Not Feeling Like Fall

A warmer pattern shaping up this week as hotter temperatures and higher humidity return. The upper air pattern that featured a strong trough over the East has flattened out. allowing for the cooler temperatures to retreat North.

      (Upper pattern Monday night showing a more zonal, or West to East, flow)

This pattern will allow a warm front to push through the State, bringing in much warmer air from the Southern Plains Tuesday

The front will stay to our North through the middle of the week, keeping showers mainly North of the Arkansas border. 

Temperatures will remain well above normal with highs in the upper 80s through the week, although well shy of record highs. 

Rain chances increase toward the end of the week as the front to our North begins to shift South by Friday.

Arctic Ice Hits Record Minimum

The Arctic ice sheet reached a record low minimum extent this season according to The National Snow & Ice Data Center. The ice sheet shrunk to about 3.4 Million kilometers, which is roughly HALF of the long term average minimum extent. Below is the extent of the Arctic ice sheet as measured by satellites for a 5 day average ending September 18th.

The white area represents actual ice cover and the orange line represents the long term average extent. The long term average minimum extent is around 6.7 million square km and the previous record minimum ice extent is around 4.1 million square km set in 2007. The graph below compares 2012 ice extent to the average and to 2007.

The minimum Arctic ice extent is typically set in mid September, when conditions become cold enough that refreezing begins. This new record is part of a longer term trend of less Summer ice extent.

The 5 years with the smallest minimum ice extent have all occurred since 2007. Note that the 2012 minimum ice extent is well below any of the other years, falling below 4 million square km for the first time since measurements began. Satellite measurements have been used to estimate ice extent since 1979.
It is important to note that loss of ice extent has NOT been observed in the Antarctic. As a matter of fact, ice coverage there has actually increased somewhat as a whole.

The blue line represents Arctic ice extent, while Antarctic ice coverage is represented in red.
According to scientists at the National Snow and Ice Data Center, climate models have shown the Arctic becoming completely free of ice during the Summer by 2050, however the observed rate of ice decline is actually much faster than what the models suggest. This suggests that Summer Arctic ice may disappear within the next decade. Such a drastic change in ice extent will very like have significant climate impacts for much of North America. It is not known, however, specifically what those impacts would be.

2012 Fall Preview

WOW! Today's weather has to be one of best this year - temperatures are in the 70's, the sky is crystal clear and the humidity levels are perfect.  It's simply amazing outside.  You could say this weather is a nice preview of the fall season.

With that thought in mind, what does the meteorology community think about the fall season ahead? Well, let's find out.

When it comes to a season forecast, we typically turn to the CPC, or the Climatology Prediction Center.  Obviously their forecast comes with a clear disclaimer that these are just forecasts and they need be taken with a grain of salt.  Nonetheless, they are intriguing and are the most relible at depicting monthly forecasts in this day and age. So here goes...

According to the CPC, we can look forward to a slightly above normal temperatures in Arkansas during the next few months.  When I look at the climatology data for the state that equates to thermometers running anywhere from the low 90's to the mid 70's during October afternoons with overnight lows occasionally dipping to the 40's.  As for November that means temperatures will generally hang out in the 70's with major dips into the 60's-50's occurring in the second half of the month.

Rain predictions for the fall season aren't that appealing.  When you look at the image above, you can make out the normal precipitation amounts expected in Arkansas and most of the U.S.  In other words, the CPC expects 4-9" in the next few months.  More of the precipitation is anticipated to occur along the gulf coast.

            (Sea Surface Temperatures anomalies late August show a spike of warmer than normal Pacific Ocean water)

If you were wondering, these predictions aren't just computer generated.  These forecasts are heavily weighted on ENSO phases.  The latest ENSO analysis shows that an El-Nĩno phase is expected to ramp up very soon.  At the moment, the CPC thinks this transition to an El-Nĩno will have a greater impact on the winter months rather than the months of fall.  That is usually the case when it comes to climatology in our country.

Only time will tell how accurate these forecasts become.  For now we'll keep these ideas in the back of our minds.  All we can hope for is a wet and pleasant fall season ahead.