Thursday, January 29, 2009

Groundhog Day Speculation

The meteorological community is abuzz with excitement today. Numerous models are all in agreement with a major storm coming up out of the Gulf of Mexico Monday and then sitting somewhere over the Northeast Tuesday into Wednesday. I thought that with all the hype around this storm already, people might be curious what I think.

First and for most, I will play the broken record and say what I normally do: It is WAY too far out. The models have been showing a storm and are all in pretty good agreement with that, so I do think a storm system will form in the Gulf of Mexico and move north. Beyond that point is where I feel it is too early to place much weight in the models with the track and strength of the storm.

Just to speculate though, here are a couple scenarios that could happen.

The Groundhog Day Blizzard: This scenario would take the low pressure system up the Eastern Seaboard to near New York City, where it would then sit for about 12 hours before heading north. For the first time now in a few years, the atmosphere is getting clogged at the perfect time for a blizzard. The models show an area of low pressure over Greenland, with a strong High over northeastern Canada. This will impede the progress of the coastal storm. This would be the perfect set up for probably the biggest snow storm Central New York has seen in a few years.

The Slop Storm: This scenario would have the storm coming up the Appalachians and either over northeast Pennsylvania and Eastern New York, or right over top of us in the Finger Lakes. This track would give us a mix of precipitation. Some warm air will be in place ahead of this storm, so our precipitation would likely start as either rain, or sleet and freezing rain. As the low tracked towards us, warmer air would come up, and we would go over to rain for a while. Then, as the low moved to our northeast, strong northwest winds would come in and change us back to snow for a moderate snowfall. If I had to guess, I would say this is the most likely scenario at this time. Will it happen? Only time will tell.

February Flooding: The final scenario has the low moving up the west side of the Appalachians. This would pound Ohio with a heavy snow, but for us in Central New York, it would mean a big warm up, probably at least into the 40s, with a soaking rain. Currently there is anywhere from 2 to as much as 10 inches of water equivalent sitting over top of us. That means if all the snow was to melt, that is how much rain it would equal. If even half of that snow pack melted rapidly, plus an inch or more of rain fell, there could be some major flooding problems.

Now, all of these situations focus on the different tracks of the storm. I am cautious right now about the strength of this storm as well, and do not think it will quite be as strong as the models are saying. That being said, the potential for a very memorable, if not historic storm is there. I will be watching this one closely over the weekend and early next week. Keep checking for more updates!

Wednesday, January 28, 2009

Not Done Yet!

The snow has ended in Central New York for now. However, we are not done with this storm yet! I do not think this is a classic dry-slotting event, as it is more of a 'bubble' inside the larger precipitation shield instead of a plume. I think this gap is more likely an area between pieces of energy associated with this storm. The warm air trying to come north created the lift needed for our snow overnight and earlier today, but now that energy has worked off to the east. The energy associated with the low remains to our west, so right now, there is not enough lifting force to precipitate. That, plus the periods of sleet and freezing rain this morning, will keep snow totals away from the 12" mark. However, another few inches of snow can be expected as part 2 comes through later this afternoon, putting most places in the 6-10" range. Here is a look at the WeatherTap Radar from 2:15pm.

Wednesday Morning Update

Just a quick update this morning. Sadly I still have classes this morning, so I won't be updating again for a while today.

Heavy snow is overspread the region and the radar shows plenty more to come. As of 8am, my house had 5.2". This will easily put us into the 7-12" range, even though it now looks like there could be some sleet mixing in for a time this afternoon. I still like the 7-12" prediction for most of the area.

The snow will continue through the afternoon and early evening before tapering off. Lake enhancement will hold the snow around after the storm moves off, giving some areas an extra couple of inches.

Weathertap National Radar:

Tuesday, January 27, 2009

Wednesday's Storm

I have decided not to issue a snowfall map for this storm simply because it looks like the entire area will have a pretty uniform accumulation from this. All of the Finger Lakes and Southern Tier look to be in for a good 7-12". I upped the amounts slightly from this morning based on the models bringing in more moisture than previous runs. I even saw some indications of amounts over a foot, but I think that is overdone.

All of the models are now in pretty good agreement with each other except for one. Normally, when a model is drastically different from the others, it wouldn't put too much of a damper on my confidence levels. However, this time it is the European model, which has been out-performing the other models all winter. The problem is...the Euro brings in enough warm air to cause a snow/sleet mix to occur over Central New York. My forecast totals do not reflect that happening, but if it does happen, I would think accumulations more on the order of just 4-8".

Another concern I have is my old nemesis, the dry slot. With any big storm, dry air works around the center and gets wrapped up into the storm from the southwest. If I mess up a big-snow forecast, usually it seems to be the dry slot that is the culprit. The models have this punch of dry air working across Pennsylvania during the day tomorrow, staying to our south. I imagine the counties right along the State Line have the best chance of being hit by it, meaning their snow totals may be on the lower end of the 7-12", where as the northern areas will be on the higher end. Like the mixing, my forecast doesn't have the dry slot coming in, but if the models miss and it ends up 50-100 miles further north, most areas will be hard pressed to get into that 7-12" range.

As for the timing of this storm, the snow will likely start tonight between 9-11PM. It won't take too long for the snow to get heavy, and we should have 3-5" by tomorrow morning's commute. I do not expect the snow begin to let up until after sunset tomorrow. Even then, we will be dealing with snow showers and perhaps some occasional periods of moderate snow right through the night. I would say a snow day is a decent bet for most places tomorrow, but its never an absolute. The WeatherChat will be opening sometime after 6:30 tonight and will likely stay open right through 11pm or midnight.