Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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235
FXUS65 KBOU 281547
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
947 AM MDT Wed Sep 28 2016

.UPDATE...
Issued at 945 AM MDT Wed Sep 28 2016

Pressure rises to our north attm will slide southward across the
nebraska panhandle and eventually over nern Colorado and nwrn
Kansas during the early to mid afternoon hours. The resultant
upslope pressure gradient should turn light n-nwly boundary layer
winds to an e-nely component as marginally cooler and more humid
air creeps westward towards the foothills mimicking a weak cold
front. models show this pseudo front backing over srn portions of
the I-25 urban corridor/Denver metro area between 18z-20z. Should
see speeds increase with the shift to a easterly wind with some
gusts in the 15-20kt range on the plains. The far northeast corner
of the state may even see temperatures top out before mid-afternoon
due in part to slight cooling aloft. Furthermore its possible but
not probable because of a strongly capped mid-trop that a few fair
weather cumulus could form later this afternoon over the Front
Range and foothills. Meanwhile mid and high-level moisture
rotating northward around a deep closed low centered over the
northern Baja may reach as far north Summit and Park counties by
mid to late afternoon. It`s conceivable a stray gusty rain shower
and/or t-storm could form over the Ten Mile and Mosquito ranges
in these counties with strong solar heating late this afternoon.
However the chance for wetting rainfall looks to be near zero.
Only minor adjustments to the current forecast are necessary at
this time.

&&

.SHORT TERM...(Today and tonight)
Issued at 428 AM MDT Wed Sep 28 2016

High amplitude upper level ridge will remain centered across the
forecast area today, and then begin to shift slowly east tonight.
This will keep dry weather in place. Clear skies this morning
should give way to a few clouds later this afternoon into the
evening but most of those would be in/near the mountains. Some
models are even suggesting enough moisture and instability for a
few afternoon/evening storms over the mountains but with upper
level ridge and the lack of moisture see nothing more than a few
high based sprinkles possible in the Summit county area.
Temperatures should be similar to those observed yesterday,
although some cooling should be noted on the eastern plains with a
weak backdoor cold front.

Dry high pressure will allow temperatures to drop to near or just
above normal for lows tonight. Expect just a few mid/upper level
clouds to remain in place as light southwest flow develops on the
back side of the ridge.

.LONG TERM...(Thursday through Tuesday)
Issued at 428 AM MDT Wed Sep 28 2016

The weakening upper level ridge over eastern Colorado will deliver
one more warm day on Thursday. The plains will be dry, but the
mountains will be under moist southwesterly flow that will bring
sub-tropical moisture to the western half of the state. Isolated
showers or thunderstorms will be the result. High temperatures
across the plains should reach the lower and mid 80s.

Sub-tropical moisture will continue moving over the state from the
southwest through Friday and Saturday as the upper ridge loses its
grasp on Colorado weather and moves off to the east. The southwest
flow aloft will continue producing the chance of showers in the
mountains through Friday and into Saturday. Some showers may
spread onto the plains Friday evening.

Over the weekend, temperatures will be gradually cooling as the
upper level pattern transitions to an upper trough approaching
from the Pacific Northwest. By the middle of next week,
temperatures will be cool enough in the mountains for
precipitation to fall in the form of snow.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 945 AM MDT Wed Sep 28 2016

Light west-southwest winds presently across the Denver metro area
are expected to briefly go calm prior to a shift to east-northeast
winds early this afternoon with a weak cold front backing into
the foothills. KDEN and KAPA could see an east wind in the 12-18kt
range with this wind shift. A dry and very stable atmosphere will
likely prevent the formation of any cloud cover over the metro
area...although could see a few cumulus type clouds form over the
foothills after 22Z. By late afternoon...mesoscale models show
winds gradually turning to a southeast direction then to a
southerly direction after 00z. Speeds during this period will be
generally under 14 kts. Overnight...should see the typical drainage
wind pattern set with speeds in the 4-9kt range beneath a clear
sky.

&&

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

$$

UPDATE...Baker
SHORT TERM...Barjenbruch
LONG TERM...Dankers
AVIATION...Baker



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