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Bill Murray

Bill Murray

Bill Murray is the President of The Weather Factory. He is the site's official weather historian and a weekend forecaster. He also anchors the site's severe weather coverage. Bill Murray is the proud holder of National Weather Association Digital Seal #0001 @wxhistorian

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Timing and Impact

| 4:20 pm February 2, 2016

Here is a look at the HRRR radar projection for this evening.

hrrr_2016020220_ref_birmingham

Here is my thinking.

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Four phases of weather will impact Alabama tonight:

1. Run of the mill showers and storms from Marshall County down through Blount, Jefferson and Bibb Counties will not be severe as they lift northeastward.

2. Tornadic supercell moving into Pickens County will continue to produce a large and dangerous tornado according to spotters and emergency management. Take cover as it approaches. This activity will impact West Central Alabama between now and 7p.m. A powerful low level jet at 5,000 feet with winds over 60 mph will continue to power these storms. Be aware that there are more lined up back into Newton County MS.

3. Activity back to the east of Jackson will follow the tornadic storms. Damaging winds will be the main threat. This activity will push across Northwest Alabama between 7-10 p.m.

4. The main squall line ahead of the cold front will arrive in Northwest Alabama around 9 p.m. and move across Northwest Alabama between 10 p.m. and midnight. It will follow this rough timetable:
Jasper 1 a.m.
Cullman/Tuscaloosa 2 a.m.
Birmingham 3 a.m.
Pell City 4 a.m.
Anniston 5 a.m.
Damaging winds will be the main threat with the main threat.

3:45 P.M. Update on the Alabama Weather Situation

| 3:48 pm February 2, 2016

Here is an update on the Alabama Weather Situation at 3:45 p.m.

Tornadic supercell thunderstorms are nearing the Alabama/Mississippi border at this hour.

There is a confirmed tornado south of DeKalb MS that will move northeast toward northern Sumter and southern Pickens Counties, in the general direction of Carrollton. There is tornado damage reported in Collinsville MS, including trees down and damage to the First Baptist Church there.

Here is a four panel radar view of the storm with (clockwise from top left) reflectivity showing precipitation intensity, storm relative velocity showing rotation, correlation coefficient showing potential debris signatures and finally vertically integrated liquid showing possible hail.

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There are reports of injuries and structural entrapment on hwy 494 in Suqualena. This is northwest of Meridian.

Damage was also reported in Prismatic just a moment ago.

Another possible tornado is near Macon MS. This storm will move toward northern Pickens and southern Lamar Counties in the general direction of Suligent.

Here is the big picture:

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These storms will move north northeastward through West Central Alabama between now and 7 p.m. They have the potential to produce damaging winds and tornadoes.

Additional storms are back to the west stretching from Jackson MS to McComb MS on I-55. These storms will impact West Central Alabama late this evening. Damaging winds and isolated tornadoes will be threat.

Finally, the main squall line is forming just ahead of the cold front over western Mississippi. It will affect Central Alabama late tonight. The main threat here will be for damaging winds, with an isolated tornado possible.

Tornado Watch for North and Central Alabama Until 10 p.m.

| 3:15 pm February 2, 2016

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Counties included are:

Bibb, Blount, Chilton, Dallas, Fayette, Greene, Hale, Jefferson, Lamar, Marengo, Marion, Perry, Pickens, Shelby, Sumter, Tuscaloosa, Walker, and Winston.

Tornado Watch Soon for North and Central Alabama

| 2:56 pm February 2, 2016

The latest from the SPC highlights the threat of a few strong tornadoes for the next few hours over western Alabama into Middle Tennessee.

The potential watch area is outlined in pink.

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Click the image to enlarge the graphic and read the full discussion.

Highlights:

…Watch likely to be issued by 4 p.m.

…Low and mid level wind shear profiles are quite favorable for tornadic supercells.

…Instabilities have been weak but are increasing. CAPE values now between 500-1,000 j/kg over western Alabama.

…The cap over Central Alabama has been eroded.

CONFIRMED TORNADO OVER EASTERN MISSISSIPPI
Radar indicates tornado debris south of Newton, just south of I-20 in Mississippi. This tornado will cross the interstate and stay west and northwest of Meridian. This tornado warning is show in purple. The other tornado warnings that are in effect are show in red. Severe thunderstorm warnings are in yellow.

