Cristobal, Rafael, and Sandy.

A little bit more on what I was saying on my Facebook weather page, about the tropical pattern last night.

The pattern looks very October like.... with the deep trough and the cold front along the Gulf Coast. This front is what has caused the convection to flare up along the southern coast.  Rule of thumb, always be aware of frontal bounties  in the Gulf in August. The waters in the Gulf are very warm this time of year.  So even if we don't have great convergence over the Gulf. it does bear watching.

The pattern over the Atlantic has gotten my attention. We have all that October like cool and dry air associated with the trough to the west of Hurricane Cristobal, and a nice southerly flow of the eastern trade wind being pulled north by the front and trough, on Cristobal's east side.

The above image shows how the wind flow is steering Cristobal.

 

                                      

Normally the easterly trade wind flows westward across the Tropical Atlantic into the Caribbean. But as I show on the image the trade winds are being pulled to the north.

Since the trades are not pushing the air into and out of the eastern Caribbean and part of the Atlantic, they are more or less just sitting around and pilling up with nowhere to go. 

Hurricane Cristobal will be moving to the northeast over the next few days. Once he is out of the way  and the trough relaxes, we will see the easterly  trades move back into a normal flow into the Caribbean.

Many times when this happens,  the build of air and all that convergence is redirected back into the western Caribbean as a low amplitude wave of low pressure and convergence, can cause development in the western Caribbean and GOM ( Gulf of Mexico).

The last time this sort of pattern was in place was back in October of 2012 when we had Hurricane Rafael  in the same general position in the Caribbean.  He had a track that was quite similar to what we expect Hurricane Cristobal to have.  Rafael moved east of Bermuda as a hurricane, whereas Cristobal is going to past west of Bermuda, but all in all the tracks will end up much the same.  Back in October of 2012 we also had a deep trough along the east coast ,  helping steer Rafael away from the east coast.  We also had the trade winds bending to the north and away from the western Caribbean.

              The low out over the Atlantic in the above image is Rafael moving north and east.

 

After Rafael moved north and then northeast out into the north central Atlantic, we had an area of low pressure develop  in the western Caribbean a few days later around the 20th of October ,  south of Jamaica, Haiti, and the Dominican Republic.  This low was caused by the redirection of the trades and convergence into the Caribbean .  In a few days this area of low pressure developed into Tropical and then Hurricane Sandy.  From here she tracked north, thanks to Rafael moving to the northeast and clearing her path. 

                                                                                                                             October 20 2012

       Oct 24, 2012 showing Sandy starting her northward move out of the Caribbean

       October 28, 2012 showing Sandy moving off the East Coast.

A couple of surface charts showing the trough and front positions during that time in Oct of 2012

You can see the two surface charts , with the trough and fronts looking much the same as the charts I've been posting on my weather page quite a bit this year...

Back to Cristobal, he will have a path much like Rafael ending up southeast of the Canadian Maritimes  just as Rafael did.

                                                                      Showing Sandy moving out of the Caribbean and Extratropical Rafael off the Maritimes.

Rafael's Track

                                                                                                                                 

Cristobal's Track

                                                                                                  

 

The models aren't seeing anything  tropical end of the weekend into the first part of next week..... But they do show some ridging along the Northeast and East Coast of the US, along with lowering pressures in the western Caribbean.

 

 

Here is the GFS showing pressures lowering in the western Caribbean as we head into next week. You can see Cristobal is in the same position that Rafael was off the Maritimes.

Pattern recognition is a very important skill when it come to forecasting weather.  I'm not saying we will see a repeat of Sandy, only that the setup is there that lead to her birth.  So we need to keep a close eye  on the Caribbean first part of next week........ with the Tropics , you never know.


 

Are We Returning To The Weather Patterns Of Past Decades Part Two

This post will be part two on "Are We Retuning To  The Patterns Of Past Decades .

If you've read my blogs or followed my Facebook weather page, you know I'm a believer in repeating patterns, not only for weather, but for climate, and even across the cosmos itself.

Pattern recognition is a very important skill when it comes to weather forecasting. When it comes to weather and climate, these cyclical weather patterns can be months, a few years, decades (as in certain Atlantic and Pacific ocean warming and cooling patterns), or even longer.

