Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 222130
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
330 PM MDT Sun Apr 22 2018

.SHORT TERM...(This evening through Monday)
Issued at 222 PM MDT Sun Apr 22 2018

High pressure ridge axis will be over Colorado tonight before
weakening and shifting east on Monday. This in response to next
upper level trof which will approach Colorado later Monday
afternoon. For tonight, there be a few lingering showers in the
mountains with the higher coverage of the divide and sections of
Summit and Park counties. Mostly clear skies over the plains with
the exception of some increase in high level moisture later
tonight from the west and southwest.

 There will be increasing lift with the incoming system with
showers/storms developing in the mountains Monday afternoon. Cold
front position will be near the Wyoming and Colorado border by
late afternoon with main impact with front and showers not until
Monday evening over much of the plains. Temperatures will be
warmer Monday with good mixing through mid levels.

.LONG TERM...(Monday night through Sunday)
Issued at 322 PM MDT Sun Apr 22 2018

Models have an upper closed low over the northern Great Plains
with a trailing upper trough back into the northern Great Basin at
00Z late Monday afternoon. At 06Z Monday night at midnight the
closed low is over central Nebraska with the upper trough
stretching southwestward to the Four Corners. By mid day
Wednesday, west-northwesterly flow aloft is over the CWA, then
northwesterly by 12Z Thursday morning. Upward synoptic scale
energy is progged on the QG-Omega fields from Monday night after
06Z through mid Tuesday afternoon. Downward energy moves in
Tuesday night and Wednesday. A decent cold front moves through the
CWA Monday evening with 15-30 knot upslope northerly flow behind
it. This upslope is in place Monday overnight, Tuesday and Tuesday
night. Weaker southeasterly flow is noted on Wednesday with
normal drainage patterns Wednesday night. For moisture, it is on
the increase Monday evening and there is fairly decent amounts
over the CWA through much of Tuesday before it decreases from
north to south Tuesday night. Wednesday and Wednesday night are
dry. There is some CAPE around Monday evening, mainly over the
southern and western CWA. Values are not significant. The QPF
fields are now showing measurable precipitation for much of the
CWA Monday overnight and Tuesday. It looks like it could be cold
enough above about 5,000 feet MSL for some snow and/or a mix of
snow/rain Tuesday from 09-18Z. The Monday night/Tuesday system
has been producing more QPF with each successive run. In the
mountains, progged snowfall values do not appear to warrant
highlights at this time. Will up pops a bit now with 40-80%s for
much of the CWA with this system. For temperatures, Tuesday`s
highs are 8-18 C colder than Monday`s highs. Wednesday`s highs
warm up 6 to 14 C warmer than Tuesday`s. For the later days,
Thursday through Sunday, there is a pretty high amplitude upper
ridge to move across Colorado late Thursday well into Saturday on
The GFS. The ECMWF keeps the upper ridge around until Sunday
evening. The GFS has an upper trough move into Colorado late
Saturday night to mid day Sunday night into day. Both models have
another upper trough nearing the state by 12Z Monday morning.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 222 PM MDT Sun Apr 22 2018

VFR with no impacts through tonight. Surface winds will be north
to northeast and then shifting southeast and south tonight. Next
main impact will be cold front which will move over the area early
Monday evening with a chance of showers/thunderstorms.

&&

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

$$

SHORT TERM...Entrekin
LONG TERM...RJK
AVIATION...Entrekin



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