Area forecast discussion
National Weather Service Denver/Boulder Colorado
1012 am MDT Wednesday may 22 2013
Update...
&&
Short term...water vapor imagery showing upper ridge moving over
Colorado today with warming temperatures over much of the area.
Shallow upslope flow will develop this afternoon as airmass
becomes slightly unstable. Forecast soundings show convective available potential energy up to
around 500j/kg but moisture mainly middle and upper level. Expect
most of the showers over mountains and higher terrain and
eventually spilling out over the adjacent plains later this
afternoon. Expect mainly gusty winds with only light rainfall
amounts with the storms.
Aviation...variable and light winds this morning will shift more
easterly this afternoon. Isolated showers and thunderstorms after
22z but areal coverage at this point low enough not to include in
local terminals. At some Point May need a tempo for gusty winds
with the showers but will see how things play out a bit this
afternoon.
&&
Previous discussion... /issued 358 am MDT Wednesday may 22 2013/
Short term...upper ridge axis will move over Colorado today.
Still a little moisture around...but warming aloft will limit
convective available potential energy and will generally cap convection today. Pressure falls with
the trough to our west will induce east to southeast winds on the
plains this afternoon...but better moisture is some distance away
so not expecting much increase during peak heating. Sweet spot
for convection should be the east slopes of the Front Range with
some moisture convergence into the terrain...will keep the low
probability of precipitation further east in case afternoon convection is able to hold
together moving into the increasing moisture this evening...but
expect any evening activity to be limited in strength and
coverage. Stratus should develop in the cooler moist air advecting
across the plains out of Kansas tonight. Situation for Denver is
complex...initially the flow will be easterly but then turn more
southeast. Expect a Denver cyclone to develop by Thursday
morning...but it may be displaced further west than usual or just
late to form because of the wind direction. There may also be a
hole in the stratus on the north side of the Palmer Divide...it
looks like the flow will be strong enough for that. Temperature
forecast looks good...warmer today and a few degrees above
guidance again.
Long term...Thursday and Thursday night...the upper level ridge
axis will shift to the east of the County warning forecast area with a drier southwesterly
flow developing aloft. In the lower levels...it will be cooler
across the urban corridor and northeast plains following the
passage of a cold front Wednesday night. Plenty stratus may be
around through Thursday morning...then it should start to erode
from west to east some in the afternoon. It may be too capped for thunderstorms
at all so will go with showers or thunderstorms in the zones. On Friday...the
best chance of thunderstorms in the late afternoon and evening will be over the
northeastern plains in the vicinity of the low level Theta-E
ridge. Not sure where it will end up by Friday afternoon as drier air
mixes in from the southwest...but that boundary will be the focus
for thunderstorms. Surface based convective available potential energy east of boundary could climb to around
1500 j/kg with some directional shear as well so the potential for
a few severe storms will exist. The prospects of thunderstorms for the
rest of the period will be confined to the far northeast plains.
A dry southwesterly flow aloft will bring a warm and dry pattern
to the rest of the County warning forecast area with temperatures climbing back above
normal.
Aviation...VFR conditions today with just a slight chance of
showers or thunderstorms...mainly over the mountains. East to
southeast winds will develop in the late afternoon. Low clouds are
expected to develop on the plains late tonight...and there is a
chance of MVFR or IFR ceilings in the Denver area Thursday
morning.
Hydrology...no concerns today.
&&
Bou watches/warnings/advisories...
none.
&&
$$
Short term...entrekin
long term....Cooper
aviation...entrekin
