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.

Winter Over? Not so fast...

Update: 1:30pm
I just wanted to add a comment here. I have been reached out to by multiple members of the Channel9 Storm Team to discuss this all further. Additionally, they posted a second post on their Facebook page to give greater clarification to their statement. This is why I started my blog post below praising the Storm Team meteorologists and expressing my great respect for them!

I've considered taking this blog down all together based on the conversations I've had with the Storm Team. I've decided to leave it up, however, because I do feel that public interpretation of forecasts is a crucial topic. I think this whole situation can shed some light on the topic for meteorologists and the public alike. Forecasting is difficult enough. Expressing the forecast to the public is another thing entirely.

Original Post:
Every once in a while, I come across a forecast that, quite honestly, makes my skin crawl. I try not to be judgmental about them- I've made plenty of bone-headed forecasts myself. At the same time though, sometimes something just needs to be said.

Let me preface my forthcoming rant with the following: I have a great deal of respect for the meteorologists at News Channel 9. I have met a number of them and they are great people. Their forecasts are typically very good and they are extremely intelligent. They do a great job.

Just not this time. This isn't meant to be an attack on them in any way, but the record needs to be set straight. It is February 17th. Historically, we could see significant snow well into April. (see April 16-17, 2007 for example). I cannot fathom how anyone can declare winter over at this stage, but that is what Channel 9 did:

First, let's look at the graphic that they are using to declare winter over. It is a probability map put out by the Climate Prediction Center for March, April and May. Areas in orange have a chance of seeing above normal temperatures, while areas in blue may see cooler than normal temperatures. Areas in white have an equal probability of seeing either cold, warm or normal temperatures. Let's zoom in and take a closer look at the Northeast:

Now, there are three possibilities for what can actually happen. We can be above average, below average, or right at normal. So in the white, "equal chance" areas, the probabilities of each of those three outcomes is about 33%. Each shade of orange/blue represents a greater chance of seeing warmer/colder temperatures. The Climate Prediction Center labels each shade with a percent value.  I have marked the 40% line, as it was a bit hard to see. Areas inside that 40% line, that is in the darker orange shade, have a 40% or greater chance of seeing above normal temperatures. The lighter orange shade, which includes Central New York, is predicted to have a 33-40% chance of seeing above normal temperatures. Given that the 33% line is very close to us, it can be assumed that it is more like a 33-35% chance.

That means we have about a 2% chance more than normal of seeing above normal temperatures.

Since the chances of a warm March, April and May are up by about 2%, and probabilities must add up to 100%, we can assume that the probabilities of a colder than normal March, April and May are running at about 31% and a normal period at 33%. Let's look at this forecast in another way:

Honestly, can you see much of a difference? Yes, we have a higher chance of above normal temperatures than anything else. But that increased chance is such a minor increase. If these were medical test results, would we want our doctors declaring definitely that the test was conclusive one way or another with a 35-33-31 distribution? I think not.

The other thing to consider is how accurate these probability forecasts are in the first place. The following as a graphic the Climate Prediction Center publishes along with their seasonal forecasts. It looks confusing, but I will explain it:

First, some background. There are numerous ways to calculate forecast accuracy. The Heidke Skill Score (HSS) is just one of those ways. A HSS of 100 means the forecast was perfect. A HSS of -50 is the worst possible forecast, and a HSS of 0 means the forecast was as good as a random guess.

We are looking at the red lines, which are labeled 'non-CL'. These 'non-CL' lines are the skill of forecasts where either colder than normal or warmer than normal forecasts are made. The year-to-year changes between these red lines are huge. You will notice a horizontal red line at 20. This is the average HSS for non-CL predictions from 1995-2008. The score is 20. Remember, a perfect forecast is 100 and a random guess is 0. A 20 is an extremely poor score and shows just how difficult it is to predict temperatures for the next three months.

Putting these two things together, we have a very slim chance of warmer weather based on a forecast that is much closer to a random guess than a perfect forecast.

With this knowledge, can you see why this upsets me? Meteorologists have an unspoken contract with the public to give accurate, informative forecasts. We have to do this to build trust between the meteorologist and the public. Why? Because when a tornado is bearing down on your neighborhood, or a major snow storm is on the way, or anything else that threatens lives and property, we need people to listen to us. Way too often, meteorologists, particularly in the media, betray this trust with garbage statements like this.

It needs to stop.

Now, I commented on that Facebook post and the response I got was "our forecasts are based on more than just what we are showing here- this graphic just happens to sum things up nicely." My argument is that 1) the graphic really shows nothing, as I explained previously and 2) there is no expression of uncertainty or these other factors. All that is said is 'winter is over.' I'm not against long-range forecasting. I am against long-range forecasts that don't express the inherent extreme uncertainty that they contain. And this is one of the worst offenders I've seen.

