Changes are coming fast and furious to Alabama’s weather in the week ahead.  Rain, a few strong storms, a big cooldown, and even a few snow flurries are all possible between now and the weekend.  Let’s get right to the meat and potatoes of it:

SEVERE WEATHER? There are some indications that we could deal with a bout of strong to severe thunderstorms on Wednesday.  A warm front will lift northward late Tuesday night, in response to a developing area of low pressure in the northern Gulf of Mexico.  That warm front will likely generate a large mass of rain and embedded thunderstorms.

Then, as the surface low wraps up and moves north-northeastward, winds will shift around to the southeast during the day on Wednesday.  This will likely lead to a modest influx of unstable, thunderstorm-friendly air into Alabama, especially areas south of a line from Evergreen to Auburn.  With plenty of wind shear, the risk of a cool-season severe weather episode is present.

A Big Factor:  The forecast track of the surface low – the 18z GFS takes the surface low from near Livingston, AL to Huntsville.  This would mean the greatest risk of severe weather in our state would likely be in east and southeast Alabama, with an even higher risk of severe weather in Georgia.  The timing of all of this also leads me to believe the risk of severe weather is highest into central and eastern Georgia.

Another big issue will be the warm front’s northward progress into Alabama Tuesday night.  If a large, persistent mass of rain sets up north of the warm front, that could keep the front farther south.  This would limit the instability return into Alabama and diminish the risk of strong storms.

Bottom Line: Expect rain, heavy at times, to begin Tuesday night and last through much of the day on Wednesday.  Thunderstorms will be involved, and some of them could be severe.  The greatest risk of severe weather will come south of a line from Evergreen to Auburn, and the highest probability of severe storms is between 4am and noon on Wednesday.  Some Alabama cities could see in excess of 2″ of rain.

MAJOR COOLDOWN, SNOW FLAKES? Much cooler air will surge into Alabama late Wednesday and into Thursday.  Thursday looks to be a raw, windy day, with temperatures doing well to hit the lower 50s.

The next system in this active southern stream setup begins to form late Friday in the central Gulf of Mexico.  With cold air in place, there are indications that we could squeeze out a few snow flurries Friday night into Saturday morning.  Moisture is VERY limited, and surface temperatures should stay at or just above freezing, so there are no major concerns here at all.  At this point, this looks like much more of a novelty item than any significant weather situation.

The big story in all of this is the change to colder weather.  High temperatures on Friday will stay in the 40s for almost all of Alabama, and a breezy north wind will make it feel even colder.  The cold temperatures will linger Saturday, before we begin to slowly warm things up over the weekend.

More on the blog throughout this wild weather week!

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The 2009 Atlantic hurricane season officially ends today marking the close of a season with the fewest named storms and hurricanes since 1997 thanks, in part, to El Niño.

Nine named storms formed this year, including three hurricanes, two of which were major hurricanes at Category 3 strength or higher. These numbers fall within the ranges predicted in NOAA’s mid-season outlook issued in August, which called for seven to 11 named storms, three to six hurricanes, and one to two major hurricanes. An average season has 11 named storms and six hurricanes, including two major hurricanes.

“The reduced activity was expected and reflects the development of El Niño during the summer,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, a division of the National Weather Service. “El Niño produced strong wind shear across the Caribbean Sea and western tropical Atlantic, which resulted in fewer and shorter-lived storms compared to some recent very active seasons.”

Two systems, Claudette and Ida, brought tropical storm force winds to the U.S. mainland. For the first time in three years, no hurricanes hit the U.S. There were 38 hurricane hunter aircraft reconnaissance missions flown by NOAA and the U.S. Air Force over the Atlantic Basin this year compared to 169 in 2008 – another indication of a less active season.

“El Niño is expected to reach peak strength this winter, and will likely continue into the spring. It is far too early to say whether El Niño will be present next summer,” added Bell. NOAA will issue its initial 2010 Atlantic Hurricane Outlook in May, prior to the official start of the season on June 1.

NOAA understands and predicts changes in the Earth’s environment—from the depths of the ocean to the surface of the sun—and conserves and manages our coastal and marine resources.

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First up, the rest of today…the main rain area is moving out of the state as it weakens, and we are left with low clouds, some patchy drizzle, and breezy conditions for the rest of today.  We have already reached our high for the day, and temperatures will continue to fall for the rest of the the afternoon and evening as clouds decrease.

Tuesday:  Easily the nicest day of the week.  Plenty of sun, and mild, with temps around 60…winds will begin to shift out of the south and pick up late in the day into the evening.

Wednesday:  Will be as ugly as Tuesday is nice. Rain begins early, and persists for a while.  Surface low pressure develops in the Gulf and moves northeast across the state; the latest data has the low tracking over Birmingham as it heads NE.  On this track, the most unstable air would be limited to along and south of a line from Jackson, AL to Montgomery to Anniston; severe weather would be likely be limited to South AL and NW Florida.  However, this assumes that the computer model forecasts are correct.  The TREND for the models, which is just as important as the actual model data itself, is for the low to be somewhat slower and further west, which would open up more of the state to a greater chance of severe weather.  Regardless of the severe weather threat it is going to be a very wet, and very windy day; there is forecast to be a tremendous amount of wind energy aloft with this system, and this should translate down to the surface.

