Is Winter Over?

There is a great deal of consternation about whether we are going to have a winter. A little snow/ice could happen as soon as this Thursday here in NC, maybe no t so much in VA. In the bigger picture, longer range models are simply not favorable for cold or snow (There are some climate model exceptions).

So ... how do we settle the dilemma? Pay more attention to the actual weather and less to Computer Weather Models being at odds with Climate Models.

The Stratosphere is warming over the Arctic. That feature correlates very well with sending real cold southward. Therefore any model showing anything more than a temporary warm-up that transits warmth north to build blocks should be questioned.  Below is the current cross-section of the polar vortex. The upper atmosphere warmth is full column.

The Arctic Stratosphere is warming.
This event is highly correlated with mid-latitude cold.
Image Source: NOAA Climate Prediction Center

So... what we have right now is a predictor of cold weather to come. Projections support the idea of a terrible middle to end of the month.  This image is a 10 day projection near the top of the stratosphere showing the warming in the Arctic and cold displaced deep into the US. 

If this projection verifies then the Eastern US is in trouble.
Notice the warm area off the SE Coast, a stormy signal?
Image Source: NOAA Climate Prediction Center.

In previous years this kind of formation has sacked Great Britain and the rest of Europe with some Little Ice Age - like winter weather. Our continent would seem to be overdue for something that severe despite the cold conditions that dominated 2009-10 and 2010-11. While we suffered those years, Europe SUFFERED. 

The question is whether we get some tropical forcing in the West Pacific and a jolt of energy to bring real winter into the Eastern US. I suggest watching Alaska. If that state trends warmer than it would suggest that High Pressure there will push the colder air SE. Another region to watch is Mexico, a persistent jet stream crossing that country from the Pacific would represent a lowering of pressure to draw the cold in and introduce more Winter Storm opportunities.

So, its time to go back to basics. Follow the satellite images and the overall weather to solve for downstream effects, While the Stratospheric warming event is not a perfect correlation to cold here in the SE US ... it is good enough to question weather models that would lead one to believe that winter is dead.
Here is a great New Year's Resolution: Follow actual weather more and models less ....

A Case for a Cold Stormy Winter

A combination of a Negative NAO and Negative AO in October has a strong correlation to Eastern US cold and/or snow.  Those who want to roll the dice on a cold, stormy winter can look to 2002-03, 2009-10 during this decade.   I do have to mention that the indices were strongly positive in October preceding legendary winters like 1977-78.  It is interesting that snowy winters like 1981-82, 1968-69, and 1960-61.  I discounted 1974 because it was a blazing La Nina year.  2006 is an oddity because it was a promising El NIno Winter which the phenomena simply shut down.

So, we have an argument for cold, stormy winter.   The fact that the legendary winters were excluded might be an indicator of the correlation working in 

+AMO (Warm North Atlantic) situation but not so much when it is negative.  There is no such thing as a perfect linear correlation in weather.

Data Source: NOAA Earth Science Laboratory

This composite Temperature anomaly from the NOAA Earth Science Laboratory covers the bonafide El Nino Winters featuring a -NAO/-AO below -1.00 in October (I excluded 2006).  The pattern of cold is what I believe will resemble the upcoming winter.

This is a composite of Sea Level Pressure anomaly.  Take note of the lowest pressure being at the 50N/50W position that argues for my idea that the upcoming season can be dubbed the Winter of the Nor'easters.  50/50 Lows favor snow/ice in NC and VA.  This data is also from the NOAA Earth Science Research Laboratory.

      That's all for now.  Later this week it will be time to discuss a potentially really cold start to December.

Finally! The Winter 2012-13 Forecast

To El Nino or not, Is that really the question?

Here in NC and VA many El Nino winters are loved because they do tend to be colder an usually contain a few good winter storms.  La Nina, on the other hand, is maligned for warm, dry, winters that lead to hot summers full of bugs and pests.   Therefore, the first question usually asked is whether to label a winter as an El Nino or La Nina.

