Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Denver/Boulder Colorado
726 PM MDT Friday Jul 25 2014

issued at 720 PM MDT Friday Jul 25 2014

Scattered to isolated weak convection continues to move across the
area. Outside of a few stronger storms that produced brief heavy
rain and possibly small hail...storms have been weak. Outflow
winds have gusted up to 40 miles per hour. As the airmass stabilizes this
evening and the lack of forcing...expect convection to end by
midnight and likely a couple hours sooner.


Short term...(this evening through saturday)
issued at 332 PM MDT Friday Jul 25 2014

Current convective coverage is about 15-20% in the mountains and
foothills Palmer Ridge and Western Plains. Nothing very strong
yet. East-southeasterly winds are most common over the plains and
foothills right now. The latest acars soundings are showing a
fairly decent cap around 450 mb. The upper ridge center is south
of Colorado tonight and Saturday...with westerly flow aloft for
the County Warning Area. The synoptic scale energy remains benign. The boundary
layer winds are all downsloping tonight...then a front moves in on
Saturday morning with upslope behind it. There is still some
moisture prognosticated overnight and Saturday. Precipitable water values
remain in the 0.7 to 1.3 inch range for the plains and foothills
tonight and Saturday. Boundary layer dew points are in the 45 to
55 f range tonight and Saturday. On Saturday afternoon...the NAM
is very excited with the cape values for most of the County Warning Area...the GFS
has very little. Models continue to show some fairly decent cape
over the eastern half of the County Warning Area this evening. The quantitative precipitation forecast fields have
a tad of measurable rainfall this evening...mostly over the
western half of the forecast area. There is more prognosticated on
Saturday afternoon and it covers more of the County Warning Area. Will keep the
current probability of precipitation going for this evening. The plains look stable on the best probability of precipitation will be over the mountains and
foothills. For temperatures...saturday's highs could be a tad
below this afternoon's.

Long term...(saturday night through friday)
issued at 332 PM MDT Friday Jul 25 2014

Some storms will be possible across the mountains...foothills and
adjacent plains Saturday evening...before ending around midnight.
Storms could produce brief moderate rain and gusty outflow winds.
There are some hints in the model boundary layer wind and relative humidity
fields of low level moisture increasing slightly across the plains
overnight. This may be the result of some convection over Kansas
and Nebraska. For now will not mention any low clouds or fog...but
will continue to monitor. On Sunday...the flow aloft becomes
northwest. Models show another surge of cooler air moving into
northeast plains during the morning...with cross cross sections
indicting some low level moisture behind this surge. This may be
sufficient for some stratus to develop along the urban corridor.
Otherwise scattered showers and thunderstorms are expected to
develop across the mountains and foothills by the afternoon and
continue into the evening. These storms will be capable of
producing brief moderate rain and gusty winds. Plains may end up
being too stable for any convection...but will maintain a slight
chance along the urban corridor and adjacent plains in case a few
storms survive away from the foothills. Highs across the plains
may be 5 to 10 degrees cooler from saturday's readings. By
Monday...low level flow becomes southeasterly as the northwest
flow aloft continues. Low level moisture will be on the increase
as a Theta-E begins to develop. Combination of instability and
moisture will lead to an increasing chance for thunderstorms. Best
chance still looks to be across the mountains and foothills...
though chances for storms could increase along the urban corridor
in the favored upslope areas. Some storms may produce brief heavy
rainfall. There looks to be enough shear for a few severe
storms...with hail and wind the main threats. On Tuesday...
northwest flow aloft to continue with the models indicating a middle
level shortwave moving across northeast Colorado. Upslope looks to
deepen to around 700 mb with decent low level moisture.
Thus...most locations should see a good chance of showers and
thunderstorms. Precipitable water values fairly storms
will be capable of producing locally heavy rain. Shear not all
that favorable for severe storms...though one or two storms could
become severe.

For the later days...Wednesday through Friday. Weather pattern
still looking a bit unsettled for Wednesday and Thursday with
temperatures remaining below normal. Best chance for storms look
to be across mountains and foothills as plains may have a bit too
much subsidence behind the tuesday's wave for much convection.
Highs across the plains may only be around 80 degrees both days.
By Friday...both European model (ecmwf) and GFS show the upper ridge building into
Colorado with a slightly warmer airmass over the region. Airmass
looks a bit drier but enough moisture for a slight chance of
thunderstorms...mainly across the mountains.


Aviation...(for the tafs through 06z Saturday evening)
issued at 720 PM MDT Friday Jul 25 2014

Showers and storms will continue to decrease through 04z. Still a
slight chance for a brief thunderstorm. Winds could shift
direction one more time before settling at a normal drainage

On Saturday...a weak front will push through during the morning
causing winds to be northeasterly. During the afternoon and
evening...another round of storms is expected. Main features will
be moderate to occasionally heavy rain and gusty outflow winds.


Bou watches/warnings/advisories...


short term...rjk
long term...d-l

National Weather Service Glossary of Abbreviations