WAFF Weather

Winter Weather Advisory...Snow Potential..

The National Weather Service continues with a Winter Weather Advisory for all of North Alabama and Lincoln, Moore, and Franklin Co. in Tennessee.  Moisture will move in from the south after midnight tonight. A winter storm warning has been issued for the Birmingham area. 



This could begin to fall as sleet but will quickly change to snow.  It is possible the light snow will begin around 3am and continue off and on through the late morning hours on Tuesday.  If we are going to have problems on area roads this will likely begin before the morning commute on Tuesday. Temperatures will be in the upper 20s overnight tonight and only make it into the middle 30s Tuesday afternoon.  Another storm system will develop over the Gulf of Mexico and track ENE beginning late Wednesday afternoon.  This storm system could create more problems with the potential for heavier snow Wednesday evening into Thursday morning.  Stay alert to changing weather conditions.  

Here is a break down for a few areas for the overnight snowfall potential across North Alabama between 3am and Noon on Tuesday.  This is strickly model data but it gives you a good idea at what we are looking at in many areas.  It still remains possible that some areas will not see any significant accumulation tonight or with the Wednesday storm.








Please stay tuned for more information on this winter weather.  There are always changes so please keep checking back.

Chief Meteorologist 
Brad Travis
WAFF 48 Storm Team
We Track Storms

Winter Storm possible Monday night into Tuesday.

Significant winter storm will likely have a big impact on North Alabama and southern Tennessee Monday evening into Tuesday afternoon.  There is also growing concern for some ice and sleet accumulation along the transition zone, wherever it sets up. Right now this zone will likely set up somewhere between Hartselle and Birmingham and areas east into southern Marshall and DeKalb County.



Snowfall accumulations could range between 2-4" where the heavy band of snow develops. Right now the model we use on a daily basis (RPM) puts this area right along the Tennessee River. The heaviest snow will likely fall overnight Monday night through 10am Tuesday. 

Current thoughts.....


The main event will begin to move in around 5pm Monday evening. Beginning in the Shoals first and tracking east, some areas could see a brief period of rain and sleet before it changes to snow. Roads could quickly become hazardous Monday evening and remain that way all day Tuesday.  If the current forecast verifies we will have hazardous driving conditions develop between 7-10pm.  Rain and sleet from earlier in the afternoon will freeze and create a layer of ice under the snow pack on area roads.


If we do get Freezing Rain along the transition zone I mentioned above, there could be a threat to trees and power lines. Too early to tell how much ice could form.

Images from Pinpoint Predictor.  The exact track and amount forecast will vary from run to run.









Bottom line. Expect about anything with this developing winter storm. Make sure you are prepared in the event it does produce hazardous weather in your area. If you are going to be traveling make sure you have a survival kit in your car that includes blankets, food and water. Try to keep your gas tank on at least 1/2 tank.

School delays and cancellations could go out as early as Sunday evening. You can check our website for more information or download our news and weather app's as well.

The WAFF 48 Storm Team will continue to track this developing winter storm and have updates on social media and the web. 

 

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

Friday morning forecast update.

Late tonight scattered showers will develop across northwest Alabama and slowly track to the east.  The amount of dry air in place over northeast Alabama could limit any significant moisture from reaching the ground for areas east of I-65.  I expect to see the light rain change over to some sleet and snow west of I-65 after Midnight.  Some accumulation of sleet could occur on bridges and overpasses early Friday morning.  There remains a lot of uncertainty on the exact areas of wintry weather and the exact amount.  The biggest challenge is the amount of moisture.

The latest forecast information shows very dry air in place. Therefore, some areas might not see any moisture until later Friday morning when temperatures rebound into the middle 40s.  Regardless the outcome, this winter weather event will be limited to a  2-4 hour window.

The weekend will be unsettled with showers and thunderstorms developing Saturday afternoon and evening into the early morning hours on Sunday.  Temperatures will be in the middle to upper 50s.  Behind the weekend storm system we will have some sunshine next week but temperatures will be below normal all week.

You can stay up to date with all the changing weather by following us on Facebook and Twitter and by going to waff.com.  Also, download our weather app for video forecast updates and an hourly look at your weather forecast.

Have a safe night.

 

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

Snow chances for Saturday.

Mother nature continues to keep us on our toes with changing weather conditions.  Right now it looks like more moisture will be on the way ahead of the next disturbance tomorrow afternoon.  Most of the week it has been looking like scattered rain showers for Saturday.  The air over North Alabama is very dry right now and for this reason it is looking like the precipitation that falls Saturday undergo a process called evaporative cooling.  As the rain begins to fall into the dry air  it will begin to cool the atmosphere and therefore could lead to a chance for a rain and snow mix in some areas of North Alabama and southern Tennessee.  Right now the most favorable areas are going to be along and north of the Tennessee River.  Keep checking in with Meteorologist Lauren Jones this weekend for the latest information.  Right now it looks like we will see little if any accumulation.





