A clipper system should slide through the Tennessee Valley, creating a windy afternoon Saturday. Colder nights coming up, but the afternoon should still be nice.

Go Fly A Kite Saturday!
A clipper system will move through the Ohio Valley Saturday and drag a cold front through the Tennessee Valley during the afternoon. This will set up a wind shift, with a breeze from the southwest during the morning, then northwest during the afternoon. The northwesterly breeze could be gusty at times from 15-25mph.

As for any precipitation, this clipper should be mostly dry, but could squeeze out some sprinkles especially northern parts of the viewing area. Some snow showers possible over the higher terrain of the Smokies Saturday evening. Much colder air will settle in behind this clipper with mid 20s by Sunday morning.

Sunday Full Of Sun!
After a cold start, we should have plentiful sunshine for most of the day Sunday. It should not be as windy as Saturday with just a light breeze from the north. Afternoon temperatures should range from the upper 40s mountains to low 50s valley.

Dry Through Midweek
Dry conditions should continue through at least Wednesday morning. Morning lows will still be below freezing through Tuesday morning, but each afternoon will be milder with temperatures nearing 60 by Tuesday. The next round of rain could roll in by Wednesday afternoon and some periods of showers should continue into Thursday.

Any Colder Air On The Horizon?
After yet another milder than normal week next week, there are some signs that colder air could filter in by next weekend. Now, will it be a prolonged cold spell? That is too early to tell, but the longer range signals that I constantly monitor are the Arctic Oscillation indices. This index continues to signal a period in the “negative” ranges, which could indicated a colder period for the eastern US. Here is a look at the latest computer model runs for the AO as of Friday morning.

GFS AO Outlook For The Next 14 Days (Negative values in blue after next week)

ECMWF (European) Model AO Outlook For The Next 10 days (Slightly negative values in blue through the 10 day period)

Both the GFS and ECMWF model trend the Tennessee Valley a little colder than normal by next weekend. We will just have to see of these trends continue. I will have a complete January assessment and look ahead to February coming up next week. I’ll have some interesting stats to show you!

David Glenn

As we have discussed in earlier posts and on-air, another soaking rainfall is headed toward the Tennessee Valley.
The best timing for the rain & storms should be Thursday afternoon through Thursday night. It appears that most of the rain is gone by sunrise Friday.

Updated Rainfall Total Projections
Rainfall projections still vary a bit among model data, but all agree on a period of soaking rain through Thursday night. Here are the latest projections.

NAM Model: 1.32″
GFS Model: 1.02″
WTVC Weather Central Microcast: 0.87″
ECMWF Model: 0.77″

Here is the NOAA Projection soaking over an inch locally and heavier amounts west. Click on map for a larger view.

What About Our Severe Chances?
With all the storm activity lately, this has been a popular question. Compared to the past two rain/storm events, this system should have a little less energy locally. It appears the better chances for severe storms could be south of Birmingham and toward the Gulf Coast. Now, as with any developing system, conditions COULD CHANGE. So, I am including the chance of thunderstorms locally for Thursday afternoon and evening, but the severe threat staying low for now.

SPC Severe Outlook for Thursday/Thursday Night…..(Green locally means non severe thunderstorms…..Yellow to our south means “Slight Risk” of severe storms)

As always, you can depend on the StormTrack 9 Team to keep you updated!

David Glenn

The blue sky and sunshine was a welcomed sight around the Tennessee Valley Tuesday, but the next round of rain is getting closer. And, some of the rain could be heavy.

A Look At Forecast Model Rainfall Projections
Although a few showers are possible Wednesday, the bulk of this upcoming rain event should be Thursday through Friday morning. Rainfall amounts vary among the forecast models, but here is a peek!

GFS Model: 1.67″
WTVC Weather Central Microcast: 1.36″ Chattanooga – 1.70″ Dalton
NAM Model: 1.20″
ECMWF Model: 0.92″

So, the range across the region could be 1″-2″. The latest rainfall projections from NOAA is in line with this as well. Click on map below for a larger view.

Severe Threat Remains Low
Some thunderstorms are possible locally, but the threat of severe storms remains low. The greatest instability with this system should stay along the Gulf coast. As always we will continue to watch this trend. Here is the latest from the Storm Prediction Center keeping the “Slight Risk” category well to our south. Click on map below for a larger view.

SPC Outlook for 7am Thu – 7am Fri

David Glenn

Temperatures should remain above normal for most of this week, but there are signs that colder air will finally move back in during the long range.

Is January 2012 The Warmest Ever?
Simply put…no. But, that has been a question that has been asked lately. Here are the stats so far. Through Sunday, the average temperature for January in Chattanooga is 43.5 degrees. This is 3.5 degrees above normal, but still far from the warmest January on record which was in 1950 with an average temperature of 53.7 degrees. 30 of the 31 days of January have record highs in the 70s which have yet to be surpassed this year so far.

