Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Denver/Boulder Colorado
1056 am MDT Friday Jul 3 2015

Update...
issued at 1052 am MDT Friday Jul 3 2015

Upper level ridge of high pressure remains centered over
southwestern Utah...with a moderate northwest flow aloft over
Colorado. At 14z...the RUC showed a 60+kt jet maximum over eastern
Wyoming. The surface gradient between high pressure over the Great
Plains and low pressure over Utah will produce light east to
southeasterly winds across the plains this afternoon and evening.
Dewpoints on the plains at 15z ranged from the middle 50s to the low
60s. The GFS and RUC show some drier air mixing down by 00z with
dewpoints dropping into the 40s in Denver...while the NAM keeps the
dewpoints in the upper 50s. I think the NAM is too high and the GFS
and RUC are too low. Therefore...I will take a compromise between
the models with dewpoints in the low 50s. The GFS...NAM and all of
the high resolution models showing scattered showers and
thunderstorms over the mountains and higher foothills later this
afternoon...with isolated activity over the plains. The activity
seems to shift into mountains south of I-70...southern foothills and
Palmer Divide this evening. There is enough shear and moisture
around combined with the upper level jet to produce one or two
severe storms east of The Divide this afternoon and evening. Storm Prediction Center has
a slight risk of severe storms across Lincoln and eastern Elbert
counties...with a marginal risk across much of the remainder of the
County Warning Area. With precipitable waters around an inch...we could also see locally heavy
rainfalll. However...the storms should have good movement which
should keep the flash flooding threat low.

&&

Short term...(today through tonight )
issued at 353 am MDT Friday Jul 3 2015

Latest upper air analysis shows an upper level speed maximum driving
southeast across eastern Wyoming. There has been persistent but
scattered convection on the southern periphery of this
feature...and expect that to continue across the eastern plains of
Colorado this morning as speed maximum continues to move southeast.
There is a chance this elevated convection could persist into the
afternoon given jet maximum location. If that occurs then storms could
eventually tap into surface based instability and intensify.
Closer to the Front Range...although isolated showers/storms are
presently in the mountains...most of the storm activity is
expected to hold off when surface based convection fires over the
higher terrain and then moves southeast into the I-25 corridor
this afternoon and evening.

It should be noted quite a few scenarios for convective
development are in play today given the strong speed maximum to our
northwest and morning convection...so overall forecast confidence
is relatively low. That said...enough parameters are in play today
for potential for stronger and even a couple severe storms given
forecast convective available potential energy of 1000-1800 j/kg and deep layer shear. Large hail
and high winds would be the primary threats. Storm motions should
be sufficiently fast to reduce threat of hydrologic issues...but
still potential for urban street and burn scar flooding as
stronger storms still have potential to produce one inch in 30
minutes.

Forecast seems like a broken record again for the overnight as
embedded disturbances in northwest flow...along with
strengthening low level jet...will likely keep a few storms going
on the eastern plains overnight.

Long term...(saturday through thursday)
issued at 353 am MDT Friday Jul 3 2015

On Independence day...the flow will remain northwesterly with the
ridge stretching from new mex into northern Nevada. The models show
some quantitative precipitation forecast Saturday morning as a weak short wave passes to the
north and east. Elsewhere...scattered thunderstorms are prognosticated to
develop over the higher terrain...with just isolated thunderstorms
over the northeast plains in the afternoon and evening. By that time...
the ridge will shift eastward allowing for increased subsidence in
the middle levels. Temperatures will climb back to around 90...with
weak Lee troughing over eastern Colorado. On Sunday...subtropical
moisture will advect northward into western Colorado through the
day. A short wave will drop out of the northern rockies Sunday
afternoon...and clip northeast Colorado Sunday evening. As it
does...a cold front associated with the system will push into the
Front Range. Post frontal upslope will allow for showers to linger
overnight. On Monday...the flow aloft will be more westerly with
the ridge suppressed to the south. Tuesday may be another cool day
as well but the temperatures should moderate somewhat. The ridge
axis will start to rebuild over Utah and western Colorado by
midweek...with a northwesterly flow over northern Colorado. Still some
potential there for a trough to brush the County Warning Area from the north so will
keep slight chance afternoon/evening thunderstorms and limit highs to the middle
80s for the middle of next week.

&&

Aviation...(for the tafs through 18z Saturday morning)
issued at 1052 am MDT Friday Jul 3 2015

Winds remains light and easterly through 23z. Thunderstorms
moving off the foothills may produce gusty variable gusty winds
after 23z.

&&

Bou watches/warnings/advisories...
none.
&&

$$

Update...Kalina
short term...barjenbruch
long term...Cooper
aviation...Kalina

National Weather Service Glossary of Abbreviations