Red Flag Warning 34, NWS Denver/Boulder, CO

906 
WWUS85 KBOU 302034
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
234 PM MDT Sat Jun 30 2018

COZ214-010000-
/O.CON.KBOU.FW.W.0034.000000T0000Z-180701T0000Z/
Central and Southeast Park County-
234 PM MDT Sat Jun 30 2018

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM MDT TODAY
FOR GUSTY WIND AND LOW RELATIVE HUMIDITY FOR SOUTH PARK FIRE 
WEATHER ZONE 214 IN NORTH CENTRAL COLORADO...

* Affected Area...Fire Weather Zone 214.

* Timing...Until 6 PM MDT today.

* Winds...West 10 to 15 mph with gusts up to around 30 mph.

* Relative Humidity...As low as 8 percent.

* Impacts...Rapid fire growth and spread are likely with these
  critical fire weather conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now....or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$
BAKER

787 
WWUS85 KBOU 302359
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
559 PM MDT Sat Jun 30 2018

COZ214-010100-
/O.EXP.KBOU.FW.W.0034.000000T0000Z-180701T0000Z/
Central and Southeast Park County-
559 PM MDT Sat Jun 30 2018

...RED FLAG WARNING WILL EXPIRE AT 6 PM MDT THIS EVENING FOR WIND
AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONE 214...

Humidities will continue to improve during the evening hours as
winds decrease, especially across Central and Eastern portions of
Park county. 


$$

Area Forecast Discussion
National Weather Service Denver/Boulder CO
426 AM MDT Sat Jun 30 2018

.SHORT TERM...(Today and tonight)
Issued at 426 AM MDT Sat Jun 30 2018

Cooler air rushing into northeast Colorado this morning behind a
cold front. There are a couple of different cloud layers trying to
form. It looks like lower clouds will become widespread across
most of the plains, but may be less solid near the mountains.
There's still a fair amount of discrepancy between the models on
temperatures today, which should impact the convection as well.

It looks like the coldest and drier air that was near the
mountains in Wyoming won't make it all the way across our area,
though this may cover the area north of Denver. Instead we'll wind
up in the less cool and more moist air coming in from Nebraska.
The greater moisture may aid the low clouds through much of the
day, but will also provide more energy for eventual convection.
However, the cloud cover will make it harder to initiate storms. I
suspect the initial trigger will be the shortwave bringing another
round of lift across the northern border this afternoon, with the
rest of the area either finally getting warm enough for convection
by evening, or being helped along by the edge of the jet-induced
lift or outflow from the earlier storms.

I did lower forecast temperatures today due to the cloud cover,
with highs in the lower to mid 70s across most of the plains, and
maybe not even reaching 70 on the northern border. But dew points
will likely still be in the 50s and maybe a few low 60s in the
corner. This will still give CAPEs of 1000-1500 J/kg this
afternoon. Combined with as much as 50 knots of 0-6 km shear, this
looks sufficient for supercells. While larger scale models just
have a blob of rain with the shortwave axis, the smaller scale
models focus more on a couple of supercells that eventually grow
upscale as they get into the deeper moisture on the plains in the
evening. Cheyenne and Colorado Springs origins appear to be
favored as is so often the case--and the northern one appears to
be likely with the jet forcing. Afternoon heating along the west
edge of the moisture over the foothills is also a candidate, but
this activity could move into the colder air and die. Overall, it
does look like a fairly active day, but I did trim the PoPs a bit
as it seems too much to promise a high areal coverage given the
cool temperatures. Threat from the storm will mainly be hail.
We've struggled to make hail this week with the warm temperatures,
but with a little cooling aloft and the strong shear, it should be
easier to realize the potential today. If we do get the discrete
supercells, there could be a small tornado threat, especially
toward evening as the low level winds become more east-southeast.

