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Central Alabama 7 Day Forecast

Winter Starts; Storms Tuesday

| 6:52 am December 21, 2014

An all new edition of the ABC 33/40 Weather Xtreme video is available in the player on the right sidebar of the blog. You can subscribe to the Weather Xtreme video on iTunes by clicking here.

There is a lot happening in the weather for Central Alabama on top of the major holiday and all of the preparations for it. Clouds held in much longer than expected yesterday and overnight resulting in a tremendous temperature gradient across Central Alabama. In the northwest counties where the sky cleared late yesterday and last night, the mercury dropped into the upper 20s, but further southeast in the Montgomery area where the clouds held tough, readings were around 50 degrees at sunrise. This gradient is the result of the variation in clouds and there isn’t even a front involved. This is a bigger gradient than we get with some fronts. The cloud cover forecast remains tough today as many spots will remain cloudy while the area northwest of Birmingham will see some sun.

On top of that, we have a weak wedge or cold air damming situation developing which could spell some light rain for the eastern sections of Alabama tonight and early Monday from about Birmingham eastward.

And on top of that, we have a major upper level storm system carving out a very cold trough over the lower Mississippi River Valley which may produce severe weather for Alabama on Tuesday, possibly lingering into the early hours of Wednesday. The models are a tad slower with everything, so it appears the best threat for severe storms will come Tuesday afternoon into early Wednesday morning. CAPE values have come up on the latest model run, and there is sufficient shear to support a tornado threat along with damaging straight line wind. But, and there is always a but, there is still some question as to the amount of instability that will occur. Simulated radar forecasts suggest a large area of storms developing along the coastal areas, and those storms could potentially limit the amount of destabilization to our atmosphere. MOS guidance numbers bring 60 degree dew points as far north as Birmingham, but if those numbers are off by just a few degrees, we might not get enough destabilization for severe storms. So the situation remains somewhat fluid at this time, and we’ll need to be watchful of future model runs to see what does develop.

The surface low and front go by us early Wednesday morning, so I expect Wednesday, Christmas Eve, to be one of those days where the temperatures do not behave in their typical diurnal fashion. Out highest temperature for the day is likely to occur shortly after midnight with the temperature falling for much of the day including the daylight hours. So I’m forecasting temperatures falling through the 50s during the day.

Christmas Day should see a return to some sun with lows in the 30s and highs in the lower 50s. Friday, the day to return or exchange those gifts that didn’t quite hit the mark, should be dry and a bit warmer with highs climbing into the lower 60s. But the next system is taking shape to bring a chance for rain to Central Alabama on Saturday, though moisture availability is questionable. And we cool down once again.

And the screaming message from the maps in voodoo country is that we are going to stay busy with a steady stream of weather systems and a chilly look to the pattern with the long wave trough anchored over the eastern half of the country.

And you can follow news and weather updates from ABC 33/40 on Twitter here. Stay in the know by following the whole gang – here’s the list…

James Spann Charles Daniel Bill Murray
Brian Peters E-Warn (AL wx watches/warnings)

James Spann will be back with the next edition of the Weather Xtreme Video by 7 am Monday. I hope you have a great day. And in the spirit of this holiday season, be sure to perform at least one act of shameless kindness with the hope that it will spread. Godspeed.

-Brian-

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Tuesday’s Severe Weather Threat

| 6:36 am December 21, 2014

Brian will be along shortly with a new Weather Xtreme video and a forecast discussion. These notes concern the potential for severe weather in Alabama Tuesday. With so many people traveling this time of the year, there is great interest in the expected weather.

SPC OUTLOOK: On the day three convective outlook from the Storm Prediction Center, which covers the period from 6:00 a.m. Tuesday through 6:00 a.m. Wednesday, they have the standard “slight risk” of severe weather identified along and south of a line from Livingston to Greenville to Geneva. A “marginal risk” extends northward to a line from Hamilton to Birmingham to Auburn…

day3otlk_0830

Let’s first point out this is nothing unusual; we are in the core of the late fall/early winter tornado season in Alabama. Having thunderstorms at Christmas time has always been common here.

TIMING: The core severe weather threat will come from about 3:00 p.m. Tuesday through 3:00 a.m. Wednesday.

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Understand showers and storms are possible Tuesday morning as well, but those storms should remain below severe limits.

HIGH SHEAR, LOW CAPE: Another thing common with cold season severe weather threats in Alabama is this kind of setup; strong shear in the atmosphere, but marginal instability. CAPE stands for Convective Available Potential Energy, and is a measure of instability. Low level (0-1 km) storm relative helicity values are impressive…

NAM_221_2014122106_F63_HLCY_1000_M_ABOVE_GROUND_0_M_ABOVE_GROUND

But it remains to be seen if sufficient instability can develop over the northern half of Alabama. Thunderstorms near the Gulf Coast could cut off the inflow of deep moisture into our part of the state, and clouds and morning showers could also limit the instability. Because of this the SPC guys have kept the core severe weather risk over the southern part of the state.

