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Area Forecast Discussion (AFD)

Issued by Denver/Boulder, CO (BOU)

                            
000
FXUS65 KBOU 231601
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1001 AM MDT Sun Jun 23 2019

.UPDATE...
Issued at 931 AM MDT Sun Jun 23 2019

The center of the slow moving 500mb low is currently over NE CO 
at this time of 15-16z. After the brief dry slot which allowed for
clear skies along the urban corridor and plains for sunrise, 
clouds and showers over the mountains and northwest CO have begun 
to spread onto the plains. Current surrounding radars and short 
term models indicate shower activity to persist over the higher 
terrain thru this afternoon hours, and then gradually increase in 
coverage out onto the plains after 18z. No significant 
additional snowfall accumulation expected in the mountains with 
and additional snow around 1 inch above 10000ft. Elsewhere, 
showers of a rain/snow mix above 9000ft. As cumulus begin to fill
in the cleared areas, capes should remain fairly low in 200-800 
J/kg range across the plains as highs struggle to reach the mid 
60s. Will expect scattered light rain showers for this afternoon 
and early evening with weak thunderstorm development across much 
of the plains. Potentially stronger storms southeast of the I-76 
stretch. For tonight, skies will clear out again and could see 
patchy fog over the low lying areas of the far eastern plains.

&&

.SHORT TERM...(Today and tonight)
Issued at 439 AM MDT Sun Jun 23 2019

The next 12 to 18 hours will bring the final phase of this
weekend's storm system and the late season upper disturbance moves
out across eastern Colorado. Dry and stable conditions that have
developed early this morning will give way to more unsettled
conditions as the coldest temperatures aloft move overhead. Flow
aloft will also switch to northwesterly which will cause the
developing shower activity to track in a southeasterly direction,
in contrast to yesterday's storm motions. Scattered showers will
begin rolling out of the mountains and foothills by late this
morning and continuing through the afternoon. Brief rains, gusty
winds and small hail will be possible with the passing storms.
Temperatures will remain chilly as the coldest part of the storm
system moves across northeast Colorado through this evening.  

In the mountains, scattered snow showers will continue through the
day, but accumulating snowfall appears to be over, and the Winter
Weather Advisory will be cancelled with the upcoming forecast
package.  

Tonight will see decreasing showers, clearing skies and continued
chilly temperatures as drier air moves into the region and the
airmass stabilizes from the loss of daytime heating and the
beginning of an upper ridge building in from the west and
northwest. 

.LONG TERM...(Monday through Saturday)
Issued at 439 AM MDT Sun Jun 23 2019

Highlights for this week include a significant warming and a 
general drying trend, so welcome to the real summer! For Monday, 
Colorado will be under a moderate northwest flow aloft with 
significant warming in the lower levels of the atmosphere as 
700mb temperatures rise to near +11c. This will bring afternoon 
temperatures to around 80 degrees across the plains, which will be
close to a 20 degrees jump of warming over Sunday. Forecast 
soundings indicate a bit of moisture in the mid and upper levels 
which would indicate isolated high based showers possible, mainly 
over higher terrain. Main impact would be gusty winds with the 
light showers.

For Tuesday, the high pressure ridge aloft builds across Colorado 
with continued warming atmosphere with another 3-5 degrees of 
warming. The flow aloft becomes more westerly and still enough 
moisture in the flow for isolated high based storms over higher terrain. 

For the period Wednesday through Friday, a strong low pressure area 
will settle in over the Pacific Northwest with a resultant southwest 
flow aloft over Colorado. This will bring even warmer temperatures 
as 700mb temperatures climb to +16c by Thursday. This will bring our 
first chance of 90 degree temperatures for Thursday and Friday. With 
this flow pattern, the airmass is rather dry but forecast soundings 
indicate enough moisture for isolated high based showers and 
thunderstorms. Expect the majority of the showers will be confined 
to mountains and higher terrain. 

By the weekend, the high pressure will be well established across 
the southern high plains which may begin to steer some deeper 
moisture across far eastern plains.  Temperatures will remain quite 
warm, with readings again close to 90 degrees through the weekend
across lower elevations.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 931 AM MDT Sun Jun 23 2019

The airmass will continue to destabilize through 20Z as surface 
temperatures warm and mid level cold pool moves across the Front
Range. However, there were some mid level clouds associated with
the deformation zone pushing southeast across Denver, so bulk of 
thunder threat may remain just east and north of the Denver area 
aiports where best destabilization occurs. Any passing showers 
however will be capable of producing brief moderate rain and pea 
sized hail, along with wind gusts up to 30 knots. Highest chance 
would be between 19Z and 23Z, before weak subsidence builds in and
temps aloft begin to warm. VFR/Visual landing conditions expected
thereafter, with any fog threat tonight confined to areas north 
of KDEN as light southerly drainage winds are expected to develop.

&&

.HYDROLOGY...
Issued at 931 AM MDT Sun Jun 23 2019

Jackson County Sheriff reported continued impacts and high water,
and water levels were only slowly receding. Therefore, we've 
extended the Areal Flood Warning another 24 hours into Monday.
With regard to the North Platte River at Northgate, it appears to
be cresting now near 8.2 feet, or just above flood stage at 8.0
feet. We expect levels to hold nearly steady through the rest of
the day, before receding slowly through Monday as the latest storm
runoff peak flows move down the basin. Flood Warning for this
stretch of the North Platte will also continue into Monday before
water recedes sufficiently.

&&

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

$$

UPDATE...Fredin
SHORT TERM...Dankers
LONG TERM...Entrekin
AVIATION...Barjenbruch
HYDROLOGY...Barjenbruch