Three Tornadic Storms in Eastern Mississippi

| 2:44 pm February 2, 2016

There are three tornado warnings in eastern Mississippi right now.

2-2-2016 2-28-54 PM

One is just west of Starkville. The warning does not include the campus of Mississippi State University. That storm shows strong rotation but no debris signature right now. This one will move toward northern Lamar and Marion Counties. It will arrive in Alabama between 4 and 4:30 p.m.

Another is near Philadelphia. It may affect Pickens County in about two hours as well.

The final one is southwest of Meridian. It could affect Sumter County later.

Over the rest of Central Alabama, storms over Bibb County will move into the Birmingham area within the hour. They are not severe at this time but could become severe. Other showers are lifting through the western part of the Birmingham Metro currently.

More storms over Perry, Marengo and Dallas Counties will take a similar route.

Everyone Knows It’s Windy (and Warm)

| 2:21 pm February 2, 2016

Who’s tripping down the streets of the city
Smilin’ at everybody she sees
Who’s reachin’ out to capture a moment
Everyone knows it’s Windy

Do you remember that song by The Association? It certainly applies to today’s weather.

This graphic shows the center of the low pressure system west of Kansas City and the surface wind field across the U.S.

2-2-2016 2-17-05 PM

Note how our surface winds over Central Alabama are “backed”, which means they are coming more out of the southeast that southwest (veered). This is a critical piece in tornado formation and it worries us about the tornado threat as long as we have instability this afternoon and evening.

Potentially tornadic storms are over eastern Mississippi at this hour. There is strong rotation east of Ackerman MS west of Columbus, but no tornado debris signature yet.

Back to the winds. Some peak wind gusts so far today:

Birmingham International Airport…31 mph
Shelby County Airport…26 mph
Tuscaloosa…31 mph
Anniston…33 mph
Muscle Shoals…35 mph
Huntsville…41 mph
Columbus MS…29 mph

It is also warm. Check out these 2 p.m. temperatures/dewpoints:

Birmingham…75F/60F
Tuscaloosa…75F/65F
Calera…74F/61F
Montgomery…78F/63F

The record for today at Birmingham is 77F. We will be very close.

The barometer is getting low as well:
Birmingham…29.86
Muscle Shoals…29.76
The low pressure center is centered west of Kansas City at this hour, with a minimum pressure of 994 millibars or 29.35 inches.

Tornado Threat Increasing for Eastern Mississippi, Eventually West Alabama

| 1:54 pm February 2, 2016

The SPC just issued a mesoscale discussion for the increasing tornado threat over eastern Mississippi.

Here is a current graphic showing the satellite, radar, temperatures, the area covered by the mesoscale discussion in Mississippi.

Click image to enlarge.

Click image to enlarge.

This activity will of course push into western Alabama between 3 and 4 p.m.

The airmass across western Alabama is increasingly unstable, with CAPE values already between 1000-15000 joules/kg.

Tornado Watches Issued

| 1:35 pm February 2, 2016

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A few things to note from the graphic:

…A tornado watch has now been issued for northern Mississippi, western Tennessee, western Kentucky and small parts of eastern Arkansas, southern Illinois and the Missouri Bootheel. It goes until 7 p.m.

…A new tornado watch has also been issued for parts of southeastern Louisiana, southern Mississippi, southwestern Alabama and the extreme NW Florida Panhandle. It includes New Orleans Biloxi, Mobile, Greenville, Evergreen, Monroeville, Atmore and Pensacola. It will go until 7 p.m. as well.

…The airmass across eastern Arkansas, eastern Louisiana, southwestern Mississippi and southeastern Louisiana has been moderately unstable, with CAPE values between 1000-2000 j/kg. The temperature and dewpoint is 70/68F at Jackson and 71F/67F at Meridian at this hour.

…There is still some capping across much of Alabama and northeastern Mississippi. That is eroding quickly. Storms will be able to form after that.

…Strong storms have formed over Central Mississippi. There is a severe thunderstorm warning west of Philadelphia.

…With some sun, temperatures have become quite warm over Central Alabama. It is now 75F/60F at the Birmingham Airport and 76F/65F at Tuscaloosa.