Occasionally we see the crazy La Nina's like 1976-77 and 2010-11 which blocking develops in NE Canada and leads to endless cold.  There are also occasional El Nino's that feature warmth closer to South America that lead to endless gray 40-50 degree rainy days.  Thus, while the labels have some reliable generalities, I think it is a good idea to analyze the whole globe for clues. The fact is that it takes a moderate to strong El Nino or La Nina to rule the roost.

What are the Oceans telling us?

There is always the question of whether the ocean temperatures are being driven by the atmosphere, "Top-Down" , or vice versa (Bottom Up).   A good winter El Nino features plenty tropical storminess near the Dateline.  I find another feature even more interesting.  Look at the Ocean Temp anomalies below:

Source: Plymouth State University Weather Center

1. Warm east of Hawaii, Cold Gulf of Alaska:  This feature appears to be stable and promotes a -EPO.  An indicator of a cool to cold Winter if the signal holds through the season.
2. Warm pool near Mexico:  Promotes low pressure at that location.  This promotes drainage of cold air from the north and a subtropical jet stream.
3. Oops!, I skipped 3 but do not want to re-do the Chart :>)
4. El Nino?:  Sort of.... warm water in the right place to promote low pressure and feed the all important Jet Streams.  I think just enough but not too much.
5. Cold Water near Darwin, AU:  Tropical cold water promotes High Pressure.  At that location it would mean a downhill slide to #4.
6. Cold Southeastern Seaboard:  This can be an indicator of cold to come if the water is caused by rain and cool Autumn.It can also be a bummer that promotes NC and parts of VA being skipped instead of targeted by Nor'easters.
7. Neutral Water near Greenland, ice already east, but warm further south: Too much -NAO snows on LA, MS, AL, FL, GA, and SC, while skipping us.   That signal is very mixed in regards to the NAO.  Winters with plenty of fluctations seem to be the most exciting.  Tough read...

The oceans seem to be indicating a much different Winter than the non-winter of 2011-12.  There are definitely ingredients for a season that is biased cold with enough "El Nino" around to send storms into the Gulf of Mexico to the East.  The cold water near the SE Coast is not something Winter lovers want to see unless it is being caused by the atmosphere ("Top Down") and not given a chance to feedback.   Hurricane Sandy and 2 Nor'easter non-effects on NC and limited in VA has me worried that a Confluence (Skip Zone) might be out there.

Other Signs and Wonders

The beautiful colorful sunsets this autumn and feverish Squirrel activity are 2 observations also supporting a cool to cold winter.  I don't think an acorn from our Oak Tree has even hit the ground!

More Seriously...

While I have my concern,,,,  this appears to be a 2003-04 type winter that  featured 2 snows and a mega-icestorm.  There will be plenty of back and forth swings in the SOI, plenty of frontal passages, and a base state that is cooler than average in the east (-EPO).  I am also impressed by blocking in the West Polar Pacific (called the -WPO) which, if it is stable through winter would provide an ample supply of Siberian air.

So, in a nutshell:

• At least 2 degrees colder than average.
• Plenty of storm, opportunities should yield 2-3 disruptive winter storms.  Hopefully the traditional school calender does not end in late June 2013.
• If we go through December and see NC and VA being skipped by Nor'easter, it will be time to lower expectations about snow,

Thought about Sandy as she approaches NJ

The long wait for Sandy is over.  As she approaches the coast the "Hurricane" aspect will rapidly transform to a full blown Nor'easter.  Similar to Irene (2011) expect belts of high wind and heavy rain/snow to form far away from center.

At the center of the system, the wind will become a non-event b/c of a lack of pressure gradient.   The big problem (also similar to Irene - 2011) is the central pressure of 943 mb (Strong Category 3) that may yet reach the Category 4 range.  Expect storm surge flooding well above and beyond the bogus Category 1 designation given to the system right now.

One of my lingering concerns is the storms hurricane force+ winds being displaced up to 175 mile s SW of the Center.  Could this imply that those well SW of the Center could see the highest inland winds?

