Hold the Hype, Please

For the past few days, the models have been very inconsistent with one another, and from run-to-run (meaning the morning version of a model disagrees with the same model's afternoon version which disagrees with the night version and so on). The problem storm is a nor'easter that is expected to develop over the Gulf of Mexico before storming northward on Monday. Some models had been pushing the storm off the east coast, while others bring it further inland. As is always the case with these types of storms, the track is everything.

The evening models last night (Thursday) finally showed some agreement with a more inland track. This had some major implications on the meteorological community: the hype machine was put into full throttle. To understand this, and the forecasts that are gushing out, the public needs to glimpse into the mind of a meteorologist for a moment.

Most of us love storms...it is just part of our nature. Active weather is exciting. Unseasonable weather gets our adrenaline pumping. Average temperatures and sunny weather are, dare I say, boring. So when there is a big storm on the horizon, there is always a temptation to sensationalize it and force our predictions into more of what we want to happen and less what the models actually say will happen. This is called 'wishcasting'.

It is difficult not to wishcast, and it is something I struggled with a lot during the early days of Grotonweather. I easily got caught up in hype and would force situations to what I wanted to happen. I would latch onto little parts of the model that supported my desire, and ignore larger parts that would indicate I was about to make a bad forecast.

So when the models came into some semblance of agreement last night, the floodgates were opened. Many now felt justified in making big predictions-- after all, the models are all agreeing now!!

Hold the hype, please.

This is a nor'easter we are talking about, a proverbial thorn in the side of meteorologists for as long as they have been predicting weather in the Northeast. The models three days out for a nor'easter often do not capture the details that make or break the storm. Sometimes even the models a day out are no good. Consistency is the key. Just because the models yesterday evening agreed does not mean they will not disagree again this morning, afternoon or evening. It would be wise to see a few more runs of consistency before calling for a monster storm.

But now, to the wishcasting.

As I said above, meteorologists love active, out-of-season weather. What is more out of season than a heavy snowstorm in late April? And that is exactly what some meteorologists are calling for over parts of the region. However, given the current models, I feel such a forecast is uncalled for. Could it happen? Sure- history shows it can. I just do not think anyone is justified in making that call yet.

The first problem is the "540 thickness line". Meteorological jargon for sure, but let me explain. One of the (many) equations we have to learn in school related the average temperature of the atmosphere above a given point to the pressure at certain levels in the atmosphere. A warmer atmosphere will cause higher pressures, and thus a "thicker" atmosphere.

There are certain rules of thumb for how "thick" an air column above a point can be before the air is too warm for snow. One of those rules is the 540 line. To keep things simple, it suffices to know that values below 540 are favorable for snow and values above 540 are going to be rain. This rule has a catch though: it works best in the dead of winter. In late fall and early spring, values at or just below 540 probably are going to be rain, or perhaps a rain/snow mix at best. I like to see values closer to 534 before I get excited about snow.

Let us now look at Monday morning at 8am, the time that many meteorologists are posting images of the models for. Surface temperatures will be coldest at this time, with daytime heating kicking in for the afternoon Monday.

Major snow storm? The models don't think so.

As you can see, these three major models all indicate little, if any, snow confined to the far western fringes of the storm. Additionally, temperatures have been unseasonably warm all winter and spring. The ground, therefore, is also unseasonably warm. Late April storms of the past (2007 and 1993 for example) have come following very snowy years where the ground was likely cooler than normal. I have a hard time believing snow would accumulate very easily except perhaps over the highest elevations unless it got very cold (surface temperatures in the 20s).

Models try to directly guess the precipitation type and snowfall amounts, and some will undoubtedly point to those model outputs as their justification. (The NAM model, for example, has 6" of snow in Ithaca on Monday). Those model predictions are basically made by taking the model predictions, putting them through more equations and conditions, and then trying to make a new prediction. They can be useful, but the more processed the model data is, the greater the opportunity for error. The precipitation type and snowfall amounts, especially from the NAM model, I have found to be rather unreliable this spring. A few weeks ago, this same model insisted on bringing Ithaca another storm of 6-12". It rained.

