National Weather Service Forecast Discussion

000
FXUS65 KBOU 222134
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
334 PM MDT Fri Jun 22 2018

.SHORT TERM...(This evening through Saturday)
Issued at 334 PM MDT Fri Jun 22 2018

There is still a little instability to fuel a second round of
showers and storms moving off the mountains the next couple of
hours and across the plains this evening. We never really realized
the bouyancy, with the jet forcing helping storms get through a
weak cap, and that will be the case with these as well. Behind
this line of convection the air is much drier and subsident. Dry
and breezy conditions in the mountains will gradually diminish
during the early evening. The Red Flag Warning for South Park
until 8 PM looks good.

Skies should clear out pretty well overnight, allowing for cool
temperatures. On Saturday temperatures should recover to be about
the same as today, but the drier air will limit convection. We`re
expecting a few storms to develop over the mountains in the
afternoon, with increasing coverage from the mountains onto the
plains in the evening as the lift from the approaching trough
arrives.

.LONG TERM...(Saturday night through Friday)
Issued at 334 PM MDT Fri Jun 22 2018

Saturday night, the short wave ridge axis will shift east of the
state, ahead of the next system. By 12z Sunday, a moderate to
strong west/southwesterly flow aloft will develop with a closed
upper trough over central WY. The trough axis at that time will
extend from central WY southwest to along the CO/UT border. Weak
to moderate mid level qg ascent will be over the area Sunday
morning, then decreasing ascent Sunday afternoon as a 60-70 kt jet
max rotating around the base of the trough slowly shifts to the
south and east of the cwa. A weak surface trough over central CO
Saturday night, will strengthen is it sets up around the OK
Panhandle by midday Sunday. This should help to enhance low level
easterly winds over northeast CO Sunday aftn. NAM12 forecast
soundings show favorable CAPES ranging from 1100-1600 j/kg.
Sufficient shear coupled with high CAPE values should support
severe thunderstorms Sunday afternoon. SPC Day 3 Outlook has the
northeast plains of CO under a marginal to slight risk of severe
storms. Sunday night, the closed low near the WY/NE border at 00Z
Monday will shift into the NE panhandle by 12z Monday. This will
result in weak mid level subsidence and downward qg over the cwa.
Due to the proximity of the upper trough near the NE panhandle
however, there should be sufficient mid level instability and
wrap around moisture to keep isolated to scattered pops in the
grids through early Sunday evening then drying. A little warmer
and drier Monday, with isolated to scattered afternoon and evening
thunderstorms mainly over the mountains and far northeast plains.
The trend for the rest of the week is hotter and drier. A
persistent west/southwesterly flow will be over the region Tuesday
through Saturday. The fire danger will increase a little each day
next week, especially over the high mountain valleys, southern
Front Range foothills, Palmer Divide.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 334 PM MDT Fri Jun 22 2018

VFR through Saturday. Scattered thunderstorms nearby until around
23z may provide some variability to the wind. After that east to
northeast winds are expected this evening, then south/west
drainage winds overnight. Only isolated thunderstorm activity is
expected Saturday afternoon with little or no impact. More
numerous showers/storms are possible Saturday evening.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM MDT this evening for COZ214.

&&

$$

SHORT TERM...Gimmestad
LONG TERM...Cooper
AVIATION...Gimmestad

NWS BOU Office Area Forecast Discussion