For most of us, the frigid memories of the past 2 colder than normal January’s makes this year feel even warmer. January 2011 had an average temperature of 37.4 degrees (2 degrees below normal). January 2010 had an average temperature of 36.4 (3 degrees below normal).

Another Soaking Rainfall Ahead
Scattered showers could return as early as Wednesday afternoon. But, the bulk of the rain should arrive for Thursday through Friday morning. Overall instability should be less that the past two rain/storm events, so it looks like that thunderstorm activity should be lower. However, with yet another soaking rainfall, the risk of some flooding in spots is possible. The NWS rainfall outlook for Thursday through Saturday morning shows the potential of over 2 inches possible for the Tennessee Valley. Click on map below for a larger view.

Most longer range models do indicate drier conditions returning for the weekend.

Colder Temperatures Possible
By late weekend, model data is showing the possibility of colder air returning to the Tennessee Valley. Though nothing arctic through the weekend or next week, but the air mass should return us to normal for late January. In previous posts, I mentioned the change in the Arctic Oscillation and there are still signs that this Oscillation is showing signs of going “negative” which means a possible colder pattern evolving as we head into February. Longer range projections show the possibility of some arctic air invading the East & Southeast during the first couple of weeks of February. Only time will tell, but right now it looks like February may not be a repeat of January. Click on each map below for a larger view.

GFS Temperature Outlook For Thursday (Orange means above normal)

GFS Temperature Outlook for Sunday (Blue means below normal)

GFS Temperature Outlook for Next Sunday (Feb 5th….Again Another possible cold shot of air)

David Glenn

A strong low pressure system lifting out of the Plains States could set up another round of severe storms for the Southeast including the Tennessee Valley for tonight through early Monday.

The Storm Prediction Center continues to keep the Tennessee Valley under the Slight Risk category for severe storms, but areas to our west have been upgraded to a Moderate Risk as the risk there could be higher. The best timing locally should be late tonight during the predawn hours of Monday and through the hours after sunrise. This type of system could generate a line of strong storms capable of producing damaging wind and hail, along with heavy rainfall. As with any threat of severe storms, isolated tornadoes cannot be ruled out.

SPC Outlook Maps Valid Today Through 7AM Monday…Click Each for a larger view

SPC Outlook for Severe Storms (Slight Risk locally and Moderate Risk to our west)

SPC Outlook for Tornado Chances (lower risk locally, but higher west)

SPC Outlook for Damaging Wind (Similar pattern of lower risk locally and higher west)

SPC Outlook for Hail (again, similar pattern…lower risk locally, and highest west)

Why Are We Having Storms In January?
That question has been asked many times recently. Any time you have warmer than normal conditions in January, the chances for thunderstorms increases. Winter patterns are quite active with frontal systems moving through more often. So, when you have a warm air mass colliding with a cold air mass, storms often result. The added jet energy and lower freezing levels aloft due to it being winter adds even more to the instability. It’s similar to what we see in late February and March as our region warms and the late winter cold fronts move through.

Looking back at our weather history during late January shows that we have had other periods like this before. Here are just a few examples.

Jan 21, 2010 – Strong thunderstorms caused 2 reported tornadoes in Marion County

Jan 19, 1999 – Strong storms produced golf ball sized hail near Cleveland, TN

Jan 28, 1974 – Strong storms produced wind gusts of 60-75mph across east Tennessee

So, while some of us enjoy these warmer than normal temperatures, it comes with a price as it increases the risk of thunderstorms. Temperatures more typical for this time of year should eventually settle in by next weekend and into early February. As a result, things should stabilize a bit.

You can depend on the StormTrack 9 Team to keep you updated!

David Glenn

An active weather pattern is producing spring-like thunderstorms across the Southeast and Tennessee Valley. The next system should move in by Sunday night. This could spark another round of heavy rain and possible strong thunderstorms from late Sunday night through Monday morning.

The Storm Prediction Center has placed parts of the Tennessee Valley once again in the “Slight Risk” for the possibility of storms that could produce damaging wind and hail. This outlook covers the time frame from 7am Sunday to 7am Monday. But, the chance locally should not be until Sunday night. (Click on map below)

The Storm Prediction Center has placed a large part of the Tennessee Valley in the “Slight Risk” category for the risk of severe storms tonight and Saturday. This means that a few storms could be capable of producing damaging wind gusts and hail. The threat of tornadoes remains low, but cannot be ruled out.

A strong, and slow moving cold front will push through the Tennessee Valley tonight and Saturday providing not only the chance for severe storms, but also heavy rainfall. A Flood Watch is already in effect for our north Georgia viewing area.

You can depend on the StormTrack 9 Team to keep you updated!

David Glenn

SPC Severe Weather Outlook For Tonight Through Saturday Morning (click for a larger view)

SPC Severe Weather Outlook for Saturday