Might they end up being right? Sure. They might. If they are, was it skill or luck? I'll let you be the judge.

Respite Coming..But so is More Rain

 7:30 PM Update-

Unfortunately, the break in the rain I talked about 90 minutes ago below is filling in already. This means even more rain than I was expecting in the last post. That in turn means more flooding. Certainly not good news at all.

Wednesday- 6PM

For the past few hours, very heavy rain has been falling across our area. Major flooding is going on nearby, with some flooding also occurring within the Grotonweather area. Flash Flood Warnings are widespread across Central New York and Pennsylvania with numerous Flash Flood Emergencies and State of Emergencies in effect for neighboring counties. This will easily end up as the most destructive flood event in the region since the deadly June 2006 flood, which mostly missed the Grotonweather area, and may surpass that in some areas.

For all the bad, there is a little glimmer of good. The current band of heavy rain is quickly lifting to the north. By 7pm, we should be in another respite with just a few showers around. THIS DOES NOT MEAN THE FLOOD THREAT WILL DIMINISH JUST BECAUSE IT IS NOT RAINING. Runoff will continue to inflate streams, which will continue to rise and create major flooding in areas. The flooding just will not be getting rapidly worse.

Until the next batch of rain, that is. Models are indicating yet another batch of heavy rain streaming northward from the Mid-Atlantic. This rain should arrive here well after dark and during the overnight hours, making it particularly dangerous. Flooding dangers at night are enhanced because it is hard to see flood waters and impossible to tell how deep they may be (not that you really can in the day time either).

This is what the HRRR (high-res rapid refresh) model predicts the radar to look like at 11pm tonight. It looks a lot like what the radar has looked like most of the day, meaning more heavy rain will be impacting our area tonight.

If you have to travel tonight: take it slow, DEFINITELY DO NOT ATTEMPT TO CROSS A FLOODED ROADWAY, and be aware that many roads south and east of our area and some roads in our area are closed. For example, every road in Chenango County has been closed. States of Emergency, in addition to Chenango County, are in effect for Broome, Otsego, and Bradfield, PA, to name a couple.

If you live near a creek, stream, river, or drainage area: Chances are you already have an excess amount of water rushing through many times the normal amounts. Additional rain could increase the amount of water attempting to flow through there. Be prepared to have to leave your home at any time, even in the middle of the night. Keep an eye on the water levels as much as you can. If you have a weather radio, keep it on tonight. There are also lots of website that will send updates to your phone...you may want to sign up.

This remains a very dangerous situation, even while the rain lets up for a while. Please, please be safe. Continue to check the Grotonweather website, facebook and twitter pages for updates. Please share this blog with others so that they can stay informed and safe as well.

No Alert Mode this time...

A potentially significant severe weather outbreak across much of the northeast, including our area is beginning. However, Grotonweather.com will NOT be going into alert mode for this event. As I mentioned in the Alert Mode blog, I take the issuing of Alert Mode very seriously. I only issue them when it seems like widespread, life threatening weather is likely.

Today's event is very close to that criteria, and I cannot say for sure that I will not issue Alert Mode status later in the day. At this point though, I do not think the storms will organize quite fast enough to bring the high risks necessary for an Alert Mode. If this site was for Chenango, Monroe and Otsego counties, I very likely would be going into Alert Mode. The worst of this event, in terms of spatial coverage and intensity, will likely be just to our east.

That being said, storms are already starting to develop in our area and just to the west. These storms will not take long to become severe, and our threats for wind damage and hail remain at a 'MODERATE' level. Winds up to 80mph and two inch hail are not totally out of the question. Stay tuned for updates!

Sleet & Freezing Rain- What's the Difference?

As posted on Syracuse.com by Drew Montreuil, 1/18/11

With icy conditions impacting Central New York this morning, meteorologists have been tossing around words such as "sleet" and "freezing rain", but what are the differences between these icy precipitation types?

For my Honor's Program thesis at SUNY Oswego, I have been investigating how the general public interprets weather forecasts, and what terminology is and is not understood. One of the survey questions I used to gather this data directly relates to today's weather.

When asked what is the difference between sleet and freezing rain, my preliminary results show that only 16% correctly understand the difference. If you do not know the difference, do not feel bad- only a little over half of the meteorology majors I surveyed fully understood the difference!

