A Look at Watch #280

The Storm Prediction Center has issued a Severe Thunderstorm Watch that stretches across almost all of New York State. It remains in effect until 7pm tonight. Here is a look at the exact counties it includes. As you can see, Tompkins, Cortland and S. Cayuga are right in the middle of it.


The main threat from this event is going to be damaging winds. Hail will also be possible, and my gut feeling is there will be a tornado somewhere in the watch box. The official probabilities that the SPC has put with the watch:
Tornadoes

Probability of 2 or more tornadoes	Low (20%)
Probability of 1 or more strong (F2-F5) tornadoes	Low (5%)

Wind

Probability of 10 or more severe wind events	Mod (60%)
Probability of 1 or more wind events > 65 knots	Mod (30%)

Hail

Probability of 10 or more severe hail events	Mod (30%)
Probability of 1 or more hailstones > 2 inches	Low (20%)

Combined Severe Hail/Wind

Probability of 6 or more combined severe hail/wind events

High (80%)

Since it is at the top of the hour, the current observations and indicies will not be in for another 20-40 minutes. Looking at the data from noon, though, it is obvious to me that the atmosphere is quickly destabilizing. Also, a pocket of strong winds in the upper atmosphere is beginning to move into Western New York, and will spread over the rest of the state, enhancing the thunderstorms. Storms are going to develop from west to east, and have already begun to fire up across Western New York, Lake Erie and Lake Ontario. These storms should organize into a squall line eventually, which is when the greatest threat for wind damage will be. The highest tornado and hail threat will be just prior to that, when the storms are more individual cells.

Be sure to keep checking back through the afternoon for the latest!

Late Season Storm

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Here is the latest on the late season snow event tomorrow.

Not a whole lot has changed since this morning. The cold front is spreading areas of rain across the region this afternoon. This front extends all the way into the southeast and back towards Louisiana and Texas. An area of low pressure is developing across the Deep South and will trigger a large severe weather out break tomorrow. The Storm Prediction Center has a large moderate risk out for that:


The front that is moving through today will stall out to our east. Meanwhile, that low will fly up the front to a position near New York City by mid afternoon tomorrow. There will be just enough cold air being pulled into the storm that it should be all snow for the areas in blue on this map I created:


The low will be moving pretty quickly up the stalled front and the ground is warm, so accumulations shouldn't be huge. The change over to snow will occur first in the higher elevations, and it will remain colder there as well, so expect the highest totals there. The rest of Central New York should get a moderate snow, but not enough to cause too many problem. It will be windy as well though, so use caution traveling tomorrow as the wind and snow will create poor visibilities. Here is my snowfall map for the entire storm, which should wind down pretty quickly tomorrow afternoon.


Where does this storm rank with some other 'out of season' storms? Its actually not very impressive. In 2007, our area was hit by almost 2 feet (18" is what I measured) on April 16-17th. In early October 2006, a monster lake effect event pounded Buffalo, causing millions of dollars worth of damage since the heavy wet snow stuck to the leaves on trees and brought them down. So this is more just a nuisance storm than anything. One commonality between the three storms is the lack of willingness on the part of the media to be bold and predict snow. Granted, the models are all over the place with this, as can be expected. But I feel really confident about this storm, as I did the April 2007 storm.

I will update again late tonight. I have a test in Tropical Meteorology (so ironic, isn't it?) tomorrow, so I won't be able to update again until 10 or 11. Stay tuned though!

Morning Storm Update

It is now quarter after 10am, and everything is going pretty much as expected. The snow started here in Groton about an hour ago, and already visibilities are down to roughly a mile as the snow has started to pick up in intensity. Looking at the official 10AM observations, Ithaca is reporting light snow, with moderate snow in Rochester, Penn Yan, and Dansville, and heavy snow falling in Buffalo. Over the next hour, expect the snow to continue to increase in intensity to the rate of an inch or so an hour. The snow will continue at least at that intensity, likely reaching 2" per hour at times, through the afternoon. Heavy and moderate snow is being reported back through Michigan. There is actually heavy snow in Wisconsin as well, but I think Lake Michigan is enhancing that snow since the winds are out of the northeast. Here is a look at the radar (from 9:30...but that is recent enough to get the point across). You can see any mixed precipitation is well south, and the snow extends back into the areas I just described. All this is moving more or less east-southeast.



