National Weather Service Raw Text Product

832 
FXUS65 KBOU 071520
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
920 AM MDT Thu Apr 7 2022

.UPDATE...
Issued at 909 AM MDT Thu Apr 7 2022

Winds are picking up as scheduled over the plains, where gusts of
55-70 mph are likely once more. Blowing dust will be an additional
hazard through the afternoon, and current satellite imagery
depicts a few dust plumes beginning to surface over Washington
County. May consider Blowing Dust Advisories down the line
depending on how widespread/persistent the blowing dust looks to
be.

Overall, we're just a little more moist compared to this time
yesterday, both on the ground and in the mid levels, with some
scattered cumulus likely over the plains through the day.
Nonetheless, Red Flag conditions look largely on track,
particularly around the Denver metro where humidity will be
lowest. May be tough to technically reach the 15% threshold over
parts of the plains with increased cloud cover and winds, but
given the strength of the winds, fire concerns are warranted
regardless. No major changes to the forecast needed this morning.

&&

.SHORT TERM...(Today and tonight)
Issued at 402 AM MDT Thu Apr 7 2022

Windy and dry conditions will persist today as the upper low 
continues to drift slowly east. The strong pressure gradient 
remains in place between that system and high pressure building 
over the Rocky Mountains ahead of the approaching ridge. The flow 
aloft will turn more northerly between them and jet winds move 
overhead. There will still be moderate to strong synoptic 
subsidence and good mixing to around 650 hPa, into 30 to 60 knot 
winds. Expect another day of strong and gusty winds across the 
plains from late morning through early evening, now more 
northerly. Peak afternoon winds should be 30 to 40 mph gusting up 
to 65 mph, strongest further east. We have maintained our High 
Wind Warning for our eastern plains from 9 AM to 7 PM. 

It will also still be quite dry with critical and near-critical 
afternoon humidity of 10 to 20 percent across the lower 
elevations. This means another day of widespread critical fire 
weather conditions across the plains. It will be driest closer to 
the foothills and the strongest winds will be over the eastern 
plains. We have maintained our Red Flag Warning for all our plains
from 9 AM through 8 PM. 

Blowing dust is also likely again due to steep low level lapse 
rates over 9 C/km. Areas of blowing dust will significantly reduce
air quality and visibility, the latter often resulting in 
significant travel impacts. This hazard has been included in our 
High Wind Warning.

The cooling trend ends today with temperatures just a few degrees
warmer than those yesterday. Highs should be in the upper 40s to 
mid 50s on the plains and 20s to upper 30s in the high country. 
Winds will decrease quickly with decoupling in the early to mid 
evening though should remain a bit breezy overnight, gusting up to
around 30 mph over the eastern plains. It should be dry and 
mostly clear through the night and low temperatures fall to the 
single digits and teens in the high country, still 20s to lower 
30s on the plains.

.LONG TERM...(Friday through Wednesday)
Issued at 430 AM MDT Thu Apr 7 2022

A broad trough that has been responsible for our windy weather 
will drift eastward on Friday. This will pull the northerly jet 
stream associated with this trough to the east with it. Wind 
speeds will decrease as a surface pressure gradient decreases and 
winds in the low levels decrease as well. Nonetheless, there may 
be some gusts across the far eastern plains up to 30 mph as some 
of the northerly winds at the top of the boundary layer are able 
to mix down with daytime heating. Meanwhile, warm air advection 
and plenty of sunshine will increase high temperatures to the 60s 
across the plains. The dry and somewhat gusty conditions will lead
to near critical fire weather conditions and the potential for
fire weather highlights is discussed in the fire weather section 
below.

A ridge will move over our forecast area Friday night and into 
Saturday with a trough hot on its tail. Continued warm air 
advection will increase 700 mb temperatures to around 8 or 9 C. 
With mostly sunny skies, near dry adiabatic low level lapse rates 
are expected and based on those 700 mb temperatures, highs in the 
mid to upper 70s will occur. Lee cyclogenesis will develop over 
northeastern Colorado and with winds aloft increasing ahead of a 
trough over the Pacific Northwest, gusty winds will form. The dry
conditions along with gusty winds will likely lead to areas of 
critical fire weather conditions across the plains that may need 
highlights. 

