Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Denver/Boulder Colorado
952 am MDT Sat Aug 23 2014

issued at 913 am MDT Sat Aug 23 2014

Precipitation and lowered ceilings are progressing through western
Colorado on the front end of the incoming trough that is prognosticated
to move through the area this afternoon. Main impacts will be to
the mountains and northern foothills as it progresses into
northeast Colorado by the early evening. Over the northeast
portion there is potential for increased wind gusts and larger
hail due to the increased cape values and qg ascent. Do not see a
reason to change current probability of precipitation and weather in grids at this time.


Short term...(today through tonight )
issued at 319 am MDT Sat Aug 23 2014

A rather strong upper level trough will move across the northern rockies
through tonight with Colorado being on the southern edge of the trough.
Meanwhile an upper level jet will remain across northern portions of the
area through this evening with some potential vorticity in the middle to
upper levels. Thus should see a good chance of showers and thunderstorms in
the mountains later this morning into the afternoon hours. Over northestern Colorado low
level moisture will mix out some through the day except over the far
northestern plains. Convective available potential energy will range from 500-1000 j/kg along the Front
Range while over the far northestern plains vales will be above 1500 j/kg.
As outflow boundaries from convection over the higher terrain move
across by early to middle afternoon expect scattered thunderstorms to develop along the
Front Range and then move rather quickly across the plains from
late afternoon into the early evening hours. With rather strong middle level
flow a few storms could produce wind gusts up to 60 miles per hour. Over the
far northestern plains where convective available potential energy will be better some marginal large
hail could occur as well. As for highs will keep readings mostly
in the lower to middle 80s across northestern Colorado.

By this evening as drier air begins to spread into the mountains precipitation
should gradually decrease over the higher terrain. Over northestern Colorado
precipitation chances should end by early evening along the Front Range and
then by midnight over the far northestern corner.

Long term...(sunday through friday)
issued at 319 am MDT Sat Aug 23 2014

Sunday and Sunday night...the flow aloft remain southwesterly.
Enough subtropical moisture will be around via the GFS/European model (ecmwf)
models to keep a chance of thunderstorms in the aftn/evng. The best chance
will be over the mountains. On Monday...the next system will
approach Colorado from the northwest...with a southwesterly flow ahead of
it. Thunderstorms will again develop over the County warning forecast area Monday
afternoon/evening with the trough itself still over southern Idaho/northern Utah by 12z
Tuesday. The European model (ecmwf)/NAM are slower than the more progressive GFS
which maintains an open wave trough...the NAM drives a closed
circulation into northern California. The European model (ecmwf) is the compromise closes the upper low but still shifts it eastward across
Colorado...but slower...Tuesday into Wednesday. Will follow this
plan for now at bump the probability of precipitation upward for Tuesday night and
Wednesday. Thursday and Friday...will continue with the trend of
drier and warmer with a ridge prognosticated to build over the western


Aviation...(for the tafs through 18z Sunday morning)
issued at 913 am MDT Sat Aug 23 2014

Expect VFR conditions prior to 21z when thunderstorm development
will be possible through the late afternoon until 01z. Expect
light to brief moderate rainshowers with potential for lighting.
Main impacts will be from wind and lowered ceilings through the
tempo period. There will be northwest winds behind the trough with
drainage returning by 7z.


Bou watches/warnings/advisories...


short term...rpk
long term...Cooper

National Weather Service Glossary of Abbreviations