SPC Expands Enhanced Risk Area; Several School Systems Dismissing Early

| 11:00 am February 2, 2016

2016-02-02_10-33-04

The morning update to the SPC severe weather outlook expanded the enhanced risk area to include much of the northwestern half of Alabama. The enhanced risk area now extends from Louisville KY to just east of Memphis and Nashville to Jackson MS and just east of Birmingham to just north of Mobile.

The tornado risk is basically unchanged, but the 30% damaging wind risk was expanded. The hail risk remains fairly low.

Parents: please note than many school systems over West and Northwest Alabama are dismissing early. Check with your sources to determine when.

Here is a weather update as we approach the 11 o’clock hour:

…instability is increasing across Mississippi, especially along the Mississippi River, south of Memphis. Storms are now well established in this zone.
…storms are growing in scale over southeastern Louisiana into southern Mississippi.
…the sun is out at least partially across much of Central Alabama. The temperature has already reach 70F at Calera and is at 68F at Birmingham and 69F at Tuscaloosa.
…dewpoints are now in the lower 60s west of I-65.
…the airmass over Mississippi is capped, meaning there is an inversion that is suppressing convection and even clouds. This is allowing the kettle to slowly simmer. It will reach the boiling point soon.
…the SPC just said that they will be issuing a tornado watch in the next couple of hours for a large part of Missisisppi and part of eastern Louisiana.
…the NWS in Birmingham will release a special upper air balloon at 11 a.m.
…we will have to see how the storms ahead of the line evolve and how the timing of the main line of storms shakes out.

Storms Have Already Formed Over Northwest Alabama

| 8:18 am February 2, 2016

Good morning!

We are settling in for a long day and night of monitoring severe weather here at AlabamaWX. We will have frequent updates throughout the day of the thinking about the meteorology and of course a running account of developments as soon as watches and warnings happen.

Click image to enlarge.

Click image to enlarge.

Showers and storms have already formed over Northwest Alabama this morning near a northward lifting warm front in an area of deep moisture convergence in the low levels of the atmosphere. When air comes together near the surface (converges) and diverges aloft, you get lift. The air piles up and has to go somewhere. The result is showers and storms.

One storm formed over northern Lamar and Fayette Counties about 7:15 and pushed across Marion County. It is now over Winston County between Haleyville and Double Springs.

It is mild and increasingly humid over Central Alabama. Dewpoints are already in the upper 50s, approaching 60F. The DP at Meridian is 63F and 66F at Jackson MS. Temperatures are in the middle 60s.

Showers and some thunder will continue over West Alabama through the morning, but that will not pose a severe threat.

Showers and storms will fire over northern Mississippi into southern Tennesse by late morning and will move into western Kentucky later. These will pose a significant severe threat, including the possibility of a couple of strong tornadoes as well as damaging winds.

For us, the first of two main threats will come just after midafternoon, when storms start forming in the unstable airmass over Central and eastern Mississippi. These storms will push into West Central Alabama starting about 4-5 p.m. and will continue into the late evening. They will have the potential to also produce damaging winds and a couple of strong tornadoes.

The final threat will last the longest as a line of thunderstorms enters West Alabama starting around 9-11 p.m., congeals with the ongoing storms across that part of the state and pushes across the rest of the area during the night. This activity should clear the Hamilton area around midnight, the Jasper/Tuscaloosa/Cullman areas around 1-3 a.m., the Birmingham/Gadsden around 2-4 a.m. and the Anniston/Alex City area around 5-7 a.m. It should finally clear Auburn around 7-9 a.m.

We have said it so many times in the past 7 days. Assess your severe weather safety plan and go over it with your family and co-workers. Monitor the weather throughout the day and night and have a way to receive warnings. Think about where you will be during the threat times this afternoon and tonight and know where you would go if a warning was issued whether that is at work, home or anywhere else. Plan your travel so it does not coincide with the time that severe weather is expected.

Don’t be alarmed. Be informed. Knowledge is the best antidote to a fear of severe weather.

Stay with us here at AlabamaWX throughout the day for the very latest on the developing weather situation.

A Look Back, A Look Ahead

| 10:00 am February 1, 2016

Looking back at the climate numbers for January in Birmingham and looking ahead to what we usually can expect in February:

The mean temperature for January 2016 at Birmingham was 42.5F, which is slightly cooler than the 43.8F average mean. The average high for the month was 52F and the average low was 33.1F. These values are 1.9 and 1.2 degrees below their respective long-term averages.