Looking back at the 1950's:

The Atlantic Basin was quite active with tropical cyclone activity during the 1950's. part one of this series covered  1954, 1955, and 1960. If you've read part one...you know 1954 and 1955 saw a lot of tropical cyclones strike the U.S. East Coast.

Here are two charts that show the Atlantic Multidecadal Oscillation (AMO) and The Pacific Decadal Oscillation (PDO).

 

   

I've talked and explained about the different oscillations many times. So I won't go into a lot of detail about what they do. Those reading this, that don't know about them, you can find Information about them on this blog post. There are other post that go into them. You can find them in the blog archives (found on the left hand side of the blog page). 

The current state of the AMO is positive (warm phase) which means warm water temperatures off the East Coast. When the AMO is in a positive phase there is melting of sea ice in the Arctic. The recent news of the Greenland ice sheet and sea ice melting is the result of the AMO being in a warm phase. When the AMO is in a positive phase Greenland blocking is more likely, which means cold air pretty much locks in place, in the East; during last winter the AMO being in a positive phase, in conjunction with the NAO being in a negative phase, was the reason New England saw so many nor'easters, with many seeing near record to record breaking snow amounts.

The PDO is in a negative (cool phase) which means cool water temperatures off the Pacific Northwest coast. When it's in a cool phase Alaska generally see harsher winters. Most of us have seen stories in the news about the harsh winter conditions in Alaska the last few years. The cool phase of the PDO has a lot to do with this. I think the PDO is also part of the reason Colorado and the Northern Plains have been seeing the late season snow.

But basically, when the PDO is in a warming phase, more of a wet pattern is seen. Therefore when it's in a cooling phase, the jet gets stronger and directs the flow toward the Pacific Northwest, air south of the jet is not as dense and tends to not rise as easily, so more of dry pattern is seen.

As you can see in the charts, the two oscillations in the same phase in the 50's, as they are now. This means, the sea surface temps off the west coast of Africa, to the Caribbean, Gulf , off the North American Coast , and most of the North Atlantic, were more or less the same then as they are now. 

Ocean temperatures. The ocean temperatures and ocean currents have an important influence on weather. Warmer temperatures will add more moisture to the air. Changes in ocean temperatures will change the wind patterns aloft. Changing the wind pattern will change how moisture is distributed. El Nino and La Nina are examples of how changing ocean temperatures can influence the weather pattern.  The PDO and AMO help anchor the jet streams which in turn amplify or de-amplify temperatures and moisture distribution. For example, A warm AMO means less arctic ice and with a cold PDO more Atlantic hurricanes.

  

 

   

 

         

 When one looks at the temperature and precipitation profiles of the 1950's, things look eerily similar to the current temperature and precipitation profiles across the country. It never ceases to amaze me how many meteorologist fail to look at past weather patterns when making a forecast. I mean if X, Y, and Z produced a certain kind of weather event, then logically those same X,Y, and Z parameters should produce a fairly similar weather event in the same general areas. Oh I know there are a lot of other factors that come into play. But still, basically the same things that happened then should happen again.

Anyway, back to the oscillations. The Atlantic and Pacific oscillations have a major impact on sea surface temperature, ocean current, and have a great deal of influence on the jet stream, which in turn controls the temperature and precipitation patterns across North America. Since the PDO is currently in cool phase and the AMO is currently in a warm phase we're seeing drought across the Midwest and Southeast and to a lesser extent the Northeast. The areas seeing the drought now are the same areas that saw major droughts in the 1950's.

Back in part one, I went into detail about the storms that struck the U.S. East Coast in 1954,1955, and 1960. During those years the PDO and AMO were in the same phases they are now. During the decade of the 1950 the U.S East Coast saw several tropical hits each year. The reason for this is:  The AMO was in a warm phase and the PDO was in a cold phase. So as the Pacific cooled down the Atlantic was warming up. Hurricanes thrive on warm water. When surface ocean temps are at 80 degrees (F) they aid in the development of tropical cyclones. So when the Atlantic Basin is warm, we see more tropical cyclone development.

