Fall Tornado Season

As the clash of seasonal air masses is upon us, so is the secondary peak of tornadic activity, across the United States. This peak in activity is no where near as intense as what happens during the spring time. This secondary peak of activity has to do with the combination of fast Jet Stream winds and strong frontal systems. A strong gradient of temperatures across the hemisphere typically drives these powerful Jet Stream winds, and creates much stronger frontal systems which help initiate thunderstorm development.

Typical October Pattern

We do not have to go back far at all to see active Fall tornadic months. In fact, 2010 was an extremely active October and November for tornadoes. Some of the tornadoes last year were even strong and ranked in ef-4 intensity. Weather patterns, with regards to La Nina, are to last year's. So, expect severe weather season to pick up has we head deeper into the fall months.

2010 Tornado Season

October Tornado Hotspots

November Tornado Hotspots

September 2011 Weather Summary For Jacksonville, North Florida, & South Georgia

September 2011 was a month of transition for the First Coast. There were periods of extreme drought, followed by heavy rainfall. Temperatures reflected this variability, with overnight lows averaging much below, while daily highs finished above normal.

September 2011: Percentage of Normal Rainfall

All in all, the majority of the area finished September with below average rainfall. Officially, the month will go down in the books with a deficit of 1.62 inches. This brings the yearly deficit to about 3.5 inches of precipitation.

September's average monthly temperature actually came in slightly below normal, thanks to overnight lows. Still, 15 of the 30 days Jacksonville reached 90 degrees or above. So far, 117 days have been above 90 degrees this year.

Forecast For Next Month:
As for October, look for temperatures to be around average or slightly below for the first third of the month. Followed by more average to slightly above average readings to finish the month out. Temperatures, on a normal day, start out around 60 degree and finish around 80. Precipitation should be much below normal. The CPC suggests at least a departure from average of more than 40%.  The First Coast usually sees around 3.86 inches of rainfall an average October. (It is important to note no rainfall fell at JIA during the month October 2010.) The only hope of seeing above normal precipitation would be from the influence of a tropical disturbance.

Tropical Season Not Over Yet...Still Watching For Caribbean Monster

Right now, there the Atlantic is busy with a couple of named storms meandering around. The good news is that these storms will never threaten land or get anywhere close to doing so. So, the question then becomes what is next in the tropics.

High Pressure Dominates Northeast

For clues on what will happen next, it is best to look at the pattern that is setting up. The new weather pattern that is setting up is classic for a fall La Nina. Generally, dry conditions in the East, associated with a large ridge of Canadian high pressure will ensue over the next couple of days. When this pattern sets up it is always a good indication to watch the Caribbean for significant tropical development. And, indeed, the forecast models are picking up on this scenario.     

 GFS Forecast Model

Long range forecast models continue to show an unsettled weather pattern through most of the first half of October in the Caribbean Sea. What will either be Rina or Sean is likely to be a significant cyclone. The main question that exists is whether or not any potential storm will threaten the U.S. Of course, it is too to early to say. Waters, in this part of the world, have been untouched this season and would likely support a major hurricane.

Potential Cyclone Energy That Exists In Water

Tropical Storm Philippe Forms

Tropical Storm Philippe has formed in the far eastern Atlantic. Its currently only about 800 miles from the coast of Africa. There are two significant pieces of news with this storm. First off, it will not gain too much strength. Water temperatures are on their way down and shear levels are on their way up. Both these factors will help to keep the storm in-check. The second piece of significant news is that Philippe will never threaten land. Within days, the storm will already start its recurvature pattern. All computer models agree with this scenario. (Philippe is likely the last storm of the 2011 season to form in the eastern Atlantic. Eyes will turn on the Caribbean Sea for the next storm.) 

Official Forecast Track

Unanimous Computer Models

Fall Begins This Friday Morning

Summer officially ends this Friday at 5:05 AM and autumn begins. With the season change comes the changing of the leaves. We don't see leaves change colors here in North Florida because of the amount of sunlight and its intensity throughout the year.

The peak times of leaves changing colors has already started across northern parts of the U.S. Places in the Southeast usually don't peak until late October through November.