My expectation continues to be that Central VA, north and east of RIC will see top wind gusts in the 60 mph range (original expectation 50-70 mph).     Here in RDU, the National Weather expects gusts to 45 mph.   There is some argument to go a tad higher but... what's 5-10 mph among friends?   On the other hand ... we do not seem to be a very windy area.

Stay safe and stay informed about the weather.  Sandy is a historic storm with a 1000 mile sphere of influence.   I am sure that there are variables that are not being well accounted by weather models.

I am impressed with the overall 72 hour accuracy of model solutions in regards to the track of the center.  It will be interesting to see what happens after the storm completes it Nor' ricane to Nor'Easter cut-off low transformation.

Hurricane Sandy a massive scale is bad news for Eastern US

My long breaks between writing have been unavoidable.  Winter is coming, therefore I know there will be plenty to write about.  Also my job transition is coming more under control.

The subject right now is Hurricane Sandy.  She is already transitioning to a massive nor'easter with a tropical core en route to a probable disastrous impact on the middle and north eastern seaboard and thousands of square miles inland,  The satellite image below  shows the tremendous inflow from across the equator and from the central Pacific.   

Hurricane Sandy well on the way to becoming a Nor-icane (Hybrid Storm)
Image Source: University of Wisconsing SSEC

This storm is not going to live the life of a traditional Hurricane that hits land and fades quickly.  This system will not only make its presence known in the form of gale and hurricane force winds but also coastal flooding and even snow!  

Tomorrow, we will look at the storm track and projected impacts.  Now that Sandy is on the move speculation will transition to greater accuracy in forecasting.   The ECMWF 3 PM run was particularly disconcerting because of a direct hit on the DelMarVA peninsula followed by a track into North Central VA.  Regardless of where she hits, there will be a lot of damage done.  If she took that more SW route then my friends and family along I-95 from RIC on north would get their 3rd hurricane-force impact in less than 10 years!  

Have a good night!  It's going to be a long weekend.

Massive Hurricane Issac strengthens as he closes in on landfall

It is still important not to focus on the wind speed as much as the pressure and the size of the system. Hurricane Issac's central pressure is 970 mb, a strong Category 2.  Storm surge near and east of the landfall will very likely be well above what one would expect off a Cat 1. Take a look at the massive sphere of influence that Issac has in the below water vapor image.  Take notice of the tremendous inflow from the deep tropics and the buildup of heat and moisture at the SE US Coast which is far away from the storm center.

Anytime a storm has this influence, it means business!
Image Source:  Univ of Wisconsin SSEC

Issac still has about 12 hours over water.  I would not be surprised to see Category 2 wind speed at landfall and a Category 3 pressure.  We really need to hope and pray for a landfall point less unfavorable to New Orleans.  No one is interested in seeing the city fill with water again.

If the NHC will not promote Issac to Hurricane, I will!

Even though the NHC calls Issac a 70 mph Tropical Storm. I confer upon the storm the title of Hurricane. Issac's 981 mb central pressure is at the low end of Cat 1 (almost Cat 2) and the Eye is becoming apparent. Therefore based on the 

Saffir-Simpson Scale (The detailed description) Issac easily fits into Cat 1.

Last year's devastating storm Hurricane Irene was a "Category 1" that contained a central pressure of 942 (Category 4!). People stayed in the impact area who would have fled. There was a miraculous preservation of life despite the flooding + amazing local wind damage for a "Category 1" storm.

So, when you examine the stats of the hurricane factor in the Central Pressure when determining likely impacts. Even though the highest measured wind speed may be low it does not mean that the ability to produce small scale wind events of much greater damage potential does not exist. The worse problem near the coast was the record storm surge at Oriental, NC, easily equal to a Cat 4 hurricane.  Another argument against Irene being only a Cat 1 was her wide area of damaging influence.  60-80 mph winds spread up the I-95 corridor, far from center.

http://en.wikipedia.org/wiki/Saffir%E2%80%93Simpson_Hurricane_Scale#Category_1