NOVEMBER AND SEVERE WEATHER

Just about every November here in the south we invariably see a round or two of severe weather from thunderstorms forming along strong cold fronts sweeping in from the north. It’s a time of the year similar to spring, where the atmosphere is in turmoil with the introduction of cold air from the north colliding with leftover warm air here in the south. Tornadoes and damaging winds are the main culprit during severe weather’s “Second Season”.  In fact last November 18th. tornadoes developed in Coweta, DeKalb and Fulton counties. Although they were small EF1 & EF0 tornadoes they still caused some minor damage.

Next week we could be dealing with one of those scenarios where a strong cold front, combined with a potent upper level system, collides with warm air already in place. The GFS model is hinting at a very strong vortex aloft sweeping in sometime next Thursday the 10th.

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This combined with a strong cold front at the surface could produce damaging thunderstorms from Mississippi to here in Georgia next Wednesday and Thursday. The 00z 6 hour precip depiction from the GFS Operational indicates a strong line of thunderstorms moving in next Thursday evening.

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Hopefully this will change, and we will come out with a gentler solution, but just in case we will be watching for the possibility of severe weather closely.

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SHOWERS & T-STORMS THURSDAY

A strong cold front will approach the Southeast late Wednesday and through the day on Thursday bringing with it showers and a few t-storms. The SPC has an area southwest of Atlanta under a slight risk for severe t-storms. The area in question would include all counties south of I-20 and west of I-75.

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If severe t-storms do occur the main threat would be from damaging winds. Lightning will also be a threat so be sure to seek shelter if a storm approaches. The best timing appears to be in the morning on Thursday and then again late Thursday night into early Friday morning.

Here is a look at two different computer models (GFS & NAM) that paint a slightly different story. The GFS model is more aggressive and faster then the NAM. Here is the GFS for 2 am Friday morning.

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If this is correct a fairly strong line of t-storms will be moving through much of North Georgia in the overnight hours into Friday morning. The NAM on the other hand shows far less activity.

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As for the timing the GFS has the rain moving out in the morning on Friday while the NAM keeps the shower activity around through Friday afternoon. Here is the GFS for 2 pm Friday clearly showing the showers well to the east and south.

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The NAM on the other hand keeps showers (although light & few) around through 2 pm on Friday.

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I’m leaning more toward the GFS with the faster solution. Once the system makes its way to the east look for another cold snap with lows down into the 40s and 30s both Saturday

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and Sunday morning.

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MINI SEVERE WEATHER SEASON, EL NINO & WINTER

Each year around this time we notice an uptick in the number of tornadoes across the Southeast and here in Georgia. November and for that matter December have been come to be known as the Second Season for severe weather after the lull that is seen during the summer and early fall.

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The atmosphere at this time of year (just like in the spring) is going through a major transition as cold air starts to shift southward. Unfortunately the warm air hasn’t completely gone away and this leads to problems. Then if we are in an El Nino year you have to throw in a very active and powerful branch of the southern Jetstream which you would think would help to produce lots of severe weather and tornadoes. But is that really the case? Is there a correlation?

This year’s El Nino is on track to rival the last major episode that took place in 1997-1998. Since then there have been two moderate episodes (2002-2003 & 2009 & 2010) and two weak episodes (2004-2005 & 2006-2007).

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Going back and comparing the El Nino episodes with tornado activity doesn’t reveal a clear picture. In fact during the strongest El Nino (1997-1998) there were only two tornadoes in November and none in December. The one episode that yielded the greatest number was the 2002-2003 moderate El Nino. November and December of 2002 saw 12 and 13 tornadoes respectively! The other El Nino episodes resulted in the following number of tornadoes: 2004-2005 (0 in November and 0 in December); 2006-2007 (2 in November and 2 in December); 2009-2010 (0 in November and 8 in December).