Leaf Change Map Schedule

How do colors change? As summer ends, the green pigments in leaves deteriorate, giving other colors a chance to shine. Carotenoids, the pigment that makes carrots orange and leaves yellow, are exposed as the green fades. Reds and purples come from anthocyanins, a pigment that is formed when sugars in leaves break down in bright autumn sunlight.

New Normal Climate: Nights Are Warmer

It doesn't take a meteorologist to tell you that temperatures are rising year after year, across the U.S. The most noticeable change over the last 30 years involves overnight lows. Overnight lows are averaging a whole degree warmer across many parts of the North. Nighttime temperatures set the stage for what happens the next day weather-wise. With warmer nights, fire season is longer. Pollination patterns may be changing. A study sponsored by Longwood Gardens showed that flowering plants have been blooming an average of one day earlier each decade. Warmer nights and later onset of freezing days also means that plants can generally survive farther north than they used to.

Average Minimum Temperature

Pests are also able to thrive and spread in forests and other natural landscapes at least in part because of warmer nights. Both the native pine bark beetle, which has ravaged forests from Colorado to Alaska, and the introduced wooly adelgid, which has been sucking the life out of hemlocks in the East, may be benefiting from warmer nights, especially in winter.

Pumpkin Growing Weather

It is safe to say that Florida is not known for its pumpkin patches. Pumpkins generally need a a temperature of 65 degrees or more to germinate, along with plenty of water. In fact, some pumpkin plants require 1 inch of water a day. Florida certainly fits the bill when it comes to moisture content and germination temperature. In order for a actual pumpkin to form, partial shade is needed to keep temperatures generally below 90 degrees. And this is where the difficulty arises. It is hard to keep pumpkins, during their growing process, in the extreme heat of Florida.

The Ohio Valley, eastern Midwest, and California are prime growing spots for pumpkin crops. Generally, pumpkins are considered a late season growing crop, because they must wait until the soils are warm. This is why there was originally some thought that there would be significant pumpkin shortages this fall season. As happens to be the case, communities which rely mainly on their own hometown production, in the Northeast, may experience shortages. Reports of wide spread shortages and/or complete devastation of this fall's crop are greatly exaggerated. 

Tropical Storm Ophelia Forms- Not A Threat To Land

First Official Track For Ophelia

Forecast Models Plot

Tropical storm Ophelia is basically a doomed cyclone from the start. First off, shear and instability are both not on the side of the tropical system. Secondly, and most importantly, the Atlantic Ocean is on verge of seeing the collapse of the central guiding ridge. (Usually, when this happens it marks then end of the tropical weather threat for the East Coast.) For this tropical storm, it means that a recurve is in its future. The only areas that might see minimal impacts are the Leeward Islands and Bermuda. Any type of strong system is out of the question, at this point, because of the future path through hostile conditions.

Synoptic Scenario For Ophelia

What is still concerning is development in the Caribbean Sea and the Gulf of Mexico. Forecast models have been depicting, for sometime, a large hurricane that will affect the State of Florida during the first week of October. This should be no surprise since forecasts have pointed at this type of pattern setting up since April.

Potential Path For Tropical Systems From April 2011

East Coast Hurricane Season Over

With the arrival of the first major frontal boundary into the eastern portions of the United States. The Eastern Seaboard can wave so long to the threat for any tropical cyclones. Frontal boundaries are simply blocking mechanisms that act as brick walls for the East Coast. Usually, once the first major one of the fall season completely sweeps through the East, conditions in the western Atlantic become too hostile for hurricanes to successfully threaten the East Coast, most of the time. There are exceptions but typically the direct threat season shuts down, in the latter half of September.   

This does not mean that the tropical season is over by any stretch of the imagination. In fact, the next threat area's season maybe on the verge of ramping up. Places in the western Caribbean and eastern Gulf of Mexico should see their fare share of activity. There are already indications in place that this is the case.

Indication #1) This is a La Nina year. La Nina years are notorious for late season Gulf of Mexico and Caribbean threats. You only have to go as far back as last year too see to see any resemblance. The majority of tropical systems that formed during the second half of last season were in the NW Caribbean Sea.