In conclusion, this is what I want the public to take away from this. We don't know what will happen yet. Confidence is low and this system needs to be watched. While I enjoy the loyalty my patrons have to Grotonweather, I encourage them to look at other forecasts, too. I have been wrong before and will be again in the future.

What I want other meteorologists to take from this is as follows: we, as a meteorological community, need to focus more on uncertainty and communicating that in our forecasts. We need to cut the hype and sensationalizing every large storm. There are times when we NEED to really play up a storm- like last weekend's tornado outbreak. There was a lot of justified hype last weekend and it saved lives. This weekend's hype is not justified. Where do we draw that line? It is impossible to say for sure. But I can say it needs to be drawn better than it currently is, or when it does matter, people are not going to listen.

Arctic Outbreak?

We all knew it was probably only a matter of time before the weather finally turned more winter like. We got a taste of winter yesterday with some lake effect snow, strong winds, and temperatures in the 20s. While we have been warm lately, 500 miles to the north has been frigid. The chill yesterday and, to some extent, today, is just a small piece of that cold pool.

A much bigger piece will be breaking off next week. It will easily be the coldest air so far this season, with highs Tuesday and probably Wednesday staying in the teens. There will be wind. There will be snow. But will this be an 'arctic outbreak'?

There is no set definition for an arctic outbreak, so the use of the term is up to the discretion of the forecaster. It seems to me, however, that 'arctic outbreak' should be a term reserved for record setting or dangerous cold. It is a strong term that grabs people's attention. I do not think it should be overused.

Does the combination of high temperatures in the teens, gusty winds and lake effect snow meet these qualifications?  I am honestly on the fence.

On the one hand, it seems to me that highs in the teens are not all that impressive, given our climatology and the time of the year. Some lake effect snow and wind? That is just normal winter weather here.

Yet, on the other hand, this has not been a typical winter. We have only one high temperature under 30º (on the 24th...the high yesterday was actually 40, albeit that was at midnight). Snow has been scarce to non-existent. Being suddenly thrust into mid-winter weather may catch some off guard and create dangerous conditions.

In the end though, I think I would hesitate to use the words 'arctic outbreak' in my forecasts for the coming cold snap. I believe that the public should be aware that the pattern is changing and, at least for a few days, winter will be here in full.

But I do not want to sensationalize things and blow them out of proportion. This event, after all, is still nearly a week away. I've seen many extreme temperature events forecast this far out, only to have the models gradually and consistently modify temperatures back towards more normal temperatures.

I want to hear what you think though. Join the discussion and post what your definition of an arctic outbreak would be on Facebook by clicking here.

Was Irene Really a Bust?

In the days leading up to Irene, the media was alive with dire warnings about how bad Irene could be. In the days following the hurricane, the buzz is about how terrible of a job the predictions were. Really? Or, rather, I should say "You've got to be kidding me!?"

If you were expecting a monster storm surge to flood into New York City like in the movie, "The Day After Tomorrow" (left), then of course you will be calling this storm a bust. That is Hollywood and nothing like that was ever predicted. The real storm surge predictions were 4-8 feet. In an area unaccustomed to hurricanes, such a storm surge could catch people unaware and prove to be deadly. It does not take much of a storm surge to be destructive. But never, ever was total destruction of New York City actually forecast. Many areas met this storm surge prediction and it was a good forecast.

The forecasts called for Irene to be a weak hurricane or strong tropical storm as she moved over top of New York City. At 9am EDT on Sunday, the center of Irene moved directly over Central Park- a remarkably accurate positional forecast which should be applauded, since one of the harder things to predict about a hurricane is its future position. When Irene moved over, the winds were at 65 mph- a strong tropical storm, as expected. Additionally, Central Park received nearly 7" of rain. That is nearly double the average amount of rain Central Park gets in August. What more do you people want before this is labeled significant?

