TIME TO GLOAT!!!! This is TONIGHT!!
Area forecast discussion
National Weather Service Charleston SC
645 PM EST Friday Jan 21 2011
Synopsis...
high pressure to the distant northwest will give way to a developing
area of low pressure southeast of the area tonight. The low will deepen
as it moves NE Saturday and could bring a wintry mix of precipitation to
some eastern areas during Saturday. High pressure will build in wake
of the low Saturday night and Sunday...with a strong high pressure
wedge to develop early next week. Low pressure will then impact the
area during the middle of next week...with dry high pressure for
later in the week.
&&
Near term /until 6 am Saturday morning/...
an area of Arctic high pressure centered in the Ohio Valley
tonight will slowly weaken as it elongates east-west tonight. At
the same time we are keeping a very close eye on a strong short
wave diving into the Southern Plains. That short wave will
strengthen as it reaches the northern Gulf Coast late tonight and
will trigger the development of a surface low along the baroclinic
zone in the area from northwest of the Bahamas and eastern Florida. Depending
upon how strong the short wave gets...how sharp the associated
short wave trough becomes and exactly where the surface low forms
and its future movement will have large bearings on the forecast.
With the back edge of the opaque cloud cover to clear pretty much
everywhere we look for temperatures to drop quickly with the dry air mass
this evening. Dew points just upstream are as low as the teens as
of late afternoon...and this will allow for temperatures to plunge with
sunset. There are some single digit dew points in the upstate and
Piedmont...but those are not presently expected to penetrate this
far south. While this is taking place as the short wave triggers
cyclogenesis over the SW Atlantic...isentropic lift will gradually
develop overnight with warm advection clouds to return back north
after midnight. How quick these clouds return will impact the fall
of temperatures...but we are anticipating that most places will be down
in the 30s when the blanketing effects of the clouds move back in.
While the initial upper jet will have shifted southeast this evening...a
secondary jet will move in late tonight...with the local area to
see upper divergence within the right rear quadrant of the 115-125 knots
jet. The upper forcing and the associated cyclogenesis suggests
that some wintry precipitation could break out late tonight...mainly in
the 09-12z time frame. However...the precipitation in the clouds will
need to fall through some dry air in the lowest few thousand feet.
This sets the stage for evaporative cooling...and we look for at
least a small chance of a winter mix of precipitation to begin close to
daybreak over the easternmost parts of the forecast area. This
would generally be near and east of US-17. With evaporative cooling
and surface temperatures down close to the freezing mark there would be
the risk of snow...sleet or freezing rain in the SC. But with a
little more of nose of warm air aloft and slightly higher surface
temperatures in southeast the precipitation would be more in the form of
rain...freezing rain or sleet.
On station meteorologists have considered issuing a Winter Weather
Advisory for the mix of precipitation. Given that there is still some
uncertainty as to whether or not the mixed precipitation will make it
onshore...and that the bulk of any winter weather event would be
Saturday...we have opted to not issue the advisory. The evening
and overnight forecasters will need to reassess the
situation...and a Winter Weather Advisory certainly could be
issued. All interests should carefully monitor National oceanic and atmospheric administration weather radio
all hazards for any changes that occur. And keep in mind that a
small change of the position of the low and its associated upper
short wave could mean a world of difference in the forecast.
There will be a sharp delineation between where we see wintry
precipitation and where nothing occurs late tonight. As a result...many
inland areas will not be impacted by anything more than some
clouds. And it is those far inland areas that will see the coldest
temperatures tonight...ranging from the middle 20s along the northwest tier...to
the upper 20s and lower 30s further east...except for a few middle
30s right along the beaches.
&&
Short term /6 am Saturday morning through Monday/...
Saturday...challenging forecast this period as an area of low
pressure develops well off the northern coast of Florida early and
then strengthens as it tracks northeast well off the South Carolina
coast late in the day. There looks to be a trough extending from the
low back toward the coast which will be a source of surface
convergence while a sharp upper trough shifts across the southeast
states. The big question is how much moisture will make it onshore
and how strong the upper trough and associated shortwave are. At
this point...the 12z/21 GFS is most aggressive with the quantitative precipitation forecast and has
colder temperatures likely due to the significant low-level wet
bulbing effects. It gives 1-2 inches across the Charleston
tri-County area with the highest amounts along the NE portion of
Charleston County. Am not ready to jump on this one model run but
most of the latest models...including the 21/15z sref...do at least
show light snow accumulations...mainly south and east of Interstate
95. Will keep precipitation chances rather low and only mention snow
accumulations of around a tenth of an inch across Charleston
County/eastern Berkeley County...which should mainly be on
non-paved/elevated surfaces. There will likely be a mix of
snow...sleet and possibly freezing rain at the onset...ending from
the south by early afternoon...transitioning to mainly snow as it
ends across the Charleston area by late afternoon. Temperatures will
be tricky as much depends on the precipitation duration/intensity.
Went with highs in the middle to upper 40s...coolest north and near the
coast...but temperatures will likely remain in the 30s where
precipitation occurs.
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or 
. Probably something like -a ridge up into Alaska the next few weeks opening doors down to the U.S. Then something like shots of cold air but depending on trajectory we either get really cold or glancing shots. Plenty of storms lined up if one connects with the cold it gets interesting. Otherwise take the blend for the superbowl could be good or bad, wink and stay tuned-
