Severe Thunderstorm Warning 43, NWS Denver/Boulder, CO

292 
WWUS55 KBOU 062146
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
346 PM MDT Sat Jun 6 2020

COC001-005-013-014-019-031-035-039-047-049-059-069-093-123-062200-
/O.CON.KBOU.SV.W.0043.000000T0000Z-200606T2200Z/
Weld CO-Park CO-Larimer CO-Gilpin CO-Jefferson CO-Boulder CO-
Douglas CO-Elbert CO-Arapahoe CO-Broomfield CO-Clear Creek CO-
Grand CO-Denver CO-Adams CO-
346 PM MDT Sat Jun 6 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM MDT
FOR WESTERN WELD...EASTERN PARK...LARIMER...GILPIN...JEFFERSON...
BOULDER...DOUGLAS...NORTHWESTERN ELBERT...WESTERN ARAPAHOE...
BROOMFIELD...CLEAR CREEK...EAST CENTRAL GRAND...DENVER AND WESTERN
ADAMS COUNTIES...

At 342 PM MDT, severe thunderstorms were located along a line
extending from 3 miles north of Drake to near Aspen Springs to 7
miles west of Elevenmile Canyon Reservoir, or along a line extending
from 15 miles west of Fort Collins to 28 miles west of Denver to 39 
miles north of Hayden Pass Burn Scar, the storms are moving 
northeast at 60 mph.
 
These are very dangerous storms.

HAZARD...75 mph wind gusts.

SOURCE...An automated weather station in Lakewood recorded a peak 
         wind gust to 70 mph at Bear Creek Golf Club in 
         southwest Lakewood.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be heavily damaged. Expect 
         considerable damage to roofs, windows, and vehicles. 
         Extensive tree damage and power outages are likely.

Locations impacted include...
Denver, Fort Collins, Greeley, Aurora, Lakewood, Thornton, Arvada,
Westminster, Centennial, Boulder, Longmont, Loveland, Broomfield,
Highlands Ranch, Castle Rock, Commerce City, Parker, Littleton,
Northglenn and Brighton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Denver Colorado.

&&

LAT...LON 4097 10470 4026 10451 3915 10458 3913 10466
      3913 10533 3892 10533 3879 10574 4098 10567
TIME...MOT...LOC 2142Z 239DEG 58KT 4048 10535 3986 10545 3886 10562 

HAIL...<.75IN
WIND...80MPH
 
$$

COOPER

Area Forecast Discussion
National Weather Service Denver/Boulder CO
248 PM MDT Sat Jun 6 2020

.SHORT TERM...(This evening through Sunday)
Issued at 248 PM MDT Sat Jun 6 2020

Current surface analysis shows surface low in southeast Montana,
with a lee trough intensifying along the Front Range. Satellite
shows an impressive comma head in northeast Utah moving
northeast, with an intense line of convection stretching south
from that through central Colorado.

High winds have developed from the eastern side of Denver metro
across the Palmer Divide, and stronger wind core is expected to
shift slightly eastward through late afternoon and early evening.
We'll keep the existing warnings in tact. Convection is expected
to spread east across the plains in these late afternoon and
evening hours, as airmass seems to be approaching convective
temperatures per latest AMDAR sounding data, satellite, and radar.
Given the 50-60 knots of wind as seen on latest vad wind profiler
between 8000 and 10000 feet MSL, only an extra 15 knots added to
that from the DCAPE near 1000 J/kg would support damaging surface
wind gusts of 70-85+ mph. Some of those wind speeds have already
been observed with storms in western Colorado, and don't see much
difference for our forecast area given the location and strength
of low/mid level wind speed core. MLCAPE is limited to about
500-800 J/kg, so main threat appears to be wind across our
forecast area.

The back edge of storms should pass to the east of the I-25
Corridor by 6 PM, and then exit the eastern plains by 10 PM.
Clearing skies and lighter winds thereafter.

On Sunday, mostly sunny but dry conditions will prevail, and winds
will again increase in the afternoon. Temperatures will push 90F
or more across most of the plains. There is just enough moisture
over the northwest portion of the state to keep a chance of
showers and storms over the north central mountains for the
afternoon.

.LONG TERM...(Sunday night through Saturday)
Issued at 248 PM MDT Sat Jun 6 2020

Will be keeping an eye on Monday and Monday night's weather as
un upper trough from the Pacific Northwest is forecast to move
across the northern half of the state. Latest model runs have been
slowing this feature down, in deference to Tropical Storm
Cristobal which is forecast to be tracking northward up the Lower
Mississippi Valley. The motion of the tropical system will be
blocking the prevailing westerly flow pattern across the country.
As the upper trough slows its motion, it will be undergoing some
amplification with cold air aloft dropping down from the northern
Rockies. This will drop snow levels down below 10,000 feet from
Monday afternoon through Tuesday morning. The period of heaviest
precipitation with this system will be Monday evening when
mountain ridges may pick up a few inches of snow accumulation.
Impact on roads should be minimal, this late in the season. On the
plains, the combination of dynamic forcing and daytime heating
should be enough to drive the formation of afternoon and evening
thunderstorms. At the current time there is a marginal risk that
some of the thunderstorms could reach severe limits. Cloud cover
through the day will help keep temperatures cool, as well as some
northerly flow out ahead of an approaching cold front. All in all,
Monday will be the third active day in a row for northern
Colorado.