So is there a correlation between El Nino and fall tornadoes. It appears not. Is there a correlation between El Nino and wetter, cooler weather in the months of November and December? Absolutely! In fact looking back at the last five El Nino episodes and the ten corresponding months of November and December, there have only been two drier than normal months (Nov. 1997 & Dec. 2006) and two warmer than normal months (Nov. 2004 & Dec. 2006).

With all of this being said where are we so far this November? As of today Georgia has seen 2 tornadoes. They occurred at the beginning of the month in Telfair County in south Georgia. There is a possibility that a few more could occur this Wednesday primarily in the southern tier of the state. Rain so far this month has been abundant. Here in Atlanta we have recorded 6.94″ which as today is 5.05″ above normal. The normal rain total for the entire month of November is just 4.10″! In keeping with the strong El Nino you would expect the temperatures to be slightly below normal, but that has not been the case. In fact as of today we are 3 degrees above average so far this November.

So what should we expect going down the road through the winter? All indications are for the El Nino to stay strong if not strengthen some. Therefore expect cooler than normal temperatures

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and above normal precipitation.

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What about snow? Below normal temperatures and above normal precipitation…..sounds promising for snow. Right? Wrong! The below normal temperatures are factoring in the increase amount of cloud cover that comes along with an increase in storm systems rolling through. Actually in El Nino years we often have a wedge type setup with cold air sliding in out of the Carolinas at the surface in advance of the storms coming in from the west. This in fact is more conducive to ice events than snow. I personally would rather have the snow!!! As they say stay tuned, I’m sure it will be an interesting if not memorable winter!

SEVERE WEATHER STILL EXPECTED OVERNIGHT

An intense line of showers and t-showers will continue to move east at 30 mph making it to west Georgia overnight.

TIMING: A squall line will reach west GA around 4am and will most likely be accompanied by damaging winds and possibly a few tornadoes. The line will weaken as it gets closer to Atlanta by 7am, but will still be strong enough to produce damaging winds. Heavy rain will also accompany the storms as they move through. A second line of storms will develop behind the first and should move through metro Atlanta around noon time. This line could also be capable of destructive winds and very heavy rain. The second line should diminish east of Atlanta later in the afternoon.

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MAIN THREAT: Damaging winds will be the main threat with this storm system, but as we stated earlier a few tornadoes could develop along the squall line as it moves into west GA. The air west of I-75 north and south will be more unstable as the line moves in. During the afternoon round just about all of north Georgia will be unstable so severe weather could occur just about anywhere as the line moves through. Also remember to download the FOX 5 StormTeam App to keep you updated on any watches or warnings issued in the overnight hours. They can alert you via your smartphone in the case of a wrning being issued for your area.

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REST OF THE WEEK: Showers may develop late Wednesday as moisture wraps around the upper low that will be to our northwest, otherwise the rest of the week should be dry. It will also be much cooler with highs Wednesday and Thursday in the 60s and lows in the 50s. Temperatures will warm back into the mid to upper 70s by the weekend along with abundant sunshine.

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STRONG T-SHOWERS POSSIBLE FRIDAY

Severe weather will continue tonight to our west and gradually diminish in intensity as it moves into north Georgia.

TIMING: Showers and t-showers will move in after midnight with the best chance developing after sunrise. The cold front currently across the Mississippi River will moves closer during the morning and afternoon increasing the number of showers and t-showers here in north Georgia. A few of the t-showers could be strong enough to produce damaging winds, but the t-showers will remain below severe levels. Look for numerous showers and t-showers throughout the morning and early afternoon before the activity moves east and the skies start to clear by the evening.

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TEMPERATURES: As the showers end the dry, cool air will start to move as the winds increase out of the northwest at 15 to 25 mph. Temperatures will drop to near  50 Friday night with highs on Saturday only in the mid to upper 60s. The coldest reading will occur Sunday morning with temperatures bottoming out in the low to mid 40s in the metro area and in the mid to upper 30s across the mountains. This won’t last long as highs will be back to near 80 next week.

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ANOTHER STORMY NIGHT!

