Severe Thunderstorm Warning 32, NWS Denver/Boulder, CO

314 
WWUS55 KBOU 052342
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
542 PM MDT MON JUN 5 2017

COC123-052352-
/O.CAN.KBOU.SV.W.0032.000000T0000Z-170606T0015Z/
Weld CO-
542 PM MDT MON JUN 5 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN WELD COUNTY IS
CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore the warning has been cancelled.  However, gusty winds are
still possible with this thunderstorm.

LAT...LON 4095 10358 4094 10358 4071 10381 4082 10404
      4100 10389
TIME...MOT...LOC 2341Z 225DEG 7KT 4085 10386 

$$

BOWEN

Area Forecast Discussion
National Weather Service Denver/Boulder CO
321 PM MDT Mon Jun 5 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 320 PM MDT Mon Jun 5 2017

Strongest convection has pushed out onto the plains and continues
to develop along the convergence zone created by outflow from earlier
foothills convection, and the east/southeast flow on the plains.
Have already had a couple of pulse severe reports, and still some
potential with sufficient CAPES near 1500 J/kg. Those storms will
continue through early evening before gradually diminishing as
they move into a more capped environment on the eastern plains.
Behind that, scattered showers and less intense thunderstorms were
occurring over the mountains, but airmass was slowly stabilizing.
A couple could still drift off the Front Range and back into the
I-25 Corridor, but bulk of activity is largely on the way down for
these locations. Don't expect more than a couple showers to
linger in the mountains and far eastern plains past late evening.

Cold front is expected to push across the plains late tonight into
early Tuesday. We are not certain on the cold frontal progression
at this time. It seems most models have backed off on how far
south and how pronounced this front will make it, so that may
allow more instability and some severe storm threat across the
plains. We still think the front should have sufficient push with
northwesterly flow aloft in place, but something to watch for
tomorrow. If the front does not push through in a strong manner,
then look for less CIN (convective inhibition) and potential CAPES
near 1500-2000 J/kg. Shear is still weak however, so that would
be a mainly pulse severe threat. Will continue to monitor this
potential through tomorrow. Otherwise, kept a pretty good chance
of storms (highest across the Front Range and Palmer Divide where
moisture banks up into the high country). Temperatures will be
several degrees cooler as long as front arrives on time.

.LONG TERM...(Tuesday night through Monday)
Issued at 320 PM MDT Mon Jun 5 2017

Showers and tstms will linger thru Tue evening especially over the
higher terrain and Palmer Divide.  On Wed an upper level ridge will
begin to build over the srn Rockies with weak nwly flow aloft. At
the sfc, the low lvl flow will be ese which will keep decent
moisture in the lower levels fm the plains into the foothills. Would
expect to see sct storms dvlp in the foothills by early to mid aftn
with some of the activity affecting portions of the urban corridor
and Palmer Divide by late aftn into the early evening hours.
Could see an isold svr storm or two due to a slightly better shear
profile. As for highs will keep readings in the upper 70s to
lower 80s across the plains.

On Thu the upper level ridge will begin to move northward into the
area with some increase in nwly flow aloft.  Moisture will begin to
decrease over the higher terrain with tstm activity becoming more
wdly sct.  Across the plains the low lvl flow will become more sse
with cape values nr 1000 j/kg along the urban corridor and up to
2000 j/kg over the far ern areas. With sse low lvl flow will
probably see a Denver Cyclone along with a convergence zone east
of the the urban corridor. If the cap can be bkn then there would
be a better threat of a few svr storms due to an improving shear
environment. The other area for possible storm development would
be near the Cheyenne Ridge with storms moving se across nrn Weld
County. As for highs with decent warming occuring in the 850-700
mb lyr expect highs to rise into the mid to upper 80s across nern
CO.

By Fri a stg storm system will move into thr Pacific NW with the
flow aloft becoming more swly as the upper level ridge flattens.
Overall this will lead to dry conditions with warmer temperatures
as the first 90 degree day of the season will likely occur at
Denver. There will be a dry line over the far ern plains however
mid lvl cap will probably inhibit tstm development nr this bndry.

On Sat the upper level trough will move east with stg swly flow
aloft. This will lead to another dry day with abv normal temps as
readings reach the lower to mid 90s.

By Sun the ECMWF and GFS differ some as the ECMWF has the upper
level trough extending fm the nrn high plains into wrn CO. Meanwhile
the GFS keeps the trough further west.  As a result the ECMWF has a
cold front moving across nern CO on Sunday while the GFS does not.
Thus the ECMWF would have highs lowering into the lower to mid 80s
while the GFS would keep readings in the lower to mid 90s.

