Current Conditions

12z 500mb Wind analysis

Much like last week with Sandy, there is a strong jet streak diving through the central US with the associated low on the left exit region of the streak.  Also much like with Sandy, there is a large area of anomalously warm water off the Mid-Atlantic and Northeast coast.  These are important details that will come into play as the storm begins to strengthen on Tuesday evening.  Temperatures in the Northeast have been well below normal since Sandy left the region.

NAO is again quite negative which will allow anything that does form off the coast to remain close enough to have some form of impact on the heavily populated region.  As is usually the case, when there is a deepening trough in the eastern half of the country an equally as high amplitude ridge forms on the other half of the country.  Los Angeles set a record high today reaching 91 degrees at the airport.

Forecast

Forecasting this storm is actually much more difficult than the forecast for Sandy.  Coastal winter storms bring with them the difficulty of forecasting the location of the rain/snow/mix line, a difference of 75 miles makes a drastic difference in snow amounts.  Another curve ball being thrown is the climatology of early November, it is rare to get heavy measurable snow in this part of the country (East of the Appalachians).  What can be said for sure is that a deepening low pressure system will form and bring with it strong winds from the east and then northeast which will push water up an already damaged shoreline.

11/5 Surface analysis showing current position of low and it’s forecast movement

Sea Surface Temperature Anomolies

Given climatology and the potential of this storm, I anticipate many areas to see snowfall in the 1-3 range.  If the storm were to take a more westerly track, parts of the Pocono’s could see 3-6 inches of snowfall while the major cities will remain warm enough for rain to fall.  Of far greater concern is the winds that will accompany the storm as it deepens on the coast; coastal locations will see winds gusting above 40 mph and sustained in the 25-35 mph range.  It is these winds which will again push water towards the coast and bring with it moderate to potentially severe coastal flooding along the New Jersey coast.

Forecast sounding for Allentown, PA. Shows that most of the column is below freezing and supportive of snow.

Potential Impacts

• Strong gusty winds at the coast (>40 mph); decreasing the further you go inland.
• Snowfall 1″-3″ over a large area; It is not anticipated to be a large impact on travel (heavily dependent on time of day)
• Moderate to severe coastal flooding; especially in areas already hard hit by Sandy
• Areas of power outages due to the gusty winds and weakened trees

I will issue a snowfall map tomorrow as we’ll have a MUCH better idea of the position of the low.

Please feel free to ask any questions in the comment section; all posts on this site will be discussions.

Powder Keg

Although Sandy is weakening, she still threatens to pack a huge punch as she approaches the Eastern Seaboard.  Media outlets have correctly been billing this storm as a hybrid storm because Sandy will lose her tropical characteristics in the next few days as a trough approaches the area.  Upper level energy will move in from the west (see image) and provide a spark for Sandy to explode into a quickly deepening area of low pressure.  Pressure gradients will be very steep which means that a very large area can expect tropical storm force winds with area along the coast experiencing hurricane force gusts.

Where and When

Everyone wants to know exactly where and when this event will take place.  Unfortunately there is still a bit of disagreement among the models as to where the storm will be strongest.  American models (GFS, NAM) suggest that the storm will make the greatest impact in Long Island and may even have the storm follow down the Long Island Sound, which would be devastating for some communities along the waterway, especially on the southern half where the sound funnels into New York City.  The every consistent Euro continues to strike Delmarva which could push water up the Delaware River into Philadelphia.  This would also impact greatly the resort towns through Delaware and Maryland.

In either case, weather will start to deteriorate late Sunday into Monday for most of New Jersey and Pennsylvania.  The worst of the storm will likely take place late Monday into Tuesday, especially if the long island sound solution verifies, New York city would take the brunt of the storm on Tuesday.

Inland Impacts

Cities well inland can expect to see several days of strong gusty winds with some heavy rains.  Areas where leaves have already fallen off of trees should see slightly less impact from the wind but that is not to say there will not be power outages.  Areas with thick foliage will experience more an amplified impact  because of the larger surface area.

Rainfall is also a big concern as the storm moves inland, it would not be out of the question to see areas with rainfall in excess of 10” with wide spread 3”+.  Rivers will rise over their banks with the NWS using the word “historic” in their briefings.  In addition to the river flooding, storm drains will be clogged with loose leaves causing very wide spread street flooding.

Coastal Impacts

Historic.

This is a place where I can assure you that somewhere between OCMD and Islip (Long Island)  there will be a massive impact from tidal flooding.  Hurricane force winds will drive water well up the coastline causing extensive damage to homes and businesses along the shoreline.  Beach erosion will be epic which is ironic because the storms name is Sandy.  Expect to see most of the Weather Channel team reporting from locations in New Jersey.

Insurance Claims

Billions of dollars in insurance claims will be paid out following this storm.  Wide spread roof damage, water damage, business destruction, and losses relating to loss of electricity.  Although it might not seem much for an insurance company to pay out for some roof damage, multiply that by millions of people and it begins to add up.  More on this will be said after the storm has left the region.