Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 280216
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
816 PM MDT Tue Jun 27 2017

.UPDATE...
Issued at 808 PM MDT Tue Jun 27 2017

A pletora of boundaries have moved across
the area fm late aftn into this evening.  Appears
the real fnt is now moving into nrn Weld county
and will pass across the plains before midnight.
Meanwhile there is still some potential for widely
sct storms over the far nern plains for the next few
hours.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 340 PM MDT Tue Jun 27 2017

A few showers and thunderstorms have developed this afternoon.
Some storms along the front range have been producing strong
microburst winds. Main shower activity should be finished by 7 or
8 PM. Satellite imagery shows that mountain areas are only seeing
fair weather cumulus development, while the plains areas are
seeing deeper and stronger showers. Surface dew points have
dropped, so most showers are expected to remain dry, with the
gusty winds. Skies should clear out overnight.

Tomorrow morning, a weak cold front is expected to move into the
region from the north. This will cool off temperatures and keep
the afternoon airmass more stable than this afternoon. By late
afternoon, convective temperatures should be reached and isolated
to scattered thunderstorms may still develop. Model soundings show
wind profiles that will be favorable for thunderstorm
organization. Aloft, westerly flow will continue with a chance
that there will be an embedded short wave that can organize bands
of shower activity. Will go with high temperatures in the 80s and
probability of precipitation values between 20 and 30 percent.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 340 PM MDT Tue Jun 27 2017

Wednesday night into Thursday a strong trough will move across
Manitoba Canada with a trough axis extending south across the
Rocky Mountain states. The GFS is more amplified with the depth of
trough than the ECMWF and thus a bit cooler as well. The trough
axis looks to cross our area midday to early afternoon, and with
the mid- level cooling and weak synoptic lift associated with the
approach of the trough axis there is a chance of thunderstorms a
cross the northern half of the area. CAPE and deep layer shear
combinations suggest that any storms that form would be capable of
hail and gusty winds, with a marginal risk of severe weather. The
threat of thunderstorms will shift from west to east and be out
of the state by late evening with the loss of surface heating and
the departure of the trough axis. Siding with the model blend for
high temperatures, which will be again a few degrees cooler than
Wednesday`s highs, generally around 80 across the Plains and mid
60s to mid 70s in the mountains because of total column cooling as
the trough axis passes across the northern half of the state.
Fire weather concerns are less compared to Wednesday given lower
temps, higher RH, and lighter winds...do not anticipate any
highlights.

Friday through Sunday a ridge builds across the west coast and
into the Great Basin, with Colorado under northwest flow. PWATS
looks to remain below normal Friday with values around 0.60"
across the plains and 0.25" along and west of the Continental
Divide. Just a slight chance of thunderstorms Friday afternoon
mainly across the Front Range mountains and the Palmer Divide.
Some moisture makes it into Colorado Saturday and Sunday, with
PWATs a little above normal with values 0.70-1.0" across the
Plains and 0.3-0.5" in the mountains. Best chance of thunderstorms
both afternoons/evenings are across the mountains and far eastern
Plains. Much better low level moisture (surface dewpoints in the
low 50s) and instability looks to set up east of a line from
Sterling to Akron to Limon. Lift for deep moist convection away
from the mountains and foothills would be provided via outflow
from Central Plains thunderstorms and/or from a dryline feature.
Temperatures will be rebounding Saturday and Sunday after another
below normal day on Friday, by Sunday reaching near 90 degrees
across the Plains and 70s to near 80 in the mountains. With
relatively weak flow aloft and weak pressure gradients at the
surface, winds will stay down most areas.

Monday and the 4th of July models are in general agreement that a
mid and upper level ridge builds over Colorado. Temperatures
across the Plains should be around 90 both days, with 70s to low
80s in the mountains. Thunderstorm chances are pretty close to
zero all areas, with the exception being a few isolated
thunderstorms across the central mountains on the afternoon of
July 4th.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 808 PM MDT Tue Jun 27 2017

The real cold fnt is now moving across nrn Weld county so
expect another round of gusty nly winds by 10 pm. Around midnight
winds may go variable before becoming light drainage by 09z.
Visible satellite is showing quite a bit of smoke aloft however
at this point don`t believe sfc visibilities will be impacted.


&&

.FIRE WEATHER...
Issued at 340 PM MDT Tue Jun 27 2017

Warm, dry and gusty conditions have developed in the high mountain
valleys this afternoon. Will let the Red Flag Warning continue
into early this evening. For tomorrow, a weak cold front passing
through will result in cooler temperatures. Pressure gradients
will also be weaker with lighter winds. Fire behavior is not
expected to be as extreme as today, so no highlights necessary.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for COZ211-213-214.

&&

$$

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



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