641
FXUS65 KBOU 201136
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
536 AM MDT Sun Apr 20 2025

.KEY MESSAGES...

- Warmer weather returns today and continues into the week.

- Elevated to critical fire weather conditions likely across the
  plains Monday afternoon.

- Active pattern expected for the latter half of the week, with
  daily chances of showers and thunderstorms.


&&

.SHORT TERM /Through Tonight/...
Issued at 302 AM MDT Sun Apr 20 2025

The upper closed low is centered over the Texas Panhandle at this
time with an upper trough axis stretched north-to-south across
the central CWA. Weak drainage winds in place across the forecast
area this early morning.

Today`s weather will feature moderately strong northwesterly flow
aloft behind the exiting trough.  By later this afternoon and
evening, weak short wave ridging moves in with the flow aloft
becoming zonal at 55 to 70 knots in speed. The synoptic scale
energy looks to be weak downward to neutral for the first two
periods. The low level pressure gradient will be weak the next 24
hours and the boundary layer winds should adhere to near normal
diurnal trends.

The upstream satellite pictures, cross section and CAPE proggs
show just enough moisture and energy for some minor late day pops,
mainly over the highs mountains.  Will go with 10-40% pops mainly
for snow showers. No pops overnight and mostly clear skies by
late evening. For temperatures, today`s highs look to be 4-7 C
warmer than yesterday`s readings which will put them in the lower
60s over the plains; or right at seasonal normals.

&&

.LONG TERM /Monday through Saturday/...
Issued at 302 AM MDT Sun Apr 20 2025

Zonal flow will be in place across the region Monday, with
temperatures warming back up into the upper 60s to low 70s across
the plains. A weak shortwave is expected to track across the
region, bringing a slight chance of some snow showers over the
mountains. For the lower elevations, guidance shows inverted-V
soundings with perhaps enough instability for a gusty shower or
two. There will also be fire weather concerns across the plains
Monday afternoon... see the Fire Wx section below for more
details.

The mid-level flow is expected to decrease Tuesday, but some
modest moisture aloft will allow for some isolated/scattered
showers across the CWA during the afternoon hours. There may be a
little more coverage over the plains compared to Monday, but
meager instability will limit PoPs to 30-40% in the evening.

The zonal flow aloft will gradually turn more southwesterly as a
broad trough begins to develop over the Western CONUS. Broad
surface moisture advection is expected across far eastern
Colorado, leading to an increase in surface-based instability for
Wednesday into Friday. A couple of shortwaves are expected to
track across the region, which should provide a good focal point
for a more organized round of showers/storms on both Thursday and
Friday. While most guidance supports at least one day of rain
(nearly every 00z ensemble member has measurable precip at DEN
Thursday/Friday), there`s still quite a bit of spread across the
overnight model suite. Either way, the increased moisture/cloud
cover will likely keep temperatures a little cooler than
previously thought... but highs will still be near normal to end
the week. The active/unsettled pattern should persist into next
weekend as the broad trough axis shifts a little closer to the CWA
by Saturday.

&&

.AVIATION /12Z TAFS through 12Z Monday/...
Issued at 535 AM MDT Sun Apr 20 2025

The winds at DIA should transition to north-northwesterlies by
late morning and stay that way into early evening before going to
normal drainage patterns by 04Z-06Z tonight. There will not be any
ceiling issues today or tonight.

&&

.FIRE WEATHER...
Issued at 302 AM MDT Sun Apr 20 2025

Elevated to critical fire weather conditions appear likely across
the plains on Monday. Temperatures should warm to above normal
values, with wind gusts of 20-30 mph likely during the afternoon.
The GEFS HDWI shows good probabilities of exceeding the 75th
percentile across most of the plains. Recent moisture and the
ongoing greenup will limit the overall fire danger, especially
closer to the I-25 corridor. Our current forecast grids would
suggest a need for highlights, but wanted to let the day shift
make the final call.

&&

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

&&

$$

SHORT TERM......rjk
LONG TERM.......Hiris
AVIATION...RJK
FIRE WEATHER....Hiris