National Weather Service Forecast Discussion

121
FXUS65 KBOU 190221
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
821 PM MDT Sat Aug 18 2018

.UPDATE...
Issued at 814 PM MDT Sat Aug 18 2018

Disturbance over nwrn Co moving southeast with
convection developing ahead of it.  Thus will
continue to see scattered showers and storms
move across nrn CO the rest of this evening.
Some of this activity will linger across
the plains through 3 am.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 244 PM MDT Sat Aug 18 2018

Upper trof shifting across northeast Colorado with water vapory
imagery showing drying over the mountains this afternoon. Most of
the storms have shifted further east, mainly along and east of
the Interstate 76 corridor. Storms so far have been under severe
limits with mainly heavy rain and gusty winds. Have already
cancelled the severe thunderstorm watch over Elbert/Lincoln
counties with lack of instability and drier air moving in.

Behind this wave, 60kt jet streak will be shifting over northern
Colorado with additional isolated- scattered storms developing
over mountains and plains towards later this afternoon and
evening. The upper low now over north central Wyoming will drop
into the central plains later tonight and Sunday. This will draw
in much cooler air over the northeast plains on Sunday with
readings only in the 70s over the plains. There will also be
showers developing over the plains on the back side of the low.
Further west...stronger n-nw low level flow will keep conditions
drier with only isolated showers expected. Have increased winds on
Sunday afternoon with the strong mid level flow.

.LONG TERM...(Sunday night through Saturday)
Issued at 345 PM MDT Sat Aug 18 2018

Models have northwesterly flow aloft for the CWA Sunday night and
Monday. The upper ridge to the west builds into Colorado Monday
night through Tuesday night. There is not much synoptic scale
energy progged through Tuesday night. The low level wind and
pressure fields still show some upslope around Sunday evening,
then they trend towards normal drainage late. East and
southeasterly winds will dominate on Monday and Tuesday with
normal drainage patterns Monday night and Tuesday night.
Concerning moisture, models dry out the forecast area considerably
Sunday evening through Monday night. On Tuesday and Tuesday night
moisture increases with precipitable water values getting up
above 1.00 inch for most areas. There is a little bit of CAPE
around Sunday evening, and again Monday late in the day mainly in
the mountains. There is more CAPE around late day Tuesday with
the greatest values in the mountains and foothills. For pops, will
go with 10%s over some of the mountains late day Monday. Will go
with "scattered" pops in the mountains and foothills late day
Tuesday, with "isolated" coverage over the plains. For
temperatures, Monday`s highs will be about 2-4 C above Sunday`s
highs. Tuesday`s highs will be 1-4 C warmer than Monday`s. For the
later days, Wednesday through Saturday, upper ridging is over
Colorado Wednesday into Thursday. There is a weak upper trough
that moves across to the north of the state later Thursday and
Thursday night. The upper ridge is still around Friday and
Saturday, but it is flat. Moisture is fairly sparse all four days;
pops will be low.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 814 PM MDT Sat Aug 18 2018

There will be a threat of showers and tstms through 06z. If
the airport takes a direct hit from a stronger storm brief
MVFR conditions may occur with wind gusts to 40 mph.  Winds
were southeast but will transition to a southwest direction
by 06Z.


&&

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

$$

UPDATE...RPK
SHORT TERM...Entrekin
LONG TERM...RJK
AVIATION...RPK

NWS BOU Office Area Forecast Discussion