Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Denver/Boulder Colorado
942 PM MDT Wednesday Oct 1 2014

issued at 940 PM MDT Wednesday Oct 1 2014

Have updated the grids to drop thunderstorms from the
forecast...and lowered the probability of precipitation across the northeast plains.
Should still see the trend of decreasing/diminishing shower
activity towards sunrise.

Update issued at 728 PM MDT Wednesday Oct 1 2014

Showers decreased across the urban corridor behind the first band
that has shifted into the far northeast plains. Another area of
showers is forming as the upper trough over northwestern Colorado
continues it track to the east. Will stick with the mention of
thunder in the mountains...but have opted to go with just rain
showers for the urban corridor the rest of this evening. The hrrr
suggests precipitation persisting through 07-09z then diminishing. Will
stick to midnight in the zones...with decreasing probability of precipitation thereafter.
Will continue with the Winter Weather Advisory for the mountains
through midnight.


Short term...(this evening through thursday)
issued at 300 PM MDT Wednesday Oct 1 2014

The upper level low with surface front has moved over the western
portions of the state switching warmer southwest flow to west-northwest
bringing cooler air down to the surface. These cooler temperatures
combined with decreasing wet bulb zeros through the afternoon have
brought snow down to 8000-8500 feet. The snow will continue through
the evening in the mountains and higher foothills with an
additional 1-2 inches overnight over the higher mountains where
you have decent qg vertical velocity and upslope. The Winter Weather Advisory
will end at midnight when the snow tapers off.

At lower elevations with the cold front and secondary surge of
cooler air from a disorganized front that will drop down into
Colorado later this afternoon showers with only isolated
thunderstorms will be possible. There is decent lift through the
period with lapse rates over Denver of 8.6 c/km but due to lack of
much heating this afternoon and very little cape widespread
development is not expected. Gusty winds are possible with the
showers with wind speeds gusting up to 25 miles per hour over the plains and
40 miles per hour over the higher mountains above timberline. Clouds will
linger over the plains and higher mountains...especially on the
western slopes and valleys through the evening with skies clearing
by morning with subsidence moving in.

Long term...(thursday night through wednesday)
issued at 300 PM MDT Wednesday Oct 1 2014

Initially...a quick moving cold front will be sweeping across the
northeast plains Thursday evening. The NAM and GFS both show a
strong thermal gradient marching across the northeast corner of
the state from 00z through 12z...but both models also limit any
area of precipitation to southeastern Wyoming and western
Nebraska. Quasi-geostrophic diagnostics show only a few hours of
rising vertical motions as the front moves through...but then
additional subsidence. Will mention isolated rain showers over the
northeast corner of the forecast area Thursday case a
line of showers develops in Wyoming. The cool air moving into the
state will linger over the plains through Friday morning. With
skies becoming mostly clear late Thursday is possible
that morning lows on Friday could be nearing the freezing mark. At
this time...only the Palmer Divide region is expected to be lower
than 32. After Friday morning...strong upper level ridging will be
building over Colorado and the southwestern U.S. Which will
continue through the first half of next week. Temperatures will be
gradually warming through the period as skies remain mostly clear.
Dry and mild will be the primary message.


Aviation...(for the tafs through 06z Thursday evening)
issued at 728 PM MDT Wednesday Oct 1 2014

MVFR ceilings...with a lower potential for IFR ceilings/MVFR visibilities at
Denver for any rains showers that redevelop this evening. Some
banded rain showers appear to be developing to the south and east
of Denver and will be moving into kden. Best window will be
through 06z then increasing stability will develop with the focus
for precipitation shifting to the east. As a result should see ceilings slowly
improve after 06z. With some middle level ceilings around toward 12z have
opted to drop vcfg from the taf but still some scattered low clouds


Bou watches/warnings/advisories...
Winter Weather Advisory until midnight MDT tonight for coz031-



short term...Bowen
long term...dankers

National Weather Service Glossary of Abbreviations