The Week Ahead Discussion

Hello Folks,

Since the 5-day forecast is already out, it's time to talk about the forecast for a more technical point of view.

The big story for the next 7 days is that we have 3 very vigorous low pressure systems looking to impact the country, each one bringing forecast challenges to meteorologists across the country. The first 5-days of the forecast looks pretty consistent, it's after that things get a bit ugly.


Here is Storm One, which will impact KY on Tuesday.;

GFS:


NAM:


Canadian:


UKMET:

While this storm is currently causing some severe weather in TX, I don't think this is going to be a big ticket item for KY, just some gusty winds and a few showers, maybe a rumble of thunder.

Storm Two, impacting KY for Wed/Thurs:

GFS:



NAM:


CMC:



UKMET:


Euro:



Okay the biggest thing I notice just looking at the surface outputs for this storm, pretty well wound up for a storm this time of year with pressure on some models around 990mb's. We will be in the warm sector for this one, and while the main low will be north of us, I am concerned about the potential for severe weather. Time for some upper air analysis. Since the GFS seems to be in pretty good agreement with all the other models shown here I'm going to use it for the analysis. For those more interested about the 3rd storm or not wanting to get into the technical discussion, please skip ahead.


Jet Stream Level:
500 MB:


850 Speeds:


Okay so are in the front entrance region of the Jet Stream, and with a speed of around 130 knots, leads to good upper level divergence, which supports lift so if storms start popping they will be supported by the upper air dynamics. Second thing we notice is that there is a VORT MAX just north of KY, and vaules of around 25 vorticity above KY, which is pretty good to support upper level divergence, which supports lift, which supports storm development.

Just looking at some of the various severe weather indecies without posting any, things aren't looking great for Supercell development, so this looks like it's mainly going to be a high wind squall line kind of event. Normally I would say this is just kind of run of the mill for us, but for folks that were affected by the ice storm, this is not good. A lot of trees are weakened from the ice and are still falling, so a strong windstorm is not what we need to help the recovery process right now. The best threat of Severe weather right now looks to be somewhere mainly west and north of London. I'm very interested to see how this line develops on Wednesday.

3rd Storm: Okay this one is going to be a headache for a couple of reasons. One the freezing line is going to be near KY, two the models are all over the place with it.

GFS:


DGEX:


CMC:



JMA:


Euro:

As you can see, they agree a storm is coming in the Saturday time frame, but disagree on the placement and strength. If you want snow you want a weaker storm so there won't be as much warm air advection. I personally think for London this is going to be a rain to snow event. Farther north has the potential to be another icy mess, but we're still far enough out I'm not going to forecast lines, or totals yet... just be warned its something we need to keep an eye on the next few days, especially the people that were hit hard by our last ice storm.

So the bottom line: Severe thunderstorm potential is there for Wednesday, followed by a potential winter storm for the weekend. So the moral of the story... ENJOY MONDAY! It's going to be a great day, enjoy it, and just be ready to enter a much busier pattern than the last few days. We'll talk again tomorrow.