163 
FXUS65 KBOU 170946
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
346 AM MDT Tue May 17 2022

.SHORT TERM...(Today and tonight)
Issued at 342 AM MDT Tue May 17 2022

Broad zonal flow should remain in place today, with a subtle 
shortwave tracking across the CO/WY border later this afternoon. 
This should provide enough lift for widely scattered thunderstorms
later this afternoon, which will be the main concern over the 
next 24 hours. At the surface, a fairly impressive moisture 
gradient has setup across the forecast area. Dew points across the
high country and the foothills are in the teens to mid 20s, with 
Td's in the upper 40s across the far northeast corner of the 
state. We should see gradual moistening, especially after noon, 
with a push of northeasterly surface flow. As temperatures warm 
into the 80s across the plains, this should lead to MLCAPE 
increasing to 500-1500 J/kg - generally east of I-25/north of I-70
- with sufficient (25-40kt) deep layer shear. 

The biggest remaining question for today is the overall 
convective coverage. CAM guidance consensus is for convection to 
initiate near the Cheyenne Ridge just after noon, and propagate 
towards the east/southeast. HREF paintball plots and the past few 
HRRR cycles suggest that storms will gradually grow upscale. 
Damaging winds will be the main hazard today... especially with 
steep low level lapse rates and >1000 J/kg DCAPE, but can't rule 
out some large hail as well. The forecast for the Denver metro is 
also relatively uncertain and will be dependent on how much 
moisture can advect into the area. Can't rule out a storm or two, 
even on the dry side of the boundary. Any storm that does manage 
to develop in the drier airmass would generally produce little 
rain but gusty outflow winds, as a result of a fairly classic 
looking inverted V sounding.

A few storms will also possible over the higher terrain, though 
with limited instability, these storms aren't expected to be 
particularly intense. There is a very low threat of burn area 
flash flooding given PWAT values less than a half inch. 

By the evening hours, thunderstorms should diminish as 
instability wanes and the more organized convective activity 
pushes eastward into Kansas/Nebraska. Overnight lows will drop 
back to the upper 40s/low 50s for the plains with cooler 
temperatures across the higher elevations.

.LONG TERM...(Wednesday through Monday)
Issued at 342 AM MDT Tue May 17 2022

On Wednesday, most of the U.S. will be under the influence of a 
zonal flow aloft with a weak to moderate west-northwesterly flow 
over Colorado. Some post frontal cooling will result in max 
temperatures on the plains being some 5 degrees cooler than 
Tuesday's readings. In addition, models are showing some increase 
in low level moisture across the plains and Palmer Divide, mainly 
south of I-70. This increase in moisture combined with daytime 
heating and a passing upper level disturbance should result in a 
better chance for afternoon showers and storms mainly to the south
and southeast of Denver. There is quite a bit of discrepancy 
between the models on the amount of instability. The majority of 
the models show meager CAPE which would result in mainly weak 
storms with gusty winds and light rainfall. However, a few of the 
models such as the NAM do show CAPE's around 1000 J/KG along with 
some shear to suggest the slight potential for one or two of the 
storms to become marginally severe during the afternoon or early
evening.

On Thursday, the upper flow strengthens over Northern Colorado as a 
broad upper trough begins to sag into the Upper Great Basin. This 
pattern will allow a much drier airmass to move into North Central 
and Northeastern CO. along with increasing westerly winds. A 
mountain wave along the lee of the Rockies could lead to windy 
conditions across the higher foothills with gusts to 55 mph 
possible. East of the mountains, downsloping flow will result in 
gusty winds, dry conditions and much above normal temperatures 
with max temperatures in the mid 80s to lower 90s. 

Much colder temperatures along with much needed precipitation is 
expected across the forecast area Thursday night into Saturday as 
the upper trough deepens and settles over Colorado. A strong cold 
front associated with the trough is progged to push across the 
Northeastern plains Thursday evening with temperatures expected to 
plummet from near 80 degrees in the early evening to the upper 40s 
around midnight.

Precipitation is expected to increase from north to south 
overnight and become likely across much of the CWA by Friday 
afternoon as upslope flow deepens and QG ascent increases. At this
time, it looks like Thursday night's and Friday's precipitation 
should be all rain on the plains with snow in the higher 
elevations. The highest potential for accumulating snow appears to
be over the eastern slopes of the Front Range Mountains and the 
foothills above 7000 feet. Friday night into Saturday morning, 
the rain may mix and change over to snow on the plains. The 
current thinking is that most of the snow should melt as it falls 
due to warm ground temperatures with only light accumulations 
expected. The Palmer Divide could see a little more accumulation 
due to colder temperatures. In addition, it's looking like many 
plains locations could see a freeze Saturday morning as 
temperatures are forecasted to fall below 32 degrees. For Sunday 
into early next week, we should see a warming trend with 
decreasing chances of showers.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1126 PM MDT Mon May 16 2022

VFR conditions will continue overnight into Tuesday. A very weak
surface boundary briefly shifted winds at DEN to the ENE but winds
at the terminals should remain below 8kt through most of the
night. A front will shift winds to the north or northeast late
tomorrow morning. Scattered showers and perhaps a thunderstorm or
two will develop after 19-20z, but most of this activity should
remain northeast of DEN. Can't rule out a brief period of variable
or gusty winds with outflow tomorrow afternoon, but confidence is
low at this point. Northerly winds will continue into the evening
before gradually shifting back to drainage winds after 06z 
Tuesday night.

&&

.FIRE WEATHER...
Issued at 342 AM MDT Tue May 17 2022

Dry conditions are likely across the southern portions of the
forecast area on Tuesday, especially over South Park, the southern
Foothills, and Palmer Divide. Winds are forecast to remain below
criteria through the day, limiting the overall fire danger.
Isolated to scattered thunderstorms are expected to develop in the
afternoon, which will bring wetting rain chances to the area, but
also variable/gusty winds and lightning.

Thursday will be dry, warm, and breezy with a good chance of Red
Flag conditions in the afternoon for the plains and lower
foothills. A cold front in the late afternoon or early evening 
will bring a shift to strong north winds. Colder temperatures and
a good chance of precipitation is expected Friday. Warm and breezy
conditions are possible again on Monday.

&&

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

$$

SHORT TERM...Hiris
LONG TERM...jk
AVIATION...Hiris
FIRE WEATHER...Hiris/jk