Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 282102
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
302 PM MDT SUN AUG 28 2016

.SHORT TERM...(This evening through Monday)
Issued at 300 PM MDT Sun Aug 28 2016

An upper low spinning over the Four Corners area continues to
bring lift and moisture to the region. As a result, scattered
thunderstorms are moving slowly north to northwest over the high
terrain as well as the Palmer Divide and northeastern plains.
Activity will be more isolated in nature over the northern urban
corridor. Winds turning upslope up to 700 mb and divergence aloft
will allow for scattered to numerous storms over the Front Range
mountains and foothills into the early evening. Higher CAPE
values over the eastern plains will allow for scattered storm
with brief heavy rain, small hail with such high freezing levels
and some gusty outflow winds. With the upper low moving closer and
a jet speed max putting the area in the favored left exit region,
hard to argue against the models showing some showers and storms
continuing into the evening and overnight, favoring areas south
of I70.

The upper low will slowly move over southern Colorado Monday, cooler
air aloft and cloud cover will allow for temperatures to be a
several degrees cooler than today. Expect another day of scattered
showers and thunderstorms producing brief heavy rain as easterly
flow deepens, perhaps slightly bigger hail with lower freezing
levels and gusty outflow winds. The stronger storms will likely be
found over the east central plains where CAPE will be larger, with
another day of north-northwesterly movement of the storms.

.LONG TERM...(Monday night through Sunday)
Issued at 300 PM MDT Sun Aug 28 2016

Upper level trough just to our south will gradually shear out and
weaken Monday night through Tuesday. Then an upper level ridge
will build to our north late Tuesday into Thursday. By week`s end,
the upper level ridge is expected to shift east into the Midwest
with increasing west/southwest flow aloft across Colorado.

For Monday night, the better moisture and weak Q-G lift associated
with the trough is still located from central and southern
Colorado into the Palmer Divide area and then eastward onto the
plains. Therefore, will continue to keep the PoPs highest in those
locations with lower chances farther north to the Wyoming border.
A few showers and storms could once again linger through the night
on the eastern plains.

Tuesday through Wednesday, the upper level ridge will begin to
build over the top of the weakening trough. This may result in a
decrease in storm coverage, with the main threat shifting slightly
farther south. Points near the Wyoming border may stay completely
dry with a drier and more stable airmass there.

By Thursday and Friday, the flow aloft will turn more
west/southwesterly as an unseasonably deep upper level trough digs
into the Pacific Northwest. This would bring warmer and drier
downslope flow to the plains, while the mountains will continue
to see a chance of showers and thunderstorms each afternoon and
evening. There may be a weak front on the plains toward Saturday
or Sunday, but overall expect above normal temperatures and just a
slight chance of afternoon and evening storms.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 300 PM MDT Sun Aug 28 2016

Scattered thunderstorms over the higher terrain and the Palmer
Divide are moving north...with hi resolution models keep
convective activity over and near the Palmer Divide through 03z,
keeping a chance of thunderstorms in the TAFs. The main impact
from the thunderstorms to the airports will be brief heavy rain
and some gusty outflows...but cigs/vis should stay VFR. Mid and
high level clouds will likely remain over the area through the
night. Easterly winds this afternoon, generally less than 10
knots will likely become some sort of south-southwesterly as
outflow from the Palmer Divide activity pushes across the area.
Winds will then eventually become drainage overnight, only to
become easterly again Monday. Urban corridor airports may have a
better chance for showers and storms Monday.

&&

.BOU Watches/Warnings/Advisories...
None.
&&

$$

SHORT TERM...Kriederman
LONG TERM...Barjenbruch
AVIATION...Kriederman



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