Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 170243
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
843 PM MDT Sun Apr 16 2017

.UPDATE...
Issued at 842 PM MDT Sun Apr 16 2017

There is still a bit of weak convection going over Logan and
Phillips Counties this evening. It is all moving east-
southeastward at 25 mph. Will adjust grids accordingly to end the
pops. Will keep the mention of patchy fog going for the eastern
half of the plains.

&&

.SHORT TERM...(This evening through Monday)
Issued at 201 PM MDT Sun Apr 16 2017

There remains a moderate westerly flow aloft across northern
Colorado this afternoon with some middle and high level moisture
streaming in from the west. QG parameters are mainly neutral with
no significant pieces of energy for tonight. Main focus for rest
of the afternoon/evening is potential convection along an existing
boundary extending from Douglas and extending northeast through
Denver and southeast Weld counties. There is better low level
moisture east of the boundary with dewpoints in the 40s and
surface based CAPE values upwards of 800j/kg across northern
Lincoln and far southwest Washington counties. High resolution
models continue to indicate some storms in this area of better
moisture. Could see some brief rain/small hail with the stronger
storms.

With continued southeast low level flow still expect an influx of
higher low level moisture leading to some stratus/fog over the
plains later tnt and Monday morning. With stronger s-sw winds
closer to the front range not expecting stratus this far west. For
Monday afternoon another dry line sets up over the plains with
another slight chance of storms, again east of Denver. Storms
could be stronger with CAPE values close to 1500j/kg and
possibility of near severe with larger hail.

.LONG TERM...(Monday night through Sunday)
Issued at 201 PM MDT Sun Apr 16 2017

WSW flow aloft will continue over the area Mon night thru Tue.
There still could be a few stronger storms over the far nern plains
Mon evening along a dry line.  On Tue a wk bndry will affect nern
CO, however 850-700 mb temps are just as wrm as Mon so this feature
will not have much affect on highs.  Thus will keep readings in the
mid to upper 70s over the plains.  As far as pcpn cross-sections
show some increase in mid moisture in the mtns nr the WY border so
will keep in a slight chc of aftn showers with dry conditions
elsewhere.

For Tue night a sfc low will dvlp nr Denver with increasing moisture
in sely low lvl flow across the far nern plains.  There could be a
few tstms overnight in vicinity of a bndry nr the WY-NE border.
Meanwhile an upper level trough will move across nrn CO late late
Tue night into early Wed and will bring a better chc of showers to
the mtns especially north of I-70.  Snow levels will be around 10000
feet.  Meanwhile as the upper level trough moves east of the area by
midday a pacific type fnt will move across the plains which will
bring gusty wnw winds by aftn.  As for highs readings will drop into
the upper 60s to lower 70s over nern CO.

By Wed night drier air will move into the area in wly flow aloft so
mention a slight chc of showers in the mtns.  On Thu an upper level
trough will move into the Great Basin as sfc high pres is over ern
CO.  Cross-sections indicate moisture increasing thru the day and
with some wk mid lvl ascent by aftn.  Thus will see a chc of showers
in the mtns and possibly along the front range as well.  Highs on
Thu will cool into the upper 50s to lower 60s across the plains.

For Thu night into Fri there still is quite a bit of uncertainty on
how the upper level trough over the Great Basin will dvlp as it
moves across the area.  Currently the Canadian, ECMWF and GFS have
an upper level low developing over ern CO on Fri with favorable mid
lvl ascent Thu night thru Fri as a cdfnt moves across nrn CO.  Thus
one would think there would be a good chc of pcpn across the area
with some snow in the mtns and foothills.  Across the plains temps
look warm enough for rain at this point.  However the ECMWF is
somewhat colder and would suggest some potential for snow.

By Sat the upper level system will move east of the area as nw flow
aloft develops.  Cross-sections show a drier airmass so will only
mention a slight chc of showers in the mtns.  On Sun dry wly flow
aloft will dvlp with no pcpn expected.  Temps will be nr normal on
Sat and then abv normal on Sun.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 842 PM MDT Sun Apr 16 2017

Most areas on the DIA airfield east and southeast winds right
now. Normal drainage patterns are a good bet before 06Z. There
will be no ceiling issues overnight. Patchy fog is possible over
the plains after 08Z, but it should stay east of DIA.

&&

.FIRE WEATHER...
Issued at 201 PM MDT Sun Apr 16 2017

there was some earlier threat of elevated fire danger on Monday
afternoon but winds over the front range only marginal with
southwest winds in the 10-17kt range for a couple of hours in the
afternoon. The winds are stronger further east on the plains but
low level moisture is higher and resulting humidity levels are
well above 20 percent. So will cancel the Fire Weather Watch for
fire weather zones 240..241..245.

&&

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

$$

UPDATE...RJK
SHORT TERM...Entrekin
LONG TERM...RPK
AVIATION...RJK
FIRE WEATHER...RPK



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