So, just what is the difference? When the water freezes. Sleet typically starts out as a snowflake while it is in the cloud. As it begins to fall, it melts into a rain drop. However, the melting is brief and, before striking the ground, it refreezes. Thus, sleet is simply falling ice pellets.

Freezing rain, on the other hand, does not fall as ice. Like sleet, freezing rain often starts off as a snowflake in the cloud, and then melts as it begins to fall. The difference here is that there is enough warm air in the atmosphere to prevent the rain drop from freezing on its way to the ground. When the rain drop does reach the ground, it freezes, typically within seconds of contact. There is one important condition for this to happen though: the air temperature at the ground must be below freezing.

While both sleet and freezing rain can cause slippery roads, it is the freezing rain that is typically more hazardous. Since sleet is already frozen when it falls, it can be plowed and shoveled with relative ease. The freezing rain forms a coating of ice on roads, cars and power lines, making it much more difficult to remove. A few inches of sleet is not a huge deal, but even just half an inch of freezing rain can bring down trees and power lines and create a very dangerous ice storm.

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!!!!

Heavy Rain Update: 4PM

4:40PM UPDATE: FLOOD WARNING ISSUED FOR S.CORTLAND AND TOMPKINS COUNTIES THROUGH 7:15 PM.

Very heavy rain has been falling across the area and will continue to do so for the remainder of the afternoon and into tonight. The regional radar loop is showing the rain tapering a bit to just showers, but not until far Southern Pennsylvania. Even then, there is still some heavy rain...just not as widespread. We very well may only be about half way through this event, and already rainfall totals are getting quite high. Take a look at some of these reports:

Game Farm Road Climate Station, Ithaca: 1.36" through 3PM
Freeville: 1.41" through 3:42 PM
Virgil: 1.54" through 3:42PM
Binghamton Airport: 1.36" through 3PM
Deposit, NY (Deleware County): 2.99" between 7AM-1:22PM

If we double these amounts, most places will be up around 3-4", as expected. There are no flood warnings in the Grotonweather.com forecast area, but most of the counties to our south, east and north are under flood warnings. Most of these flood warnings are for larger rivers in anticipation of this additional rain. No flash flood warnings are in effect yet.

There are actually some more intense areas of rain and wind within the main area of heavy rain. A severe thunderstorm warning was even issued for Broome County a little while ago! I changed the scaling on the radar program I use to make these areas stick out. The brighter the color, the heavier the rain. The heaviest rain seems to be concentrated over the Finger Lakes, with some of those heavier cells moving through Cayuga and Cortland Counties, as indicated by the dark reds and pinks. It is where these cells hit that the greatest chance for rainfall totals over 4" will occur.

As we go into the evening hours, I am anticipating starting to see some flash flooding problems as we start to approach the upper limits of what the ground and streams can handle. I will get the word out about any Flash Flood Warnings as soon as possible. Remember, NEVER drive through a flooded roadway! If you come to a roadway, turn around. There is no telling just how deep the water is. Just 6" of quick moving water can sweep a car away! It is especially dangerous at night, when it is even harder to see flood waters. Anytime you get rainfall of this magnitude in such a short (about 12-18 hours) time span, the runoff can produce dangerous conditions. Please stay safe tonight, and stay tuned to Grotonweather.com for the latest! Do not forget to visit the chat room by clicking the "Open Chat" icon to the right. The Chat will be open through the early evening. Furthermore, make sure you tune in for tomorrow's podcast as we talk about this event!

Note: One of the quickest ways to get updates from Grotonweather.com is on our facebook page! Become a fan now by clicking here!

1PM Severe Weather Update

2PM Update: SEVERE THUNDERSTORM WARNING FOR S. CAYUGA COUNTY UNTIL 2:45 pm. A severe storm over Ontario county will move into S. Cayuga county over the next 30-60 minutes. I expect the warning to be extended/overlapped as the storm moves into the area. If the storm remains severe (and there is not really any reason for it not to), Groton, Homer and Cortland will have to watch out for this storm between 3-4 pm. Interesting note: All of the Grotonweather forecast area but extreme northeast Tompkins and northern Cortland Counties have been under severe thunderstorm warnings at some point today already! And our watch goes for 6 more hours.

Original 1PM post: Lots going on this afternoon already. A severe storm tore through central Tompkins county last hour. It is looking a bit less organized as it moves into S. Cortland county. I was in Ithaca, on the 11th floor of Bradfield Hall, Cornell as the storm passed. There was rotation with it, and I got some awesome pictures I will post tonight. The storm produced 1" hail in Trumansburg and took out "many" trees and powerlines in Lansing. No other reports yet (as of 1PM).

