Welcome to your Thursday.
I thank you for checking out the weather blog, and I hope you find it informative and as least confusing as possible ;-) As always, feel free to ask any questions or make any comments you'd like in the discussion section below and I'll get to what I can. Some foundational topics in forecasting may have been already covered in a previous blog post, so I can refer to them if you're interested.
A-waiting the Clipper Ship...
This morning we see the departure of our weak and quick system that skipped through the region, hanging up a few snow showers in the eastern WV mountains in typical fashion. On the horizon, a large area of high pressure:
|HPC - Surface Map - Thursday PM|
1040mb is a large area of high pressure, and normally would be sufficient to mandate sunshine the whole of the mid-west. However, the upper-air pattern is very swift-moving, and conditions will not become stagnant enough to bring this about. Instead, most likely what we'll have on Friday is what is called an "Alberta Clipper".
I drew a blue arrow on the map above indicating the most likely track of the area of low pressure located at the Canadian border at the time of this map. This small system will become the beneficiary of a stout jetstream:
|GFS - 300mb Chart - Friday AM|
This map shows wind speed in the coloration, and the wind direction can be followed simply by tracing the black lines from left to right on the map. Notice the burst of fast winds originates from near the Canadian province of Alberta, and then dips across the Ohio Valley. According to the legend, this wind exceeds 130mph at times. You can cover a lot of distance when carried along by that kind of current-- which is exactly what these "Clipper" systems are known for (being named after the ship). So, even though we start off with practically a clean slate Thursday afternoon, by Friday afternoon our snow event will be whisking through town. The GFS and Euro are both on this trail, having shifted to it yesterday. The last few runs (as some of the model-watchers have pointed out) have been trying to put more snow into the mix.
|GFS - Friday Early AM||GFS - Friday Early PM||GFS - Saturday Early AM|
For full disclosure, the NAM model is still trying to work itself out by holding onto that southern branch of energy working into the Tennesee Valley (and keeping it separate from the Clipper system), but I'm not favoring that solution at the moment. Purebred Alberta Clippers tend to be 'the thing' that occupies the weather for a region as it goes through, and much less often becomes wrapped up in this weird hybrid of a loose relation to another area of low pressure.
Has the snow forecast changed?
Here's what the latest runs are spitting out raw for snowfall. Compare with yesterday:
|GFS - Snowfall Projection - By Saturday Evening
||NAM - Snowfall Projection - By Saturday Evening
We have more snowfall on the models, but not quite rising out of the categories that I put together yesterday on my "first call" forecast. In fact, instead of marginally qualifying, I simply have more confidence in them now.
One thing that is becoming clearer that will affect my forecast is that the consensus is that rainfall (and even a wintry mix) is less likely, even in Kentucky. As a result, some of those accumulations should be spread across the Big Sandy-- even if we're only talking about 1-2". That would still represent the first such snowfall of the meager season for them.
I should be posting my "Last Call" forecast map later today.
|Regional Radar/Satellite with Warnings Tracking||
From the Storm Prediction Center (below): Click For a Larger Image
|Activity Overview||Storm Outlook||Watches||Potential Watches||Storm Reports|
|Temperatures||HD Doppler Radar||Estimated Rainfall||Active Warnings|
|Click For Larger||Click For Interactive Radar||Click For Larger||Click For Larger|
Have a great day everyone!