More showers and t-storms will be moving through the southeast tonight on the backside of the same storm system that affected us yesterday. The greatest risk for development of tornadoes will once again be to our west across Mississippi and Alabama.

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As the evening progresses the t-storms will eventually reach Georgia. We are in a slight risk category for severe t-storms for the remainder of tonight with the greatest threat locally from damaging winds, large hail and very heavy rain. Tornadoes although not likely cannot be ruled out.

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The timing of the system will bring the strongest storms into Alabama during a 6-8pm time frame, while the strongest storms will arrive in north Georgia between 8pm and midnight. More showers and storms will linger overnight leading to the threat of flooding from persistent heavy downpours.

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MONDAY-WEDNESDAY SEVERE WEATHER THREAT

Showers and t-storms will roll through the southeast beginning this evening and lasting on and off through early Wednesday morning.
OVERVIEW: A large and very intense area of low pressure is moving out of the Rockies spreading severe weather across the Plains and Lower Mississippi Valley. As the storm system progresses east the threat of severe weather will increase here in the southeast.
TIMING: Severe thunderstorms will start to push into north Georgia beginning Monday night. This first round will last into early Tuesday morning with a threat of damaging winds and possible tornadoes in the overnight hours. Once the first round is over more showers and t-showers will redevelop throughout the day on Tuesday with damaging winds and tornadoes possible until late Tuesday night into early Wednesday morning. After Wednesday morning the threat of severe weather will shift into the Carolinas.

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HAZARDS: Main threat with this system will be damaging winds, isolated tornadoes, large hail and minor flooding due to the possibility of 2-4” of rain Monday night through Wednesday night. Stay alert throughout this event by either monitoring us here at FOX 5 either on TV or on the internet at myfoxatlanta.com or fox5storm.com and if you have a NOAA weather radio make sure that you install fresh batteries in case the power goes out.

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FRIDAY STORM AND MORE

An active weather pattern to our west will catch up with us on Friday bringing with it a showers and a few t-storms. The Storm Prediction Center has included the much of northern Georgia including Atlanta in a slight risk category mainly for the late morning and early afternoon.

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FRIDAY MORNING: Although we need to watch this closely it looks like the strongest dynamics with this system will pass to our north as the storm exits Arkansas and Western Tennessee on its way into the Ohio Valley. A line of t-storms will more than likely form across northern Mississippi and spread northeast into middle Tennessee early Friday morning.

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As it moves northeast it will weaken with the remaining showers entering Georgia by later in the morning.

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Later in the afternoon we may see another round of showers and possibly a t-storm, but even then the instability and shear will still be minimal.

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 SEVERE POTENTIAL: As stated earlier this system by the time it reaches us will be much weakened with the severe potential greatly reduced, but never the less we will be keeping a close eye on it. If any severe t-storms do develop the main threat will be from damaging winds. Of course this scenario is 36-48 hours from happening so continue to track the storm at FOX5Storm.com, and of course on air throughout the day on FOX 5 Atlanta.

Rising Pollen Counts And T-storms Return: A Sure Sign Of Spring

The warmth of spring has been much applauded after a winter that seemed like it would never end, but now the undesirable after effects of the warm up are on the way. Today the pollen count started to creep back upward undoubtedly heading toward the peak numbers in the thousands that come every April. Today’s count although only 214 puts us well into the high category.

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Expect that number to rise this week as dry and warm conditions will persist through Thursday. Meanwhile a slow-moving cold front will continue to produce showers and t-storms across the Southern Plains and lower Mississippi Valley. Eventually those t-storms will approach our area on Friday.

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The threat of any severe t-storms will remain well to our west the several days. As the storm system moves east most of the strong dynamics will pass to our north giving us little chance of severe weather. The instability as well as the wind shear will diminish greatly compared to what it will be to our west Wednesday and Thursday, but since temperatures will be in the 70s the system will still produce t-showers that should remain well below severe limits. Hopefully we just pick up some much-needed rain late Friday and early Saturday.

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