So to answer the question, are we retuning to a the patterns of the 1950's? The answer is a resounding yes. The cold PDO and warm AMO will make a great breeding ground for Atlantic Basin tropical cyclones, for several years to come. The pattern is such that the East Coast can expect more storms like Irene, Lee, and Sandy over the coming years.

A little about Sandy:

The media loves to use terms like extreme when describing major weather events. To quote Greenpeace co-founder Patrick Watson : “It doesn’t matter what is true, it only matters what people believe is true…You are what the media define you to be.”

Here's a chart put together with data from the National Climatic Data Center ( NCDC) . For those who don't know, the NCDC is a NOAA climate research unit. The chart shows the maximum temperature record for each state, going back to 1890 (Interestingly, the NCDC refers to these as 'climate extremes').  But IMO, it would be more accurate to refer to them as just weather extremes.

     

As can be seen, through 2011, no maximum temperature records have been set since the 1990's. This is simply amazing since all the climate doomsday scientists and pundits have stated that recent global warming was "unprecedented" and that U.S. temperatures were rapidly increasing due to CO2 levels. Per NOAA, 82% of all maximum records were initially set prior to 1960 and prior to the accelerated growth of human CO2 emissions and atmospheric CO2 levels.

One might ask, why show data on CO2 levels? The answer is, because the media and sadly many people in the meteorological field used terms like extreme, one of a kind, unprecedented when it came to describing Sandy back in October of 2012. Even President Obama blamed global warming. But in fact Sandy was just a very powerful storm...Incredible yes....unprecedented no. Remember that quote, “It doesn’t matter what is true, it only matters what people believe is true…You are what the media define you to be.”

Well say something enough times and people will start to believe it. By saying Sandy was extreme, people will start to think the weather has never been as bad as it is now. But this is not a post on global warming. You can find a post I did on the subject here. I've also done several blog post on Sandy including her timeline, you can find the other post in the blog archives.

Sandy was the deadliest and most destructive hurricane of the 2012 Atlantic hurricane season, as well as the second-costliest hurricane in U.S history. last October the media was using terms like Frankenstorm, when describing Sandy. Al Gore said she was extreme and unprecedented. My response to Mr. Gore is that's a bit of a exaggeration, to say the least. 

Sandy was born in the western Caribbean Sea, fueled by the warmth of the sea. As far as tropical cyclones go Sandy was fairly typical., as she raged across Haiti and the Dominican Republic, Cuba, Jamaica, Puerto Rico and the Bahamas, causing at least 65 deaths.

As she exited Cuba, her structure became disorganized due to strong shear. But she maintained convection due to the influence from the approaching trough moving east out of North America. By the time October 27th arrived, Sandy was no longer a fully tropical system. The National Hurricane Center (NHC) downgraded her to a tropical storm. But she soon got her act back together and regained hurricane status. However, has she moved north along the U.S East Coast she became more distinctive. She was undergoing a transformation from a tropical type storm into something called an extra-tropical storm (kind of a hybrid).

The difference between a tropical and an extra tropical storm is how the storms get their energy. Tropical cyclones are fueled by warm water evaporating into the air; as I said above, water temperatures 80 degrees (F) or greater will enhance tropical development. Therefore, waters colder than that will inhibit tropical storm development. However, extra-tropical storms get their energy from  the battle between warm and cold air masses. Normally a storm like Sandy would lose their power by moving over colder northern waters. But because Sandy was turning extra-tropical she was able to feed off both types of energy. Therefore when she plowed into New Jersey she was still gaining strength and increasing  in size and wind coverage. 

The 1991 storm nicknamed "The Perfect Storm" was of a similar type when a nor'easter fed by Arctic air absorbed Hurricane Grace. But thankfully that storm never made landfall. Most likely several of New England's major storms in the past, including the great 1938 Long Island Express, the storm that other storms are still measured by today, were extra-tropical.  Had Sandy acted more typical of similar systems, she would have gone out to sea, with only some heavy rain, strong gusty winds, and beach erosion to note her passage. However, Mother Nature had other ideas.

So then, what caused Sandy to behave the way she did?

The conditions that lead to her behavior are rare but not unique.

There was a blocking high-pressure centered west of Greenland (remember when the AMO is in positive phase, Greenland blocks are much more likely). There was also a trough of cold air moving eastward across the United States. Behind the wave of cold air was a big arctic storm dropping out of Canada.