The GFS and ECMWF show the core of the upper trough over northeast
Colorado Tuesday morning, moving out the state by evening.
Temperatures across the forecast area will be quite cool, only in
the upper 60s and lower 70s across the plains and 30s and 40s in
the mountains. Behind the passing trough it should be quite
subsident so no precipitation is expected after Tuesday morning.

The rest of the week will feature an upper ridge re-building over
the Southern Rockies with a gradual warming trend across north
central and northeast Colorado. By late in the week we should
again see the return of afternoon and evening thunderstorm
activity. By next Saturday, high temperatures will probably be
getting back close to 90.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 248 PM MDT Sat Jun 6 2020

Strong winds will continue through the rest of the afternoon with
peak gusts around 50 knots at KDEN and KAPA. Scattered storms will
move across the area with even stronger and damaging gusts
upwards of 60 knots possible. Blowing dust may reduce visibility
to less than 5SM at times. Winds will gradually subside 00Z-03Z.
Light and normal drainage winds expected to reestablish themselves
by 06Z. Winds will increase again 15Z-18Z Sunday, with speeds of
20-25 knots from the southwest, with gusts to around 35 knots
holding through 00Z Monday. KBJC may see lighter winds in the
southwest flow pattern.

&&

.FIRE WEATHER...
Issued at 248 PM MDT Sat Jun 6 2020

Strong winds combined with warmer than average temperatures will
keep fire danger high across the eastern plains into early this
evening, despite the marginal humidity values. However, given
the magnitude of winds any fire could spread rapidly out of
control.

Continued critical fire weather conditons expected again on
Sunday afternoon. Good mixing will result in southwest wind
gusts up to 40-45 mph by afternoon. Humidity levels will be lower
than today so critical fire weather conditions will redevelop over
east central Colorado and the Palmer Divide where fuels are
driest. We'll also issue a Red Flag Warning for the southern
foothills and Park County (Zones 214 and 216) where it will be
drier tomorrow.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 9 PM MDT this evening for COZ041-045>051.

Red Flag Warning until 9 PM MDT Sunday for COZ241-245>251.

Red Flag Warning from noon to 9 PM MDT Sunday for COZ214-216.

High Wind Warning until 6 PM MDT this evening for COZ040-042>044.

&&

SHORT TERM...Barjenbruch
LONG TERM...Dankers
AVIATION...Barjenbruch
FIRE WEATHER...Barjenbruch

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1055 AM MDT Sat Jun 6 2020

COZ030>051-071700-
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-
1055 AM MDT Sat Jun 6 2020

...HIGH WINDS...SEVERE STORMS WITH DAMAGING WINDS...AND HIGH FIRE
DANGER TODAY...

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

.DAY ONE...Today and Tonight

Scattered thunderstorms developing this afternoon will be capable
of producing damaging winds. Wind gusts as high as 80 mph can be
expected from the stronger severe storms, possibly resulting in
property damage and dangerous travel conditions. High profile
vehicles should not travel this afternoon, while others should
remain aware for very strong cross winds and areas of blowing
dust. Visibility may be suddenly reduced near open fields.

Outside of the thunderstorms, gusty winds of 45 to 60 mph will
develop in all areas this afternoon. The strongest of these more
persistent winds are expected to develop over the Palmer Divide
and just east of the I-25 Corridor.

Fire danger will also be very high over the eastern plains and
Palmer Divide as high winds combine with unseasonably warm
temperatures. Avoid burning or any outdoor activity that may
produce sparks, as rapid fire growth is possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

The plains will see very warm temperatures and gusty south winds
increasing by late Sunday morning which will raise fire danger
again to critical levels through early Sunday evening. Wind gusts
up to 50 mph are expected Sunday while humidity levels will be
under 15 percent. Conditons will be drier with no thunderstorms
expected.

On Monday, another upper level weather disturbance will be
passing over the northern half of Colorado with showers and
thunderstorms over the mountains moving out onto the plains in the
afternoon. Some thunderstorms may become severe Monday afternoon
over northern sections.

Cooler temperatures are expected through the middle part of next
week with a little less thunderstorm activity for Tuesday and
Wednesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated today and tonight. However,
any reports of strong wind gusts or wind damage will be
appreciated.

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
118 PM MDT SAT JUN 6 2020

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

0100 PM     NON-TSTM WND GST 3 E PARKER              39.51N 104.71W
06/06/2020  M71 MPH          DOUGLAS            CO   TRAINED SPOTTER

            MINOR TREE DAMAGE.

1247 PM     NON-TSTM WND GST 2 SE DENVER INTL AIRPOR 39.84N 104.65W
06/06/2020  M59 MPH          DENVER             CO   OFFICIAL NWS OBS

1234 PM     NON-TSTM WND GST 2 NE LONE TREE          39.56N 104.85W
06/06/2020  M62 MPH          DOUGLAS            CO   ASOS

            CENTENNIAL AIRPORT.