While all this was going on, the SPC moved us into a moderate risk. This is primarily for the threat of damaging winds. Now, we've already experienced severe weather...but is more on the way? Our watch goes until 8pm, afterall. The answer is yes, our threat still continues. There are more showers and storms forming over western New York back into Canada. The cold front itself stretches from Ontario back into Ohio and Indiana. The air just upstream is very unstable, and the storms we've already had shouldn't have much of an effect on our instability for the middle or latter part of the afternoon.

If you haven't become a fan of Grotonweather on facebook or a follower on Twitter, you will want to do so now! I've been posting up a storm (pun intended) on those two sites all morning with the latest updates and will continue to do so through the day. Also, the Grotonweather Toolbar is a great way to keep your eye on the latest forecast. Download it here. And, as always, the main site/blog will be updated throughout the day to keep you safe!

That's all for now. Keep checking back!

Blizzard Video

Here is my video update on the blizzard. Please leave feedback!

Snow Map

There have only been a couple changes to the forecast in the past 24 hours since last night's blog entry. Firstly, there is little question now that the entire storm over our area will remain as snow. The main stream of warmer air will remain north of us, and I question how far west it will make it. This makes it a very difficult forecast for Syracuse, but I think even they will remain mostly or all snow. The second change is more precipitation for the Grotonweather area. These two factors combined have given me the confidence to up my snow totals to 12-18" for most of the area. Here is my snow map for the entire storm.



I apologize for not having more updates today and not having a video, but its been a busy week at school this week. I am planning to do a video tomorrow morning though, so make sure to check in sometime after 10am. Oh, and Groton students, enjoy your day off- School has already closed for tomorrow!

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!

Ticking Time Bomb

I like severe thunderstorms. They are fun to try to forecast and I find them exciting to experience. I of course don't like it when they do major damage or pose a significant threat to the safety of people. So, you could say there is a certain intangible threshold where a situation goes from enjoyable, to scary. I think we've already crossed that threshold today, and the nearest storms are just starting to pop in eastern Michigan.

Now, if you checked my site early this morning, you would have seen that I had taken it down and had prepared it to sit dormant for the next 10 days or so due to a variety of circumstances. However, things are evolving in such a way that I really feel like I need to be updating today.

Ok, so whats going on. If you haven't stepped outside lately, go do so. You will be greeted by a blast of heat and oppressive humidity when you do. Temperatures have already shot up into the 80s, and dewpoints are in the low 70s. This has already led to instability levels that are rare for our area, and high even by the standards of the Great Plains. So often, I talk about the role of cloud cover in severe weather outbreaks. Often times in our area, clouds in the morning and early afternoon inhibit destabilization, which is why we don't see extreme instability like we are seeing now very often. But it has been sunny and will continue to be sunny through the afternoon, which means things will only continue to destabilze to levels that far exceed anything we have seen this year, possibly even the past few years.

Instability alone is not enough to create a severe weather outbreak. You also need a trigger to get storms going. For us, that is a disturbance moving towards the east along a cold front. Right now, it is over southern Michigan...which is why the storms are forming there. As it moves east, this energy will provide the lift needed to allow storms to continue to form. As they interact with the unstable air, they will intensify. One more piece is needed though, and that is shear, or a change in wind speed or direction with height or horizontal distance. In this case, we are looking at speed shear from both the ground up into the atmosphere, and horizontally from south to north. This is because of an area of strong winds in the jet stream called a 'jet streak' that is to our north. This will provide the shear needed to organize the storms into segments, or even a squall line.

The way I see it right now, all of the ingredients are evolving to come together for a significant severe weather event for all of Central New York. The only question I really have is whether or not a massive squall line will form out of those storms in Michigan, or if there will be multiple, but smaller lines of storms. That is something that will only be determined as the afternoon goes on. Regardless, there is the potential for strong, destructive winds after roughly 4pm tonight. It wouldn't hurt to take some precautions now by putting away lawn furniture, securing loose objects, etc. The biggest threat from the storms is definatly wind and, if I was updating my site as normal, I would likely place it in the 'high' category. I believe that most, if not all counties in Central New York will experience at least some wind damage to trees.

Another danger tonight will be flash flooding....some areas, especially in Cortland County, got 3"+ of rain yesterday, with mudslides and road closures overnight in Cortland County. It won't take much heavy rain to create more problems. NEVER drive through a flooded roadway! Flooding is the number 1 weather killer in the United States, and most of those fatalities occur in automobiles.

Watch for another update between 3 and 5pm, or sooner if a watch comes out. This is one forecast I hope I am not right on.

