000
FXUS65 KBOU 301031
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
431 AM MDT Sun Apr 30 2017

.SHORT TERM...(Today and tonight)
Issued at 431 AM MDT Sun Apr 30 2017

The strong Spring storm remains over western Kansas this morning
with only minor impacts on northeast Colorado, except for the high
cloud cover on the west side of the vertically stacked system.
Radar data shows that the precipitation shield has retreated to
the east of Washington and Lincoln Counties, leaving the northeast
Colorado plains under dry and stable north to northwesterly flow.
Temperatures have dropped into the mid and upper 20s at most
locations along the I-25 corridor while holding in the lower to
mid 30s over the northeastern counties. Cloud cover associated
with the storm system has reduced the amount of radiational
cooling. Will let the Freeze Warning continue across the plains
since there is still a couple more hours of possible cooling.

Partly cloudy to mostly sunny skies will be the rule across the
forecast area as the Spring storm gradually moves away from
Colorado. Strong insolation will warm temperatures into the 50s,
melting off the snow cover. In the mountains, sunny skies this
morning will give way to increasing clouds during the afternoon as
moisture aloft arrives from the Pacific Northwest. Later tonight,
light snow is expected to develop in the mountains as the moisture
aloft continues increasing. Accumulations should be less than a
couple inches. Low temperatures on the plains are expected to only
drop to the mid 30s tonight, due to modification of the airmass
today and the presence of increasing moisture aloft from the
northwest. There will be no need for any Frost or Freeze
highlights.

.LONG TERM...(Monday through Saturday)
Issued at 431 AM MDT Sun Apr 30 2017

Nwly flow aloft will be over the area on Mon into Mon night with
some moisture embedded in the flow.  Orographics will remain
favorable in the mtns with lapse rates in the 5-6 c/km range.  Will
see steadier snow showers in the morning but activity may become
more sct in the aftn.  Across the plains there may be enough
instability fm the aftn into the early evening hours to keep in a
slight chc of showers.  As for highs readings will be in the upper
50s to lower 60s over nern CO.

For Tue into Wed there is still some uncertainty on the strength and
how fast an upper level trough will move across in nw flow.  The 12z
data was slower and stronger with this feature while tonight`s data
is faster and weaker.  At this point it appears main impacts of this
trough would be fm Tue aftn into early Wed.  With mid lvl ascent and
decent lapse rates along with favorable orographic flow, snow
should increase in the mtns Tue aftn into Tue night. Across nern
CO still expect a good chc of showers late Tue aftn into Tue
night as main system moves across. Soundings show there could be a
mix of rain and snow down to 5500 ft late in the night into early
Wed morning.

By Wed aftn the upper level trough should move se of the area with
pcpn chances ending.  As for temps will keep readings in the mid to
upper 50s across the plains.

For Thu and Fri an upper level ridge will gradually build into the
area.  This will lead to a dry ptrn with much warmer temps.  In fact
by Fri, highs over nern CO will be in the 75 to 80 degree range.
On Sat the upper level ridge will remain over the rgn as a stg
upper level low is located along the West Coast. Some mid lvl
moisture may be emdedded in swly flow aloft which could lead to a
slight chc of showers mainly in the mtns. Highs across nern CO
will be in the upper 70s to lower 80s.


&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 431 AM MDT Sun Apr 30 2017

Aviation impacts should be minimal today and tonight as dry air
has moved over the I-25 corridor and storm system over western
Kansas is forecast to travel northeastward, away from Colorado,
through today. Northerly pressure gradients will keep the wind out
of the north to northwest until this evening when pressure
gradients will relax and drainage southerlies develop overnight.
Wind speeds through the afternoon will be 10 to 15 knots with
gusts of 20 to 25 knots at times. Ceilings and visibilities should
remain unlimited.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until 8 AM MDT this morning for COZ038>051.

&&

$$

SHORT TERM...Dankers
LONG TERM...RPK
AVIATION...Dankers

NWS BOU Office Area Forecast Discussion