For Sun night into Mon the ECMWF has a wk upper level trough moving
across with a chc of pcpn mainly Sun night into early Mon. Meanwhile
the GFS is roughly 24 hours slower with the upper level trough and
doesn't have it moving across until Mon night.  Thus it has the best
chc of pcpn Mon aftn into Mon night.  At this point will keep in a
slight chc of pcpn with cooler temps.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 320 PM MDT Mon Jun 5 2017

Main thunderstorm threat has already shifted east of the Denver
metro area airports, but still a 20-30% chance of a
shower/isolated storm til about 02Z. Winds will be variable and
occasionally gusty to around 25 knots due to storm outflow.
Otherwise look for VFR conditions to prevail until cold front
arrives late tonight or early Tuesday. There is more doubt to the
potential stratus or MVFR development as front appears less
pronounced as earlier model runs. 30-40% chance of thunderstorms
moving over the airports on Tuesday afternoon with gusty winds,
brief heavy rain, and small hail.

&&

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

SHORT TERM...Barjenbruch
LONG TERM...RPK
AVIATION...Barjenbruch

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1033 AM MDT Mon Jun 5 2017

COZ030>051-061645-
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Grand and Summit Counties Below 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet-
Central and Southeast Park County-
Larimer County Below 6000 Feet/Northwest Weld County-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
Northeast Weld County-Central and South Weld County-Morgan County-
Central and East Adams and Arapahoe Counties-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County-
Southeast Elbert County Below 6000 Feet/South Lincoln County-
Logan County-Washington County-Sedgwick County-Phillips County-
1033 AM MDT Mon Jun 5 2017

This hazardous weather outlook is for northeast and north central
Colorado.

.DAY ONE...Today and Tonight

Scattered thunderstorms will continue to develop and become more
numerous through the afternoon. The storms will transition from
the mountains to the plains through the afternoon and early
evening hours. Storms over the higher terrain and I-25 Urban
Corridor will produce brief heavy rain, mainly small hail, and
wind gusts up to 45 mph. A stronger storm could produce minor
flooding in a burn scar, and minor street flooding in urban
areas.

Storms may become stronger on the plains, roughly along and east
of a line from Greeley to Denver International airport to Castle
Rock. Isolated brief severe storms will be capable of producing hail
up to one inch in diameter and wind gusts to 60 mph.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Thunderstorm chances will increase Tuesday with a very moist
post-frontal airmass covering the plains of northeast Colorado.
Some storms over the Palmer Divide late on Tuesday could produce
locally heavy rainfall. Thunderstorm coverage will become more
scattered on Wednesday and Thursday. Drier and warmer weather
will return for the weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated today or tonight, but any
reports of heavy rainfall or hail would be appreciated.

Special Weather Statement
National Weather Service Denver CO
230 PM MDT MON JUN 5 2017

COZ040-041-045-046-052115-
Elbert/Central and East Douglas Counties Above 6000 Feet CO-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County CO-Central and East Adams and Arapahoe Counties CO-
North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe
Counties/East Broomfield County CO-
230 PM MDT MON JUN 5 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN ELBERT...CENTRAL
ARAPAHOE AND SOUTH CENTRAL ADAMS COUNTIES UNTIL 315 PM MDT...

At 229 PM MDT, Doppler radar was tracking a strong thunderstorm 6
miles east of Arapahoe Park, or 22 miles east of Denver, moving
southeast at 15 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Eastern Aurora, Bennett, Watkins and Manila Village.

LAT...LON 3942 10449 3966 10469 3984 10452 3953 10417
TIME...MOT...LOC 2029Z 322DEG 12KT 3963 10456

BOWEN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
249 PM MDT MON JUN 05 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0234 PM     TORNADO          3 SSW BENNETT           39.72N 104.44W
06/05/2017                   ARAPAHOE           CO   STORM CHASER

            A WEAK LANDSPOUT TOUCHED DOWN BRIEFLY AND TOSSED SOME
            SMALL LAWN FURNITURE.

0232 PM     TSTM WND GST     1 SSW BENNETT           39.74N 104.43W
06/05/2017  M62.00 MPH       ARAPAHOE           CO   MESONET

&&

FCOOPER

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
333 PM MDT MON JUN 05 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0238 PM     TSTM WND DMG     2 SE BENNETT            39.73N 104.40W
06/05/2017                   ARAPAHOE           CO   STORM CHASER

            ONE POWER POLE SNAPPED NEAR THE I-70 AND HIGHWAY 36
            INTERCHANGE NEAR MILE MARKER 91.

0234 PM     TORNADO          3 SSW BENNETT           39.72N 104.44W
06/05/2017                   ARAPAHOE           CO   STORM CHASER

            A WEAK LANDSPOUT TOUCHED DOWN BRIEFLY AND TOSSED SOME
            SMALL LAWN FURNITURE.

0232 PM     TSTM WND GST     1 SSW BENNETT           39.74N 104.43W
06/05/2017  M62.00 MPH       ARAPAHOE           CO   MESONET

&&

FCOOPER