Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 250210
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
810 PM MDT Tue Apr 24 2018

.UPDATE...
Issued at 757 PM MDT Tue Apr 24 2018

Upper level trough is slowly moving southeast
as snow continues over the srn Foothills and
portions of the Palmer Divide.  Based on radar trends
appears this pcpn should gradually end by 10 pm.

Overnight fog potential will depend on how much clearing occurs.
Simulated imagery suggests cloud cover will diminish by 10z.  If
that does happen then there would be potential for fog late
tonight into Wed morning in some places, although confidence
isn`t high as to exactly where it may occur.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 143 PM MDT Tue Apr 24 2018

Radar and observations showing decent coverage of mainly snow
showers over the mountains, foothills and adjacent plains this
afternoon. This is in response to persistent yet shallow upslope
flow and 80+ jet streak draped across northern Colorado. There is
already a trend to some drying over far northern Colorado and
this drying will very gradually works it way southward through the
evening hours. Expect a slow diminishment of the showers later
this afternoon and evening. With the convective nature may see 1-2
inches of snow in the foothills through this evening. Gradual
clearing is expected later tonight leading to a sunny and much
warmer day on Wednesday. If skies do clear enough could be some
patchy fog that develops especially with the lingering surface
moisture and close temperature and dewpoint spreads. Will add some
patchy fog to the forecast for the plains.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 143 PM MDT Tue Apr 24 2018

Wednesday night into Thursday upper level ridging will be in place
over the state as the next disturbance pushes into Montana. The
upper trough is set to drop into northern CO by Thursday morning
with the accompanying cold front pushing cooler and more moist air
from the North. At this time mid level moisture looks fairly week
and shallow with only the plains and areas of the foothills getting
precipitation according to model cross sections. This increased
moisture will help to push clouds across the plains and help to push
the best lift along the foothills and Palmer Divide. The mostly
cloudy skies will keep temperatures lower with highs reaching into
the low 50s. Subsidence will increase sharply behind the trough
helping to clear out the plains resulting in cooler overnight lows
in  the 30s.

On Friday, an upper level ridge will move over the region bringing
warm and dry weather through Saturday morning. Temperatures will
gradually increased through Sunday with highs approaching 80 by
Sunday. By Saturday afternoon/evening upper level flow will switch
to the SW ahead of the next upper level system. Models show a
shortwave trough embedded in the flow which could produce scattered
to isolated thunderstorms. Most models show the activity firing off
late Saturday into early Sunday.

For next week models mainly agree on an active pattern...however,
they diverge on placement and track of various upper level
disturbances. West to southwest flow dominates the pattern, which
will help to keep highs in the 70s through Tuesday. Will keep some
low pops in the extended to account for the slight chance of
convection.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 757 PM MDT Tue Apr 24 2018

Ceilings in the 4000 to 5000 ft range will continue although they
should begin to break up around 09z or so. Winds were northwest
but should become more westerly by 06z and then light southwest by
09z. Overall not sure about fog potential. Although skies will
clear late tonight, latest data suggest sfc winds will be
southwest with no signs of a Denver cyclone. Thus this may reduce
the threat of fog in the 10z-15z time frame at DIA.


&&

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

$$

UPDATE...RPK
SHORT TERM...Entrekin
LONG TERM...Bowen
AVIATION...RPK


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