Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Riverton Wyoming
1147 am MDT Monday Mar 30 2015
Short term...Monday through Wednesday night
The period once again looks to start out quiet. A ridge of high
pressure will once again bring mainly quiet weather to the region
with only some passing high clouds. There will be a gusty breeze at
times and as a result there could be some fire danger. It is
borderline...but we will let the red flag warning ride for now
across the Wind River basin...even though it will be mainly for
western areas and not Riverton or Lander.Mainly dry weather should
hold through Tuesday morning as the ridge holds on.
Things do become more unsettled later in the period however. Some
moisture moving toward the area ahead of an advancing cold front
will move into the west on Tuesday afternoon. This could be enough
to bring some showers and thunderstorms to western areas in the
afternoon and evening. Continuity had this covered fairly well so we
made few changes at this time. Meanwhile...southwesterly flow east
of The Divide will bring another very warm day with some new record
highs possibly being set. At this time...the 700 millibar winds do
not look strong enough to warrant high wind highlights except for
the maybe the favored areas around the Cody foothills...especially
around the most important Crossroads in America...Clark.
However...it will should be enough for some fire weather highlights.
We will hold off for now to see if any new fuel reports come in to
see if more zones need to be included...but a Fire Weather Watch
looks to be a good possibility to issued sometime today. The
downsloping flow should also keep most areas east of The Divide rain
free through Tuesday night. With the front approaching the west
Tuesday night...some snow showers will continue across the west.
The cold front then crosses the state on Wednesday and will usher in
some sharply cooler temperatures...especially after the long stretch
of warm weather we have experienced. The models do have some showers
around but quantitative precipitation forecast amounts are not that heavy through the day.
Again...with continuity looking reasonable we made few changes. Some
transitory ridging across the area Wednesday night should keep
things mainly dry.
Long term...Thursday through Monday
The weather system for Thursday into Thursday night does not look as
interesting on this set of 00z runs for the GFS/European model (ecmwf) models. It
seems the best dynamics will be to our south. Still expecting snow
showers for the mountains. 700mb temperatures are cold enough to support
snow showers for the lower elevations. Will keep a mix in the lower
elevations but would not be surprised to see snow showers dominate.
Would not see much accumulation at the lower elevations until
after sunset Thursday night. Friday morning may see some lingering
light snow with drying in the afternoon with lingering mountain snow
showers. Dry Friday night. Saturday now looks dry. The models are
again different on Sunday and Monday with the weather pattern.
The GFS maintains a weather system for Sunday night into Monday
with precipitation in the west on Sunday into Sun night...then scattered
showers east of The Divide Sun night into Monday. The European model (ecmwf) has a
SW flow aloft Sunday and Monday with weak weather systems
impacting mainly northwest Wyoming both days. With this uncertainty I have
gone with low precipitation chance in northwest Wyoming Sunday and Monday and leaning
toward the European model (ecmwf) solution for now. Will see how things look
tonight and adjust as needed. As for temperatures...colder highs Thursday
and Friday...then warming back up for Saturday and Sunday. Will
keep Monday mild as well...again leaning toward the European model (ecmwf)
solution next Monday.
High pressure will keep VFR conditions across area terminals
through the forecast period. Some high level clouds will begin to
move in after 12z Tuesday...but are not anticipated to have a
significant impact on Airport operations. The main weather concern
through 18z Tuesday will be the gusty winds which will be present
through around 04z this evening. Winds will begin to increase
again after 15z Tuesday...with stronger wind expected outside the
time frame of this taf set.
Mainly dry weather will continue through Tuesday morning. A gusty
breeze will blow at times across the Wind River basin therefore a
red flag warning will be continued but this will be mainly from the
Riverton Airport and westward. Elsewhere...there although red flag
conditions are not expected...there could be near critical fire
conditions at times in Natrona County. An approaching cold front
will bring windier conditions for Tuesday and will increase fire
danger across many areas east of The Divide and southern Wyoming.
red flag warning until 7 PM MDT this evening wyz283.