Back to work everybody! (Well, me anyway) :-)
Thank you very much for stopping by the weather blog. Here we break down the current weather forecast and take a look at anything interesting downstream, particularly in a more 'weather-geek-y' kind of way that is several slices of the onion deeper than what we do on air, or on the weather discussion at www.wsaz.com/weather . In that vein, we'll be looking at this week from a more technical perspective.
Let's start with the arriving showers this week. There are several interesting features, but first the maps from the NAM model:
|NAM - Monday Afternoon||NAM - Tuesday Morning
||NAM - Wednesday Afternoon|
As our system approaches Monday, the winds will be out of the southeast, which puts them just about perpendicular to the Appalachians. If anyone recalls the "donut hole" often seen in snowfall accumulations along a good swath of I-64 in the River Cities area, then you should already be up-to-speed on what's happening here. Just as wind going up the mountains enhances precipitation, the wind going down the mountains can dry out and warm the air. This process is sometimes called a 'shadow' effect. Depending on your perspective, this is good news, as it has been pushing the axis of greatest rainfall to places farther north and west of a lot of us.
Tuesday appears to be the generally showery day, with over-running moisture in the tri-state as our storm system continues to develop and move northward to our west. By Wednesday, the system is stronger, and can now channel a lot of airflow around itself from both the north and south. Notice the lack of rainfall on the Wednesday map along with the wind arrows coming in from the southwest. Our area will be in what is called the "Dry Slot" of this storm system. What happens is that the storm will develop spiral bands of wet and dry air, and the biggest "dry slot" ends up being close to the center of circulation. There we can see seasonably mild temperatures and some breaks from the rain-- even sunshine. Here's another way of looking at it:
|GFS - 700mb Chart - Wednesday Afternoon|
The brown represents areas of low humidity, while the greens are obviously the wetter kind. At this stage of a storm system's life, there comes to be a "yin and yang" look to it in terms of humidity. Bands spiral around the system bringing stretches of steady rain and clouds, while others get a noticeable respite.
Upper Air Pattern Rules
Now it's going to get a little more technical again, so bear with me (and feel free to ask questions in the comments section if you like). We're going to bring two major shots of energy in the upper levels of the atmosphere through the region during the second-half of the week. Here's a look at the GFS again...
|GFS - 500mb Chart - Wedensday PM|
Okay, now to get a little un-technical... These X's... Think about them the same way you would as women in a roller derby :-) Kind of like this:
The "whip" move is a lot like what these bundles of vorticity (the X's) do when they rotate around the base of a trough in the jet stream. They don't really enhance much of what's going on until they approach the base of the trough, and can be especially potent when they round the base. The more short-waves of vorticity upstream that are available to round the base of the trough, the more potent the forecasters expect the final result to be when it does. So then the task becomes... Where will this storm be when these X's round the base of the trough. Well, in our case, we've got one to our west on Wednesday, but the next one strengthens just to our east at the end of this upcoming weekend. It will be pulling down a lot of cold air behind itself, right into our neck of the woods:
|GFS - Sunday PM|
That thick black line is the 0-degrees (as in 32 F) temperature at the 850mb level (about 5,000 ft up). The dashed lines north of it are even colder. That would represent the farthes plunge of this very useful line (we use it in rain-vs-snow situations) thus far this season. With the presentation that the GFS is giving us today, I wouldn't be surprised at all to spot some flakes along the lakes Sunday evening :-) It's getting to be that time of year again...
|6-10 Day Outlook - Temperature||6-10 Day Outlook - Precipitation|
Anybody like some cold early October weather? For the snow-loving folks, however, this is not a good sign. Remember last year we had even more anomalous cooling locally, even snowfall in the Appalachians... These sorts of patterns often run a course of 1-3 months before shifting. Our winter got decidedly lame once it got time for some real snow. And see Alaska up there in the 'warmer' than normal category? Well, it set all-time snowfall records last year. Food for thought.
|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!