Flash Flood Warning 15, NWS Denver/Boulder, CO

455 
WGUS75 KBOU 080107
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
707 PM MDT Wed Jun 7 2023

COC069-080117-
/O.EXP.KBOU.FF.W.0015.000000T0000Z-230608T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
707 PM MDT Wed Jun 7 2023

...FLASH FLOOD WARNING FOR THE CAMERON PEAK BURN SCAR WILL EXPIRE AT 
715 PM MDT THIS EVENING FOR EAST CENTRAL LARIMER COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed any road closures.

A Flash Flood Watch remains in effect until 900 PM MDT for portions 
of central and north central Colorado.

LAT...LON 4046 10536 4045 10525 4045 10520 4049 10521
      4052 10518 4056 10525 4058 10530 4060 10539

$$

Hiris

Area Forecast Discussion
National Weather Service Denver/Boulder CO
228 PM MDT Wed Jun 7 2023

.SHORT TERM...(This evening through Thursday)
Issued at 227 PM MDT Wed Jun 7 2023

Radar shows scattered thunderstorms continuing over the high
country with a continued concern for flash flooding over the burn
areas. Ample moisture continues to be transported into the region
resulting in above normal precipitable water values. SPC
mesoanalysis shows values in the 0.5-0.7 range over the high
country this afternoon. Storms are quite notably moving very slow,
which is no surprise given the weak steering flow aloft. Storms
will be capable of producing localized heavy rainfall. This will
support the continued threat for flash flooding over the burn
areas, thus the Flash Flood Watch will continue through this
evening for portions of north/central high country. Scattered,
lower coverage showers and storms are possible over the plains
later afternoon/early evening, some potentially containing small
hail, brief heavy rain, and gusty winds. Storms weaken and move
eastward mid-late evening.

Thursday, a broad trough remains off to the west with weak flow
aloft. Above normal moisture and marginal instability will support
afternoon scattered showers/storms in the high country with a
chance for scattered storms to spread onto the adjacent
plains/Palmer Divide and eventually eastward. Coverage trends
less than Wednesday over the high country with weak synoptic
subsidence in place. Storms will still be capable of brief heavy
rain, small hail, gusty winds. Given weak flow and moisture, a
flash flooding threat exists, although lower than Wednesday. Highs
in the 70s across the plains and 50s/60s for most of the high
country.

.LONG TERM...(Thursday night through Wednesday)
Issued at 227 PM MDT Wed Jun 7 2023

Not much adjusting planned in the extended period. Temperatures
will remain below normal through the middle of next week. Thursday
night and Friday, the blocking ridge will continue over the
central U.S. with light mid and upper level winds over CO. Similar
temperatures expected with enough moisture around for a persistent
chance of thunderstorms. Thursday night the best chance of storms
will be over the high terrain, then the focus will shift more to
the plains on Friday. GFS/NAM12 Layer Precipitable Water (PWAT)
values will range from 0.40-0.50 inch in the mountains, 0.50-1.0
inch across the plains.

Over the weekend,  the ridge remains over the central U.S. but it
starts to get widdled away to some degree by trough on each side,
one over the Southwest/Great Basin and the other over the Great
Lakes region. An upper level disturbance dropping down the east
side of the ridge is still expected to bring a cold front into the
northeast plains on Saturday. Northeast/east post frontal winds
will allow for the focus of showers and thunderstorms to shift
back into the foothills and Palmer Divide. The coolest and wettest
day on the weekend will be Sunday. Model PWAT values will
increase: 0.50-0.80 inch in the Front Range mountains/foothills,
0.8 to 1.25 inches across the plains. Locally heavy rain and the
potential for flash flooding will continue due to persistently
higher moisture and slow storm motions.

Next week, the ridge finally weakens enough to allow trough over the
Desert Southwest to move across CO.  The upper level flow will
remain weak, disorganized and unsettled, with a good chance of
afternoon and evening thunderstorms expected each day.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1140 AM MDT Wed Jun 7 2023

Light and variable winds become light easterly this afternoon.
Thunderstorms remain possible this afternoon. Some uncertainty in
the best timeframe, but likely looking like 22-03z for storms to
be at least be in the vicinity, with potential for some to push
over the terminals. Brief heavy rain, small hail, and brief gusty
winds up to 35 kts are possible. Nearby activity could still
produce the threat of outflow gusts which may produce a wind shift
or two. Winds return to light drainage overnight. Light and
variable winds for a good portion of Thursday with a chance for
scattered storms in the mid/late afternoon.

&&

.HYDROLOGY...
Issued at 227 PM MDT Wed Jun 7 2023

Limited threat for flash flooding over the burn areas Thursday.
Moisture remains in above normal ranges with instability building
in the afternoon to support scattered showers and thunderstorms in
the afternoon/early evening. However, coverage trends lower than
Wednesday due to drier weak subsident flow working in. Weak winds
aloft and storms capable of localized heavy rainfall will still
warrant a limited threat the burn areas.

On Friday, the threat of flash flooding will be limited in the
burn scars as the best thunderstorm coverage may shift to the
plains. Over the weekend, a cold front will push into the
northeast plains and settle along the higher terrain. This will
increase the coverage of showers and thunderstorms back over the
burn scars, with elevated risk possible especially for Cameron
Peak and possibly Calwood.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 9 PM MDT this evening for COZ030-032>034.

&&

SHORT TERM...Mensch
LONG TERM...Cooper
AVIATION...Mensch
HYDROLOGY...Mensch/Cooper

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1011 AM MDT Wed Jun 7 2023

COZ030>051-081615-
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-
1011 AM MDT Wed Jun 7 2023

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

.DAY ONE...Today and Tonight

Showers and thunderstorms will develop again today, most numerous
over the central and north central mountains. Heavy rainfall and
small hail will accompany the stronger storms. There is an
elevated risk for flash flooding on the East Troublesome, Williams
Fork, and Mullen burn areas where a Flash Flood Watch is effect
for this afternoon and evening. There is a slightly lower risk for
Cameron Peak and Calwood burns due to lesser storm coverage. Storms
across the foothills, Urban Corridor, and eastern plains will
more scattered, but also capable of producing heavy rain, small
hail, gusty winds.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

There will be no change to the wet and cool pattern in the long
term period. Scattered showers and storms will develop every day
with the higher terrain usually seeing the bulk of the storms.
The primary concern will be flooding, particularly flash flooding
in the recent burn areas. The days with the highest chance of burn
area flash flooding will be Saturday and Sunday. Gusty winds,
small hail, and lightning will also be threats.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today or tonight. However,
any significant rainfall and flooding reports will be
appreciated.

Special Weather Statement
National Weather Service Denver CO
335 PM MDT Wed Jun 7 2023

COZ036-039-072200-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County
CO-
Jefferson and West Douglas Counties Above  6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet CO-
335 PM MDT Wed Jun 7 2023

...A strong thunderstorm will impact portions of northern Jefferson
County through 400 PM MDT...

At 334 PM MDT, Doppler radar was tracking a strong thunderstorm over
northeastern Golden, or 12 miles west of Denver, moving northwest at
5 mph.

HAZARD...Winds in excess of 30 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Northern Lakewood, Arvada, Wheat Ridge, Golden and White Ranch Open
Space.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 3982 10507 3971 10514 3976 10535 3989 10524
TIME...MOT...LOC 2134Z 115DEG 3KT 3979 10518

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...30 MPH

HIRIS