Just
two weeks ago a winter storm moved through the region producing a combination
of rain, freezing rain, sleet, and snow.
Many thought this was it for the winter, but Mother Nature had other
ideas. Look here for a rundown of
WinterMess #1.
Incredulously
another winter storm is headed through the Southeast. This time it will be a little different from
the previous storm (i.e., no two storms are identical). A complex weather pattern will develop over
the Southeast with an upper-level disturbance moving east and helping to
develop a low pressure system off the Carolina coast. A surge of cold air will be pushing into the
Carolinas ahead of this which will turn the rain into a wintry mix.
The
models are a little better in converging on a solution. There is still considerable uncertainty due
to the tight area that the worst will fall.
A difference of just 20 miles can make a huge difference in the forecast
even at this time range (less than 48 hours).
This
blog post is designed to give you a heads up on our thinking and the time frame
that things will occur. There is only
moderate confidence in the details, but the overall picture has good
confidence. The scenario and forecast
that follows was derived from the 09z, 12z, 15z, and 18z runs of the WSI RPM
model along with the 12z runs of the WRF, GFS, ECMWF, and GEM models on Sunday,
February 9, 2014. Each model is slightly
different, but the details were mainly from the RPM model. This represents my best guess at this point.
Clouds
will be increasing across the Midlands Monday and it should be mostly cloudy
into the evening. There is no concern
about the weather through Monday night, so if you have plans, no need to
change.
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| A depiction of the surface weather pattern for 7 pm EST Monday (top) and 7 am EST Tuesday. Little if any precipitation is expected Monday night, but a wedge of cold air will be developing as high pressure to the north builds down the eastern seaboard. The cold air wedge will be in place by daybreak Tuesday. Click on the image for a larger view. Image Credit: WLTX-TV. |
The
onset of precipitation is likely to be during the day on Tuesday. It may begin as rain until evaporational
cooling and cold air advection changes it to snow over some parts of the
Midlands. The timing of precipitation is
uncertain, but roads will likely be fine into the early afternoon. However, they could deteriorate rapidly
toward sunset.
 |
| A depiction of the surface weather pattern for 7 pm EST Tuesday. The onset of precipitation is likely around midday changing to snow and tapering off toward 7 pm. Click on the image for a larger view. Image Credit: WLTX-TV. |
It
may get quite interesting Tuesday night.
The snow may change to rain and freezing rain which will change to sleet
overnight. Much of the Midlands will see
sleet or freezing rain early Wednesday morning.
There could be an prolonged period of sleet into daybreak for the
central Midlands. This will likely
change to freezing rain shortly thereafter which could last until early
afternoon. During this time the ice
accumulation could be significant leading to power outages. The precipitation may diminish some in the
afternoon, but it will not end until Thursday morning.
 |
| A depiction of the surface weather pattern for 7 am EST Wednesday. There will be a significant amount of winter precipitation overnight. The intensity of the cold air wedge will be greatest on Wednesday. Click on the image for a larger view. Image Credit: WLTX-TV. |
 |
| A depiction of the surface weather pattern for 4 pm EST Wednesday. The precipitation may diminish near sunset, but precipitation to the north is likely to move through overnight before ending. Click on the image for a larger view. Image Credit: WLTX-TV. |
The
precipitation could increase and change to sleet and snow Wednesday night
before ending. Any additional amounts
during this time are NOT figured into my snow and ice forecast. Thus, it could get a little worse Wednesday
night. The precipitation should be over
by daybreak on Thursday as the storm moves up the eastern seaboard.
One
of the biggest complexities in this forecast is the fact that the Midlands will
be on the boundary between rain and snow.
In fact the precipitation is likely to change phases many times before
ending. This makes any forecast of snow
and ice exceedingly difficult.
The
following forecast is a snow forecast ending at 7 a.m. Wednesday morning. In this forecast is also an accumulation of
sleet which I did not break out since both may fall at the same time.
 |
| A forecast of snow accumulation (not snow depth) by 7 am EST Wednesday. Most of the snow will be Tuesday with sleet (included) Tuesday night. Note the tightness of the snow bands. Click on the image for a larger view. Image Credit: WLTX-TV. |
The
ice forecast is ice accumulation from freezing rain. Significant ice buildup is not expected until
Wednesday. The greatest accumulation of
ice may be Wednesday morning. Thus, the
ice forecast is up to 7 p.m. Wednesday evening.
 |
| A forecast of ice accumulation by 7 pm EST Wednesday. The most significant ice accumulation from freezing rain is likely Wednesday morning. Note the maximum ice accumulation is through the central Midlands. Click on the image for a larger view. Image Credit: WLTX-TV. |
It
is hard to express the difficultly in this forecast. Many hours were spent comparing computer
models and analyzing their results.
There is moderate confidence in the result. The biggest uncertainty lies in the narrow
range of ice. This may be adjusted north
or south based on later information, but the overall pattern seems good. This will be a longer event than the last one
and could last into Thursday.
The
biggest problem for decision makers may be Tuesday. The onset of precipitation may determine how
fast conditions deteriorate. What is
certain is that a winter storm for Wednesday is likely.
Be
sure to catch breaking news by following me on Twitter: @JimGandyWLTX along
with my colleagues @Daniel_Bonds, @amyaaronson, @ChristineWLTX. Also you can follow News19 on Twitter at:
@WLTX and also on Facebook. I will have
on updated blog post on this late on Monday.
