National Weather Service Forecast Discussion

000
FXUS65 KBOU 201152
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
452 AM MST Wed Feb 20 2019

.SHORT TERM...(Today and tonight)
Issued at 452 AM MST Wed Feb 20 2019

Low clouds and flurries are just about out of the eastern fringe
of the eastern edge of our area. Westerly low level flow has
brought drying, but there`s a patch of fog sitting under these
west winds in the river valleys from Fort Collins and Longmont
east across Weld and Morgan counties. This should scour away/burn
off by mid morning. Meanwhile, there`s a little mid level moisture
creeping back into the mountains which should produce light snow
showers through the day. Warm advection aloft creates a window for
some wave amplification this morning, and we`ve seen some of that
the last few hours with 40-50 mph gusts over the higher east
slopes of the Front Range. The temperature structure for this
fades by around noon, and the flow isn`t really that strong
either, so we probably won`t get too much more than that. There
will be more wind mixing down into the lower foothills and onto
the plains, especially near the northern border, by afternoon.
Models have also become pretty insistent on a Longmont anticyclone
by the end of the day, so we`ll go ahead and show southeast winds
developing in the Denver area late in the day. This could bring a
few degrees of cooling as it comes in.

For tonight, moisture increases from the west but winds diminish,
so we may lose the accumulating snow in the mountains but there
will probably still be flurries. The flow starts to go southerly
late which turns on mid level warm advection and likely creates a
cloud deck from that. This will help keep temperatures a bit
warmer--despite still being in the cold air it will be coming in
from a more southerly location. The previous forecast had all this
covered pretty well, except for higher PoPs in the mountains for
light snow showers during the day today.

.LONG TERM...(Thursday through Tuesday)
Issued at 452 AM MST Wed Feb 20 2019

On Thursday, a closed low will be over the Great Basin with a
moderate southwesterly flow aloft over the cwa.  Moisture will
increase over western Colorado ahead of this next system with
some light snow developing in the mountains, especially over zones
31 and 33. Temperatures across the northeast plains will warm
slightly but still below normal with highs in the lower to mid
30s. Thursday night, the upper trough will shift further south
into west central AZ by 12Z Friday. A 100+ kt upper level jet max
rotating around the base of this system will move southwest to
northeast across the cwa overnight. Light snow will increase in
coverage across the mountains. Across the northeast plains, a
shallow cold front will backs its way into the northeast
plains/urban corridor. East to northeast surface winds will usher
in stratus deck that will settle over the area through Friday
morning. Some freezing drizzle may develop late Thursday on the
plains evening, but as the jet max lifts south to north across
the cwa then there may be chc/slight chance of snow developing 06z
to 12z Friday with the highest pops along the northern border.
Friday into Saturday will remain unsettled, as the trough axis
moves west to east across the state. The strongest qg ascent
associated with this system will pass to the south and southeast
of the cwa. Overall snow amounts in the high country should be on
the light side. At this time, 24-hr storm totals should be in the
2-5 inch range in the mountains, generally Trace to 3 inches
possible over the northeast plains, with the greatest
accumulations over eastern Elbert and Lincoln counties. Saturday
night and Sunday, an increasing zonal flow aloft will develop.
There may be some lingering snow showers over the higher west
facings slopes in the mountains, but dry elsewhere. Temperatures
will be a little warmer by Sunday, with highs in the lower 40s.
Monday into Tuesday the models now have a strong zonal flow aloft
over the state. Pacific moisture will makes its way into the
mountains of northern CO by Monday afternoon. An embedded short
wave will move across northern CO Monday afternoon and Monday
night. This will result in colder temperatures on Monday with a
chance of snow for the urban corridor and northeast plains as
well. By Tuesday an upper level ridge will build over the west,
shifting the jetstream further north and east of Colorado
resulting in drier and warmer conditions.


&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 452 AM MST Wed Feb 20 2019

VFR conditions through tonight. There will be an area of fog north
of Denver between about Fort Collins, Longmont, and Brush until
around 16z. Winds in the Denver area will be a bit complicated
today as southerly winds east of the mountains will mostly give
way to west winds at 10-20 knots by 18z, but then back to south or
east by 00z. KBJC will likely be west at 15-25 knots most of the
day, but there may be periods of lighter winds, especially this
morning.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Gimmestad
LONG TERM...Cooper
AVIATION...Gimmestad

NWS BOU Office Area Forecast Discussion