Don't Let your Guard Down

Although Irene will not re-strenghten into a Category 3 Storm before hitting the coast of North Carolina and maximum sustained winds may not be quite as high across the tri-state area as orginally thought, this is still a very dangerous situation. Irene is very large and is going to have ample opportunity to pile up water in areas where storm surge is an issue. The thinking now is that the center will come ashore along the south shore of Long Island, in Nassau county. The highest winds will be just east of there. Wind gusts over 80 mph are quite possible at those locations. Although much of the tri-state may not have sustained winds at hurricane force, we do expect hurricane force gusts every so often and sustained winds will easily be tropical storm force. Keep in mind that the high winds will occur during a relatively long period of time, so we still anticipate that there will be quite a bit of wind damage, especially to trees. As you are probably aware, a number of mandatory evacuations were ordered. Please follow them. They are for your own safety. The weather will start going down hill Saturday evening. Expect the worst conditions late Saturday night through Sunday afternoon. As Irene begins to pick up more speed, conditions should rapidly improve Sunday night. The good news is the weather looks marvelous next week... just in time for the start of the U.S. Open tennis tournament.

Hurricane Irene's Impacts to be long-lasting

Hurricane Irene is currently about 350 miles outh of Cape Hatteras, NC and is forecasted to pass either directly over the Outer Banks of NC or just inland. It is moving north at 14 MPH. It currently has maximum sustained winds of 110 MPH, making it a strong category 2 storm on the Saffir-Simpson scale.

Below is the latest official forecasted track from the National Hurricane Center. After the storm passes near eastern, NC, it will ride up the Mid-Atlantic Coast and will likely be within a zone between NYC and 60 miles east of there, making the greatest landfall threat in Nassau county on Long Island. Below is the latest visible satellite image of the storm. This classifies as a large hurricane. Unfortunately, this is bad news for many reasons:

1) The aerial coverage of hurricane and tropical storm forced winds will extend hundreds of miles, affecting a large population area.

2) Large hurricanes weaken much slower than small hurricanes. So although, Irene will encounter cooler waters and southwesterly wind shear as it moves into New England, it may stay a hurricane well inland.

3) Since the storm is far-reaching, there is the potential for a greater storm surge, as it will have more time to pile up water near the coast. Making matters worse, we at a time of astrological higher tides.

Hurricane Irene will soon pass through a small stripe of warmer waters known as the gulf stream. This will give Irene an additional opportunity to strengthen back into a category 3 hurricane. Thereafter, gradual weakening should occur.

This is a dangerous hurricane, affecting a large population center. The impacts will be severe. One of the largest disruptions will likely be power, which in some cases could be out for weeks in some locations.

The next update for the National Hurricane Center will be within the hour.

Big Storm On The Way!

This winter has been very entertaining, to say the least, here in the NYC metro area. We had a huge snowstorm in mid December, which dumped record snows across parts of Long Island. We had a storm that was so close, you could literally taste it, but did not quite make it all the way up to our area.

The mid-atlantic has seen record snowfall this season with tremendous snow storms, dropping several feet of snow. Even the deep south has had unusual snow events.

When I think about the winter that Florida had, this was may be the most interesting aspect of all, being a traveler to the state many times and having family there. Florida had a record stretch of cold weather in early January. Snow fell in areas that had not seen anything of the likes since 1977.

Much of this winter was dominated by the negative phase of the North Atlantic Oscillation (-NAO). What's interesting is that it hasn't really been brutally cold, but it was the meridional extension of how far the cold air was able to penetrate south this winter which was truely amazing.

I also think about the blocking of storms just to our south and how most of new england has wondered what has happened to the snow, while those to the south were buried. Well, that is until this week.

So, here we are again, on the verge of another significant snow event. Though this storm will likely be the most intense of the season, it might or might not be the biggest snowfall of the season, depending on where you live. Every storm is unique in some way. This storm will be unique in it's long duration. It will track to a favorable position that generally gives the tri-state heavy snow, but will then stall out and perhaps retrograde north and west slightly, before finally weakening and move out to sea.

Temperatures are just cold enough to support snow across a good portion of our area. This will be a heavy wet snow, that will be a pain to shovel.

Below is the projected snowfall accumulation map.

More Uncertainty Builds!

For NYC snow lovers, the 06Z NAM just dissapointed you in a major way. It has trended offshore towards the GFS. This could be a crushing blow to a promising storm. However, this is only 1 model run and we will see if it is blip or a trend, when the 12Z run comes out later this morning.