Hurricane Season 2010- Shows clustering of storms in NW Caribbean

In addition to last year, some of the most notable storms in history have formed during the months of September and October. Two examples include Hurricane Mitch in 1998 and Opal in 1995. Both, at one point during their lives, were major hurricanes and each caused billions of dollars worth of damage.

Hurricane Mitch 1998- October Hurricane

Hurricane Opal- Late September/Early October Hurricane

Indication #2) Forecast models are indicating an uptick in tropical activity towards the last week in September and the first week of October. This is being shown on numerous model runs and by numerous forecast models. Florida is the target on many of the runs, which should not be a surprise.

GFS Model for October 3rd

Smoke In Jacksonville, North Florida, and South Georgia Continues

Anytime the wind is blowing from the west or the northwest expect to smell smoke. There are multiple large fires that continue to burn in Southeast Georgia and North Florida. The Okefenokee Swamp Fire is the biggest culprit from the smoke. Some 310,000 acres have burned in the refuge. The main fire that is burning in North Florida is in the southern portions of the Osceola National Forest, just to the north of Lake Butler.
 

Wildfires Erupt Around The First Coast

Duval and Nassau Counties remain the driest counties, in the State. In fact, parts of Downtown Jacksonville, Fernandina and Amelia Island are desert dry. There is a small chance of rain this weekend, but it will not do anything alleviate the drought situation.

KDBI- Drought Index

Satellite picture from the morning of the 13th below. Shows a shield of smoke over North Florida from the numerous forest fires burning to the west of town.

Below Average 2011 Hurricane Season Continues

I know that what when some read the headline, they will think that either I am wrong or it is a misprint. But, it is not. The 2011 hurricane season continues to bell well below average. We have had many named storms but the truth none of them have been impressive. It seems as if the National Hurricane Center has given a name to everything that has spun out there in the tropics. This is why we are already at the "O" storm (Ophelia).

There are two measures that justify this being a slow season. [Reason 1] This season has seen just 2 hurricanes. This is 50% below the value for what it should be; it should be at 4. [Reason 2] The energy that each tropical system produces called Accumulated cyclone energy (ACE) is well below average. The ACE of a tropical system is the only true form of how powerful a storm remained, during its lifetime. So far, this season has recorded a total ACE of  68.505. An average season has an ACE around 87.5 units.

FSU- Measure of ACE Per Year In The Atlantic Basin.

Average Tropical Season: 
12 Named Storms
6 Hurricanes
2 Major

This Year (So Far):
14 Named Storms
2 Hurricanes
2 Major

Actual Weather On Sept. 11, 2001

9-11-2001 Weather

9-11-2001 High and Low Temperatures

9-11-2001 Precipitation

Jacksonville (Sept. 11, 2001)
Low: 72
High: 86
Precip: 0.14

New York City (Sept. 11, 2001)
Low: 67
High: 84
Precip: 0.36 (during pre-dawn hours)

Katia No Threat To U.S.

Official Forecast

From the beginning, Katia was always a behaved cyclone. This is hard to believe since it had such a complicated weather pattern to progress through. Soon, Katia will be non-tropical low pressure system and will actually end up causing havoc across parts of Europe.

Personal Forecast For Katia

Florida-Georgia Drought

Active Fires Exist West and North of Jacksonville

If you are smelling smoke, there is good reason. Five major fires continue to burn in the surrounding areas of Jacksonville. Already this month, the deficit stands at 1.35 inches. This puts this year's deficit at around 3 inches. The combined deficit over 2010 and 2011 is around 22 inches. The only hope of substantial rainfall is from a tropical system. As of now, the combination of tropical systems has only produced dry air.

Current KBDI Index

All of this news and dry air should not be a surprise. As first mentioned on this blog, the end of summer and the early part of fall always had the set-up as being dryer than average. What is concerning is La Nina's status is close to paralleling that of last year. This means that October, November, and December could be bone dry, if not for help from the tropics.

