeast plains
with gusts above 40 mph in Logan and northern Weld Counties. The
forecast remains on track for light rain/snow showers to develop
over the plains this afternoon with light snow showers over the
higher terrain. It will be interesting to see how low the dew
points will get. The HRRR has dew points in the negative teens
across a decent portion of our CWA. While the dew points may get
down to around 0 F, the lack of moisture in the high resolution
models may be carrying over into tommorrow`s forecast. So we will
have to monitor how the humidity changes for tomorrow`s system
coming through to see if QPF amounts could be increased.

&&

.SHORT TERM /Through Tonight/...
Issued at 428 AM MDT Wed Apr 2 2025

Drier air will move in today as northwest winds increase. However,
lapse rates remain steep and we will likely still have some
convection in the drying air mass. For early this morning, there`s
still a lot of weak convection over the mountains producing light
showers, while east of the mountains there are still some showers
southeast of Denver while another batch could bring some flurries
to the northeast corner over the next couple of hours. We`ll
likely see some clearing and then diurnal warming will produce
whatever we get this afternoon. The chance of getting anything
significant east of the mountains looks really low given the
drying, just some light showers passing by. The mountain ridges
could still get some accumulation.

Despite the cool temperatures, the drying will create elevated
fire danger in areas that haven`t had much precipitation. Drier
areas aren`t really near Red Flag criteria today though.

The diurnal showers will die this evening, though the mountains
may not completely shut off. Then we`ll start to get lift coming
up from the south overnight, with increasing clouds and a chance
of light snow in areas along and south of Interstate 70 late
tonight.

&&

.LONG TERM /Thursday through Tuesday/...
Issued at 428 AM MDT Wed Apr 2 2025

On Thursday, a large upper level trough of low pressure will cover
the western half of the U.S. with a moderate southwesterly flow
aloft over North Central and Northeastern Colorado. QG lift is
expected to increase across the forecast area in the morning and
continue through the day as an upper level shortwave caught up in
the flow moves across Colorado. The circulation associated with the
shortwave will help produce a moist and somewhat deep easterly
flow from the Front Range Mountains eastward across the plains.
This flow combined with the QG lift and some instability should
result in widespread precipitation spreading from south to north
across the forecast area through the day.

At this time, the precipitation looks relatively light, with a
mix of rain and snow across much of the plains and all snow across
the mountains, foothills and Palmer Divide. The general consensus
of the models is that snowfall amounts will not be too impressive
with a trace to 1" across Metro Denver with higher amounts
between 2 and 6 inches across the Front Range Mountains, Foothills
and Palmer Divide Thursday afternoon and evening. However, there
is still quite a bit of uncertainty in the snowfall amounts due to
model differences and run to run inconsistencies. For example,
the ECMWF has only 1-2" of snow across the Front Range
Mountains/Foothills and Palmer Divide, while the HRRR and RAP
solutions show 6-10" of accumulation in these areas. If this
verifies, we could see some travel impacts. Since it is
Springtime in the Rockies, we can`t rule out the higher amounts
and need to monitor the model trends. Precipitation chances should
slowly decrease through evening hours before ending sometime
after midnight.

On Friday, the large upper trough closes off over Arizona with a
secondary weaker shortwave diving south across the the Northern
Plains States. Most of the QG lift associated with the closed
upper low will remain over New Mexico, with some weak QG lift
over our CWA. The day should start off mostly dry with mostly
cloudy skies across much of the area. By late morning, the surface
pressure gradient over Northern Colorado should increase as upper
level high pressure builds over the Northern Rockies and Plains
States. This pattern should allow a northeasterly upslope flow to
develop along and east of the mountains by late morning or early
afternoon with increasing moisture behind it.

Consequently, precipitation is expected to increase again with
another round of accumulating snow across the Front Range Mountains,
foothills and Palmer Divide where 3-10" of snow and travel impacts
are possible. Further north and east across the Front Range Urban
Corridor and plains, snowfall amounts should be less with minimal
impacts on travel expected.

Dry weather along with a warming trend is expected Sunday into
early next week as upper level high pressure builds over the Rocky
Mountain Region.

&&

.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 428 AM MDT Wed Apr 2 2025

VFR conditions are expected through tonight. Winds will become
westerly and start to increase 12z-15z, with gusts of 20 to 30
knots between 18z and 00z. The chance of needing west all
operations at KDEN is less than 10%, as the strongest winds in the
afternoon will likely have a bit of a northerly component.

&&

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

&&

$$

UPDATE...Danielson
SHORT TERM...Gimmestad
LONG TERM...JK
AVIATION...Gimmestad