Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Denver/Boulder Colorado
316 am MDT Thursday Aug 28 2014

Short term...(today through tonight )
issued at 316 am MDT Thursday Aug 28 2014

A middle level circulation is near the Colorado-Wyoming border early this morning and
will move east across NE Colorado through this afternoon. Cross-sections show
quite a bit of moisture in the mountains with northwest flow at 700 mb which
will lead to orographic precipitation through the day. Temperatures will be cold
enough for some light accumulation of snow above 11000 feet through middle
morning. Over northestern Colorado with cold pool aloft over area and convective available potential energy
forecast to range from 500-1000 j/kg should see scattered showers and thunderstorms
develop by early afternoon. As for highs readings should stay in the 70s
over northestern Colorado.

By this evening the upper level trough will move east of the area
with moisture decreasing so showers should gradually end by middle

Long term...(friday through wednesday)
issued at 316 am MDT Thursday Aug 28 2014

A dry and stable northwesterly flow aloft moves over the forecast
area on Friday as an upper level ridge moves in from the Great
Basin. A typical early morning surface wind drainage pattern is forecast to
shift to northwesterly by late morning...then northeasterly during the afternoon. This
upslope flow will combine with daytime heating is expected to
produce isolated to scattered showers/T-storms over the Front Range
mountains during the late afternoon and evening hours. Because of the
drier atmosphere...precipitation amounts should be on the light side.
Temperatures on Friday will still be below average.

Over the weekend...temperatures continue to warm on Saturday as the
low amplitude upper level ridge passes by. Downslope flow will
generate additional warming and drying east of the Front Range
probably making Saturday the warmest day during the extended period.
Looking for highs in the middle to upper 80s on the plains and 60s and
70s in the high country. On Sunday...the upper ridge moves east
allowing a broad upper level trough to swing down from the Pacific
northwest. Through the day should see synoptic scale lift increase
with divergent southwesterly flow aloft and an increase in instability
resulting in isolated to scattered T-storms over the high terrain
during the afternoon and evening hours. This southwesterly flow aloft may
carry a few storms over the adjacent High Plains late in the day
where gusty winds and lightning will be more of a concern due to a
relatively dry boundary layer. Meanwhile a weak surface cold front is
forecast to slide south out of southeastern Wyoming Sunday afternoon as the
upper trough passes overhead. Storms may become more numerous across
northern sections of the County Warning Area in the higher humidity behind the cold
front. Not sure how far south these storms will develop. Latest
model runs keep this Post-frontal convection north of the Denver
metropolitan area. For now will follow guidance and keep things dry across
central and southern portions of the I-25 corridor. Temperatures on
Sunday look to be at least 3-4 degree c cooler than the day before.

For Labor Day...drier and slightly warmer conditions return to the
forecast area with the region remaining under the influence of a broadupper
level trough. See little in the way of storms with the drier
conditions. Will go with highs in the low/middle 80s at lower
elevations and 60s/lower 70s in the high country.

See little change for Tuesday and Wednesday as a strong high
pressure ridge expands across the western Continental U.S.. after a slight
dip in temperatures on Tuesday...should see temperatures near to
slightly above average on Wednesday.


Aviation...(for the tafs through 12z Friday morning)
issued at 316 am MDT Thursday Aug 28 2014

Winds will be south-southwest this morning and then become northerly by 18z. There
will be a chance of showers/thunderstorms between 20z and 01z. North winds
may reach speeds of 15-20 miles per hour with a few gusts to 25 miles per hour for an
hour or two as showers/thunderstorms move across.

For this evening shower/thunderstorm threat should end by 01z. Winds may
become more northwesterly for a few hours and then transition to drainage in
the 03z-06z timeframe.


Bou watches/warnings/advisories...


Short term...rpk
long term...Baker

National Weather Service Glossary of Abbreviations