If you are still not satisfied, we can chalk New York City up to being spared the worst and, if you really wish to believe so, over-hyped by the media (not the meteorologists). But the miss was pretty much only for there. It is extremely insensitive and just plain wrong to say Irene was a bust.

As of this writing, 2.5 million homes and businesses were still without power, 2-3 days after Irene came through. Roads throughout the Northeast are washed out or impassible due to fallen trees. Homes have been washed away. Entire towns have been flooded or cut off completely. Some towns have lost all their bridges. Some of these bridges that were washed out have been in service for over 150 years. Even part of the New York State Thruway remains closed. If this storm was such a bust...such a run-of-the-mill storm...nothing worse than a nor'easter...then why all the unprecedented destruction?

And that is just the material loss. At least 40 people have died from this "over-hyped bust" of a storm. Any loss of life is tragic. Those 40+ deaths translate to 40+ tragedies. Ask the family members of any of those who lost their lives if Irene was blown out of proportion. Perhaps they would have a different perspective.

The bottom line is this: even large weather systems like Irene have small subtitles that are not understood and certainly not possible to forecast. The geography of an area also plays a significant role in what exactly happens during a storm. Just because New York City was spared destruction does not mean other areas were. Look beyond your own backyard, your own town, even your own part of the state. It is easy to forget the sufferings of other and blast the forecasters for crying wolf. Just because the wolf didn't get you this time doesn't mean that next time you will be so lucky.

Monday's Historic Thunderstorms

Story originally published on Syracuse.com by Drew Montreuil.

I wanted to take a couple moments and point out some pretty amazing things that happened Monday across the eastern half of the nation. A huge severe weather outbreak blasted across the Ohio and Tennessee Valleys and into the southeast. Severe weather was reported from Texas to Florida, northward into Pennsylvania. Even here in Central New York, we had a few strong thunderstorms. Three-quarter inch hail was reported Monday morning near Ithaca and in Norwich. Hail must measure one inch in diameter before it is considered "severe".

While the National Weather Service continues to do surveys of the damage, the number of reports will continue to increase. But here are some numbers that are just mind blowing:

As of 10AM Wednesday, there were 1377 total reports of wind damage, 1"+ hail or tornadoes from Monday. Since 2000, there has not been a single day with this many severe weather reports. Of the nearly 1400 reports, 1245 were damaging wind reports. The squall line responsible for this outbreak did not stop producing severe weather because it died; it simply moved off shore over the Atlantic Ocean. Unfortunately, there were a number of fatalities associated with these storms as tornadoes destroyed homes and trees were downed onto houses. The image above, from the Storm Prediction Center, shows the severe weather reports from Monday's historic outbreak. Blue dots represent wind damage, while red dots are tornado reports and green dots are hail an inch in diameter or greater. Click the image for a larger view.

More spring-like weather will be on the way for the East, including Central New York. Another powerful storm system will form over the Great Plains this weekend and head up into Canada. A cold front will blast across the Midwest, Southeast and Northeast, with more severe weather possible. Currently the Storm Prediction Center is highlighting areas from Minnesota and Wisconsin south to Texas and Louisiana and eastward to Ohio, Kentucky and Tennessee as the highest potential for severe weather. As we get closer to the weekend though, I would not be surprised to see that threat shifted further to the east. Whether or not we get into the thunderstorms once more is still a bit questionable, but at the very least, our temperatures will shoot into the 60s, maybe even near 70 Sunday and Monday.

Major Flooding Reported

9:45PM UPDATE: The rain in Pennsylvania has still not turned east and is making me very nervous. The rain is as far north as I-80 in Central Pennsylvania. I unfortunately will not be able to update again until after after 12:30am. I will post a quick update at the time though.

The back edge of the rain shield is beginning to move through the Grotonweather tri-county area and will continue to do so over the next hour or so. Rainfall totals are over 3" over most of the area, and radar estimates max out at 4-5" over southern Cortland County. In all honesty though, it appears the radar is under estimating the precipitation, so I would not be surprised if places like Marathon got even more.