Dry Air Scenario

Nate Forms In Gulf Of Mexico- Not A Threat To U.S.

Tropical Storm Maria Forms

Maria Official Forecast

Tropical storm Maria becomes the 12th named storm this season and likely the third hurricane. Maria's intensification over the next several days will be gradual and not rapid. There are 2 hindering factors as she continues to move to the west and west-north-west. First off, shear looks to be moderate in nature over the next couple of days. A second hindering factor is simply how fast the storm is moving. Maria continues to plow westward at nearly 20 mph. The combination of shear and its fast movement serve as a hindrance and will make it tough for the storm, in the SHORT TERM, to become a hurricane.   

Shear is steady ahead of Maria

This storm will likely become a hurricane during the early part of the weekend, once conditions become more favorable. One thing this storm does have going for it is that it is in a moist, tropical envelope. And the fact it is not dealing with dry air is a rarity this season. This conducive envelope will allow the storm to strengthen into a hurricane as it threatens the northern Leeward Islands. As I see it now, the Leeward Islands will likely feel the force of category 2 hurricane. 

Moist Environment Surrounds Maria

As for long term threats, it appears that that will depend on exactly how fast the storm moves. A faster moving storm will likely recurve and miss the United States. My personal forecast calls for direct effects from the storm to be felt in Central/South Florida and the Carolinas. A very similar path to Irene is a plausible forecast, at this point in the game. 

My Personal Forecast

Hurricane Irene's track: August 2011

Hurricane Katia Threat

The current forecast models are not sophisticated enough to pick-up on the complicated weather pattern that is evolving over the eastern part of the U.S. There are 3 troughs, 2 areas of high pressures, and tropical storm Lee to put into the equation. When things are all said and done, Katia, in her hurricane form, will get dangerously close to the Outer Banks and possibly other locations along the Eastern Seaboard. At this point, it is too early to exclude North Florida from the realm of possibilities, with this storm.  

Current Models

Hurricane Katia Satellite

The first trough that affected Katia has already moved off into the Atlantic waters. While between troughs, Katia will move on a more westward track. Trough number "2" should turn the storm more northerly, but only briefly. This second trough is weak and eventually will die out; this process is already happening. (These events are part of the easy part of the forecast. 

The turning mechanism for Katia is over the Heartland of the U.S. It might or might not combine forces Lee over the coming days. Without Lee and the next trough combing, Katia will get dangerously close to the Southeast U.S. (This include Florida), before lifting out. If Lee does not help to amplify the ridge in the Northeast and, in fact, acts as some sort of mechanism to deepen the trough, the threat from Katia will be much higher up the East Coast.

Here are possible future scenarios:
1) If Lee moves towards Texas...Katia will be a FL/GA Threat
2) If Lee Continues to propagate around Louisiana...Katia will be a Threat to SC/NC
3) If Lee dies out over portions of the Southeast...Katia will be a Threat GA/SC/NC
3) If Lee only makes it to the Tennessee Valley...Threat will be north of North Carolina and include the Northeast

Any threat from Katia, to any coastline, would not come before September 9th.

The Navy NOGAPS model, a model that has a lot of weight in my tropical decisions, has Katia making landfall, as hurricane, in Southeast Georgia next week. 

Navy NOGAPS

August 2011 Jacksonville Weather Summary

August 2011 goes down in the record book as being the 7th hottest on record. Every day of the month was spent with high temperatures in the 90's; this was the first time in history that a month of August has recorded every day spent in the 90's These warm temperatures also paint the picture on how dry it was. The month closed out with a deficit of -1.51 inches of rainfall. Only 5.03 inches of rain fell at Jacksonville International. Many areas of Northeast Florida saw only about 75% of their usual rainfall, while Southeast Georgia fared much worse. In fact, some areas saw only about 10% of the average rainfall they expect to see.

August Precip. Percentage of Average.

The maximum sustained wind was 26 mph and the maximum wind gust was 37 mph; both occurred on August 9th and were not associated with Hurricane Irene.

A normal year, in North Florida, only sees about 42 days of 90 degree readings. So far this year there have been 70 days.