Area forecast discussion
National Weather Service Denver/Boulder Colorado
308 PM MDT sun may 19 2013
Short term...cool and unsettled best describes the weather
conditions expected during the next 24 hours. Deep upper trough
encompassing the northern/central Rocky Mountain region and northern
Great Plains this afternoon will make very slow eastward progress
during the next 24-36 hours. The 500mb low was centered over south
datoka with the 850-700mb low nearly stationary in central
Nebraska. The Nebraska low has produced most of the weather for
northeastern parts of the forecast area since last night. Scattered
showers and T-storms tracking eastward across Logan...Sedgwick and
Phillips counties have just about moved out of the area with
drier northwest flow spreading down from Wyoming. Another batch of
low top convection now passing through Elbert and Lincoln
counties should exit the area in the next hour or so. Will stick
with scattered showers and isolated T-storms in the mountains and
on the plains for rest of this afternoon. Precipitation should generally
remain light and of short duration.
Tonight and tomorrow...with the upper trough shifting east flow
aloft over the forecast area becomes northwesterly. Northern mountain
ranges will be in the best position to see measurable precipitation
during this period. Snow level up around 10000 feet at this time
forecast is forecast to lower to around 8500 feet overnight and then back
up to around 9500 feet or so on Monday. Snow accumulations
expected by 00z/Tuesday will range from 3 to 7 inches on the higher
west/northwest facing mountain slopes in zones 31 and 33. Valley areas
may also pick up an inch or two by late Monday morning. Not
expecting much if any accumulation on roadways in the
valleys...but the High Mountain passes along and north of I-70 could
become pretty messy late tonight and early Monday Monday when
temperatures at their coldest. Will be issuing a Winter Weather
Advisory for this area. Advisory will run from 03z/Monday to 00z/Tue.
On the plains looking for gusty northwest winds to develop on Monday
with isolated to scattered rain showers and isolated T-storms.
North-northeast upslope flow along the Palmer Divide will
probably concentrate most of the precipitation east of the mountains in this
area. Temperatures in the next 24 hours 1-2c cooler than those
observed today.
Long term...northwest flow aloft will prevail Monday night and
Tuesday as an upper level low spins over the northern plains.
Chance for showers decrease through the night as the low continues
to move away from the state. It will still be cold over the higher
terrain with the snow level as low as 9000 feet. For
Tuesday...drier air will move over Colorado. Still enough
instability and moisture are in place to produce isolated showers
over the higher terrain and eastern plains.
An upper level ridge will be over The Rockies on Wednesday while
upper level lows reside over the Pacific northwest and the Great
Lakes. Models showing low level moisture returning the Front Range
as southeast winds develop. Dew points will climb into the 40s and
convective available potential energy will reach up to 800 j/kg. Expect to see isolated to scattered
convection to fire over the higher terrain and move across the Front
Range.
Better chance for showers and storms will occur Thursday as moisture
and instability continue to increase. Dew points will be in the 40s
and may be near 50 degrees along the Front Range with convective available potential energy reaching
1200 j/kg. Airmass will also warm a few degrees which will help the
instability.
Southwest flow aloft will prevail through the weekend as the upper
level low remains over the Pacific northwest and a ridge resides
over the central U.S. Drier air will move over Colorado under this
pattern. Still some uncertainty if the drier air will make it all
the way across Colorado. Will hang onto low probability of precipitation over the eastern
plains this weekend. For Friday and this weekend...best chance and
likely the only chance for storms will be east of the dry line that
sets up. Temperatures will warm with highs reaching the 80s this
weekend.
&&
Aviation...isolated showers and thunderstorms in the Denver area
now through 03z this evening. Precipitation will be light and brief. Do
not expect any reduction to visibility and cloud bases should
remain above 5000 feet above ground level. Overnight VFR conditions with broken
to overcast ceilings at or above 9000 feet above ground level. On Monday...
similar conditions with a 20-30 percent chance of rain showers in
the Denver area starting early to middle morning. During the
afternoon it is possible that bjc and apa could see MVFR ceilings with
upslope showers and isolated T-storms. Again any precipitation should be
light. Winds north-northwest 10-20kts through 03z this evening...
with west-northwest at 6-12kts...then back to north-northwest on
Monday at 10-20kts. Dia could see gusts approaching 28kts in the
afternoon.
&&
Hydrology...no concerns at this time.
&&
Bou watches/warnings/advisories...
Winter Weather Advisory from 9 PM this evening to 6 PM MDT
Monday for coz031-033.
&&
$$
Short term...Baker
long term....meier
aviation...Baker
