Severe Thunderstorm Warning 210, NWS Denver/Boulder, CO

Area Forecast Discussion
National Weather Service Denver/Boulder CO
340 PM MDT Sun Aug 11 2019

.SHORT TERM...(This evening through Monday)
Issued at 252 PM MDT Sun Aug 11 2019

Strong to severe thunderstorms are ongoing across the eastern
plains this afternoon. The best threat for severe storms will be
along and north of a boundary that is currently across southern
Washington to eastern Arapahoe Counties due to better instability
and shear there. Dew points are in the upper 60s to low 70s across
Logan, Sedgwick and Phillips Counties and precipitable water
values are near 1.5 inches so heavy rain and flooding are
possible there. The storms will move east of our CWA by around
midnight tonight with near normal low temperatures.

NVA behind a departing trough along with a low level high
pressure center moving over the area tomorrow will dry things out.
The only chance for showers and storms will be over the high
country mainly south of I-70 and the Palmer Divide. Northwesterly
winds will increase during the late morning with sustained winds
between 10-20 mph, highest across the Cheyenne Ridge. With
minimum relative humidities reaching as low as 15 percent over
Weld and Larimer Counties, there will be elevated fire weather
conditions. However, a red flag warning will not be needed due to
the moisture in the ground from recent storms. Otherwise, highs
will generally be near or slightly below normal.

.LONG TERM...(Monday night through Sunday)
Issued at 335 PM MDT Sun Aug 11 2019

Models have a flat upper ridge Monday night building back up a
bit west of out CWA late Tuesday through Wednesday night. The flow
aloft will be southwesterly Monday night, then westerly on
Tuesday into Tuesday evening, then northwesterly later Tuesday
night through Wednesday night. There is weak downward synoptic
scale energy progged for the CWA on the QG Omega fields Monday
night through Wednesday evening. The boundary layer winds should
adhere to normal diurnal trends all five periods. For moisture,
precipitable water values generally range from 0.50 over the
western plains to about 1.0 over the far east. So it dries
somewhat compared to of late. There is some CAPE around through
the periods. Values are fairly significant over the far northeast
corner late day Tuesday and late day Wednesday. The basic trend
for the forecast will be drier conditions, less pops and
temperatures right around normals. For temperatures. highs on
Tuesday will be similar to Monday's. Wednesday's readings warm up
1-2 C from Tuesday's highs. For the later days, Thursday through
Sunday, models have the upper ridge over Colorado flattening on
Thursday. A fairly decent upper trough/closed low moves into the
northwestern United State Thursday night into Saturday. A flat
upper ridge is still around for the CWA through Sunday, with the
flow aloft to be west-southwesterly. Moisture is not great all
four days. Temperatures may be a tad above seasonal normals Friday
through Sunday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 252 PM MDT Sun Aug 11 2019

A westerly push from the outflow of showers over the foothills
has moved across the airport this afternoon. Additional storms and
outflow boundaries will develop this afternoon with strong wind
gusts being the main concern the airports. Storms may lower
ceilings and visibilities to IFR temporarily as well. Winds will
turn southerly this evening and before trending toward drainage
tonight.

Northerly winds will increase during the late morning tomorrow as
conditions should remain dry at the airports.

&&

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

SHORT TERM...Danielson
LONG TERM....RJK
AVIATION.....Danielson

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1052 AM MDT Sun Aug 11 2019

COZ030>051-121700-
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-
1052 AM MDT Sun Aug 11 2019

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

.DAY ONE...Today and Tonight

Scattered thunderstorms will develop over the mountains by noon
and spread across the northeast plains during the afternoon and
evening hours. Storms may become severe on the plains, especially
east a line from Greeley to Denver International Airport. Impacts
will be large hail up to 2 inches in diameter, damaging winds to
60 mph, and even a brief tornado. Very heavy rain may also be a
factor with rainfall rates up to 2 inches in less than one hour.
This may lead to localized flooding. Storms will end from west to
east this evening.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Mainly, a slight chance of late day showers and thunderstorms can
be expected through the period. The high country will see a
better chance than the plains will. The storms will produce light
rain showers and gusty outflow winds. Temperatures will be at or a
tad above seasonal normals most of the time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed across the northeast
plains of Colorado after 2 pm this afternoon.