You can also keep up with the WAFF 48 Storm Team on social media and through our weather app for your iPhone or Android.

Temperatures will rebound into the upper 40s and lower 50s for Sunday and Monday.

 

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

Back to winter.

After highs in the middle to upper 40s on Thursday  the clouds will return ahead of an arctic cold front.  There will likely only be snow flurries along the front due to the lack of any significant moisture.  The bigger story will be the colder air moving in Friday morning. 

The chance for seeing some snow flurries Thursday night will be best from NE Alabama into the Cumberland Plateau in Tennessee after 10pm.

Pinpoint Predictor has very limited moisture and well pronounced cut off as you get into Tennessee. 

Forecast temperatures at 11pm Thursday night.

Much colder air moves in before sunrise Friday morning.

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

Winter Storm Winding Down. Patches of Ice Possible Friday AM.

The Winter Storm Warning will expire at 6pm.  Some areas will likely be dropped from the warning before that as the snow moves away.



For the rest of the day the area of heavy snow will continue to track east and impact areas East of I-65.  Most of the slush on the roads will continue to melt soon after the snow stops falling.  An additional 2-3” of snow is possible in areas of Northeast Alabama in DeKalb, Jackson and Marshall counties.  The snow will be gone in all areas by 6pm. 



Overnight tonight the concern will be the freezing temperatures that will move in behind the storm system.  Temperatures will being to fall into the middle to upper 20s early Friday morning. Expect delays with your morning commute.  This will be temporary because we are expecting sunshine and warming temperatures later in the morning. 



Saturday still looks great with highs around 54 and plenty of sunshine.

 

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

On the edge. Heavy rain or Heavy snow? Winter Storm Warning Issued.

A winter storm warning has been issued for Jackson, Marshall and DeKalb County for Thursday. A winter weather advisory for the counties in purple.




The rain will change over to snow in some areas late Thursday morning with accumulation possible on grassy areas but not the roads.  A winter storm watch has been issued for all counties east of I-65.  This also includes Limestone and Lawrence counties.   One to three inches of snow is possible with the best chance of a three inch snowfall being over Cullman, Marshall and DeKalb counties. Although most of the roads will just be wet as the snow falls, there could be some heavy bursts of snow that could make bridges and overpasses slushy and slick Thursday afternoon.  Overnight Thursday into Friday the temperatures will fall into the middle and upper 20s.  With temperatures well below freezing Friday morning we will likely have black ice on many roads that remain wet.

Here is a timeframe on when to expect the rain to change over to snow if it is going to.



Looking at the latest forecast guidance it is going to be a very close call regarding precip type and snowfall amounts. 

Model guidance is stuggling with the amount of warming that is going to take place from the upper level cold core low pressure system.  It looks as if this area will be warming as it move over North Alabama and NW Georgia.  This cold pocket of air what will change the rain over to snow.  If the models are correct we will likely only end up with some minor accumuations of 1-2 inches. Most of which will melt soon after it falls and only accumulate on grassy surfaces. 



Tonight the RPM model we use most of the time for Pinpoint Predictor is showing an increase in the rainfall amounts and rainfall rates over NE Alabama early Thursday afternoon.  It is calling for about a .5 inch of rain before the possible transition to a rain snow mix that produces another .90" of liquid equivalent.  If this were to fall as snow we could see a larger areas of more signficant snow accumulation.


The image above shows the 11am timeframe.  In the image you see the pink and blue mixed in with the normal heavy rain we show in yellow and green.  This is showing how close we are to having heavy snow instead of heavy rain in these areas east of I-65 late Thursday morning.


If the upper level temperatures don't cool as much as the forecast models think they will we could be dealing with more of a 3-5" swath of snow from Cullman County into Dekalb County into Thursday afternoon.  I stress this is a big if right now.  Somethign we will keep an eye on. Regardless we are still just expecting snow accumulations on grassy areas.  Keep in mind if we do see some heavy burst of snow bridges and overpasses could become slick and slushy in a hurry.


Travel problems could develop overnight Thursday into Friday as water from rain and melted snow begins to freeze.  Tempeatures will be in the middle to upper 20s. 

By Friday afternoon temperatures will warm into the upper 40s with some sunshine returning.  Most of the roads will be dry Friday night into Saturday but due to recent rainfall we could see some fog form early Saturday morning.  The weekend looks dry with highs in the 50s Saturday.  A cold front will move in Sunday an push temperatures back into the 40s for afternoon highs.  Early next week is looking cold with highs around 40s and lows in the lower to middle 20s.

Have a great night.

 

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

Early thoughts on next weeks storm system. Snow is a possibility.

