Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 240303
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
903 PM MDT SAT JUL 23 2016

.UPDATE...
Issued at 903 PM MDT Sat Jul 23 2016

Main area of convection with gusty winds and lightning moving east
across the plains. Behind that, airmass was stabilizing. However,
still a low threat of storms overnight mainly near the Wyoming
border area where proximity of upper level jet may keep a few
storms going per latest model data. Could see some redevelopment
on the northeast plains as well with low level theta-e advection
overnight.

That theta-e advection will continue into Sunday with the airmass
becoming more moist and unstable across the plains. Scattered
storms will be developing through the afternoon hours. Shear
profile should be sufficient to pop a couple severe storms with
main threats wind and marginal hail due to warm airmass still in
place and relatively deep subcloud layer.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 237 PM MDT Sat Jul 23 2016

So-called cold front dropping past Longmont and Greeley at this
time. The combination of the new airmass and some thunderstorms
behind the front are dropping temperatures down to around 90.
Previous thinking had been that the drier air behind the front
would not support storms, but this is not the case as there
appears to be some forcing aloft stretching from north of Grand
Junction toward Cheyenne and the slight cooling/drying is not
enough to suppress the storms. So the main change to the forecast
was to include some low POPs across northeastern Colorado and
increase clouds through the night. Still expecting not much rain
with most of the storms, and localized gusty winds.

Sunday looks like our day 2 scenario, and at first appeared to be
more active. However there is only slight cooling aloft and the
incoming air is cooler but still fairly dry at first. We may
recover to a temp of 90/dew point of 50 in Denver by the end of
the day, but that is still not enough to generate surface based
convection. Suspect it will wind up being like the last couple of
days where the activity was more toward evening and really
depended on storms originating over the mountains and boundary
collisions on the plains to force convection through a weak cap.

.LONG TERM...(Sunday night through Saturday)
Issued at 237 PM MDT Sat Jul 23 2016

Weak jet dynamics and upslope flow will help scattered
thunderstorms to continue Sunday evening, mainly along and south
of I-70 and some possibly strong, heading east towards Kansas.
The main hazards will be strong outflow winds, some hail and
lightning. A few storms may last after midnight over the far eastern
plains.

The upper high will move north over the state to bring warmer and
drier weather on Monday. Most convective activity will remain over
the higher terrain and south of I-70, with gusty outflow winds as
shown by the inverted-v forecast soundings.

A weak disturbance and cool front will move over the area Tuesday
which should stabilize the northern areas of the forecast area and
produce convection over the south. Temperatures will remain
similar to Monday`s readings.

Dry northwest flow aloft is expected for Wednesday for a warm and
dry day. A shortwave in the flow Thursday will send down another
cold front for upslope flow through Friday. Expect cooler
temperatures and a chance of storms across the forecast
area, mainly east of the divide.

The upper ridge will then build north again over the four corners
area to bring warmer and drier conditions.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 903 PM MDT Sat Jul 23 2016

Most of the high based convection has ended but still a few
sprinkles with local gusty winds. Overnight winds should settle to
normal drainage flow but possible weak Denver cyclone wind pattern
may develop around 12Z. Otherwise VFR conditions will prevail.
Main thunderstorm threat on Sunday will be after 22Z, with more
gusty winds but possible local visibility restrictions due to more
moisture and heavier rain in storms than Sunday.

&&

.BOU Watches/Warnings/Advisories...
None.
&&

$$

UPDATE...Barjenbruch
SHORT TERM...Gimmestad
LONG TERM...Kriederman
AVIATION...Barjenbruch



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