Special Weather Statement
National Weather Service Denver CO
323 PM MDT Sun Aug 11 2019

COZ030-031-112200-
Jackson County Below 9000 Feet CO-
West Jackson and West Grand Counties Above 9000 Feet CO-
323 PM MDT Sun Aug 11 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL JACKSON COUNTY
UNTIL 400 PM MDT...

At 322 PM MDT, Doppler radar was tracking a strong thunderstorm 6
miles west of Cowdrey, or 52 miles southwest of Laramie, moving east
at 20 mph.

Heavy rain, frequent cloud to ground lightning, penny size hail and
winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Cowdrey.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4095 10621 4095 10622 4094 10621 4093 10622
      4092 10621 4091 10622 4086 10618 4082 10612
      4081 10611 4079 10646 4098 10652 4099 10624
TIME...MOT...LOC 2122Z 256DEG 18KT 4088 10642

COOPER

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
324 PM MDT SUN AUG 11 2019

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

0317 PM     HAIL             1 N AKRON               40.18N 103.21W
08/11/2019  M1.50 INCH       WASHINGTON         CO   TRAINED SPOTTER

            AT THE AKRON AIRPORT

0307 PM     TORNADO          4 ESE PLATNER           40.14N 103.00W
08/11/2019                   WASHINGTON         CO   STORM CHASER

0255 PM     HAIL             6 NW AKRON              40.22N 103.29W
08/11/2019  M1.00 INCH       WASHINGTON         CO   TRAINED SPOTTER

0142 PM     HAIL             2 ESE PONDEROSA PARK    39.39N 104.60W
08/11/2019  M1.00 INCH       ELBERT             CO   TRAINED SPOTTER

&&

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE DENVER CO
339 PM MDT SUN AUG 11 2019

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

0317 PM     HAIL             1 N AKRON               40.18N 103.21W
08/11/2019  M1.50 INCH       WASHINGTON         CO   TRAINED SPOTTER

            AT THE AKRON AIRPORT

0307 PM     TORNADO          3 NE AKRON              40.20N 103.17W
08/11/2019                   WASHINGTON         CO   STORM CHASER

0255 PM     HAIL             6 NW AKRON              40.22N 103.29W
08/11/2019  M1.00 INCH       WASHINGTON         CO   TRAINED SPOTTER

0142 PM     HAIL             2 ESE PONDEROSA PARK    39.39N 104.60W
08/11/2019  M1.00 INCH       ELBERT             CO   TRAINED SPOTTER

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
345 PM MDT SUN AUG 11 2019

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

0326 PM     TORNADO          4 NW OTIS               40.19N 103.02W
08/11/2019                   WASHINGTON         CO   TRAINED SPOTTER

            MULTIPLE REPORTS OF A TORNADO NORTHWEST OF OTIS.

&&

RDANIELS

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
346 PM MDT SUN AUG 11 2019

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

0142 PM     HAIL             2 ESE PONDEROSA PARK    39.39N 104.60W
08/11/2019  M1.00 INCH       ELBERT             CO   TRAINED SPOTTER

0255 PM     HAIL             6 NW AKRON              40.22N 103.29W
08/11/2019  M1.00 INCH       WASHINGTON         CO   TRAINED SPOTTER

0307 PM     TORNADO          3 NE AKRON              40.20N 103.17W
08/11/2019                   WASHINGTON         CO   STORM CHASER

0317 PM     HAIL             1 N AKRON               40.18N 103.21W
08/11/2019  M1.50 INCH       WASHINGTON         CO   TRAINED SPOTTER

            AT THE AKRON AIRPORT

0326 PM     TORNADO          4 NW OTIS               40.19N 103.02W
08/11/2019                   WASHINGTON         CO   TRAINED SPOTTER

            MULTIPLE REPORTS OF A TORNADO NORTHWEST OF OTIS.

&&

RDANIELS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
353 PM MDT SUN AUG 11 2019

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

0351 PM     HAIL             3 W OTIS                40.15N 103.02W
08/11/2019  M2.50 INCH       WASHINGTON         CO   TRAINED SPOTTER

&&

RDANIELS