Sunday, June 29, 2008

Split Forecast Area

The 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.

Friday, June 27, 2008

Severe t-storm approaching!

The National Weather Service in Binghamton has issued a Severe Thunderstorm WARNING for Northern Tompkins County and surrounding areas. This includes Groton. A large thunderstorm, likely containing hail, is currently just west of Cayuga Lake, moving east. Expect torrential downpours, hail and frequent lightning with this storm!

Sunday, June 22, 2008

I think its a flop

I really am having my doubts about our severe weather chances. There seems to be a 'dead zone' in the atmosphere were some dry air has worked in. Our dew point is currently sitting at 54, which is normally much too low for severe weather. This area of dry air extends well to our west and south west, so I am not anticipating much to pop.

Now, if some more moist air can work its way in during the next two or three hours, we could get some storms later this evening...but I really think that, for our area, this one is a flop.

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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!

Monday, June 16, 2008

Still not done

Our watch has expired, and just when it looked like things were going to calm down, storms began to explode again. There is currently a storm hitting Cortland with another about to strike Groton. These storms may contain gusty winds and some hail, as has been the case all day. I'll simply update this post if any warnings get issued.


On a wider scale, thunderstorms have fired along what appears to be a mini-cold front caused by a lake breeze off of Lake Ontario. These storms will continue to fire up for the next hour or two. It is hard to say if they will survive long into the night. Stay tuned.

Severe Thunderstorm Warning

A storm has been tracking across northern Tompkins County and has prompted the National Weather Service to issue a Severe Thunderstorm Warning for Groton. This storm has the potential for hail, strong winds and frequent lightning.

I am working at Cornell this summer, and, being on the 11th floor of one of the buildings, I got a great look at this storm as it crossed Cayuga Lake. There was a good deal of cloud-to-ground lightning, so watch out!

Here we go!

The 12:30PM Update of the SPC Outlooks has the moderate risk area bumped to the northwest. This shift puts the border of the moderate risk area right overhead. Our hail remains at 30% with hatching, which, if you didn't read today's first blog, indicates a 10+% chance of 2" hail or larger.

An hour ago, the radar was quiet. Now, thunderstorms have fired all across the state. Already a few of these have Severe Thunderstorm Warnings with them. As the afternoon progresses, more storms will develop and become severe.

Stay tuned for updates if any severe storms approach!

Watch Issued

Severe Thunderstorm Watch #550 has been issued. This is quite a massive watch, encompasing most of New York and about 70% of Pennsylvania. With a watch that large, probablities aren't overly helpful for local forecasts. Nonetheless, there is an 80% chance of 10+ wind damage reports and a 70% chance of 10+ hail reports within the watch area. The watch runs until 7PM.

There really hasn't been anything developing yet, thought there is one shower in Western New York that has popped up, so I am expecting more storms to fire during the next couple of hours. The next SPC outlook will be out by 12:30. It will be interesting to see if they change anything.

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.

Tuesday, June 10, 2008

6PM Update

Thunderstorms are currently moving into the area, developing as they approach. In just about 15 minutes, a cell started to form by Ithaca, then moved just south of Groton. By this time, it had prompted a Severe Thunderstorm Warning. Winds both in and out of these storms will be gusty, with the stronger winds of course being in the storms. There are no tornado warnings in effect at this time. Here is the latest radar image:

These storms will continue to move through during the next hour or so. Stay away from windows, stay inside and, if you have wind damage, feel free to send me a report!

A New Weather Watch

The Storm Prediction Center just issued a Severe Thunderstorm Watch for Central New York and points south until 10 PM. This watch replaces the tornado watch that has been in effect. This doesn't mean the tornado threat is totally gone, however. A lot of the severe weather composite index values that are used to predict severe weather show a semi-tornadic environment overhead. However, wind damage and hail will continue to be the main threats for the rest of the day.

Onto the radar now. As you can see, thunderstorms have again developed to our west into a bit of a broken line. Like this morning, these aren't severe. However, I expect these to strengthen as they head into the more favorable atmosphere sitting over us.

Stay tuned throughout the afternoon and evening as round 2 begins!

Not Done Yet

One round of severe storms has exited the region and pressed eastward. This line didn't look like it was going to do much for Tompkins, Cortland and Southern Cayuga counties, but right as it got here, it exploded rapidly. Just shows what a little bit extra heating and humidity can do for storms, as tempertures before the storms had reached into the mid 80's. These storms have caused quite a few hail and wind reports, as expected. Here is the storm report map as of 1:02PM.

Tempertures are back into the low 80's after about a 15 degree drop with those storms. That means we are certainly still have fuel to work with for the rest of the day. Thunderstorms are also now starting to develop well to our west along the cold front in Ohio. They haven't been going for long, but are already looking strong and developing into a line. This is what I have expected to happen, so everything still looks favorable for another, possibly more intense, line of storms later this evening.

In between then and now, additional storms are possible, also with damaging winds and hail. I'll continue to update through the day, so stay tuned!


The southern portion of that line of storms has exploded very rapidly over Western Tompkins county. Severe Thunderstorm Warnings now run from Lake Ontario to Pennsylvania, including the Groton area. A large cell is about to hit Groton with lightning, strong winds and some hail likely. Take Cover now!


Tompkins County, along with all of Central and Eastern New York is now under a TORNADO WATCH until 6PM tonight!

A little known fact about watches is that they each have probablities of certain severe weather events occuring. For this watch, there is over a 95% chance of 10 or more wind damage reports, as well as over a 95% chance of 10 or more hail reports and a 40% chance of 2 or more tornado reports. That means the main threat is still damaging winds, but tornadoes are becoming an increasing threat.

