Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Denver/Boulder Colorado
946 am MDT Sat Aug 29 2015

issued at 945 am MDT Sat Aug 29 2015

Smokey skies this morning the product of numerous active wildfires
scattered from west through north of Colorado basically the only
weather to talk about at this hour. Thickest smoke in Colorado
based on visible satellite imagery now over northeast and east
central sections of the state...roughly east of the I-25 urban
corridor. However skies along the foot of the Front Range still
looking quite milky. Should see gradual improvement in
visibilities on the plains later this morning once the convective
temperature in the lower 80s is reached and as the northwest fringe of
this smoke plume begins moving over the area. Otherwise rest of
the forecast appears to be on track.


Short term...(today through tonight )
issued at 339 am MDT Sat Aug 29 2015

Upper level ridge axis will be shifting east across the forecast
area today and tonight. This will result in warmer temperatures
with highs pushing into the lower 90s over most of the
plains...upper 70s/80s foothills...and upper 60s/70s mountains.
Mainly sunny skies will prevail with further warming aloft and a
drier airmass. Only chance for storms will occur from the
mountains roughly along/south of I-70 into Park County where there
is slightly better moisture.

Southerly breezes will increase on the plains increasing the fire
danger...but both humidities and wind speeds fall short of red
flag criteria.

Mountain convection will come to an end this evening with the
loss of daytime heating. Low temperatures will be a few degrees
above normal with the warm airmass in place.

Long term...(sunday through friday)
issued at 339 am MDT Sat Aug 29 2015

The persistent upper level ridge pattern over the southern Continental U.S.
Continues for the extended. Small perturbations in the
positioning of the ridge combined with increasing monsoonal
moisture due to a long wave trough over the western Pacific will
keep a slight chance of storms in the forecast through Tuesday.

Sunday will be a transitional day with the ridge moving south and
east with a strong trough moving through the Pacific northwest.
Subtropical moisture will increase over the state through the day
bringing increased chances of precipitation to the higher terrain
through the day. Temperatures on Sunday will be above seasonal
normals with highs in the lower 90s.

Monday through Tuesday will see a series of small disturbances
moving through the dominant SW upper level flow. Precipitation
chances will increase in the mountains with some storms moving off
the higher terrain and over the plains by the afternoon and late
evening. Precipitable water values increase on the plains to around 1 inch with
increasing moisture. There is minimal cape but some convection
will be possible by Monday and Tuesday afternoon with brief heavy
rain being the main threat with increasing gusty winds by Tuesday
afternoon. Temperatures will cool a bit into the middle 80s for
Monday and upper 80s for Tuesday.

Wednesday through Friday will see strong upper level SW flow
continuing with enough low level moisture to keep a slight chance
of convection in the mountains through the period. The GFS has
some light quantitative precipitation forecast on the plains but the ec remains dry. Will maintain
a slight chance for Wednesday and Thursday with some lingering
moisture as monsoonal flow progresses eastward while keeping
conditions drier for Friday. Temperatures will fluctuate around 90
for the remainder of the week with a possible drop into seasonal
normals by the weekend.


Aviation...(for the tafs through 18z Sunday morning)
issued at 945 am MDT Sat Aug 29 2015

Marginally reduced visibilities due to smoke from upstream
wildfires will gradually improve through the morning as the main core
of smoke drifts southeast away from the Front Range. Thus ils
approaches at dia may not be necessary by late morning or early
afternoon once strong mixing of the boundary layer kicks in. A
shift from light northwesterly mountain top flow to a light
10000-12000kt mean sea level southwesterly flow this afternoon should further aid in
clearing out much of this least in the Denver area.
Otherwise current terminal forecasts appear to be on track with
light S-southeasterly surface winds rest of today going to light S-southwesterly surface
winds by this evening under clear/mostly clear skies.


Bou watches/warnings/advisories...


short term...barjenbruch
long term...Bowen

National Weather Service Glossary of Abbreviations