As I have been saying, if these rainfall amounts occurred in our area, the ground would not be able to handle it. Unfortunately, that prediction has come true. Here are a couple of the flooding reports I have heard so far, all from Cortland County:

• NO UNNECESSARY TRAVEL IN CORTLAND COUNTY UNTIL FURTHER NOTICE
• Route 11 between Reagen Road and Hoxie Gorge Road is CLOSED due to a mudslide
• Other mudslides have also been reported
• In Homer: The Haights Gulf Bridge is out.
• In McGraw: Roads IMPASSABLE throughout the village
• Red Cross Shelter for evacuees in the gymnasium at the County Office Building

I have not heard of any flood reports in Tompkins or Cayuga Counties, but that does not mean it is not occurring. I cannot stress enough, never drive through flooded roadways!! There are roads underwater in the area. DO NOT attempt to cross the flood waters. Doing so may put your life in jeopardy. If you are told to evacuate your home, do so!

As I stated at the start, the rain is ending. However, this does not mean the flood threat is ending! Runoff will continue to create flood problems into tomorrow. Area rivers are not expected to reach their peak heights until about this time Friday.

There may be some additional rain tonight. What is left of Tropical Storm Nicole is moving up through North Carolina and Virginia currently. The models have consistently kept this rain off to our east tonight. However, the fact that the models were too far east with today's storm, and the fact that the radar from that region looks very much like it did last night (namely a large area of rain seemingly heading right at us) has me a little nervous. I should stress, though, that we are not in the same sort of set up now, and, thankfully, I do see indications in the upper atmosphere that this rain will turn to our east, as the models indicate. If the models were wrong, which I do not think they are, and we were to get another couple inches of rain tonight, it would be disastrous. Again, I do not think this will be the case.

In summary...the rain may be ending, but the flooding will continue into tomorrow. Stay safe!!!!

Video: Severe threat update

Largest Snowfall of 2009-2010 Winter Looming

The largest snowfall for the Grotonweather.com area is on our horizon. This storm has consistently been on the models since Saturday, and I've just been waiting for it to become obvious that it won't happen. Over the past day and a half, I began to believe that this storm actually was going to happen, but the models remained inconsistent with the timing and exact location. There are still plenty of uncertainties to be figured out, but its time to start nailing down the seriousness of the storm. My main concern is not how much snow actually falls, but rather the blowing of the snow as the low explodes to our southeast. It will be a significant snowfall too, probably on the order of about a foot, but winds will make it seem like its snowing even heavier with near zero visibilities at times. Lets take this storm one aspect at a time.

Overall Pattern:
Low pressure is developing off the Southern New England coast this evening and tracking north. This is not the main storm. As it moves north, it will run into a sprawling area of high pressure and begin to weaken. Meanwhile, an upper level trough will dig into the eastern third of the county. This will create prime conditions for explosive storm development off the coast yet again. This low will absorb some of the energy from the dying low and continue to rapidly intensify. As it moves north towards New England, it will encounter that same high pressure, and begin to move more westerly. Over time, the storm, which still wants to move to the northeast, will do a loop over Southern New England and Southeastern New York, before heading out to sea.

Timing:
The snow will being to work into our area sometime in the morning Thursday and become heavy into the afternoon and evening. The snow will taper off in intensity Friday, but will still be around. By Saturday, everything should be pulling out, making the total time of this storm somewhere around 36 hours, with probably 12 hours of the heaviest snow.

Precipitation:
Snowfall totals are still a bit up in the air. I am concerned that warm air wraps around the system and causes a variety of precipitation types. The further to the west this storm comes, the more a concern that is. If we did change over to rain for a while, it would be later Thursday evening most likely. The models are not in agreement with whether or not this will happen, and it will have huge impacts on the total snow fall from this storm. Assuming an all snow event, which I think it probable at this time, snow fall totals should end up around a foot, give or take a couple inches. Expect a snow map Wednesday evening.

Winds:
With the low pressure coming into Southern New England and even Eastern New York, winds will become quite strong. Winds could be sustained near 25 mph for a time Thursday afternoon and evening with higher gusts. With the heavy nature of the snow, this could cause some tree damage and power outages, not to mention near zero visibilities and large snow drifts.

