Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 161038
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
438 AM MDT Mon Apr 16 2018

.SHORT TERM...(Today and tonight)
Issued at 438 AM MDT Mon Apr 16 2018

A dry and warm day is in store across the state as an upper level
ridge moves over the region. Skies will be partly to mostly cloudy
through the day as a fair amount of high level moisture has been
entrained into the ridge. No precipitation is expected, but
temperatures may a few degrees cooler than would be expected with
a strong ridge over the area. High temperatures across the plains
are still expected to be in the lower and mid 70s, making for a
pleasant Spring day. A lee trough of low pressure will form over
the I-25 and urban corridor, allowing for downslope breezes along
the foothills and southeasterly winds across the eastern plains.
Dry and seasonal conditions are expected to continue overnight as
deeper moisture is not expected to arrive in the mountains until
late morning tomorrow.

.LONG TERM...(Tuesday through Sunday)
Issued at 438 AM MDT Mon Apr 16 2018

An upper level trough will move across the area on Tue with decent
mid lvl ascent thru 18z which will then switch to rather stg downard
descent by late aftn.  There will be a quick shot of moisture in the
mtns Tue aftn into early Tue evening with rather unstable lapse
rates.  Thus may see some convective activity with enhanced snowfall
rates for a few hours.

Across the plains, sfc low pres will be near Denver at midday and
then move quickly southeast into wrn KS by early Tue evening.  There
is quite a stg low lvl gradient thru midday over the Palmer Divide.
700 mb winds are fcst to be fm 50-60 kt in the morning thus it
wouldn`t be total surprise to see a few gusts aoa 60 mph for a
few hours if decent mixing occurs. Biggest question is duration
and overall coverage so have refained from a high wind watch for
now. Meanwhile by early aftn a pacific/bora fnt will begin to
move across nern CO with very windy conditions developing behind
it. Wind gusts could get close to high wind criteria by mid to
late aftn into early Tue evening as stg subsidence develops behind
passing upper level trough. For now have kept gusts just blo high
wind criteria. As fas as pcpn there still could be a chc of
showers nr the WY-NE border in the aftn. Highs will generally be
in the 60s across nern CO.

On Wed a more tranquil pattern will develop as an upper level ridge
will build over the area.  Thus will see a dry day with temps near
seasonal normals.  Winds will remain gusty over portions of the
plains especially nr the WY-NE border, however speeds will be lower
than Tue.  By Thu a storm system will develop over the wrn US as
SWLY flow aloft increases.  Not much moisture is shown thru the aftn
hours so will keep a dry fcst in place. Over nern CO, sfc low
pres will intensify near the Foothills with gusty south to
southeast winds developing over the plains by aftn. As for highs
will keep readings mainly in the 60s.

For Thu night into Fri so far the longer range models have been
consistent in showing an upper level low moving into the four
corners area by 12z Fri and then moving into sern CO/nern NM by Fri
night. With the flow aloft becoming rather diffuent Thu night,
along with some increase in low lvl moisture across the plains due
to sely flow, there could be a chc of showers/tstms overnight. By
Fri cross-sections continue to show moisture increasing over the
area along with favorable QG ascent. In addition as a sfc low
develops over sern CO a cold front will eventually move into nern
CO by aftn with a gradually increase in upslope flow. As a result
should see pcpn increase thru the day into Fri night. Current
soundings show temps will be warm enough for all rain at lower
elevations thru Fri aftn, however, by Fri evening may see rain
begin to change to snow. Over the higher terrain there certainly
could be significant snow if the upper level low moves across as
currently shown. In addition there is some potential for heavy wet
snow along the front range urban corridor and over the Palmer
Divide Fri night.

On Sat there is still some uncertainty as to how fast the upper
level low will exit the area.  The lastest runs are slower in moving
it out as compared to what was shown last night.  If it ends up
being slower then pcpn may linger thru midday Sat especially across
nern CO.  By Sat night into Sun the system should gradually move to
the east with improving weather conditions.


&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 438 AM MDT Mon Apr 16 2018

No aviation impacts expected through the next 24 hours. The
airmass will be dry with only high level cloud cover expected.
Winds will be light and variable through late in the morning and
then will trend to the east and southeast through the afternoon.
Later tonight, drainage southerlies will trend toward the
southwest after midnight.

&&

.FIRE WEATHER...
Issued at 438 AM MDT Mon Apr 16 2018

Have gone ahead an issued an RFW for the Palmer Divide on Tue
due to expected strong winds and low humidity which will produce
extreme fire danger. With recent pcpn not sure about areas around
Denver north to the Wyoming border. Day shift may need to expand
warning further north based on fire managers input.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 10 AM to 8 PM MDT Tuesday for COZ241-
245>247.

&&

$$

SHORT TERM...Dankers
LONG TERM...RPK
AVIATION...Dankers
FIRE WEATHER...RPK



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