Saturday, July 14, 2012

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Why Oceans Matter: 
Heat Capacity & Climate




10:00 AM EDT 7/14/12 (Meteorologist/Oceanographer Alex Davies and Forecaster Mike) Did you know the heat capacity of the ocean is four times great than that of the atmosphere?


That means it will take four times longer to heat and cool a volume of water compared to volume of air under similar environment conditions. This is why it takes a while to boil a large pot of water when your make pasta, even though the heat coming-off the stove top burning is extremely hot.



So why does that matter in terms of local or global climate? 
The ocean acts as the great regulator of our land surface temperatures, especially near the coast, and help to re-distribute heat from the equator to the poles through large-scalar surface current like the Gulf Stream, and through deep-ocean currents known as Thermohaline Circulation (meaning "heat" and "salt") or the "Ocean Conveyor Belt." 

"Ocean Conveyor Belt" from Oceanmotion.org

Have you ever noticed that on hot summer days like we experienced a week ago, it was more pleasant in places along the coast like Bethany Beach, Delaware and Fenwick Island, DE compared with inland locations like Salisbury, Maryland, Dover, Delaware, and Richmond, Virginia? This was because the ocean temperature during that time was only in the upper 70s, while the inland air temperatures were topping-out near 100 degrees, or more. The same thing happens in the early winter as places near the ocean or along The Chesapeake Bay or Delaware Bay often have a tougher time getting "all snow" events as the air temperature is being impacted by the relatively warmer water temperature.

THE OCEANFRONT TODAY - For some regions, the beach this Saturday could be much better. This includes the Delmarva beaches which are covered by the Bayshore zone. This zone always is an excellent illustrator of the temperature differences mentioned earlier. With mostly cloudy skies overhead the beachfront will try to hit temperatures around 83-85º, while the inland Delmarva will likely be closer to 86-88º. Since the water is still cooler than the air, those close to the shore are a little cooler. However, because of the clouds overhead today, that effect is lessened since the land cannot warm up as much.

Today's rainfall estimates by the HPC

WHERE IT'S NICE - WIth widespread showers and thunderstorms across the east, it's tough to find a place where there is nice beachgoing weather! However, the lucky people will be on the South Atlantic coastline, including those in the often-overlooked Southern Georgia zone. The area is sometimes bypassed by vacationers heading to Florida, but that area has a share of beautiful beaches of its own! There is a slight chance for thunderstorms, but with skies being mostly sunny, it can't ruin the whole day!

Have a fantastic Saturday and enjoy the water!

Thursday, July 12, 2012

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"It's A Grand Night For Singing" 
- from the 1945 Rodgers & Hammerstein musical State Fair


Thank you to Central MD/Bayshore Fan Connie for this
beautiful sunset out of Ocean City, MD Thursday night
5:50 AM EDT 7/13/12 (Forecaster Mike & Advisor Foot) - State Fair season is getting started across the country! If you have any state or county fairs going on within the next several weeks, please let us know. One fair is getting underway this weekend in the Central Maryland region. The Baltimore County 4-H Fair is already underway and continues through the weekend. While conditions could be better, the area will likely see some partial sunshine with highs in the mid to upper 80s. It definitely was a great night for singing across that region, where another beautiful sunset covered the evening sky!

"The Stars are Bright Above" – The lucky ones with a clear view of the sky and comfortably cool temperatures may be in our Southeast Wisconsin zone, stretching eastward across the Great Lakes region. After that beautiful sunset in Maryland, we can look at some clear and starry skies in some portions of the country. Unfortunately, a very significant portion of the country will not have visible starts because of a persistent cloud cover in place.  Southeast Wisconsin can expect lows down in the mid 60s so it may be a nice night for some stargazing!


"Shiny and Silvery Blue" – One of the reasons the evening is especially nice for stargazing is the crescent moon in place.  The Central Colorado zone is on the fringe of the clouds coming in from the southwest, but partly cloudy to mostly clear skies may make for a nice moon view right before sunrise as is the case during a waning crescent moon.We are coming off of the last quarter on July 10th, and heading to the New Moon on July 18th. For some areas of the northern Plains and northern Rockies, we may be able to see that “shiny and silvery blue” crescent moon above the landscape tonight.



