332
FXUS65 KBOU 301828
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1228 PM MDT Tue Apr 30 2024

.KEY MESSAGES...


- Gusty west winds to 40 mph in/near foothills and over far
  northern Colorado.

- Cooler Wednesday night and Thursday with a chance of scattered
  showers and light mountain snow.

&&

.UPDATE...
Issued at 919 AM MDT Tue Apr 30 2024

Current radar indicates the snow is diminishing in the northern
mountains as expected this morning. There was a brief passing
shower here at the office as some of the mountain showers made
their way off the higher terrain bringing some gusty westerly
winds and a very picturesque double rainbow. These showers are
quickly fading and still on track for all precipitation to come to
an end by late this morning. All else looks on track with the
current forecast, therefore we will let it ride.

&&

.SHORT TERM /Through tonight/...
Issued at 312 AM MDT Tue Apr 30 2024

Radar showing a band of rain and mountain snow over northwest
Colorado and southern Wyoming in advance of an upper level trough.
This trough will race east-northeast this morning and be over
western Nebraska and South Dakota by early afternoon. As this area
rain and mountains moves across the northern mountains, expect it
to drop 1 to 5 inches of snow by mid morning. It quickly dries
behind the trough axis by late morning. Dry conditions are
expected east of the mountains with a westerly downslope flow
prevailing. A shallow cold front drops south across eastern
Colorado around sunrise, but downslope flow will exist above it.
The shallow cool airmass is expected to mix out and gusty westerly
winds to 30-40 mph are expected spread across the foothills and
far northern Colorado by noon. Surface low pressure trough forms
along the base of the foothills late in the day. This will cause
winds to turn easterly over the plains and transport moisture into
eastern Colorado tonight. A few weak showers will be possible
late tonight over the plains. Better chance for showers will be
over the northern mountains after midnight where the right
entrance of the jet could produce showers. After this morning`s
snow over the north central mountains, any additional
precipitation tonight is expected to be very light due to limit
moisture.

&&

.LONG TERM /Wednesday through Monday/...
Issued at 312 AM MDT Tue Apr 30 2024

Not too many changes in the long-term forecast package as an
unsettled pattern brings increasing chances of precipitation across
northeastern Colorado. Southwesterly flow and mid-level moisture
increase Wednesday as the first shortwave trough approaches
Colorado. This system mostly clips our area with majority of
upper level forcing staying to the north in Wyoming. MLCAPE values
remain weak and range between 100-200 J/kg. Additional, lapse
rates near 7 C/km and weak 3km shear values of 15-20 kts should
lead to scattered showers and an isolated thunderstorms or two for
the lower elevations. With scattered to numerous showers
continuing through Wednesday evening, light snow will occur for
elevations above 10k ft through Thursday. Highest accumulations of
3-6 inches could occur for the Park and Gore Ranges.

Thursday morning and afternoon, temperatures are slightly cooler.
The mountains and valleys With model guidance trending downwards on
shower coverage. Cross sections indicate a substantial amount of
dry air aloft between the 500-700mb layer. Thus, PoPs were also
lowered Thursday afternoon as showers could be more isolated
across the region. An additional shortwave trough arrives Friday
which increase precipitation chances once more. This pattern
continues through Saturday although, coverage of showers decrease
especially across the mountains.

500mb ensembles display a ridge building into the region by
Sunday. This update includes an increase to afternoon temperatures
Sunday into next week with majority of guidance favoring the
return of above normal temperatures.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1159 AM MDT Tue Apr 30 2024

VFR through the TAF period. Gusty northwesterly winds have caused
an anticyclone to develop across eastern Colorado. This has
elevated uncertainties for wind directions this afternoon.
Fortunately winds are staying light enough to keep impacts
minimal. Timing on when this pattern will break down is also
uncertain. The chances for gusty west winds is diminishing as
previously expected.

&&

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

&&

$$

UPDATE...Bonner
SHORT TERM...Meier
LONG TERM...AD
AVIATION...Bonner