Thursday: The system will be exiting the area during the day, and a very cold airmass will trail behind it…this could be some of the coldest air of the year so far, and temperatures will struggle (and probably fail) to reach 50 in the afternoon, with very brisk north winds.  Clouds should clear late, but it would not shock me if we got a report of a flurry or two Thursday night across the Tennessee Valley before the clouds finally clear.

Friday:  Prior to about 11am this morning, this was a pretty easy forecast, but some changes in the modelling from this morning has made this forecast at least trickier…here is why.

This is output from the US GFS (Global Forecast System) model from this morning for this Friday.  The colored areas are precip over the previous 12 hrs (in this case Friday morning), the black line are lines of equal pressure (isobars) and the colored lines are the temperatures at 850 millibars (roughly 5000 ft above the earth’s surface).  Notice that most of Alabama is between 0 and -10 degrees (C) at 5000 feet with precip being recorded.  What is happening is a weak wave of low pressure is redeveloping in the Gulf, and is creating an overrunning event over Alabama.  This is the most common scenario for winter type weather generation in the south:  A cold airmass in place is overrun by warm moist air aloft which can generate various types of precipitation.  In this case, if this model is correct, we would see some sort of light wintery mix across the state during the late day Friday.  However, while there is some support from some other modelling this morning for this solution, this is JUST ONE SET OF DATA.  The first hint of this was this morning; the previous modelling holds off precip until the late weekend after we warm back up.  I am not prepared to call for winter weather in the state Friday…it’s just not very likely at all…but we will have to monitor new data as it arrives to see if these models are really on to something, or is this is just a bad run of data.  Regardless, it’s going to be cold Friday, with morning lows in the upper 20’s.

I will post more this evening if the model data lends more support to the ideas for Friday.

Jason Kelley
Fox 6 Meteorologist
jkelley@wbrc.com
Twitter: Fox6WxJason
Facebook: wxman007

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There is a lot of interesting weather ahead this week as we deal first with a double-barrel storm system, followed by s sharp shot of much colder winter weather.  The system bringing today’s rain across the area will be east of here tonight.  Clouds will increase again on Tuesday and rain and thunderstorms will overspread the area tomorrow night and Wednesday.  Rainfall with the second part of this storm system could be rather significant with several inches of rain possible in south Alabama.

Some strong to severe thunderstorms are possible, especially across south Alabama with this system.  Right now, the Storm Prediction Center has outlined the best chance of severe weather across southeast Alabama on Wednesday.  Here is the current Day 3 severe  weather outlook.

Behind the storm system, look for much colder air to stream into Alabama!  We could easily see lows in the 20’s by late in the week.  Get ready for a real shot of winter weather during this first week of December.

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The following is from our friends at the National Hurricane Center -

The 2009 Atlantic hurricane season officially ends today, marking the close of a season with the fewest named storms and hurricanes since 1997 thanks, in part, to El Niño.

 Nine named storms formed this year, including three hurricanes, two of which were major hurricanes at Category 3 strength or higher. These numbers fall within the ranges predicted in NOAA’s mid-season outlook issued in August, which called for seven to 11 named storms, three to six hurricanes, and one to two major hurricanes. An average season has 11 named storms and six hurricanes, including two major hurricanes.      

 “El Niño is expected to reach peak strength this winter, and will likely continue into the spring. It is far too early to say whether El Niño will be present next summer,” added Bell. NOAA will issue its initial 2010 Atlantic Hurricane Outlook in May, prior to the official start of the season on June 1.

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The rain was coming down this morning as expected.  I just took my son to school and the visibility was fairly low due to heavy rain along highway 280.  It appears the heaviest rain will continue at least through 9am.  I’m still thinking we’ll see some gradual clearing this afternoon.  As my mom would say, this is great sleeping weather.

Here’s big heads up:  Wednesday will be windy.  Whether or not we see severe weather here – expect winds upwards of 35mph.  If you have Christmas decorations or lawn furniture that can easily be picked up by the wind – please make sure it’s put away by Wednesday or it’s likely to be in someone else’s yard or destroyed.  We’ll see an incredibly tight pressure gradient along with a 120kt+ low level jet on Wednesday.  Severe weather still looks likely in the Southeast.  Again, the best chance will remain Montgomery southward.  But, if the forecast models are underestimating instability even slightly it could get active in Central Alabama.  We’ll likely see rainfall in the 2-3″ category. We’ll keep you posted.

James-Paul Dice
Fox 6 Chief Meteorologist
james.dice@wbrc.com

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Moderate to light showers are moving through our area today. Most of the rain north if I-20/59 should end by noon. The remainder of our showers should end by sunset. Skies are expected to rapidly clear tonight, with lows dropping into the mid-30s by tomorrow morning.

