Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 152119
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
319 PM MDT Wed Aug 15 2018

.SHORT TERM...(This evening through Thursday)
Issued at 319 PM MDT Wed Aug 15 2018

GOES-16 water vapor shows the low circulation and vort max NE over
Nebraska with the dry conveyor belt stretching across the northern
portions of the state. There is an influx of moisture from the south
that is firing off convection across the four corners and portions
of southern Colorado. The stabilizing influence of the dry belt will
help to keep storms out of most of the plains for this afternoon.
The exceptions will be the far eastern plains where a boundary has
set up with SE wind influence and the northerly winds from earlier.
CU clouds can be seen on visible forming along the boundary that is
stretching from Lincoln county, North into Sedgwick and Phillips.
Storms could fire off this area and produce a quick batch of rain
and gusty winds before moving eastward. Storms could form to the SW
and move across areas south of I-70 through the late afternoon.
While severe is not expected some storms could produce rain, small
hail and gusty winds.

For Thursday, a frontal push from the NE is expected in the morning
that will stabilize the plains to keep storms at bay for another
day. Expect the convection to be isolated to the higher terrain for
Thursday afternoon. PW values are lower than the past few days so
moisture will not be as high. Temperatures will be slightly cooler
than today with highs in the mid 80s on the plains and 70s in the
mountains. Smoke will continue to be high in the morning hours
according to the HRRR smoke model with improvement by the late
afternoon in the post frontal airmass.

.LONG TERM...(Thursday night through Wednesday)
Issued at 319 PM MDT Wed Aug 15 2018

Showers and storms over the high terrain and over the Palmer
Divide will be weakening Thursday night. Northeastern plains
should still be under a stable cap so not expecting activity out
that way. Easterly winds from the surface high pressure over the
Great Plains will advect in higher dewpoints for areas of fog to
likely develop after midnight across the eastern plains.

On Friday, a weak shortwave will move over the plains to take
advantage of the increase in moisture over the northeastern
plains. Expect the normal diurnal cycle of thunderstorms starting
over the high terrain, then pushing out over the plains and
lasting over the eastern plains through the evening.

On Saturday, a much larger and stronger upper trough will move
from the Northern Rockies and into the Northern Great Plains. MLCAPE
values will likely be up near 2000 J/kg or more along and east of
a line from Sterling down to the Palmer Divide. PW values of
1.1-1.4 inches are progged for that area, likely at or above the
90th percentile for the date. Therefore there will be a good
chance for stronger storms with some reaching severe criteria.
Storms will take a while to diminish overnight, and may last into
the morning over the far eastern plains.

Sunday will be cooler in the post trough and frontal airmass, with
strong northerly winds pushing over the area. The airmass should
dry out quite quickly with almost no precip expected in the stable
airmass.

Yet another shortwave diving down along the Great Plains will
bring back diurnal thunderstorms across the area Monday, then
high pressure will build back over the southwestern US. However
moisture will be trapped under this ridge, so continue to expect
diurnal storms each afternoon and evening for Tuesday and
Wednesday with temperatures starting to warm again.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 319 PM MDT Wed Aug 15 2018

VFR conditions are expected during the period. Winds will continue
from the NE through 22z where they will gradually shift to the SE
with speeds from 7 to 12kt with some isolated gusting up to 24
kts. Winds will move to drainage by 04z with normal daytime
transition patterns back to the NW by 14z Thursday. Storms chances
are very low for the terminals with storms expected to form over
the higher terrain to the West. Biggest challenge during this
period will most likely be wildfire smoke that could affect
approaches and arrival rates during the late afternoon and
evening hours.

&&

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

$$

SHORT TERM...Bowen
LONG TERM...Kriederman
AVIATION...Bowen


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