But, model data hints Birmingham could approach 70 degrees Tuesday afternoon, with dewpoints rising to near 60, which will help to create low level instability.

Keep an eye on blog updates for potential changes.

CHRISTMAS EVE: Rain will push out of the state Wednesday morning… the map below is valid at 12:00 noon CT Wednesday (from the new high resolution parallel GFS model)…

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Wednesday will be mostly cloudy, windy, and colder with temperatures falling through the 50s. There might be a snow flake or two over the far northern part of the state under the cold core upper trough passing overhead, but it won’t amount to anything with surface temperatures far above freezing, and the deeper moisture long gone. And, the latest model data suggests no risk of flurries over far North Alabama… just too warm.

CHRISTMAS DAY: Looks very nice with ample sunshine and a high in the 50s.

ONE MORE THING: We live in a world of weather hype thanks to national news media and the clickbait guys using outrageous headlines on social media. This is not a “monster storm”, “unprecedented”,  with “millions in the path” that “stuck without warning”. And, Alabama will not have a White Christmas with big Christmas Eve snow storm. Seems like we spend most of our time these days putting down the insanity that is floating around.

On our blog, we are not always right, but we use sound science, level heads, and do our best to simply communicate the truth.

Stay tuned for updates later today….

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Christmas in Fairhope

| 5:23 pm December 20, 2014

Fairhope, a charming community on Alabama’s Gulf Coast, comes alive with color and decorations during the Christmas season.

Enjoy this video montage shot earlier this week, showing what Fairhope looks like at Christmas…

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Severe Weather Potential Tuesday

| 2:27 pm December 20, 2014

This is a preliminary look at the severe weather potential across Alabama Tuesday, December 23. With so many people traveling that day, we all need to pay attention to the situation, although this early in the game there are more questions than answers.

LARGE SCALE SETUP: A vigorous, 500 mb upper trough will form west of Alabama early in the week, providing excellent support for showers and thunderstorms Tuesday.

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A low level jet (about 5,000 feet off the ground) will develop, in the 40-50 knot range, by Tuesday afternoon.

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So, the dynamic setup is impressive, but as always in the cold season, the big question is the instability, or the ability of air parcels to freely rise and become buoyant. A narrow tongue of higher instability will form ahead of a rapidly deepening surface low across Alabama Tuesday evening…

gfs_cape_mslp_ky_15

It doesn’t take much CAPE (convective available potential energy) for severe weather issues in December, and even with CAPE values of 500 j/kg we will need to watch the situation closely. The 12Z GFS model is printing a high of 71 degrees for Birmingham Tuesday, with potential for dewpoints to rise into the 60 degree range.

TIMING: The highest risk for severe weather across Alabama will come, most likely, during the afternoon and evening hours Tuesday, when the air is most unstable. I would say now the prime window is from 12:00 noon to 12:00 midnight. But, understand this could easily change for an event three days away.

PLACEMENT: The SPC Day Four convective outlook suggests the primary risk of severe weather will come over Southwest Alabama…

day4prob

However, based on the forecast parameters, I would say most of the state will have some risk of severe storms, especially along and south of U.S. 278 (Hamilton to Cullman to Gadsden). I expect the SPC outlook to expand northward and eastward in future updates.

MODES OF SEVERE WEATHER: This is what has happened with similar surface and upper air conditions, using the top 15 analogs (from CIPS analog guidance)…

SVRgfs212F096 (1)

You can clearly see that all modes of severe weather will be possible with a setup like this, including a few tornadoes. Remember, this graphic is showing total severe weather output from 15 events, so it won’t be this active Tuesday… just a way of looking at what has happened in the past with a similar setup.

IMPORTANT: While the overall synoptic scale looks favorable for some severe weather Tuesday, we really won’t see how the mesoscale features will play out until tomorrow night and Monday. So, determining the overall threat level this far out is very difficult to do. Don’t let the social media kings of hype bother you, this doesn’t look like some “historic” event with “millions in the path”… just a situation that we have fairly often this time of the year. This is still the core of the late fall/early winter severe weather season in Alabama. Not unusual at all.

We will post frequent updates here as we get closer to the event.

CHRISTMAS EVE: The social media hype guys will also probably push a chance of snow on Wednesday under a very cold upper trough moving over the state.

gfs_ptype_slp_ky_19 (1)

Could there be a few a few flurries over extreme North Alabama Wednesday? Yes, but the deeper moisture will be long gone, and temperatures will be well above freezing. The bigger issues will be north of here with a very deep surface low just north of the Great Lakes…

gfs_ptype_slp_east2_19

This will bring lots of wind and snow to the Great Lakes region Wednesday, and lots of rain for the eastern seaboard.

CHRISTMAS DAY: Looks like beautiful day for Alabama, with a sunny sky and a high in the 50s.

Again, stay tuned to the blog and we will keep you advised. If you are traveling, stay safe!

