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Area Forecast Discussion (AFD)

Issued by Denver/Boulder, CO (BOU)

FXUS65 KBOU 260239

Area Forecast Discussion
National Weather Service Denver/Boulder CO
839 PM MDT Sun Aug 25 2019

Issued at 839 PM MDT Sun Aug 25 2019

No changes to the forecast this evening as fair weather cumulus
clouds have been diminishing with the loss of daytime heating.
Temperatures should remain mild most of the night as the cold
front is not expected until after midnight. The cold front is now
visible on satellite imagery, moving through Casper, Wyoming as
the outflow boundary from a convective cluster moving into
southwestern South Dakota. Front should be moving over the
northern Colorado border around 1 AM and then through the Denver
area by 4 or 5 AM. Temperatures will be 15 to 20 degrees cooler 
tomorrrow than they were today. Some clouds are expected through 
the morning and early afternoon, but no showers are expected. 


.SHORT TERM...(This evening through Monday)
Issued at 241 PM MDT Sun Aug 25 2019

Satellite pictures are showing some weak convective cloudiness 
over the CWA right now, maybe 10 percent coverage. Temperatures 
are mostly in the mid 90s across the plains. There are pretty 
uniform west-northwesterly winds across much of the CWA as well. 
Moderately strong northwesterly flow aloft will cover the CWA 
tonight and Monday. A decent cold front is expected to push across
the CWA overnight tonight. It should be through the CWA by 12Z 
Monday morning. There is weak downward synoptic scale energy 
progged on the QG Omega fields. The low level winds are progged to
relax somewhat this evening, then even get some drainage 
patterns. A cold front will move down from 09Z-12Z with north-
northeasterlies behind it. East-northeasterly winds are progged on
Monday. Concerning moisture, it should stay quite dry overnight 
and Monday, the exception being an intrusion of enough low level 
moisture, with the upslope flow, for some scattered Stratus 
cloudiness, for about the eastern 3/4rds of the plains from 11Z-
16Z. Precipitable water values are in the 0.25 to 0.75 inch range 
for the CWA tonight and Monday.  There is very little CAPE 
progged on Monday, just a tad over the south-central CWA Monday 
afternoon. There is nothing on the QPF fields for the first two 
periods. Will leave pops out this update. For temperatures, 
Monday's highs will be 7-10 C cooler than this afternoon's highs. 

.LONG TERM...(Monday night through Sunday)
Issued at 241 PM MDT Sun Aug 25 2019

A shortwave embedded within a longwave trough over the northern
Great Plains will move across far northeastern Colorado on
Tuesday. This will aid in the development of a lee cyclone over
eastern Colorado during Tuesday morning before a cold front pushes
through during the afternoon. This cold front will not have much
moisture associated with it and a dry inversion around 650 mb
will limit the instability. Consequently, only a few light 
showers or storms will be possible throughout the day along the 
cold front and also over the Palmer Divide during the afternoon. 

A mid to upper level ridge will strengthen and expand in coverage 
over the Desert Southwest on Wednesday and Thursday. With
precipitable water values less than half an inch on Wednesday,
there will not be enough moisture to develop storms so POPs were
kept below 10 percent. On Thursday, the moisture increases very
slightly which may lead to a couple stray storms but the coverage
should be low. As for high temperatures, they will warm slightly 
above normal on Wednesday and will gain another 5 degrees on 
Thursday. This may take high temperatures into the mid 90s in 
Denver on Thursday depending on the amount of sunshine. 

A cold front moves through the eastern plains on Thursday night
increasing low level moisture and this moisture will stay in 
place through much of the weekend due to the development of 
surface high over the northern Great Plains. As weak shortwaves 
move over Colorado, showers and storms will be possible Friday 
through Sunday with the best coverage of storms appearing to be on


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 839 PM MDT Sun Aug 25 2019

No aviation impacts overnight as skies will trend to clear with
light winds. Some low clouds will be possible tomorrow morning
after 5 AM as the cold front moves through with a wind shift to
the north. Cloud bases could be as low as 1500-2000 feet AGL, but
no ceilings are expected. Winds should be out of the north to
northeast through the rest of tomorrow. 


Issued at 839 PM MDT Sun Aug 25 2019

Red Flag Warning has been allowed to expire for tonight. 

The fire danger will remain elevated at times in North, Middle 
and South Parks on Monday due to persistent dry conditions from
continued westerly flow aloft. 

Locations on the plains and in the lower foothills are expected 
to be cooler with higher humidities and lighter winds due to the 
cold front moving in from the north. 




LONG TERM.......Danielson