Area forecast discussion
National Weather Service Cheyenne Wyoming
1021 PM MDT Wednesday may 22 2013
Update...
issued at 810 PM MDT Wednesday may 22 2013
Isolated showers linger early this evening to the west of the
Laramie range. There were a few lightning strikes in that area
several hours ago...but have since ended. A tight southeast
surface pressure gradient over southeast Wyoming tonight will
produce gusts as high as 40 miles per hour. Perhaps the biggest question
later tonight will continue to be the timing of the westward
spread of the lower clouds to over the Laramie range. The
expected winds and surface pressure gradient may create enough
mixing to limit the visibility reduction in fog some. The
clouds and fog should move to over the Laramie range between 06z
and 09z. The fog will likely be dense at times over the southern
Laramie range starting after 09z. Areas of drizzle will also be
possible over the East Part of the County Warning Area later tonight as the
cloud depth deepens. The clouds and fog will be slow to lift
on Thursday...with cloud cover over the East Part of the County Warning Area
lasting for much of the day. Have made minor first period
adjustments in a recrny update.
&&
Short term...(this evening through thursday)
issued at 233 PM MDT Wednesday may 22 2013
A few showers have developed this afternoon across Albany and
Carbon counties. Isolated shower activity will continue into early
this evening before dying off. Showers will try to push eastward
and could reach the Nebraska border by this evening...but that may
be pushing the eastern extent of any activity as a low level
inversion will be strengthening this evening as cool moist low level
air advects westward. Shower activity could be accompanied by a few
weak thunderstorms...but those will be few and far between. Severe
thunderstorms not expected but could see a few stronger wind gusts
given 30 to 40 degree surface dew point depressions. There is a
very small chance for elevated showers to spread east across the
Panhandle this evening in association with an elevated warm front.
Not a lot of moisture to work with so kept probability of precipitation below mention in
the forecast but something to keep an eye on this evening.
Stratus deck has held firm all day at Chadron and Alliance. The
stratus will work its way west this evening...banking up along the
Laramie range. Some of the low clouds may spill into the Laramie
valley. Fog will be possible across the Nebraska Panhandle and
portions of southeast Wyoming...especially along the Laramie range
where locally dense fog may form tonight. Southeast winds will
ratchet upward tonight with some of the strongest winds east of the
Laramie range. Could easily see some gusts over 40 miles per hour tonight
such as around Douglas.
With the stratus deck holding firm Thursday under southeast
flow...temperatures will struggle to rise anywhere east of the
Laramie range...while mostly sunny and warm temperatures will be
found in the west under southwest flow. Cut back on chances of
thunderstorms east of the Laramie range with isolated showers and
thunderstorms west. Chances for thunderstorms along the Laramie
range are difficult to handicap...depending on whether or not low
clouds mix out. Certainly a convergence zone with southwest winds
meeting southeast winds...so should cap weaken...a few storms
would be possible. Not expecting severe thunderstorms...but with
cape and shear would be supportive of a few stronger
thunderstorms.
Status should stay locked in over the area into Thursday
evening...but the models are bringing in a strong punch of dry
southwest flow aloft Thursday night and Friday. Stratus should
erode from west to east during this time. This will mean much
warmer temperatures Friday for places such as Cheyenne and
Douglas. The main question is how far east will the dry air make
it. A large temperature difference can be expected over a short
distance come Thursday afternoon...but where that line sets up is
the main question. Chances for thunderstorms will exist along and
east of the dry line Friday afternoon. Shear and cape profiles
conducive of severe thunderstorms capable of producing large hail
with tornadoes not out of the question. For Friday evening...the
dry line is expected to retreat westward. Storms very well may
fire along the retreating dry line.
Long term...(saturday through wednesday)
issued at 310 PM MDT Wednesday may 22 2013
Warmer and mainly dry conditions expected Saturday in southwesterly flow
with surface boundary expected to be northeast of the County Warning Area...though not
far. Pattern then remains quite similar Sunday through Wednesday
with SW flow aloft over the County Warning Area ahead of an upper trough that will
hold over the Pacific northwest. Periodic upper shortwave will pass
across the region and bring some afternoon and evening convection
but hard to say which days will be best for this. Right now Monday
and Tuesday looking somewhat better. Temperatures will remain warm
through the period.
&&
Aviation...(for the 06z tafs through 06z Thursday evening)
issued at 1018 PM MDT Wednesday may 22 2013
Widespread IFR developing overnight in fog and low clouds...except
at Rawlins...with ceilings and visibilities improving to VFR after
15z Thursday. Gusty south to southeast winds to 35 knots after
15z Thursday.
&&
Fire weather...
issued at 233 PM MDT Wednesday may 22 2013
Low clouds and fog to spread across the Nebraska Panhandle and
southeast Wyoming east along and east of the Laramie range tonight.
While the fog will burn off Thursday but low clouds and cool damp
conditions will persist. West of the Laramie range it will be
dry and warm under southwest flow aloft. For Friday...dry conditions
are expected to shift east across the remainder of Wyoming along
with much warmer temperatures. Thunderstorms are possible over the
Nebraska Panhandle Friday afternoon and evening.
&&
Cys watches/warnings/advisories...
Wyoming...none.
NE...none.
&&
$$
Update...Weiland
short term...liebl
long term...re
aviation...Rubin
fire weather...liebl