Potential Blizzard On The Way!

Winter officially begins in a couple of days and it may be off to quite a start this year, if things pan out the way they seem to be trending. Within 24 hours, a storm that appeared destined for the fish in the Atlantic Ocean, now has its sights set on the entire eastern seaboard.

This will be my first detailed weather model analysis and discussion of the storm. At this time, a good portion of the 00z model data has come in. The real eye opener came this afternoon with the 18Z NAM. It has a major shift of the storm track closer to the coast line. It hopped on board with the EURO (one of the more respected models). The GFS is basically the only model that has not jumped on the bandwagon at this poing. Being that it is currently the outlier, we'll use the 00z as the model of analysis.

Let's set the stage and look at the surface features in play. I have circled the key features in red. A strong, Canadian high pressure system is in control of the northeast. This is one of the coldest airmasses of the season. Unlike many storms that come up from the south, this one will not be able to drag a lot of warm air up with it, so it almost a guarantee that we are going to be dealing with snow only. An area of low pressure has already developed over the Gulf of Mexico. This is the storm we are watching.

Now, let's take a look at the latest run of the NAM. We'll start by looking at the initialized analysis at 500 mb. This gives us a flavor of the overall weather pattern and potential evolution and track of storms. One of the key things Meteorologists look at in determinng the potential of a major east coast snowstorm is a term called the "North Atlantic Oscillation" (NAO), which is the difference of normalized sea level pressure anomaly between Iceland and the subtropical eastern North Atlantic. It has 2 major phases: Positive and Negative. For big snowstorms along the east coast, we look for negative values. Negative values of NAO are associated with unusually high geopotential height values at 500 mb across the north atlantic. This is sometimes known as a "Greenland Block". This anomalous condition forces deep troughs of low pressure to form along the east coast, which can generate big storms. Because there is a blocking upstream, these troughs tend to negatively tilt and even cutoff. This leads to intense and slow moving storm systems that can produce very heavy precipitation. The image below is a great representation of a negative NAO situation, which is leading to this potential nor'easter. Anomalously high geopotential hight values of 570 DM are over Greenland and is producing a blocking situation. This is forcing the polar vortex south eastward to southern Canada. A strong, confluent flow is over the northeast.. a sign of high pressure over the region and typically a forerunner of east coast snow storms.



Now, let's jump ahead to the height of the storm and see how the 500 mb pattern evolves. As you'll see, what has not changed is the Greenland Block. But now, the trough that developed across the central and eastern United States amplified tremendously and a cutoff system is over the Atlantic. Boxed in red is an area of tremendous upper level divergence, which will aid in deepening the surface low pressure along the coast. Though not shown on this map, water temperatures are still rather warm, so the storm will feed on a tremendous temperature gradient and could likely cause a coastal front to form. These can generate a tremendous amount of snowfall.

The surface map for this same timeframe tells the story. A very heavy snowfall would be occurring Saturday night with 2-4 inch per hour snowfall rates.

There's alot more weather maps I can go through, but I'll leave you with what the potential snow amounts could be. Below is an output form BUFKIT, a tool which produces graphical outputs on many weather parameters. It is outputting 1.9 inches of snow. Now before you start wondering why I'm making a big stink over 1.9 inches... this is liquid equivalent. On average, 1 inch of liquid equates to 10 inches of snow. However, because this could be a dry, powdery snowfall, the ratios could be even higher. So, bottom line here is that we could be measuring snow in feet, not inches.

Stay tuned for further updates on the storm and predicted snowfall accumulations.

Earliest snowfall I can ever remember!

Last year, we had a bit of snow in late October, which I thought was pretty amazing. I didn't think it would be topped, but I was wrong. It was a surreal sight today watching snow fall and seeing most of the trees not even turning colors yet. I have to admit, I was a bit surprised how far south the snow got today... and with another coastal storm this weekend, there's another chance of a mixed precipitation event, and then back to reality. We should be back up near 60 by the middle of next week.

Not Like the Octobers of yester-years!

If you remember way back to 2 years ago, we had one of the warmest Octobers on record. That is not going to be the case this year. In fact, with a potential coastal storm late this week and a unsually cold airmass in place, you won't need to travel too far to see some snowflakes. Areas of central PA into central, NY actually have a decent shot of some accumulating snows. After this storm goes by, no big warmup in sight. It looks like we're stuck in a pretty cold and damp pattern.