Severe Thunderstorm Warning 115, NWS Denver/Boulder, CO

Area Forecast Discussion
National Weather Service Denver/Boulder CO
802 PM MDT Thu Jul 9 2020

.UPDATE...
Issued at 749 PM MDT Thu Jul 9 2020

Isolated strong to severe storms are continuing across the
northeast plains of Colorado this evening with large hail. Main
concern is further development further west over the northern
Front Range with weakening intersecting boundaries expected
between 8 and 9 pm. Low level moisture has increased over much of
the area with dewpoints well into the 50s across the urban
corridor. Latest HRRR has developing cells over Eastern Boulder
and Southwest Weld counties which may track just north and east of
Denver through midnight if this comes true. Already seeing some
building towers looking outside our windows here in Boulder. Will
add some pops for thunderstorms further west for the rest of the
evening with the potential for a strong to severe storm.

&&

.SHORT TERM...(This evening through Friday)
Issued at 325 PM MDT Thu Jul 9 2020

Main focus for late this afternoon and evening will continue to be
the potential for severe thunderstorms. The frontal boundary
continues to shift more westward than the models initially had it,
with dewpoints over northeast Weld County in the low 60s early
this afternoon. Latest HRRR has initiated the developing
thunderstorms a little further west, over northwest Weld County by
early this evening. Will adjust the pops accordingly. MLCAPES
around 1700 j/kg at that time, with favorable shear as well. Best
window in the 00-03z period this evening. Diminishing pops by
late evening, but could see some patchy fog over the northeast
plains late tonight. For Friday, dry and stable with temperatures
back near 100. Fire danger will be elevated with dry fuels, single
digit rh's and gusty winds primarily in the high mountain
valleys, and along the northern border areas. Reference the fire
weather discussion below.

.LONG TERM...(Friday night through Thursday)
Issued at 325 PM MDT Thu Jul 9 2020

Through the weekend, hot weather will continue as the strong upper
level ridge remains in place over the southwestern United States.
700 mb temperatures are forecast to reach the mid and upper teens
Celcius through the weekend, implying surface temperatures on the
plains well into the 90s and approaching 100. Sunday looks to be
the warmest day of the weekend, where even Denver has a shot at
the 100 degree mark. Temperatures at the mid-levels will be so
warm that the airmass will remain capped, and convective shower
development will be minimal. Skies should remain sunny both days
except for some fair weather cumulus that develops over the
mountains each afternoon. The warm temperatures will lead to
afternoon humidities dropping into the teens, but pressure
gradients should remain weak, leading to only light winds.
Although Fire Danger levels will be high, the threat of dangerous
fire growth will be limited by the light winds.

From Sunday night through next week, the medium range models begin
moving sub-tropical moisture into the state from the southwest.
The center of the upper level ridge is also forecast to progress
eastward to a position over the southeast United States. This will
allow for more southerly flow aloft which will contain the
increasing moisture levels. Temperatures will remain very warm,
but afternoons will begin seeing more thunderstorm activity
develop. For the time being the forecasts will mention a slight
chance of thunderstorms during the afternoons and evenings. Areas
that receive precipitation will see some cooling, but overall the
airmass over the state will remain warm. which will keep the
streak of 90 degree days on the plains going. As the week
progresses, we will need to keep an eye out for locally heavy rain
from the storms that begin developing. All in all, a pretty
typical summerlike pattern for Colorado.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 749 PM MDT Thu Jul 9 2020

Can't rule out an isolated thunderstorm forming over the terminals
through 05z with intersecting boundaries and have also seen an
increase in low level moisture. Storms should end after midnight
with gradual clearing skies.

&&

.FIRE WEATHER...
Issued at 325 PM MDT Thu Jul 9 2020

Best combination of gusty winds, low rh and dry fuels will be in
North, Middle and South Parks, the northern Front Range Foothills
and Cheyenne Ridge Friday afternoon. Consequently, a Red Flag
Warning has been issued for these areas. This could be expanded
if winds in the other zones pick up.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 8 PM MDT Friday for COZ211-
213>215-238-242.

&&

UPDATE...Entrekin
SHORT TERM...Cooper
LONG TERM...Dankers
AVIATION...Entrekin
FIRE WEATHER...Cooper

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1054 AM MDT Thu Jul 9 2020

COZ030>051-101700-
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-
1054 AM MDT Thu Jul 9 2020

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

.DAY ONE...Today and Tonight

An isolated strong to severe thunderstorm will be possible late
this afternoon and evening over the northeast corner of the state,
mainly along and east of a line from around Sterling to Akron.
Damaging winds and large hail will be the main threats.

Hot temperatures can be expected again, with highs reaching the
lower to mid 90s across most of the plains. Those working or
spending time outdoors today should stay well hydrated by drinking
plenty of water, and seek shade if possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Elevated Fire Danger will be in place on Friday and continue
over the higher terrain through the weekend.  There will be
a slight chance of thunderstorms mainly over the plains on Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated today or tonight, but any
reports of severe weather over the northeast corner of the state
would be appreciated.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
838 PM MDT THU JUL 9 2020

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

0819 PM     HAIL             6 SW WESTPLAINS         40.80N 103.58W
07/09/2020  M1.75 INCH       WELD               CO   PUBLIC

            TIME ESTIMATED FROM RADAR.

&&

ZH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
901 PM MDT THU JUL 9 2020

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

0835 PM     HAIL             4 W BRIGHTON            39.99N 104.87W
07/09/2020  M1.00 INCH       ADAMS              CO   TRAINED SPOTTER

            STRONG WINDS WERE ALSO OCCURRING AT THE TIME OF THE
            REPORT. TIME ESTIMATED BY RADAR.

&&

ZH

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