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Clearing Slowly Advancing

| 9:56 am December 20, 2014

Your day is either very bright and sunny or cloudy and dreary depending on exactly where you are. See the satellite image below. Places like Hamilton and Double Springs are in the sun while places like Anniston, Talladega, and Lineville will probably not see much sun until later in the day.

-Brian-

Visible Satellite on Dec. 20, 2014,at 9:30 am.

Visible Satellite on Dec. 20, 2014,at 9:30 am.

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Rain Out of Here

| 7:11 am December 20, 2014

An all new edition of the ABC 33/40 Weather Xtreme video is available in the player on the right sidebar of the blog. You can subscribe to the Weather Xtreme video on iTunes by clicking here.

Central Alabama enjoyed a nice soaking rain overnight, and the rain has moved east of the area this morning. Clouds will hang in there for much of the day, but we should see some peeks at the sun during the late morning and afternoon hours. It will be about typical for this time of year with highs in the middle 50s.

Don’t get used to the dry weather because it looks like rain chances return Sunday night and stick with us until Christmas Eve. A short wave zips by on Sunday night and early Monday setting up a wedge situation that will likely bring the best rain chances to eastern sections of Central Alabama. That short wave moves quickly by as a deep trough begins to get carved out over the Central US. This will keep us unsettled with rain chances into Wednesday.

Tuesday and Wednesday, a deep trough is carved out over the Central US that is going to bring quite a chill down for Christmas Eve and Christmas Day. Look for rain chances Tuesday and Wednesday with the rain coming to an end late in the day Christmas Eve. But temperatures on Christmas Eve are not likely to get out of the 40s for Central Alabama.

The trough moves by us on Christmas Eve, but the upper air pattern will retain the long wave trough position along the Mississippi River keeping us cool into next weekend. Christmas Day should be dry so the kids can get outside to play with whatever Santa Claus brought with highs back into the 50s. We should stay dry until Saturday with temperatures pretty close to seasonal values.

Looking out into week 2, also known as voodoo country, the pattern maintains a cool look with a long wave trough situated over the eastern half of the country. Looks like some wet weather as we head into 2015.

And you can follow news and weather updates from ABC 33/40 on Twitter here. Stay in the know by following the whole gang – here’s the list…

James Spann Charles Daniel Bill Murray
Brian Peters E-Warn (AL wx watches/warnings)

I plan to have the next Weather Xtreme Video posted here by 8 am or so on Sunday. Enjoy the day and be sure to perform at least one act of kindness today. Godspeed.

-Brian-

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Rainy Night for Central Alabama

| 8:57 pm December 19, 2014

The latest radar mosaic showed that rain was occurring over almost all of Central Alabama at 8:45 pm and that rain extended southwestward all the way to the Louisiana coast. This means the rain is not going to be ending any time soon.

The latest upper air sound from the Shelby County Airport was interesting. It is actually warmer at about 870 millibars, roughly 4,200 feet, than it was at the surface by a couple of degrees Centigrade. Imagine what would be happening if the freezing level which was at about 750 millibars were much lower!

Most of Central Alabama had received between a tenth of an inch and a quarter of an inch. I’ve recorded 12 hundredths of an inch so far, but the storm total precipitation estimates from the Doppler radar network showed an area lying northeast to southwest just northwest of Demopolis where as much as 1 to 1.5 inches of rain may have fallen already. Quantitative precipitation forecasts, or QPF, project rainfall amounts between about a half inch in the northwest counties like Marion County to as much as 1 inch or a little more to the southeast in Montgomery County.

The latest GFS MOS guidance suggests that the rain should be ending across Central Alabama around sunrise Saturday morning, perhaps lingering across the area east and southeast of Birmingham until 10 am or so.

Be sure to check back tomorrow for the latest Weather Xtreme Video which should be posted here by 8 am.

-Brian-

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Warnings Count

| 4:11 pm December 19, 2014

Here’s something a little different. Daryl Herzmann, with the Iowa Mesonet, has created a page where you can plot the total number of tornado and severe thunderstorm warnings for a particular WFO (Weather Forecast Office), or for all WFOs in the continental US. I think we all know that the amount of severe weather this year is down, way down – and I count that as a blessing. So how does the warning count look? Well take a gander at the graph below which shows that the warning count, both tornado and severe thunderstorm warnings, was down similar to 2013.

This is indicative of two things. First, and the most important, WFO Birmingham has made a very serious effort to reduce the false alarms (FAR or False Alarm Ratio) by undertaking more local studies, putting more meteorological reasoning into warning decisions, and not being too quick to issue a warning for storms. It’s important that everyone understand that by doing this, the meteorologists at the NWS risk missing a few events, but most likely the ones they might miss, whether severe thunderstorm or tornado, will probably be on the low end of intensity. But I believe that is a risk that should be taken in order to reduce the number of warnings that are issued where no significant severe weather occurs. And I applaud this genuine effort to keep people safe but not cry wolf too much.

Second, it also shows that the occurrences of severe weather has been down. I, for one, am thankful for that.

-Brian-

Warning Count for WFO Birmingham, AL

Warning Count for WFO Birmingham, AL

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