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.

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.

Growing Flood Concern

 4:30PM Update-

Everything is progressing as I feared and a FLASH FLOOD WARNING has been issued for Tompkins and southern Cayuga Counties. The ENTIRE Grotonweather forecast area is now under FLASH FLOOD WARNINGS. This is going to be a long night for our area.

Wednesday- 2:15PM

So far, the Grotonweather.com tri-county area has more or less been spared of major problems, at least that I am aware of. Our neighbors to the south and east in Tioga, Broome and Chenango counties have not been as fortunate. Massive and widespread flooding has prompted Flash Flood EMERGENCIES for all three counties, with a State of Emergency also in effect for Broome County. Many roads are under water and bridges are in danger of washing out. This is a very dangerous and deadly situation in these areas. Under no circumstances should you be traveling to those areas tonight.

Here is what is really worrying me though...our luck could soon run out. In the image below, you can see a band of very heavy rain moving north through Pennsylvania right towards our area, which is outlined in red. The heavy rain to our east will continue to move to the northeast.

This band of rain extends all the way down past Washington DC and seems to only be increasing in size and intensity. If the flooding that is occurring to our south and east is any indication what a couple more inches of rain will do, our area may be in trouble.

I urge everyone to be extra vigilant this afternoon, evening and overnight. This is one of the most dangerous situations in Grotonweather history, if not for our immediate area, then for our neighbors directly nearby. DO NOT drive or walk in flood waters. If the water is flowing, chances are that you will need to be rescued. If you are told to evacuate, do so. In fact, if you live near a stream that is already full or near...be prepared to leave on a moment's notice. The time to prepare is now.

Please share this post with your friends and family.

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.

Winter's Fury Unleashed

As posted by Drew Montreuil on Syracuse.com, 1/21/11

Old Man Winter sure is angry these days, and we will not be escaping his wrath over the next week or so. The first fits of his anger are already being felt across much of the northern half of the country. Yet another Nor'easter is striking parts of New England. This storm brought us 3-6" of snow overnight, but parts of Maine will see over a foot.

In the Midwest, the National Weather Service (NWS) issued an 'Extreme Cold Warning' for parts of Minnesota last night. The Extreme Cold Warning is a new warning the NWS is trying out for temperatures lower than -40º. The warning surely verified, as temperatures this morning in International Falls, Minnesota got down to a mind-numbing -46º. Even Rochester, Minnesota, in the southern part of the state, dropped to -20º.

Some of the cold is on the way for us, but Old Man Winter has another shot to throw at us first: another bout of heavy lake effect snow. Schools across northern Cayuga, northern Onondaga and Oswego counties are dismissing early in anticipation of the lake effect blitz.

A huge contributor to heavy lake effect snow in a set-up like today's is whether or not moisture from the Upper Great Lakes is able to feed the Lake Ontario band. Observations from Canada this morning are indicating that the connection is being made, which only will increase the chances of heavy snow.

The lake effect will start up this afternoon and last into tomorrow morning before only gradually weakening and moving northward tomorrow. Some areas across Oswego, Oneida and northern Onondaga counties could see upwards of 2 feet by late tomorrow morning.

If that was not bad enough, the cold temperatures and winds will bring wind chills down to potentially dangerous levels late this afternoon and tonight. Even those not impacted by the lake effect will want to make sure they are properly bundled up against the cold.

This is all just the beginning though, and the next assault from Winter's War comes in Sunday and Monday. The bitter cold air mass that was over Minnesota this morning will work its way over us later this weekend.

High temperatures Sunday and Monday will struggle to reach 10º, and Sunday night will be the coldest night we have seen in a few years. Many areas across Central New York will see the mercury drop to -10º, and some of the outlying areas may even see -20º.

And now, could a grand finale to Old Man Winter's assault be in the works? The latest long range weather models are showing hints of another coastal storm in the works for the middle of next week. If the current model projections hold true, Central New York could be looking at its biggest widespread snow of the season so far. While it is way too early to tell whether or not that will come to pass, it will need to be watched as we head into next week.

On the bright side...at least its not -46º!

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!!!!

Into the Moderate Risk

The Storm Prediction Center has moved our area into a "moderate risk" zone. This is their 3rd of 4 severe weather categories...and the 4th and final one is rarely issued anywhere, and I cannot say that I have seen it used up here. I would say we see a moderate risk every other year or so. Sometimes we get in a pattern where we get a couple in a short time span, but then there are occasions when we don't get any in a whole year. So, in conclusion of all that...when the SPC puts out the moderate for our area, its time for me to really look at things.

