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October 25, 2012

Big Story Weather Special Storm Report – October 25, 2012

redOrbit Meteorologist Joshua Kelly

Today's Special Storm Report focuses on two major weather systems in the United States. The first is in South Dakota and the second involves Hurricane Sandy.

SOUTH DAKOTA - A strong area of low pressure moved just to the southeast of South Dakota on October 24, 2012. This low pressure was the same low pressure responsible for the tornadoes in California that occurred a few days earlier. The storm took a southern route out of California and then turned towards the Northeast after coming out of Colorado. Once the storm moved into the Southern Plains, it had enough cold air wrapped into it that snow started falling in Colorado. Many places in this region picked up some measurable snowfall amounts greater than 1 inch.

Towards the afternoon and evening this storm started to produce rain in Western and Central South Dakota as it moved just southeast of the area. However, by mid-afternoon, places in Western South Dakota saw the rain change over to snow. In the image below we can see snow piling up near the city of Spearfish, SD.

“Spearfish South Dakota did get reports of 2.5 inches upwards to 4 inches in some places throughout the local area. While places further south in the Black Hills got upwards to 9 inches of snow,” according to Spearfish resident Chris Orr. As the day went on, the snow continued to pile up across this region.

After the snow moved out, the colder air mass took hold and temps fell below freezing for many locations. Strong Northwesterly winds were responsible for bringing down the wind chill values across the area.

Later that evening, the storm system slowly moved further eastward of the region. However, in the overnight hours and early morning hours, it hit with more snow around Dimock, SD with a light dusting as well possibly upwards to 1 inch on the ground as we can see in the image below.

The storm continued to march northeastward and now, as of October 25, 2012, the center of the low is over the Great Lakes and headed into Canada. This same low pressure system is being watched for impacts to the weather along the East Coast this weekend and into next week. The frontal boundary associated with this low is forecasted to move into the Northeast and it will then interact with Hurricane Sandy as that storm also moves northward into the region.

EAST COAST - A developing story is starting to unfold across the Eastern United States. Hurricane Sandy is now a CAT 1 storm and it might possibly make it to CAT 2. This storm is now to the north of Cuba and is continuing to move in a northward direction. Also, two other areas that are being watched is the next spot up near the blue star in the image above. This region is where a piece of the Greenland High is beginning to ridge westward and absorbed the High pressure that will be leaving the Maine area over the region. The third piece of this puzzle is the frontal boundary that is moving through the Great Lakes this afternoon. It will track towards the Northeast. A lot of these things are starting to look fairly familiar to another event that happened in October of 1991 known as the “Perfect Storm”. What happened during that time is a hurricane came out of the Southern Atlantic and made its way up the seaboard just like what we are beginning to see take shape today on the weather maps.

Hurricane Sandy is going to continue to track north-northeastward over the next few days before it starts to feel the frontal boundary from the west. There is a chance that this frontal boundary will pick up Hurricane Sandy and rapidly shoot the system to the North and then even Northwest. If we look at the image above and see the red outlined area, this is my thought on where this may happen -- very close to the same area the “Perfect Storm” happened. If this event does setup, we could be looking at seas off the coast running in the 12+ foot range and even higher in the open waters, which will make navigation of the seas impossible. The next big thing is that if enough cold air can get wrapped into the system, we could have a large snow field develop over the Northeast with some places in Maine and New Hampshire getting upwards to a foot of snow or more. The third huge impact this storm is going to have is the winds. The gradient winds around this system are going to be huge and wind speeds in excess of 70mph will be common in this area where the storm hits the Northeast.

We will have to watch the storm early on as it pushes up the coast as it could bring Tropical Storm force winds to the East Coast of Florida along with large storm surge and onshore flow. Then Sandy will shift northward into the Cape Hatteras area where it will be possible that we could see hurricane force wind gusts along with high seas and heavy rainfall.

Once the storm heads into the Northeast, we will be watching the cold air interact with this storm making it become Extra-Tropical and also deepen rapidly as it runs into the front. The high pressure to the east is very crucial for this system in that it looks like it may stay in place long enough to create a block of the region forcing the low to retrograde back to the west into the Northeast around Maine and Boston area.

Remember this is still a few days away and anything could happen. However, indications are supportive that we may just have the event of 1991 unfold in front of our eyes again. That being said, it would be very unique in that these scenarios don´t happen all that often where a hurricane is the main attention-getter of the storm. This hurricane will make it stronger than a normal Nor´Easter.

If you live in the Northeast, now is the time to start planning for an event like this and it may just become the next “Perfect Storm of 2012”.

This situation is unfolding and will need to be watched very closely for anyone that lives up the Eastern Seaboard, there is also still that slight chance that the ridge is not strong enough and makes all of this become nothing more than a dream. The ridge as I mentioned is going to be a huge factor in this storm panning out. If it moves just a bit further north the hurricane could slide to the northeast earlier along the Gulf Stream and not even make it up to the northeast. So we need to watch that ridge in the Atlantic closely over the next few days to see if this will play into the favor or force the storm to set sail and miss the coast all together.

So for all snow and storm lovers, let´s hope the ridge holds.