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Area Forecast Discussion (AFD)

Issued by Denver/Boulder, CO (BOU)

                            
000
FXUS65 KBOU 191644
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1044 AM MDT Mon Aug 19 2019

.UPDATE...
Issued at 1040 AM MDT Mon Aug 19 2019

No changes to the forecast at this time. Temperatures at DIA
already at 89, with the record of 97 within reach. 
&&

.SHORT TERM...(Today and tonight)
Issued at 424 AM MDT Mon Aug 19 2019

Today's forecast of near record highs is looking good. There is
some high cloudiness across the southern half of Colorado and this
may creep northward a bit as the day goes on. However, it's fairly
thin and should be mainly south and east of Denver through midday,
so it shouldn't have much impact on temperatures. Moisture near
the eastern border will likely remain capped, although there may
be one or two storms out there and with CAPEs of up to 1000 J/kg
if there is something it could be a strong storm. Further west
over the mountains there should be deep mixing but the air mass is
pretty dry, so isolated virga/sprinkles is about all that's
expected. For tonight, there will be a bit more cloud cover so
another mild night is expected.  Forecast lows look about right.

.LONG TERM...(Tuesday through Sunday)
Issued at 424 AM MDT Mon Aug 19 2019

An upper level ridge will be be over Colorado on Tue with weak 
southwest flow aloft.  At the sfc, a cool front will move into nern 
CO during the aftn hours, with northeasterly low level flow 
behind the front. Cross-sections show some influx of subtropical 
moisture by aftn which may allow for widely sct high based tstms 
over portions of the higher terrain.

Meanwhile, over nern CO, there are some major differences as to 
where the best focus for tstm development will be late in the aftn
through the evening hours, as a weak disturbance moves across. 
The ECMWF continues to focus activity over the far nern plains 
while the GFS has convection firing closer to the front range. The
hi res solutions are closer to the ECMWF. At this point have 
rather low confidence as to where the best chance of convection 
will be. Naturally with weak flow aloft and favorable theta-e 
values, in the 850-700 mb layer, advecting into nern CO, there 
would be the potential for slow moving tstms that would produce 
very heavy rainfall in some areas. Finally as far as highs, it 
appears it will be another hot day across most of nern CO with 
readings in the 90's in advance of the cool front.

On Wed, the upper level level ridge will flatten some, however, the 
flow aloft will remain weak westerly.  Meanwhile easterly low level 
flow will be in place over nern CO behind the front.  Cross-sections 
still show some influx of subtropical moisture and with the approach 
of a weak upper level jet max should see a good chc of tstms over 
the higher terrain and along the front range. Once again, with 
weak mid level flow, storms will be slow moving and will produce 
heavy rain in some areas, especially from the foothills across 
the front range. Highs on Wed will drop into the upper 70s to mid 
80s over nern CO.

By Thu, the flow aloft aloft will remain westerly as the low 
level flow becomes southeasterly across the plains. There should 
still be enough moisture for a chc of tstms over the higher 
terrain and across the plains. Highs will be near seasonal 
normals.

For Fri, the flow aloft will remain westerly as a weak system 
moves across the nrn Rockies. In addition, a weak front may move 
across nern CO during the day. There will be some decrease in 
moisture, however, with decent MLCAPE over the plains will keep in
a slight chc of storms along the front. As for highs readings 
will remain near seasonal levels.

Looking ahead to the weekend, dry northwest flow aloft will be in 
place as the upper level ridge shifts westward.  Overall it looks 
mainly dry across most of the area.  The only exception might be 
over the far nern CO, where decent cape will exist in the 
vicinity of the upper level jet. Thus this could lead a few late 
afternoon or evening tstms. Temperatures will be above normal both
days. 

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1040 AM MDT Mon Aug 19 2019

VFR through tonight with light diurnal winds.

&&

.FIRE WEATHER...
Issued at 424 AM MDT Mon Aug 19 2019

Near record warmth and very dry low level air will keep fire
danger high to very high across the area. It will be breezy this
afternoon over the mountains, and the lower elevations of Jackson
and Grand counties and the higher foothills of Larimer and Boulder
counties will be near Red Flag criteria for a few hours this
afternoon.

Elevated fire danger will continue on Tuesday, over the higher 
terrain and along the front range, due to above normal 
temperatures and low humidity values. However, winds will remain 
generally light.

&&

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

$$

UPDATE...Dankers
SHORT TERM...Gimmestad
LONG TERM...RPK
AVIATION...Cooper
FIRE WEATHER...Gimmestad/RPK