Risks Upgraded

There have been a couple of changes in the forecast this morning as things area already rapidly evolving. Probably the most significant of these changes is that, instead of all the clouds and rain the models had been forecasting for us this morning, skies are clear. This is causing the atmosphere to destabilize quicker and more intensely than had been forecasted. Another thing to look at is the radar. Thunderstorms are widespread just west of Buffalo, and already, there are some storms popping out ahead of this main area...so the question of whether or not storms will form is out the window.

The Storm Prediction Center has us in a 30-30-5% risk for wind-hail-tornadoes, respectively. All three of those are on the upper end of their 'slight' risk category. After looking at a couple things, I moved my hail and win up to moderate, and kept tornadoes at slight. Since storms are already firing, I moved the thunderstorm risk all the way up, which the NWS in Binghamton also did on their threat outlooks.

Here is what I am expecting for each threat:

Thunderstorms: Extreme-
Widespread thunderstorms can be expected with almost everywhere getting a storm. Frequent lightning should accompany the storms, and a fair number of them will likely be severe.

Wind: Moderate-
With the sun out this morning and strong upper level winds, wind damage is likely somewhere in Central New York, with some possibility of widespread damaging winds. 3 to 7 damaging wind reports are possible in the Grotonweather forecast area (Tompkins, S. Cayuga and Cortland Counties), with more elsewhere in Central New York. Should a widespread wind event evolve, this will be increased to high.

Hail: Moderate-
With extra instablity from the sun this morning, and indications of favorable hail formation from both the models, and current observations, hail could become a major factor today. 3 to 7 severe (0.75" of bigger) hail reports in the forecast area is possible, with more elsewhere in Central New York. Hail sizes should stay below 1.5", but an isolated storm could produce up to 2" hail. An upgrade to a high risk is not expected at this time.

Tornadoes: Slight-
Little changes to the tornado forecast have been made. A tornado somewhere in Western and Central New York seems almost likely. Multiple tornadoes could be possible, but this certainty isn't enough for a moderate risk at the time. However, with strong southeast winds at the surface, winds at low levels out of the southwest, and upper level winds coming in from the west, the threat for tornadoes will need to be watched closely.

Friday Afternoon's Severe Weather Outlook for 7/11

I spent the morning and early afternoon down at the National Weather Service in Binghamton, where I am an intern this summer, and used some of their in-house tools to try to get a better handle on the severe weather threat tomorrow. I will mention that the meteorologists there this morning believe tomorrow will be an active day and seem to have a high confidence level.

One of the tools I used this morning was a form called the 'severe weather checklist'. This form has you enter in forecasted values for a variety of severe weather parameters. After doing so, it returns the 5 most similar severe weather days in recent Central New York history. When completing this checklist this morning, it returned 4 days of 'isolated supercells', including May 16th, 2009, which had 3 tornadoes in the area, and May 31, 2002, which had 4 tornadoes. The fifth day was classified as a 'broken line'. Hail was the primary threat from the five days collectively. That tells me that not everywhere tomorrow will see a strong thunderstorm....some areas may barely even get any rain. However, there is certainly potential for some severe weather, and someone will likely have to deal with a damaging storm.

Here is a glance at where I have my threat levels, and an in depth look at exactly what I mean by each threat level, as well as what would need to happen for an upgraded risk:

Thunderstorms: moderate-
Thunderstorms are likely across much of the area. A few places, however, will be missed and get little to no rain. Frequent lightning will accompany some of the storms.

High Winds: slight-
Some storms may contain strong winds. Wind damage will be isolated to scattered, with 3 to 10 reports in Central New York. Sunshine in the morning would increase the chances of wind damage, and could get this bumped up to a moderate risk.

Hail: slight-
Small hail will be possible with stronger storms tomorrow, but most hail should remain uner 1" in diameter. The strongest storms may produce up to 1.5" hail. 5-12 Severe hail (over 0.75") events can be expected in Central New York. This is still rather uncertain, and could be upgraded to a moderate risk should the models show a bit better conditions for hail tomorrow morning.

Tornadoes: slight-
Conditions are favorable for rotating storms, and tornadoes could form. My best current guess is that somewhere in Western, Central and Southern New York will see a weak tornado, but as many as 2 or 3 wouldn't surprise me. This would most likely not be upgraded to moderate unless numerous storms that have already developed are showing signs of becoming tornadic.

Expect the next website update to occur between 9 and 11 am tomorrow. A blog update should occur within 30 minutes of that. There also could be a quick blog update tonight. During the afternoon tomorrow, I plan to have the weather chat open and will be updating th blog and website as needed. Stay tuned!