Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231944
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
144 PM MDT MON MAY 23 2016

.UPDATE...
Issued at 1029 AM MDT Mon May 23 2016

Convective clouds are increasing evidenced on satellite and
webcams across western and north-central Colorado this morning as
a jet max pushes into the western part of the state. Hi-res models
continue to initiate convection over Clear Creek and Gilpin
counties just before noon with it then spreading over the metro
areas early afternoon. No impressive CAPE values until later this
afternoon and evening over the eastern plains...and even
overnight. May see a few stronger storms out that way later on.
This is all covered with the current forecast...no need to adjust
much at this point.

Focus will be shifting to tomorrow afternoon`s convective
potential across the plains. CAPE values will be much higher,
between 1000 and as much as 3300 J/kg with good shear as well.
NWS SPC has the forecast area in a SLIGHT to ENHANCED risk for
severe storms.

&&

.SHORT TERM...(Today and tonight)
Issued at 431 AM MDT Mon May 23 2016

Still a few showers going on the tail of a jet streak that moved
across overnight. These should continue to slowly fade as they
drift northeast over the next few hours. Weather maker for today
is a stronger jet max that will lift from northern Arizona
northeast across the state today. This is generating banded high
clouds over the dry air in Utah now, and will bring lift to
northeastern Colorado as it passes this afternoon. The convective
environment today is not that great otherwise, with slightly
cooler temps and dew points in the 30s and 40s. Models all show
some convection with the jet streak, and it is probably enough to
overcome the weak capping, especially given a little bit of
easterly low level wind to aid convergence once storms get
started. It could wind up being a fairly early show, perhaps early
afternoon storms over the mountains and Denver, then toward the
eastern border by evening. Nice shear but not much CAPE, we will
be hard pressed to get more than about 800 j/kg. So maybe more
coverage of the storms but not a lot of strength. With the shear
there could be a low threat of marginal wind/hail over the
eastern portion of the plains, especially if the storms get
organized which they well could.

Clouds and showers should diminish quickly this evening. Prefer
the cooler GFS guidance which was a couple degrees cooler than our
previous forecast.

.LONG TERM...(Tuesday through Sunday)
Issued at 431 AM MDT Mon May 23 2016

For Tue and Wed...a relatively dry southwesterly flow aloft will
remain over Colorado ahead of an elongated upper trough over the
west...stretching frm central CA to MT Tue aftn. The southern
branch of the trough will make its way into southern NV by 00Z
Thu. The general trend both days will be for some tstms over the
mountains. a Denver cyclone Tue aftn will generate a boundary
that will act as a focus for tstms late Tue aftn/evng. best chc of
storm possibly severe will occur along and east of this boundary.
The NAM12 mdl shows the development of this pattern with the
strongest storms develping over central Weld County and lifting
to the northeast...which seems reasonable. Boundary layer CAPE
1000-2000 j/kg in this area...but some CIN as well. The NAM12
however shows a weak upper level disturbance which may help to
initiate tstms as it move across western and northern CO around
00Z Wed. On Wednesday...the flow will be more south/southwesterly
with more mid level subsidence under a short wave ridge. Sfc based
CAPE much lower so weaker tstms with lesser coverage as well. Thu
through Fri...the mdls still show the upper low approaching the
Four Corners region by 12z Thu...then lifting east/northeast
across CO. Best QG ascent in the mid levels will occur late
aftn/evng period which will help to produce a better chc of
showers/tstms over the entire cwa. A little cooler as well. the
GFS is about 6 hrs faster than the ECMWF regarding the passage of
the trough. By the weekend...the flow aloft drier and more
west/southwesterly. still tstms in the grids each aftn/evng but
mainly slgt chc pops.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 139 PM MDT Mon May 23 2016

VFR conditions expected through Tuesday afternoon. Scattered
thunderstorms across the Denver area airports will last through
about 00z before the main activity pushes east over the plains. Wind
gusts to 30 knots and brief heavy rain are possible with the
storms over the urban corridor...with stronger winds and small
hail possible over the eastern plains. Easterly winds at 15 to 25
knots will become variable with the convection, then trend
northeasterly early this evening before trending toward drainage
tonight. More convective activity is expected tomorrow, especially
over the far northeastern plains where strong winds and hail are
expected.

&&

.BOU Watches/Warnings/Advisories...
None.
&&

$$

UPDATE...Kriederman
SHORT TERM...Gimmestad
LONG TERM...Cooper
AVIATION...Kriederman



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