Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 281716
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1116 AM MDT TUE JUN 28 2016

.UPDATE...
Issued at 1054 AM MDT Tue Jun 28 2016

Stratus over the plains burnt off by 9 AM MDT this morning. You
can see the smoke plume on the visible satellite pictures from the Beaver
Creek Fire in north central Jackson county right now. Dew point
numbers over the plains are in the upper 50s to mid 60s F right
now. The wind field over the plains is light and all over the
place in direction. Models show the higher dew points to
decrease/mix out over the western half of the plains by 21Z. The
models keep the CAPE values over 2000 J/kg over the northeast
corner this afternoon and evening. The rest of the CWA has
750-1500 J/kg. There will be more of the same, as yesterday, for
the eastern plains, strongest over the far northeast corner. Will
keep the pops in the 10-20% range for most of the CWA, with higher
chances over the far northeast corner.

&&

.SHORT TERM...(Today and tonight)
Issued at 345 AM MDT Tue Jun 28 2016

Main concern again today will be potential for severe storms
across the plains of Northeast Colorado. Currently, there is
still lingering storms over Eastern Phillips and Sedgwick county
but this activity will likely diminish by sunrise. 11/3.9
Satellite imagery showing some patchy low clouds and fog
developing over the plains given moist, low level flow and
dewpoints in the mid 50s to lower 60s. Will add patchy fog to
forecast for early this morning.

Broad ridge of high pressure remains over the region with center
across Utah and resultant moderate Northwest flow across the
plains of NE Colorado. The focus again today will be over the far
plains. Based on model forecasts...storms will initiate North of
Colorado in Eastern Wyoming and Nebraska and move Southeast across
the plains by late afternoon/evening hours. Surface based capes of
1500-2500j/kg will support large hail again today with good low
level moisture still in place. Tornado threat appears less but
can`t rule out a brief weak tornado.

Further West towards the urban corridor and Front Range airmass is
drier, despite dewpoints now in the mid 50s to lower 60s. This
moisture is rather shallow and expected to mix out this afternoon
with dewpoints in the 40s. With storms in this area...areal
coverage more isolated and expect main threat of gusty winds with
drier low levels. Should also see some isolated storms in the
mountains today as moisture levels have increased a bit more from
yesterday based on PW values from GJT 00z sounding. Temperatures
will be similar to yesterday`s readings.

.LONG TERM...(Wednesday through Monday)
Issued at 345 AM MDT Tue Jun 28 2016

On Wednesday, the upper level ridge of high pressure is centered
over New Mexico, with a weak west to northwest flow aloft over
Colorado. Some moisture caught up in the ridge, combined with
daytime heating will help produce scattered afternoon and evening
showers and thunderstorms, most numerous over the higher terrain.
The low level moisture seems to be limited, therefore the storms
should be high based with light rain and gusty winds.

On Thursday, the upper high shifts east into central Texas. The
circulation around the high allows subtropical moisture to move into
Colorado from the south and southwest. In addition, a weak cold
front will move across northeastern Colorado Thursday morning,
with increasing low level moisture behind it. GFS and NAM
soundings show PW`s in Denver at or above 1.30 inches by 00z
Friday. The combination of high moisture values, plenty of
instability (capes around 1000 j/kg) and upslope flow from the
surface to 700 mb should result in scattered to numerous afternoon
and evening thunderstorms across north central and northeastern
Colorado. Soundings also indicate a weak sfc-6 km mean wind which
should allow for slow moving storms and the possibility for
localized very heavy rain. Models show the best chance for heavy
rain from the foothills and adjacent plains south across the
Palmer Divide. Storms should decrease after midnight, possibly
lingering across far southeastern sections of the CWA through
early morning.

On Friday, the pattern looks similar to Thursday with the exception
that we lose the upslope flow. As a result, the storms should be
less numerous. However, there should still be plenty of moisture
around combined with daytime heating to produce another round of scattered
afternoon and evening showers and storms across the region. Some
of the storms could be strong and produce locally heavy rain and
some hail.

Warmer and drier weather is expected to return to the area over
the weekend as the upper high re-establishes over the southwestern
states and the subtropical flow of moisture into Colorado gets cut
off.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1054 AM MDT Tue Jun 28 2016

Winds at now near due easterly at DIA. Models show them to get
more southeasterly by 19Z with speeds below 10 knots. Drainage
winds are a good bet by 03/04Z this evening. Will leave Thunder
out of the 18z TAF for now. There should be ceiling issues with
convection later today and this evening.

&&

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

$$

UPDATE...RJK
SHORT TERM...Entrekin
LONG TERM...Kalina
AVIATION...RJK



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