When it comes to winter weather forecasting in the Tennessee Valley many times you don't know what to expect until the night before.   To get snow in North Alabama you need the perfect setup.  You typically need a surface area of low pressure to the south.  The closer this area of low pressure is to  the Gulf of Mexico the better.  You also need a good supply of arctic air moving south. There is also a process through dynamic cooling from a cold core upper level low pressure system that can bring down the snow even though temperatures to start the day are not even close to freezing at the surface.   Some storms systems in the Tennessee Valley are a combination of both. 

The one thing we are trying to do this far out is get closer to a more accurate solution for the Tuesday/Wednesday time frame next week and find some forecast model consensus.  Depending on the exact track and strength we could end up with just cold rain or we could see some accumulation of snow on grassy areas.  Other areas of the Southeast could be dealing with stronger thunderstorms.  Regardless of what the setup  looks like right now the system is still nearly a week away and a lot of fine details will not show up for several more days.  Here are some graphics that show you what we are dealing with as we track the evolution of this developing storm system.  There are two primary long range forecast models we use.  1.  The GFS (American model) 2.  The ECMWF (European model) 

Three things we need to keep in mind as we go forward.  1.  Models have a hard time dealing with the extend of Arctic Air that is on the move.  2.  Models have difficulty with storm systems coming out of the Desert Southwest and parts of Mexico.  3.  Any error on the model run early in the run will only grow exponentially with time.  Meaning if the beginning model solution is not accurate the forecast days that follow are useless. 

Plenty of Arctic air in central Canada. Today December 11, 2012

Here is the European model solution for Tuesday December 18th at 4pm. 


The rain/snow line in the dashed purple line is across NW Alabama with the surface low near Montgomery.  This low placement isn't bad for snow in North Alabama.  The blue arrows represent the jet stream.  This would give us a rain changing to snow from west to east situation.  The changeover would be due to evaporative cooling from the cold core low.  Strong thunderstorms for SE Georgia and north Florida.

Below is the GFS (American model solution)

The rain/snow line is almost identical.  The time frame is moved up to 1pm Tuesday.  The surface low placement is not good at all for snow in North Alabama.  It is closer to Chattanooga.  We would need a lot of moisture and some strong dynamic cooling to change the cold rain to snow.  The surface low is stronger than the European model. 

The closer the solutions by these two models the better.  That will increase the accuracy and the confidence of forecasting this system.  If we can get a slower developing storm system that is farther to the south we might be in business for some snowfall.  Ground temperatures are warm for this time of year so chances are if we get any snow it would likely only stick to grassy areas.   But it is still possible the Arctic area will make it farther south that the models think.   As I mentioned earlier they have trouble with Arctic air on the move.

Stay tuned but don't go getting your bread and milk just yet.  I'll keep you updated with each model run.  I will focus on the morning and evening model runs. 

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

More rain tonight followed by a chance of snow Wednesday

We continue to monitor our changing December weather pattern.  A powerful upper level storm system will approach from the West overnight tonight.  As this disturbance gets closer expect scattered showers to develop late this evening and overnight tonight. 

The middle of the morning on Wednesday some of the rain will begin to change over to snow along and west of I-65.  This transition will continue from west to east during the early afternoon hours. 

This is a forecast image from WAFF 48 Pinpoint Predictor showing the transition from rain to snow in pink and the snow in white.  around 9am.

Tempeatures will remain above freezing into the early afternoon hours.

The moisture will be on the way out of North Alabama by 6pm and temperatures will being to fall below freezing just before 9pm.  There will be a short window of opportunity for the roads to dry before some patchy ice begins to form late Wednesday evening.  We will continue to monitor the latest forecast guidance as the storm system gets closer.  Stay tuned to WAFF 48 News on TV and online. 

Brad Travis
Chief Meteorologist
WAFF 48 Storm Team
We Track Storms

Pinpoint Predictor for 3pm.

Forecast temperatures for 9pm Wednesday.

Watching the Weekend.

While Thanksgiving, Black Friday and the Iron Bowl look rain free, late Saturday night a storm system is developing that will likely bring heavy rain, strong gusty winds and just maybe a chance for snow.

 

Shower and thunderstorm chances will go up Saturday evening and continue into Sunday morning.  Depending on the location of the upper level part of this storm system we could see some snow develop Sunday night into Monday.  This will be a very difficult forecast this far out and it will likely undergo several changes over the coming days.  Even if we see snow we are not anticipating any travel problems due to the warm ground temperatures. 

Here is the latest short range forecast model (below) that is now out to Saturday morning.  On it you will see the colder air developing over the Rocky Mountains under the 1049mb area of High Pressure.  That is a very strong area of high pressure for this time of year.  The air behind the blue dashed line is close to the leading edge of the much colder air mass.  The green areas represent forecast rainfall.