Tuesday should begin with sunshine. Tuesday night into Wednesday night a strong upper Low will be moving through our area from the southwest. That low will bring a chance of strong to severe thunderstorms mainly to southeast Alabama, but we won’t rule out a chance of isolated strong storms to central or north central Alabama as well.

Clouds could linger through part of the day Thursday.

Dry weather is expected Friday through the weekend along with some of the coldest overnight temperatures so far this season.

A chance of showers returns to our forecast by Monday of next week.

Mickey Ferguson

FOX6 Weather

mferguson@wbrc.com

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The fall severe weather season has generally been quiet. We had the one tornado event just before that ushered my good friend Jason Kelley onto the FOX 6 StormWarn Team, but after that, things have really been quiet. I get the idea that may be changing. By Wednesday morning, an intense area of low pressure will be rapidly organizing at the surface near coastal areas of Louisiana, in response to a potent upper-level disturbance coming out of Texas. The surface low will lift to the northeast and rapidly deepen through the day as the upper-level disturbance takes on a negative tilt. Negatively tilted systems are often associated by very dynamic weather that changes very rapidly over short distances. From the looks of it now, 60-65+ dewpoints will come onshore south of a warm front that will lift northward with the surface low. Below is a plot from the 00Z NAM, that shows the CAPE and vertical wind shear at 6 pm Wednesday.

The NAM is projecting surface-based CAPE values to exceed 500 j/kg over west central Alabama by Wednesday evening, and this would progress eastward with time, as the storm system lifts off to the northeast and the cold front charges eastward. I think that 400-500 j/kg of CAPE is very doable up to near the warm front, in the warm sector of the storm system. The main question I have is the track of the surface low and how rapidly it lifts northeastward. This will determine whether any part of the FOX 6 viewing area breaks into the warm sector, or if the warm sector stays south and east of the coverage area. The NAM… and to a degree, the UKMET… lift the surface low across MS and west AL into TN Wednesday, and aren’t as fast as some of the other models in doing so. This allows the warm sector to lift as far north as central portions of Alabama during the day. Other models, such as the GFS, Canadian, Euro, and previous UKMET runs actually lift the storm system northeastward more rapidly and are also a little further east with the surface low track, generally lifting it uo I-65. This would keep the warm sector from ever reaching the FOX 6 coverage area, and would keep any threat of severe weather south and east of our area. It bares monitoring because the UKMET did shift westward on Sunday’s daytime run… and the GFS nudged slightly westward also. It’s a really murky situation right now. The dynamics and shear are there, and actually favor a higher-end event. However, that cannot happen if the instability and low-level moisture aren’t there also. I think that even in the worst-case scenario possible, there will NOT be enough instability and low-level moisture for a major severe weather event. Having said that, if a western and/or slower surface low track verifies, enough instability may creep into parts of central Alabama for a few warnings to occur…. possibly even a tornado warning or two. The track and speed of the surface low will be very crucial in determining what kind of threat, if any, the FOX 6 viewing area faces.

We urge you to be mindful of the weather situation as we approach midweek, and check back with FOX 6 and the weather blog here for updates as we get closer to this storm system. If you have a NOAA Weather Radio, check the batteries to make sure they’re fresh…. and if you don’t, think about buying one as you go out holiday shopping. You can get a great weather radio for around $35, and if your family is safe during a severe weather event because you were awakened for a weather warning during the overnight, it’s the best $35 you’ll ever spend.

Fred Gossage
Blog Contributor
http://www.twitter.com/fredgossage

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There will be tornadic storms in the Southeast Wednesday and possibly early Thursday morning.  The question is where.  At this point, I’d say the best chances will be South Alabama, South Georgia, Florida’s panhandle, and maybe even the Carolinas.  However, if we get any instability across Central Alabama – the weather will get active very quickly.  These high shear/low instability situations can sometimes catch you by surprise.

We will need to monitor Wednesday closely for the possibility of some quick spin-up tornadoes.  I will say convection to the south of us should limit our severe weather threat.  One of the purposes of this blog is to give you some insight and even a behind the scenes look at the forecast process.  My experience as a meteorologist tells me when you have helicity this high – you can’t let your guard down.  I have included NAM model output displaying a shear bullseye over Alabama. The best chance for severe storms (if we’re going to see something) would be Wednesday afternoon.  We’ll keep you posted.

James-Paul Dice
Fox 6 Chief Meteorologist
james.dice@wbrc.com

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You may have noticed a strange ring around the moon tonight.  We’ve already received a number of calls from viewers noticing the same thing.  Here’s the explanation.  The ring is caused by the refraction of moonlight (which is reflected sunlight) from ice crystals in the upper atmosphere.  The hexagonal shape of these crystals is focusing the light into a ring.

Here’s a bit of weather folklore that relates directly with the ring around the moon.  It’s said the ring signifies bad weather is coming.  There is a bit of truth to that.  If you’ve been watching the forecast, you know rain is on the way.  The approaching front typically creates more cirrus clouds which are made of ice crystals.  So actually, the ring around the moon is a pretty good indicator of approaching rain.

Have a great week!

James-Paul Dice
Fox 6 Chief Meteorologist
james.dice@wbr.com

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