1130 AM     NON-TSTM WND GST 13 ENE KIOWA            39.41N 104.24W
06/06/2020  M59 MPH          ELBERT             CO   MESONET

            MESONET STATION AR864 KIOWA.

&&

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
227 PM MDT SAT JUN 6 2020

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

0212 PM     TSTM WND GST     1 ENE BERTHOUD PASS     39.80N 105.77W
06/06/2020  M75 MPH          GRAND              CO   AWOS

            AWOS STATION K0CO BERTHOUD PASS.

0154 PM     TSTM WND GST     3 ESE COPPER MOUNTAIN   39.47N 106.10W
06/06/2020  M79 MPH          SUMMIT             CO   MESONET

0154 PM     TSTM WND GST     1 S COPPER MOUNTAIN     39.48N 106.15W
06/06/2020  M74 MPH          SUMMIT             CO   AWOS

            AWOS STATION KCCU RED CLIFF PASS.

0102 PM     NON-TSTM WND GST 2 SE DENVER INTL AIRPOR 39.85N 104.65W
06/06/2020  M60 MPH          DENVER             CO   ASOS

            ASOS STATION KDEN DENVER.

0100 PM     NON-TSTM WND GST 3 SSW CASTLE ROCK       39.34N 104.86W
06/06/2020  M64 MPH          DOUGLAS            CO   MESONET

            MESONET STATION DW6400 CASTLE ROCK.

0100 PM     NON-TSTM WND GST 3 E PARKER              39.51N 104.71W
06/06/2020  M71 MPH          DOUGLAS            CO   TRAINED SPOTTER

            MINOR TREE DAMAGE.

1247 PM     NON-TSTM WND GST 2 SE DENVER INTL AIRPOR 39.84N 104.65W
06/06/2020  M59 MPH          DENVER             CO   OFFICIAL NWS OBS

1245 PM     NON-TSTM WND GST 13 ENE KIOWA            39.41N 104.24W
06/06/2020  M71 MPH          ELBERT             CO   MESONET

            MESONET STATION AR864 KIOWA.

1234 PM     NON-TSTM WND GST 2 NE LONE TREE          39.56N 104.85W
06/06/2020  M62 MPH          DOUGLAS            CO   ASOS

            CENTENNIAL AIRPORT.

1125 AM     NON-TSTM WND GST 3 NNW LOUVIERS          39.51N 105.02W
06/06/2020  M67 MPH          DOUGLAS            CO   MESONET

            MESONET STATION AT112 LITTLETON.

&&

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
246 PM MDT SAT JUN 6 2020

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

0234 PM     TSTM WND GST     8 WNW LAST CHANCE       39.75N 103.73W
06/06/2020  M71 MPH          ADAMS              CO   MESONET

0214 PM     TSTM WND GST     CEDAR POINT             39.35N 103.82W
06/06/2020  M85 MPH          ELBERT             CO   MESONET

0212 PM     TSTM WND GST     1 ENE BERTHOUD PASS     39.80N 105.77W
06/06/2020  M75 MPH          GRAND              CO   AWOS

            AWOS STATION K0CO BERTHOUD PASS.

0154 PM     TSTM WND GST     3 ESE COPPER MOUNTAIN   39.47N 106.10W
06/06/2020  M79 MPH          SUMMIT             CO   MESONET

0154 PM     TSTM WND GST     1 S COPPER MOUNTAIN     39.48N 106.15W
06/06/2020  M74 MPH          SUMMIT             CO   AWOS

            AWOS STATION KCCU RED CLIFF PASS.

0102 PM     NON-TSTM WND GST 2 SE DENVER INTL AIRPOR 39.85N 104.65W
06/06/2020  M60 MPH          DENVER             CO   ASOS

            ASOS STATION KDEN DENVER.

0100 PM     NON-TSTM WND GST 3 SSW CASTLE ROCK       39.34N 104.86W
06/06/2020  M64 MPH          DOUGLAS            CO   MESONET

            MESONET STATION DW6400 CASTLE ROCK.

0100 PM     NON-TSTM WND GST 3 E PARKER              39.51N 104.71W
06/06/2020  M71 MPH          DOUGLAS            CO   TRAINED SPOTTER

            MINOR TREE DAMAGE.

1247 PM     NON-TSTM WND GST 2 SE DENVER INTL AIRPOR 39.84N 104.65W
06/06/2020  M59 MPH          DENVER             CO   OFFICIAL NWS OBS

1245 PM     NON-TSTM WND GST 13 ENE KIOWA            39.41N 104.24W
06/06/2020  M71 MPH          ELBERT             CO   MESONET

            MESONET STATION AR864 KIOWA.

1234 PM     NON-TSTM WND GST 2 NE LONE TREE          39.56N 104.85W
06/06/2020  M62 MPH          DOUGLAS            CO   ASOS

            CENTENNIAL AIRPORT.

1125 AM     NON-TSTM WND GST 3 NNW LOUVIERS          39.51N 105.02W
06/06/2020  M67 MPH          DOUGLAS            CO   MESONET

            MESONET STATION AT112 LITTLETON.

&&