Meanwhile, the warm dry mountains will be just a little more
humid today. With the bit of moisture and the jet forcing, there
should be some thunderstorm activity, especially north of I-70.
Still not real wet though and downward momentum transport will
bring a higher threat of strong outflow winds. Smoke transport
which is initially from the WSW should become more WNW toward the
end of the day.

Shortwave timing requires some PoPs in the evening, but it should
clear pretty quickly behind whatever convection we have. I lowered
the lows a couple degrees.

.LONG TERM...(Sunday through Friday)
Issued at 426 AM MDT Sat Jun 30 2018

Zonal flow aloft will develop over the area on Sun as a sfc lee
trough forms along the front range.  Appears tstm activity will be
rather limited and confined mainly to the Palmer Divide.  Temps will
be near seasonal levels.

On Mon the flow aloft will become more WSW.  Moisture will remain
limited over the higher terrain with only isold high based
convection.  Across the plains there will be decent mlcape in the
aftn with a possible weak convergence zone so will keep in a isold
to wdly sct tstms.  Highs will rise back into the lower to mid 90s
across nern CO.

For Tue into Wed the flow aloft will gradually become more SSW. Some
subtropical moisture will become embedded into the flow,  Thus may
see some increase in higher based storms across the mtns,
although precip amounts will probably be on the low side. Across
the plains there will be enough moisture for isold to widely sct
aftn/evening storms as well both days. Highs will remain in the
90s both days across nern CO.

By Thu into Fri an upper level high will build into the area with
weak flow aloft.  There still should be some subtropical moisture
affecting the area both days with somewhat better specific
humidities based on current data.  Thus this would lead to a better
chc of storms actually producing some rain over the higher terrain.
Across nern CO, the best chance of storms looks to be on Thu with
lower chances on Fri.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 426 AM MDT Sat Jun 30 2018

Ceilings between 020 and 040 will prevail today. Scattered
thunderstorms are expected between 20z and 04z. There is a chance
of brief IFR conditions, hail and wind gusts to 40 knots with the
stronger storms. The main threat of that in Denver is between 22z
and 00z. Skies will clear this evening.

&&

.FIRE WEATHER...
Issued at 426 AM MDT Sat Jun 30 2018

Temperatures will be much cooler with higher humidities over the
plains today behind a cold front. Scattered strong thunderstorms
are expected this afternoon. For the mountains it will be slightly
cooler with some increase in humidity. There will be scattered
afternoon storms in the mountains, mainly north of I-70, with
light rainfall and a threat of outflow winds up to 50 mph. Despite
the moderation, conditions will still approach Red Flag criteria
in the valleys for a few hours this afternoon.

Fire danger will remain elevated Sunday and Monday across the
the higher terrain, however winds should be lighter with slightly
higher humidity levels.

&&

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

SHORT TERM...Gimmestad
LONG TERM...RPK
AVIATION...Gimmestad
FIRE WEATHER...Gimmestad/RPK

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
614 AM MDT Sat Jun 30 2018

COZ030>051-011215-
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-
614 AM MDT Sat Jun 30 2018

...SEVERE STORMS POSSIBLE OVER THE PLAINS THIS AFTERNOON AND
EVENING...

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

.DAY ONE...Today and Tonight

Scattered thunderstorms are expected this afternoon and evening.
Some of the storms on the plains may be severe with large hail up
to golf ball size, wind gusts to 60 mph, and brief heavy rain. An
isolated tornado is also possible. The threat of severe storms is
greatest in the area from the lower foothills east to Sterling
and Limon between 3 PM and 8 PM. Over the mountains it will still
be warm with high fire danger, but there will be enough moisture
for some weaker thunderstorms. Wind gusts to 50 mph and small hail
are possible, especially north of Interstate 70.

The storms will end from west to east early this evening.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Dry and warmer weather will return for Sunday with only a slight
chance of storms across the Palmer Divide. For Monday through
Wednesday there will be a slight chance of thunderstorms across
the area although mountain areas may see a better chance of
storms by Wednesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed after 2 PM.

Gimmestad/RPK