So what is going on that has prompted this? A strong area of low pressure with strong winds aloft will be moving eastward towards us overnight tonight. This system has produced plenty of severe weather already. Currently, there is a line of thunderstorms stretching from Michigan down into Indiana, then stretching back into Illinois and Iowa as the low moves across Wisconsin. These storms will not effect us. The part of the line moving across Michigan will turn southeast and die out. However, in its wake, new storms will develop later this afternoon and form into another cluster. This cluster will move eastward into Western New York later this evening and into the first part of the night and then towards our area after midnight. As it crosses Michigan, southern Ontario and into western New York, it will be producing widespread damaging winds...and it is for that reason that the moderate risk has been posted.

The question for us, on the far eastern edge of the moderate risk, is whether or not the line's severe potential continues overnight. We are in the 45% range for damaging winds. That percentage means the SPC thinks there is a 45% chance of damaging winds within 25 miles of a point. Statistically, from the center of the Grotonweather forecast area, a 25-mile radius covers the entire forecast area and some...so we can assume just a slightly lower probability of damaging winds in our area...very roughly 40%. That may not seem like a very high chance, but in reality, it is. I, however, am not so convinced, and would put the threat at maybe 20-30%. Here is why:

By the time the storms come over here, it will be well after dark. Typically, this would be very unfavorable for any severe weather with the loss of the daytime heating. However, our instability will actually increase overnight and, if the models are correct, peak sometime near or after sunrise tomorrow morning. From what I have been seeing on the models, the line should run our ahead of the main instability and thus weaken itself. Additionally...it will also likely outrun the upper level forcing and stronger winds aloft, which also come through tomorrow morning. If the timing of these matched up better, I would be more convinced a once-every couple years event was indeed unfolding.

Does this mean severe weather is not possible tonight? Absolutely not. These complexes of thunderstorms often develop their own mechanisms for keeping themselves going. If this were not the case, I wouldn't be overly concerned at all. Our instability will still only be marginal to moderate and, as I said earlier, the forcing and upper level winds aren't quite as good as a real classic event would have them. But since these things have a life of their own, there very well could be damage across our area overnight tonight. I do not feel at this time that the damage will be widespread, and certainly not on the scale of our area's most infamous overnight line of storms: The Labor Day 1998 event that destroyed the New York State fairgrounds.

Bottom line is this: Sometime after midnight, a line of thunderstorms should roll through our area. Frequent lightning, heavy rain, maybe a little small hail and gusty winds are likely. Some wind damage is not out of the question, but shouldn't be widespread. Rain and thunderstorms may continue to impact the region tomorrow morning though. Some models have shown very heavy rain in here tomorrow morning, so flash flooding could become a threat.

If anything looks like it has changed, I will post another update this afternoon. Otherwise, an update will be issued around 9m tonight to see how things have evolved through the day.

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!

Flooding Weather Video

I have decided to try my hand at video blogging for the upcoming flood potential. Let me know what you think!

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.

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!

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!

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

Late Season Storm

Click here to return to the homepage

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!

Flooding Concerns

Over the past few days, a couple of heavy rain events have effected our area. This has left rivers near or just starting to go over their banks and the ground saturated. With another heavy rain event on the way, this is a bit closer look at the potential impacts.

The Advanced Hydrologic Prediction Center puts out river forecasts for the more major rivers. In the Cortland-Southern Cayuga-Tompkins tri-county region, there are three locations that get these forecasts: The Tioughnioga River in Cortland, and Cayuga Lake and Fall Creek in Ithaca. Each location has 4 levels of flooding: action stage, flood stage, moderate stage, and major stage. The action stage is the only one where flooding does not actuall occur. Currently, the two stations in Ithaca are below action stage and are not forecasted to rise to action stage. Our attention then turns to Cortland, where the Tioughnioga is already above flood stage, but is not quite forecasted to get to the moderate stage: (click to enlarge)


Here also is the projected rainfall for Cortland, as forecasted by the NWS: (click to enlarge)


While this rain will certainly swell the Tioughnioga, major flooding problems should be avoided. Now, there are plenty of other small streams and rivers in the area that are swollen. With my resources, I can't tell you which ones will have more flooding problems than others. If you live near a stream, just keep an eye on it, especially tomorrow morning towards the end of the rain. Most importantly though, if you are driving, and you come to a water covered roadway, do not try to drive through it. There is no telling how deep the water is.

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.