A trough that was over the Pacific Northwest on Saturday will dig
towards Colorado on Saturday night and Sunday. Strong 700 mb 
frontogenesis along with QG ascent from the trough will combine to
create scattered showers late Saturday and into Sunday morning. 
These showers will be focused over the mountains, in particular 
the western slopes, while the downslope, westerly winds dissipate
most of the showers across the plains. Over some of the higher 
mountain peaks and ridges there will be an inch or two of snow 
accumulation. A cold front that pushes across the area will 
decrease high temperatures 10 to 20 degrees on Sunday. 

There are considerable model differences in the Sunday and Monday 
timeframe. Some solutions show this period being mostly dry as zonal 
flow or slight ridging result in weak subsidence. Other solutions 
show this period being active with warm air advection and 
frontogenesis providing lift. It is hard to tell which solution 
will be right at this time due to the large range in solutions but
it warrants a mention of precipitation in the forecast. 

A secondary shortwave trough will move over the West Coast late on 
Monday and will be near the Four Corners on Tuesday before it 
ejects onto the High Plains on Wednesday. It is this trough that 
will need to be watched closely as there is potential for 
significant impacts. This is because this trough is forecast to be
2 to 3 standard deviations below the normal 500 mb heights with 
an anonymously strong ridge over the eastern US. In between, a 
strong temperature gradient will form and will be the focus for a 
deep surface cyclone to develop. It is still too early to talk 
about specific details in the forecast since there is too big of a
spread in the different global models and their ensembles on the 
location and strength of this trough. However, recent model runs 
have shifted this trough further north and if this trend 
continues, there will be less precipitation that falls over our 
forecast area and the chance for critical fire weather conditions 
would increase. If the model solutions that have the trough going 
further south verify, our forecast area would see more 
precipitation and snowfall along with colder temperatures and a 
smaller fire weather threat. The only thing that seems like a good
bet is a healthy mountain snowfall since the NBM has 
probabilities of over 6 inches of snow well over 50 percent from 
this storm. Due to the northward shift in model predictions for 
the trough, PoPs were lowered across the plains Tuesday and 
Wednesday to take out the mention of likely precipitation. There 
just seems to be too high of a chance that our area has the dry 
slot go overhead to have likely PoPs in the forecast. 

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 909 AM MDT Thu Apr 7 2022

VFR through TAF period. N winds will strengthen late morning into
afternoon, with gusts 30-40 kt likely and possible periods of BLDU
in vcnty of KDEN. FEW-SCT mid level clouds AOA 080. Rapid
weakening of winds expected after ~01Z, with some uncertainty in
wind direction until 08Z before return to SW drainage flow
overnight. Leaning toward period of NE winds after 02Z with
clockwise rotation toward drainage through the evening.

&&

.FIRE WEATHER...
Issued at 402 AM MDT Thu Apr 7 2022

Windy and dry conditions will persist today and there will again
be widespread critical fire weather conditions across the lower
elevations from mid morning through early evening. Expect strong
and gusty northerly winds across the plains, 30 to 40 mph gusting
up to 65 mph by early afternoon. These winds will be coincident 
with critical and near-critical humidity of 10 to 20 percent 
across the lower elevations. It will be driest closer to the 
foothills and the strongest winds will be over the eastern plains.
We have maintained our Red Flag Warning for all our plains from 9
AM through 8 PM. 

Temperatures will warm slightly above normal on Friday with the
dry air remaining in place. Minimum relative humidity will drop to
the mid teens across the plains as a result. With regards to fire
weather conditions, winds will be the biggest uncertainty.
Forecast models that have better mixing show stronger winds with
gusts up to 30 mph possible. However, there is a chance those
models are over doing the mixing and wind gusts will only reach 20
to 25 mph. Therefore, there is potential for critical fire weather
conditions to occur across the plains but there is too much
uncertainty to issue highlights at this time. 

Temperatures warm further on Saturday with similar moisture in 
place meaning relative humidity will drop to the low teens. West
to southwest winds will increase in the afternoon due to a
developing low pressure system in the area with gusts up to 30 
mph. Critical fire weather conditions are likely and fire weather 
highlights will be needed soon. 

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 7 PM MDT this evening for COZ042-044-
046>051.

Red Flag Warning until 8 PM MDT this evening for COZ238>251.

&&

$$

UPDATE...Rodriguez
SHORT TERM...EJD
LONG TERM...Danielson
AVIATION...Rodriguez
FIRE WEATHER...Danielson/EJD