Bottom line is the snow is going to come down hard very soon and continue at rates of 1-2" per hour until at least sundown. There may even be some thunder and lightning in the snow during the early and mid afternoon. Please leave a comment here, or log onto the chat (assuming it is open) and report any thunder! The chat room will likely be open most of the day today as well. I will continue to update this blog hourly, probably just with snow totals, but also any new information that comes in.

Love That East Bias!

I hinted this morning in my forecast discussion that "If it [the storm] really gets its act together, we could end up on the high end of those totals [from last night's snow map]." Well, the storm remains very impressive on satellite and radar. One thing is very evident though. The eastward bias of the models I was talking about is showing up perhaps even more significantly than I thought it would.

When I looked at the models last night, the back edge of the precipitation was roughly from a Pittsburgh, PA to Rochester, NY line. Already though, precipitation is being detected on radar as far west as Cleveland and Buffalo (though it is probably not yet reaching the ground). The low right now is over northern Georgia and is already a good one hundred or so miles further west than it is supposed to be.

The National Weather Service and local media stations have picked up on this finally and have more or less come into agreement with what I was saying yesterday. Tompkins and Cortland Counties are now under WINTER STORM WARNINGS instead of the Advisories that were in effect. Those last until 10AM tomorrow. Since the low will track a little further inland, the precipitation may be a bit heavier and last a bit longer than last night. I also mentioned this morning the possibility of expanding the 6-10" range west. As you can see, I have now done that with this new data.



After school activities have been canceled for many schools in our area. I would say that the chances of a snow day have increased a bit. It is still far from a certainty, but there is certainly cause for hope!

Also, if you haven't heard yet, I have a new feature on the site that I just added this morning. If you look to the black bar on the right side of the page, you will see a link to the 'GrotonWeather Weather Chat.' The text will either say the chat is open, of that it is closed. If it is open, it means I am sitting in the chat room, ready to give you whatever information you want to know about the weather! So, if you see that the room is open, come on in!

So it begins!

The snow has started to fall here ever so lightly, but it is just the start of things to come. Despite most other people still insisting on sleet mixing in, I am sticking to my guns and saying this will not happen. So far, it looks like conditions are starting to favor the all snow forecast.

Temperatures at the surface are in the 30's all the way into North Carolina. Another interesting thing going on in the Carolinas is the winds and pressures are starting to indicate the development of the coastal storm. This is happening way faster than the models projected. As a result, the low to the west of the Appalachian Mountains will not be as strong or make it as far north as the models show. This will in turn mean the warm air won't get in here...not that it would have an easy time doing so since the cold air is so entrenched anyways.

Another thing about the models and cold air is showing up over Ohio. The models had temperatures there in the upper 30's and low 40's...but instead, temperatures have stuck near or just above freezing. So the models are too warm as well, which also translates to a lower chance of sleet here.

All in all the models have not been handling this well so I have pretty much thrown out the recent runs and my thinking from the previous days has not changed. The only thing I would change on my snowmap from last night would be to extend the 12-18" line to include more of Western New York and maybe up the 18" to 20" or even 24". Other than that, everything looks good locally.

Now, as you wake up tomorrow, there will likely already be at least 3-6" of new snow. As the day goes on, the snow will become very heavy and the winds will pick up as well. This will make travel very, very dangerous, so if you don't have to go out tomorrow, stay home. This will continue into tomorrow night before tapering off sometime after midnight.

Severe Thunderstorms Overnight?

A line of severe thunderstorms has developed over Western New York. These storms have had winds upwards of 65mph in Buffalo and are barreling to the east. It appears the strongest of the storms are heading north of Groton and Tompkins county. However, the line of storms extends well south, so the severe threat is there across all of Central New York and Pennsylvania. Expect these storms to move in probably between 11 and midnight tonight. I will not be updating again tonight....I have class at 8AM tomorrow!