An update on that line of storms: The northern portion appears to be the stronger part, with numerous warnings now in effect. Stay tuned for more updates on these storms.

Also, the National Weather Service confirmed my belief about multiple lines of storms today when they issued this statement at 10:05AM:

... Severe thunderstorms are expected across the region today...

An initial line of thunderstorms will cross The Finger lakes
region... the twin tiers... the Mohawk Valley... and the southern Tug
Hill region this morning... generally between 930 am and 12 noon.
This includes Elmira... Corning... Syracuse... Utica... Binghamton...
and Montrose. Localized strong damaging winds and hail are
possible late this morning.

This afternoon... another round of thunderstorms is anticipated.
Additional lines of storms are expected to cross the area... generally
between 2 and 6 PM. Once again... strong winds and hail are the
primary threats.

Stay tuned to NOAA Weather Radio... or local media outlets... for the
latest updates. Watches and/or warnings may well be issued later

Pre-frontal Storms

The first storms of the day have been ongoing across Western Pennsylvania and Western New York. There have been occasional warnings with these storms, so they have the potential to be severe. However, this isn't the main event today. The cold front still sits way back to the west over Southern Ontario, Western Ohio and Eastern Indiana. On the radar image below, you can see the line of storms along the front begining to form just east of Michigan.

The Storm Prediction Center also updated their outlooks and maps (which I don't have graphics for at this time...). We are still in the moderate risk zone, but the core of it was shifted to the east. All this means to me is the SPC is thinking the line will for a little further east. While I agree with extending the zone further east into Vermont and New England, I am not so sure I agree with cutting the Western Finger Lakes out. We will see.

9:50AM Update: The Storm Prediction Center is now saying they will issue a watch shortly for our area. Stay tunde for updates as the watch is issued!


A very serious situation is unfolding today for our area, with the Storm Prediction Center placing us under a MODERATE RISK zone. To put this in perspective as to how rare this type of severe weather outlook is for our area, I can only remember 1 other time during the lifetime of that we have been under a moderate risk, and NEVER have we been under one to start the day! I do have to say, however, that I was thinking last night that this would happen. Here are the areas under the moderate risk (pink in the top image) because of the wind threat (red in the bottom image).

As I have been indicating the past 24 hours, everything is coming together for a major severe weather outbreak. Hot, humid air is and has been in place. This will interact with a cold front and trough of low pressure that will progress eastward through the day. The final piece to the puzzle will be the strong jet stream winds. The thunderstorms that explode later this morning across Western and Central New York will be able to tap into these winds. Winds in some of the storms today could exceed 70, even 80 or 90 mph. The tornado threat is a tad higher than I thought last night as well. I will be updating throughout the day, so make sure to stay tuned here for the most up-to-date, in depth forecasts and outlooks you will find on the web for this area!

(Your normal forecast will be coming by 8AM. To find the forecast, hover over the "Grotonweather" tab in the menu above, then click the "Homepage" link!)

Sunday, June 08, 2008

Round Two Begins!

The clusters of thunderstorms that moved through earlier today have shifted well off to the south and east. While these storms stabilized the atmosphere for a while, in the long run, they only made things worse. Over an inch of rain fell in Groton earlier. Now, with the sun back out, that inch of rain is returning to the atmosphere. Dewpoints have shot up into the mid to upper 70's, making it feel over 90 despite temperatures being in the low to mid 80's. All this moisture is fueling another round of thunderstorms which is just now starting to explode.

Right now, most of these storms are in the southern counties of New York, but there is a large cell over Lake Ontario as well. Further rapid development of storms is certainly possible over the next few hours. There is currently (4:30) a small cell near Trumansburg that will have to be watched for rapid development in the next hour or so. A severe thunderstorm watch remains in effect as well.

Looking into this evening and overnight, there is a very strong line of severe thunderstorms over Michigan right now. These storms have a severe thunderstorm watch for Michigan, and a torando watch issued by the Canadian Weather Service for Southern Ontario. It is hard to say if this line will hold together long enough to effect us, but it is something I will be watching through the evening.

On this radar image (from you can see the numerous cells firing up in New York, along with the line of storms in Michigan marching eastward.

Sunday, June 01, 2008

Storm Reports, May Stats

While there wasn't a whole lot of widespread severe weather yesterday across Central and Western New York, the one area that did seem to get hit hardest was in fact our area. Most of the forecast range (Tompkins, Cortland and Southern Cayuga Counties) ended up under a severe thunderstorm warning at one point or another as two separate severe storms crossed the area.

The first storm tracked across Southern Tompkins and Cortland Counties in the early afternoon, well ahead of the cold front. This storm produced numerous hail and wind reports, especially once it moved into Broome and Chenango Counties. The second storm came through at about 6pm. This storm took out trees in Cortland and Locke, while hitting West Groton with 3/4" hail, with some smaller hail in Groton.

I have overlayed yesterday's storm reports on Google Earth and marked a few of the towns for reference. The blue circles with a "W" represent a wind damage report, while the green circles with an "H" represent hail. Not a huge outbreak by any means, but considering the lack of severe storms elsewhere, we got hit decently hard.

Onto other things now...did you think May seemed abnormally cold? Well, if you did, you are correct. In fact, the differences between this May and last May are quite staggering. Our average high this May was a very chilly 64.0 degrees. This ended up 12 degrees colder than last May, which averaged 76.1 degrees. In fact, there were only 3 days in which our high this past month reached 76 degrees! (Those days were the 7th at 76, the 26th at 82, and the 31st and 76). Our warmest day this May was 82, much lower than last year's 92 and even lower than 2006's 95 degree day. On the whole, it was the coldest May on my records (2003-present) by three degrees. We also had our coldest nights, with our average lows falling below 40 for the first time.