A Few Thoughts On SandyOctober 26th, 2012 at 9:37 pm by Jeremy Wheeler under Weather
Just wanted to put a couple of thoughts out there about Sandy before I go to bed. Sandy did weaken earlier to a minimal hurricane. The winds dropped to 75mph, and it was moving north at about 7mph. The pressure was at 970mb (28.64″). It may be a tropical storm by the 11pm update, but we’ll see. The wind shear and some dry air have been working to weaken the system. On it’s slow motion I wonder if upwelling will begin to have an effect on it as well. That is something that hasn’t been talked about too much with the slowing motion expected. Anyway, I’ve shown the water vapor product from NOAA. That basically shows the varying amount of humidity in the mid-upper levels of the atmosphere. In the picture below orange is dry air. Blue is humid. It shows quite a bit of dry air wrapping into the system. The National Hurricane Center Indicated earlier that it could be reduced to a tropical storm.
If the storm weakens further, then it’s possible that it will track farther to the east. One of the main reasons that I say this comes from the BAM model. The shallow version has been showing a more easterly track for a while, while the deep version has been showing more of a route near the coast. I believe this is due to the storms ability to be steered by the upper level winds. Also a lot of the models have been shifting east in the next 60 hours. Regardless, the storm is still expected to restrengthen, and I think it will undergo a transition to a nor’easter type storm sooner than predicted.
One thing that I think should be said is that even if the storm stays out to sea we will still get the winds off of the ocean. That is due to the expanding winds from the storm and the long fetch. However, the track will change the tidal forecast. This is due to the amount of time that we have strong northeast winds. A system farther out to sea will not produce as long of a period of northeast winds. They would still be northeast Saturday into Sunday, but they would be more northerly late Sunday and then north-northwesterly around Monday. That would probably still allow for moderate tidal flooding along the coast, but it might not stack up in the Bay as much. Here is a place to go to look at the latest tidal forecasts: http://www.erh.noaa.gov/er/akq/brief/tides.php Go to MDL to get the latest graph. It has Sewell’s point at 5.5 and 5.8ft Sunday and Monday mornings respectively. That is moderate tidal flooding. We talked about how that relates to some past storms in the previous two blogs. Irene for instance was 7.55ft. Duck N.C. looks to get up to 7ft by Monday morning. This will be moderate and could be pushing major. Wachapreague is forecast to be over 7ft. Normal tide is about 4.5-5ft for reference. Again follow the link for the latest updates, and keep in mind that a change in the track will change the tidal surge.
I still think heavy rain for along the coast. Possibly 4-9inches, but I’m still not seeing over 2-4 inches in inland areas. At least not yet. HPC has about 3-5 inches in the metro and inland areas. If these tracks keep shifting offshore though, then amounts should be reduced.
Winds will still be strong and gusty. I still think gusts to 65mph near the shore and up to 45mph inland. Sometimes winds can shoot straight across the bay and filter farther inland.
One other thing that I’ve been thinking about, and someone mentioned it in a discussion somewhere is that the models have overforecasted a lot of storms and hurricanes that come up from the south. Irene and Earl were two good examples. Remember, they were major hurricanes (cat 3 or higher) to our south and they weakened quite a bit before moving up this way. So if the storm does stay tropical, then that is something to keep in mind. Again, I do believe that the system will become extratropical (nor’easter) sooner than forecast. So that could allow it to get a boost as the models have kept showing.
Also, while it does look like a landfall closer to New Jersey or Delaware is more likely, the models do show the area of low pressure now sinking back to the south a bit. That would still give us some strong winds, but they would be from the northwest. That would happen into Tuesday, and could create a very breezy Halloween on Wednesday.
These are just some thoughts that I wanted to put on here tonight. The situation is still a bit fluid, but we are still confident about getting very windy and wet weather by Sunday. As always, prepare for the worst…hope for the best. Jeff will be in the morning, and will have a new blog out then. Have a good night. Oh and he did write a good blog this afternoon that talked about the European versus the GFS model.
Meteorologist: Jeremy Wheeler