Temperatures:
Temperatures during the storm should stay in the upper 20s and low 30s for Thursday (mid 30s if we change to rain, but I just am not seeing that) before dropping off a bit Friday.

Stay tuned for the latest, as I will be tweaking this forecast over the next 24-36 hours. I will try to get a forecast video done tomorrow evening.

3PM Snow Video

NOTE: The watches, warnings and advisory part of the show is already out of date, with a WINTER WEATHER ADVISORY in effect for the entire Grotonweather.com forecast area, and WINTER STORM WARNINGS in the bordering counties south and east. Enjoy the video...leave comments!

First Watch of the Season!

12:45 Update: Severe Thunderstorm Watch issued! Full blog post analyzing the situation coming...

The Storm Prediction Center has outlined Central and Eastern New York as an area where a weather watch will "likely" be needed. The watch will likely be issued by 1PM. Stay tuned! I am watching this carefully and will have the watch up on the site within moments of its issuance!

>Click here for your full forecast

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 grotonweather.com for more updates!

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.

Dry Slotting

Snow Totals:
10AM- Dusting
11AM- 0.5"
12PM- 1.5"
1PM- 3.2"
2PM- 4.2"
3PM- 4.6"

Post:
Bad news for snow totals, good news for traveling...but the storm's dry slot is going to just hit Groton. It is racing eastward across Southern New York and should be entering Tompkins and Cortland Counties by 3:30. This should more or less end the snow.



Now, the low is forecast to start taking more of a southeasterly track, so I think we will get back into the snow this evening. However, we will be hard pressed to get to 8" I think...let alone a foot. I think 5-9" total would be a good projection for Groton now. Areas just to the north, however, that remain in the snow will stick in that 8-14" range.

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.

Another Friday Snow Storm

Another Friday, another snow storm for Central New York. Unlike last week's storm, this storm is not a nor' easter. It is pretty much moving west to east, so there is no worry about the models having an eastward bias. That makes my life a little easier this time around. I decided to do a snow map after all, even though the entire GrotonWeather forecast area should get the same amount.



As you can see, this will be a big storm, despite its relatively short duration. The snow will being to move in during the morning, before coming heavy by 10 or 11AM. It will really come down hard for a period of 6-8 hours, likely exceeding an inch per hour at times. By the evening, it will quickly taper off to just flurries over night.

I am going to dinner now, but once I get back (by 6:30-7), I will open the chatroom to field questions...and I will likely be there a good part of the night!

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!

Nor' Easter, then Lake Effect

Our nor' easter is starting to really wind up off of the New Jersey coast this morning. This has spread a solid area of precipitation from the Finger Lakes, east. Most of what you see on the radar is rain, but it has already changed over to snow in Binghamton and Scranton.


At 9AM, it was 37 in Ithaca, so that, combined with where it is already snowing in Binghamton, has made me expect a change over to snow a bit earlier than I was anticipating last night. This has been reflected in the higher snow amounts on the snow map below. For Groton specifically, since I placed us on the boundary between two areas, I would expect to see 2 or 3, maybe 4 inches downtown, with as much as 5 or 6 on the hills.

This storm should be well on its way out by midnight tonight. However, just as that storm departs, the Lake Effect machine will kick in for Wednesday and Wednesday night before tapering off Thursday. It is still too early to tell where exactly the heaviest lake effect will set up, and whether or not it will remain snow, but here is my best guess for snow intensity at this time:

If you want to help me out with this, as I sit up here in Oswego, it is very hard for me to know what exactly the precipiation type is elsewhere. It would be very helpful if you could leave a comment on here letting me know when you first see snow, no matter where you are. Current data from spotters is very imporatant to meteorologists, so I would really appreciate your observations! Thanks!

First snow of the season!

