Severe Thunderstorm Warning 413, NWS Denver/Boulder, CO

Area Forecast Discussion
National Weather Service Denver/Boulder CO
237 PM MDT Sat Aug 5 2023

.SHORT TERM...(This afternoon through Sunday)
Issued at 232 PM MDT Sat Aug 5 2023

Convection continues developing at this time, with the strongest
cells over the Palmer Divide.

Forecast pops are in fairly good shape. The southern half of the CWA
still has 1000-2000 J/Kg of MLCAPE. It is under 1000 J/kg north of
there. The downdraft CAPE is around 1000 J/Kg for all the CWA.  The
high resolution models keep the best convective coverage over the
southern CWA with a less batch to run across the CWA northern
border.  So will go with the highest pops in those areas.  Most of
the convection will be done by 06Z.

On Sunday, the CAPE is best over the western and southern CWA.
The northeast looks pretty stable with the cooler airmass in
place.  For temperatures, both tonight's lows and Sunday's highs
should be 5-12 F below seasonal normals; at least for the plains
and foothills.

.LONG TERM...(Sunday night through Friday)
Issued at 230 PM MDT Sat Aug 5 2023

The eastern plains will be more stable into Sunday evening as
cooler air continue to push in from the northeast. However, there
is a weak wave in west/northwest flow aloft as noted in the QG
fields, and we'll have a continuation of shallow upslope flow into
the Front Range. As a result, we'd expect at least scattered
showers and a few storms to be able to spread off the Front Range
and across the adjacent plains Sunday evening. Intensity should be
limited by the lack of instability, but still some brief heavy
rain and small hail from the stronger storms.

On Monday, temperatures will be warming as low level flow turns
south/southeast. There will be plentiful moisture on the plains
and building instability and a theta-e ridge nosing northward.
MLCAPE of 800-1800 J/kg, with the highest values expected to set
up on the eastern plains. We'll start the day strongly capped, but
another speed max/upper level disturbance is forecast to approach
the area from the northwest which combined with daytime heating
should be enough to break the cap. Bulk shear is an impressive
35-50 knots, so a few severe storms will be possible on the plains
along/east of the theta-e/instability axis.

Tuesday could still be an interesting/impactful weather day as one
last and potentially stronger shortwave arrives. At this point, it
appears models have slowed sufficiently to allow continued upward
forcing, weakening cap, strong shear, and enough instability for
one last day of severe storms for awhile. The highest coverage and
threat should stay east of the I-25 Corridor, but something to
keep en eye on should that disturbance slow any more.

Drier weather arrives for Wednesday and will stick around through
the end of the work week. Temperatures will also be turning warmer
during this period, with highs rebounding into the lower 90s on
the plains.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1042 AM MDT Sat Aug 5 2023

Models keep weak winds at DIA into the afternoon. A cooler airmass
with north-northeasterly winds behind it is expected sometime
after 21Z. Concerning thunderstorms, will go with a "VCTS" and a
TEMPO group with VRB18G40KT in it. There should not be any
ceiling issues.

&&

.HYDROLOGY...
Issued at 240 PM MDT Sat Aug 5 2023

Scattered showers and thunderstorms are expected over the burn
areas the rest of this afternoon into early evening. The storms
will be moving fairly fast so there will only be a limited threat
of flash flooding.

The flash flood threat remains limited Sunday, Monday, and
Tuesday as scattered showers and storms are possible each
afternoon. They will move rather quickly, however, so despite
brief heavy rain the threat should remain relatively low.

Drier weather will prevail Wednesday to Friday with no threat of
flash flooding.

&&

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

SHORT TERM...RJK
LONG TERM....Barjenbruch
AVIATION.....RJK
HYDROLOGY....RJK/Barjenbruch

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1050 AM MDT Sat Aug 5 2023

COZ030>051-061700-
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-
1050 AM MDT Sat Aug 5 2023

...SEVERE STORMS POSSIBLE THIS AFTERNOON AND EARLY EVENING...

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

.DAY ONE...Today and Tonight

Some severe thunderstorms are possible this afternoon and evening,
especially south of a Denver to Akron line. Large hail and strong
damaging winds up to 70 mph will be the main threats associated
with the storms.

The rest of the forecast area can expect isolated to scattered
showers and thunderstorms with small hail and gusty outflow
winds to 50 mph. There is a limited threat of flash flooding in
the burn areas this afternoon.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Scattered showers and storms are possible Sunday and Monday mainly
late afternoon into early evening hours across the region. These
storms may produce brief heavy rainfall and small hail, although a
couple storms especially on Monday may become severe on the
plains. This pattern will lead to a limited flash flood risk for
the burn areas both days.

Starting Tuesday through late next week, thunderstorm coverage
becomes isolated and high temperatures increase once more.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed after 2 pm, especially over
southern portions of the I-25 Corridor and eastern plains.

Preliminary Local Storm Report
National Weather Service Denver CO
209 PM MDT Sat Aug 5 2023

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

0200 PM     Hail             13 NNW Simla            39.30N 104.21W
08/05/2023  E1.00 inch       Elbert             CO   Trained Spotter

&&

FMC