Water Vapor image over the Southwest from the NWS



"To Add to the Show" – What a way to break the Excessive heat – with the beginning of a monsoon situation in the southwest. After many days of Excessive Heat Warnings and high temperatures rocking well above 110º and even 120º, that dark pink on the Advisory map has been replaced by the green of a Flash Flood Watch! Scattered thunderstorms will be possible across much of the southwest including the Death Valley area and the Las Vegas area. We may even see some thunderstorms heading over to the Grand Canyon, so keep your eye on the sky if you are vacationing in that region!

Have a wonderful Friday! 
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Tired of the heat?
Then let's talk about Winter!

6:35 AM EDT 7/12 (Forecaster Mike & Advisor Foot) - So when would you like for us to start giving you the inside scoop on winter? Could there ever be a repeat of 09-10, and if so, are there climate indicators that give early clues about the winter ahead? New readers may not be aware of our Winter Stormcast Team, which has quite the track record for snowfall forecasting in recent years I'm told. One little winter forecast indicator they follow is Arctic Sea Ice decline in summer and recovery starting in September.

For students and teachers aggravated at the paltry snowfall this past winter year, the recently released NOAA Climate Report shows us just how big an impact the loss of Arctic Sea Ice can have on large scale climate here in the U.S. 



ANALYSIS - Our team examined this latest graphic from the National Snow & Ice Data Center, and then did a comparison of the Sea Ice decline levels in the years noted to the snowfall at BWI for the following winter, and here's our question for you. Do you see a correlation between the two? Why is it that 2008 sea ice decline was not much different than 2009, but the 09-10 winter was heads and tails more catastrophic for Maryland than 2008 despite such a tiny difference in Sea Ice levels? The answer may lie in the data for El Nino vs. La Nina! 
The latest Sea Surface Temperature Anomaly in the Pacific as of July 9, 2012 from NOAA
EL NINO/LA NINA - While the results can never be blamed on one single long range signal, El Nino vs. La Nina is always a very important consideration. With a large amount of sea ice through the summer of 2009, we headed into the winter season with strong El Nino conditions in place – much warmer than normal temperatures in the equatorial Pacific. However, the year before was bringing cooler than average temperatures in the Pacific, but it would need to have been cool longer in order to be considered an official La Nina event that year. Still La Nina conditions persisted through the fall and winter that year, which was a sharp contrast to the El Nino a year later.

HOW 2010 GOES AGAINST THE GRAIN - Also, you may be wondering how 2010 fits in here. As you can see from the graphic, sea ice in 2010 was at its record lowest at this point two years ago. However, many of you may remember that 2010-2011 was the Baltimore “snow-hole” winter, where BWI was still able to reach near average. That was also the record breaking year throughout much of the country in terms of snowfall, and this may seem to go against everything else because of the low sea ice present and a Moderate La Nina in place. That year, typically hostile conditions for snow were completely overridden by another group of short range signals, the NAO and AO, which you may hear us discuss.

AND THIS YEAR? - Now where does 2012 fit into all of this? As you can see on the graphic, the sea ice through June is pretty low. The National Snow and Ice Data Center reports that June 2012 saw the record steepest drop in sea ice for the month of June. On the other hand, the La Nina that struck for both winters 2010-11 and 2011-12 has waned and we currently have neutral conditions in place. This may not be the case by the winter though, and we are keeping a very close eye on all of these signals, and more beyond the El Nino/La Nina and the sea ice heading closer to the season!

The extent of Sea Ice as of July 10, 2012. 

While it's not an precisely scientific technique to compare just 6 recent years to each other, it is interesting to point out how much higher the 2009 Arctic Sea Ice levels were  in the summer than all others in the most current data set. In future reports, we will be detailing a much larger swath of data sets across several disciplines in Earth Systems Science related to winter weather indicators.


Our bottom line right now: If you want a lot of snow this winter, better cheer on that sea ice... it's got a lot of fast refreezing to do come fall to make up for the approximately 5.6 million square kilometers of loss observed since its peak in March 2012!