Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 242235
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
335 PM MST Fri Nov 24 2017

.SHORT TERM...(This evening through Saturday)
Issued at 335 PM MST Fri Nov 24 3357

A strong northwesterly flow aloft this afternoon and early
evening with a 120 kt upper level jet max will translate south
and east across the cwa. A band of showers along the northern
border this aftn has also produced a couple of lightning strikes
as well. Will keep sct to likely pops in the high country, with 10
to 20 percent coverage across the northeast plains. Best chc for
pcpn will be from around 20z this aftn to 02z this evening. Cold
front has pushed through Greeley an should push into the Denver
area in 22-23z period. Will add isolated thunder to the mountains,
foothills and northeast plains through 23z due to the upper level
jet and afternoon instability. By this evening, the focus should
quickly shift to the Palmer Divide. Will keep isolated pops there
until mid evening but drop the thunder. Strong wind gusts will
likely persist in the mountains above timberline tonight, then
decrease on Saturday. Dry and stable on Saturday with high
pressure at the surface and aloft. Gusty winds in the mountains on
Saturday as well but not as strong as today. A little cooler with
the highs around 60 for Denver.

.LONG TERM...(Saturday night through Friday)
Issued at 335 PM MST Fri Nov 24 3357

Moderate westerly flow aloft will continue with several embedded
features. Pretty good model agreement through Tuesday, then models
are completely out of phase by Friday.

A weak warm front aloft will move over bringing some clouds
Saturday night, the the ridge axis will be over on Sunday.
Temperatures will be warmer with very dry aloft that should mix
some lower dew points to the surface. Flow will be a little
stronger on Monday with similar temperatures aloft. There will
likely be a bit better mixing for more wind and a little more
warming on the plains. There may also be a window for some wave
enhancement with another weak shortwave early Monday, but in
general just expecting the same pattern of winds mixing down the
east slopes that we have had this week. Wave clouds will likely
vary, but in a dry air mass they should be less and thinner on
Sunday and Monday.

Some convergence in model simulations for the Tuesday/Wednesday
trough. EC has been slower/deeper/further south but has come back
a bit with a low just closing off but progressive across the
southern Colorado border Tuesday night into Wednesday. GFS has
been weaker but is trending toward this solution. Enough
confidence to bump up PoPs a bit in this period, though the focus
could well be across southern Colorado. Temperatures warm at the
start of this, but then cooling so probably snow or a rain/snow
mix on the plains.

Fair agreement on another wave coming Wednesday night or Thursday,
though the timing and placement varies a bit. Looks to be strong
enough for at least some showers and another surge of cooler air.
This time it should be cold enough for all snow. Raised mountain
PoPs and introduced some on the plains. After that, there is
enough difference in timing and development that the models are
out of phase for Friday. Some agreement on a dry environment and
continue westerly flow. Forecast highs range from around 40 to the
lower 60s depending on which run you look at.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 335 PM MST Fri Nov 24 3357

Cold front to the north and east of the terminals at this time,
but gusty west/southwest winds at this time may delay its arrival
until 00-01z. Convective showers around at this time with
colliding boundaries likely confusing the wind forecast over the
next 2 hours. Will keep vcsh out of the terminals with primarily
virga around Denver and the potential some stronger gusts
associated with outflow boundaries. Overall, VFR through the
period, with lowest cloud bases 080-090 kft agl through 01z.
Northeast winds 10-15 kts this evening as the boundary pushes
through the Denver area, with a delayed transition to southerly
drainage winds after midnight.

&&

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

$$

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


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