Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 251018

Area Forecast Discussion
National Weather Service Denver/Boulder CO
418 AM MDT Thu May 25 2017

.SHORT TERM...(Today and tonight)
Issued at 418 AM MDT Thu May 25 2017

An upper level trough will extend fm the nrn Rockies into the
Pacific NW with nrn CO in WSW flow aloft.  At this point really hard
to define any disturbance embedded in the flow, however, there will
be favorable upper level divergence across the area thru tonight.
Meanwhile at the sfc low pres will be over ern CO with no real
defined bndry thru the aftn hours. Overall best instability will
be over the far nern plains where capes will be around 1000 j/kg
with lower capes further west along the front range. With decent
lapse rates over the higher terrain expect sct showers and tstms
will dvlp by midday and then move rather quickly across nern CO by
mid to late aftn. Appears most of the convection this aftn will
be outflow dominated with main svr threat being gusty winds over
the plains. If updrafts can sustain themselves over the far nern
plains then there would be a marginal hail threat as well. As for
highs across nern CO will have readings ranging fm the mid to
upper 70s along the front ragne with upper 70s to lower 80s futher

By tonight a wk cool fnt will move across the plains early this
evening. With favorable upper lvl divergence in place sct showers
and a few tstms will linger thru the late evening hours fm the
higher terrain across the plains.

.LONG TERM...(Friday through Wednesday)
Issued at 418 AM MDT Thu May 25 2017

It appears that an active weather pattern will persist over the
state through the next week as a slow moving upper trough takes a
couple days to cross the state over the weekend and then weak
ridging builds over the western United States through the middle
of next week.

The slow moving trough which will be moving over northern Colorado
Friday and Saturday will provide dynamic forcing aloft which will
aid in the development of afternoon thunderstorms. Model soundings
for Friday afternoon show 1500-2000 j/kg of CAPE if the dew points
reach the 50 degree mark. Wind profiles also show a favorable
shear profile for organized convection as low level easterly winds
veer to moderate southwesterly flow aloft. The combination of
instability and winds will make strong or severe thunderstorms
possible with large hail, damaging winds and brief heavy rainfall.

Saturday will be the coolest day of the lot, in the wake of Friday
evening`s rainfall. The upper level trough axis is expected to
move out over northeast Colorado sometime in the afternoon. Model
soundings show less instability due to cooler temperatures at low
levels, but winds will have a stronger upslope component. The
combination of dynamic forcing with upper trough, daytime warming
and upslope low level winds should be enough to initiate afternoon
thunderstorms that progress eastward with the upper trough. High
temperatures on Saturday may only be in the lower 60s.

From Sunday through Wednesday, the medium range models show an
upper ridge building over the western U.S. that leaves Colorado
under weak to moderate northwesterly flow aloft. The ridging will
not be particularly strong, and short wave impulses are expected
to move through the ridge each day. Moisture will also be able to
move over the ridge and accompany the short wave troughs.
Temperatures in Colorado will return to seasonal normals, but each
afternoon will probably see showers develop over the mountains and
then move onto the plains.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 418 AM MDT Thu May 25 2017

Winds were drainage early this morning and may stay in that general
direction thru the late morning.  By midday not sure which direction
they will trend.  Some solutions have a wsw component while others
have them becoming more nwly.  At any rate there will be sct showers
and tstms by 20z with chaotic wind ptrns due to outflow boundaries.
With decent flow aloft could see some gusts in the 40-50 mph range
for brief periods of time between 20z and 01z.  By early evening
winds may becom more n or ne as a wk fnt moves into the area. Latest
data suggest the threat for sct showers and a few tstms could linger
thru 06z.




LONG TERM...Dankers
AVIATION...RPK is the U.S. government's official web portal to all federal, state and local government web resources and services.