The past 24 hours have been crazy on the weather models. Yesterday, all but one model, the North American Mesoscale (NAM) were showing an area of low pressure heading into eastern New England, leaving Central New York more or less alone, with lake effect kicking in towards Tuesday night and Wednesday. The NAM, however, brought the storm much closer, giving our area its first accumulating snow of the year. Over the past 24 hours, however, the other models have come into agreement with the NAM, and suddenly we have a snow storm on our hands!

Now, keep in mind, I use 'snow storm' in the context of a normal October. We won't be seeing feet of snow, but for a first snow, this is pretty big. Here is what is happening:

An area of low pressure is beginning to form over North Carolina. Already moisture is spreading northward ahead of this, though most isn't reaching the ground yet. As this storm explodes and heads north, it will pull down some chilly air. That will make the precipitation that starts tonight and for the first part of tomorrow mostly rain. More importantly, however is that this rain will be snow not very high up in the atmosphere. As it melts, it will aid in cooling things down and changing precipitation over to snow. The higher elevations will see the change over first, probably as early as mid to late morning tomorrow. The lower elevations will begin to change over during the afternoon and evening hours. By tomorrow night, everyone should be seeing accumulating snow. Cayuga and Tompkins counties are not under any advisories, but Cortland county, with its higher hill tops, is under a Winter Weather Advisory.

The winds will be gusty with this as well. That, plus the heavy, wet nature of this snow could cause some branches to come down in the higher terrain. Had this come a week or two earlier, when the leaves were still on the trees, we would have some problems. We are lucky though and I am not anticipating many, if any, power outages.

This storm will be a quick mover, so real high totals aren't expected. The map below shows what to expect through 9AM Wednesday. Beyond that, Lake Effect snows will set up, but probably stay to our north, with additional accumulations. Stay tuned!

Split Forecast Area

The grotonweather.com forecast area has been split by Severe Thunderstorm Watch 638. Cayuga County is under the watch, while Tompkins and Cortland got left out. In all honesty, however, that is just a technicality. Conditions are just as favorable for severe thunderstorms in Tompkins and Cortland Counties as they are in Cayuga...the SPC has to draw the line somewhere, however. I am expecting another watch to be issued later this afternoon that will include the rest of the area.




Numerous thunderstorms have developed over Western New York and Western Pennsylvania. These storms will track east, with damaging winds and hail the main threats. Other storms will develop as well, so it looks like we may have a decent severe weather event on our hands.

Severe Thunderstorm Watch

Thunderstorms have begun to develop all across the Northeast and Ohio Valley, including Central and Western New York. This has prompted the Storm Prediction Center to issue a Severe Thunderstorm Watch for all of the counties shaded in blue below, including Tompkins County pretty much smack dab in the middle of the watch:



The probabilities with this watch indicate that the SPC is most concerned with hail, followed closely by damaging winds. The chances of 10 or more hail reports in the watch area is 70%, with a 50% chance of 10 or more hail reports.

Looking at the regional radar, you can see lots of thunderstorms scattered about the area. These will continue to develop, increasing in strength and coverage.
Stay tuned for any warnings!

Its going to be close

The severe weather threat is already ending up higher than I anticipated last night. For the second time in a week, the Storm Prediction Center has issued a Moderate Risk area for portions of the Northeast. At this time, we are just to the northwest of this area, with the boundary running from southwest to northeast through about Binghamton. Here are the hail (top) and wind (bottom) outlooks for today from the SPC. The hail one in particular has me concerned, since we are on the edge of the hatched area, which means a 10% or greater chance of hail over 2" in diameter.


8AM Edit: The visible image shows clearing skies behind this morning's area of rain. Since this satellite image was taken before the sun got very high in the sky, the dark area over Western New York is where the sun will be out. That was the key that was going to make or break us: sun. Yesterday, I wasn't calling for much if any sun. But now, things have changed.


I will continue to monitor this situation as it develops. Stay tuned for the latest! The next outlook from the SPC will come around 9:30, so check back closer to 10 for an update.

10AM Update: The newest SPC outlooks remain the same for our area. That keeps us right on the edge of the 30% wind and 30% hail lines, along with the edge of the hatched hail area.