Low pressure systems have counter-clockwise winds. High-pressure systems feature clockwise winds. So when Sandy got close enough, those clockwise winds from the blocking high started pushing her to the west. But still this was not enough to cause what happened.

The other player in the setup was that wave of cold air moving eastward. The timing couldn't have been more disastrous. The trough grabbed on to Sandy and pulled her to the west. Because of these two forces acting on Sandy, the stage was set for a catastrophe. 

The East Coast is not the only place these hybrid storms can strike. The great Columbus Day Storm of 1962 was a Pacific Northwest windstorm, that struck the Pacific Northwest. This storm also underwent a similar transition from Typhoon Freda to an extra-tropical storm.

Well that's it for part two. I hope you enjoyed reading it, and learned a thing or two. I will close by saying this:

As I've shown in part one and part two, the East Coast of the U.S. has seen years that featured several Sandy type storms. In fact many of these storms made Sandy tame by comparison. The East Coast has seen a huge amount of development since the 1950's, if a Carol or Donna where to hit now, the devastation would be worse than anything we've ever seen. The reason for this is simple, it's not that the storms are anymore extreme, unprecedented, or more powerful. Instead it's our failure to learn from the past that is making the situation so much worse than ever before.

Rebecca

Sandy will she come and visit the Northeast?

I thought I would post a very quick update on Sandy.


Sandy:


Here is the latest Euro model run.


  I think we can agree this looks very ominous. But it is only one model. We have 6 days where lots of things can change. The weather models have had some trouble handling tropical systems this year. Also, no storm that was once a hurricane has made a Northeast landfall after September, going all the way back to 1900.







The track forecast from the National Hurricane Center has not changed. Winds are 50mph, central pressure is down to 993mb, she is moving north northwest at 8 mph. The tropical storm wind field extends 90 miles.

 Here  is a little on Sandy. I think it is fairly safe to say most of us have been thinking and talking about Sandy and what she might do.   While she is only moving at 8 mph now, she will pick-up speed has she moves north over the next few days. She will be moving into an area where there is little in the way of vertical shear and the Sea Surface Temperatures are over 80 degrees. So she should become a hurricane around Jamaica.

We're going to have a negatively tilted trough moving south during the later part of the work week. What this trough does will be critical to Sandy's track.

The European and Canadian models are very amplified and show Sandy interacting with an arctic air mass and pull the storm inland, phasing it and dragging down unseasonably cold air. The earlier GFS runs had Sandy farther east and out to sea. However, As of this writing, the 18z GFS run had a major shift westward. It remains to be seen if it will shift more to the west or trend back to the east. As for the QPF, we only have to look back at Wilma to know what can happen when tropical moisture rich air, meets cold arctic air.....Lots of heavy snow...... in-fact some of the models are showing QPF amounts of 6-10 inches of precipitation. The Euro and Canadian have a very tight < 950mb pressure gradient , throw in the highly supportive low level jet , cold 0C H85 Temperatures, and dropping surface temps. It doesn't take much imagination to see snow in parts of Pennsylvania, New York, and New England. How much snow there is (if any) will depend on Sandy's track and intensity.  


 Severe weather:

We will also have severe weather Friday and Saturday in the Midwest. The Trough that is going to affect Sandy will also kickoff a bit of severe weather. An upper level low will be moving into the Plains. Cape Values will be marginal as will lapse rates. But, there will be a lot of shear and moisture in place. There will be enough directional shear that any thunderstorms that do develop will start to rotate. Right now, I think the major treats will be wind and hail......but there will be a few tornadoes thrown in as well. The upper level low will bring snow to the Great Lakes.

So what is the bottom line:

There isn't one really, there are still details to be ironed out. But the chances of a Northeast hit from Sandy, have gone up a notch.  I think the 00 GFS will come into alignment with the Euro. One thing I want to mention, the models are only a tool, there are many factors in play, only some of which I've mentioned here. We have a lot of time for things to change. One only has to look back at Isaac and New Orleans, the models will still making adjustments at land fall, so don't panic.   I will continue to watch the upper air patterns and see what the models do.

That’s about it…….I will post more blog updates as we get closer to the weekend.


Rebecca