National Weather Service Forecast Discussion

000
FXUS65 KBOU 191028
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
428 AM MDT Sat Sep 19 2020

.SHORT TERM...(Today and tonight)
Issued at 316 AM MDT Sat Sep 19 2020

An upper level trough will move across the nrn Rockies today thru
tonight.  At the sfc, a lee trough will be in place along the front
range, with gusty south winds, over the far ern plains.

Overall, there is quite a bit of mid and high level moisture
moving across the area today, however, lower levels will remain
dry. Meanwhile MLCAPE is very low with soundings having an
Inverted V shape. Thus, any shower activity this aftn, will be
high based with mainly virga and gusty winds, over the higher
terrain and possibly along the front range. As for highs, readings
across nern CO will range from the mid 80s to lower 90s.
Depending on cloud cover and lingering smoke, readings could be a
few degrees lower than fcst in some areas.

For tonight, the nose of an upper level jet will move across srn WY
and nrn CO along with some mid level cooling. Thus, the best chc
of shower activity along with isold storms, will be in the nrn
mtns this evening. Across nern CO, it will be dry, although I
can`t rule out an isold shower or two, late this evening, north
of Denver to the Wyoming border. Finally, as the upper level jet
moves across and subsidence occurs, may see a period of stronger
winds, in the 06z-12z period, over portions of the nrn mtns and
foothills.


.LONG TERM...(Sunday through Friday)
Issued at 420 AM MDT Sat Sep 19 2020

Models have flat upper ridging in place over the CWA along with
weak zonal flow aloft Sunday through Monday night. There is weak
downward vertical velocity progged on the QG Omega fields for the
CWA Sunday into Monday morning, then weak upward motion the rest
of Monday and Monday night. The low level pressure and wind fields
keep weak troughing east of the mountains and normal diurnal wind
trends Sunday through Monday night. Concerning moisture,
precipitable water values are in the 0.40 to 0.80 inch range range
Sunday through Monday night. The better moisture is progged on
Monday. Instability is lacking for much of CWA on Sunday, with
only a tad of CAPE indicated over the mountains. CAPE is better on
Monday with decent amounts in the mountains and even a tad over
the northeastern corner. For pops, will keep some minor pops in
over the mountains late day Sunday, but better pops in mountains
for late day Monday. Will even need a bit of measurable rainfall.
For temperatures, Sunday`s highs are 0-1.5 c cooler than today`s
expected highs. Monday`s readings are very close to Sunday`s
highs. For the later days, Tuesday through Friday, upper ridging
will remain in control of the CWA`s weather. The upper ridge is
centered over the south central U.S. on Tuesday, then is over the
southwestern U.S. Wednesday through Friday. The flow aloft remains
weak all four days. There is okay moisture for Tuesday, less
Wednesday then very little Thursday and Friday. Temperatures are
to stay above seasonal normals all four days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 316 AM MDT Sat Sep 19 2020

Winds will be west to southwest this morning and then
transition to a light east or northeast direction by midday.
Soundings show some potential for virga by mid to late aftn
with brief gusty winds possible.  Thus speeds and directions
could be rather chaotic thru 00Z. Duringh the evening hours
winds should eventually transition to drainage and continue
overnight. As far as smoke, impacts should be less today versus
the past few days.

&&

.FIRE WEATHER...
Issued at 420 AM MDT Sat Sep 19 2020

Elevated fire danger will exist over much of the area this afternoon
into the early evening hours due to warm temperatures and dry
conditions. Winds will be gusty over the higher terrain and far
eastern plains as well.

Fire danger will elevated Sunday afternoon and early Sunday evening
over the some of the plains with fairly low relative humidities
expected.

&&

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

$$

SHORT TERM.....RPK
LONG TERM......RJK
AVIATION.......RPK
FIRE WEATHER...RPK/RJK

NWS BOU Office Area Forecast Discussion