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The mercury dropped to freezing or colder 17 times in January 2016, slightly more than the 14.9 times that we average. The coldest reading was 19F on the 19th. The warmest was the 72F we saw yesterday.

2016-01-31_19-28-49

A total of 3.28 inches of precipitation fell in the month, well short of the average 4.84 inches we would expect. Rain fell on 6 days, something that usually occurs on 10.5 days on average.

A trace of snow was reported. On average, we receive 0.6 inches of the white stuff. In January, we experienced thunder on one day, something that occurs on average 1.9 times in the month.

A rough approximation shows that we received about 55% of normal sunshine this month, up from the 41% we usually see in our gloomiest month. So if you were a little chilly last month, at least you had a little extra sunshine to show for it!

LOOKING AHEAD

February 2nd is Candlemas Day. It is the traditional midpoint of winter. You know it as Groundhog Day. By early February, Alabama is beginning to really feel the move toward spring. Days are lengthening and average temperatures are slowing warming as the amount of sunshine increases each day. At the beginning of the month, the average high and low for Birmingham is 55F/35F. By the end of the month, the averages are 62F and 40F. On average, the mercury drops to freezing or below on 9.7 nights, down slightly from the 114.9 in January.

2016-01-31_19-35-03

Birmingham’s coldest day on record (-10F) occurred on February 13, 1899, during the mother of all U.S. cold waves. Records in Birmingham were kept at the U.S. Weather Bureau Office in Fountain Heights then. If the observation had been made at the current Airport location, the all time low would probably be -14F. The warmest February reading on record in Birmingham is 83F, recorded on three different dates in history.

February is the middle month in the wettest three month period on average in the Magic City. During our “rainy season,” we typically receive just under 15 inches of rain. On average, 4.53 inches of rain falls in Birmingham in February. 17.67 inches fell in February 1961, the wettest second month observed here. February 1968 saw only 1.20 inches of rain, the driest February ever. The 6.00 inches of rain that fell on February 7, 1903 is the daily record for the month.

Typically, it will rain on 10 days in February and thunderstorms occur on 2.3 days. By these measurements, February looks a lot like January. On average, Birmingham receives a 0.1 inches of snow in February. The greatest daily amount of snow observed in the city is 5 inches on February 23, 1901.

After January, which features the lowest percentage of possible sunshine at 41%, February is sunnier featuring 50% of possible sunshine on average, moving toward the sunniest month, May which features 66% of possible sunshine on average. Fog reduces visibility to ¼ mile or less on one day during the month.

Late Night Thoughts on Tuesday Evening

| 11:02 pm January 31, 2016

The evening run of the North American Mesoscale Model has increased concerns for the possibility of severe weather, including tornadoes over Central Alabama early Tuesday evening. Early looks at the GFS are not quite as bullish, but also indicate the possibility for severe weather a little earlier, just after sunset over North Central Alabama. This is still a developing weather situation and one we will have to watch very closely during the day on Monday and into Tuesday.

Let’s discuss some severe weather parameters and what you might can expect.

2016-01-31_22-11-28

INSTABILITY: Temperatures will be in the lower 70s and dewpoints in the lower 60s. The general thinking over the past few model runs has been that instability would be low, less than 500 joule/kg, but we note that the evening run of the NAM is more bullish on instability, which ramps up the severe weather threat for any storms that form ahead of the main line of storms. The evening run of the NAM shows a little higher instability by 6 – 7 p.m. at Birmingham and shows an Energy Helicity Index of over 2, which is indicative of a more significant severe weather threat. It also ramps the Significant Tornado Parameter up over 1.5 across Central Alabama near and south of Birmingham. If these trends continue, it would increase our concern that there could be supercells and tornadoes ahead of the main line early in the evening.

2016-01-31_22-13-13

WIND SHEAR: The overall wind shear needed for organized thunderstorms will certainly not be lacking as bulk shear values will be over 60 knots. Low level helicity will be very high as well. The GFS and NAM rate it at over 400 m2/s2, which will overcome the low instability to produce a few tornadoes in the risk area, and especially in the enhanced risk area over Northwest Alabama, northern Mississippi, western Tennessee, southern Kentucky and extreme eastern Arkansas.

MODES OF SEVERE WEATHER: Damaging winds will be the main threat, but there will also be a few tornadoes. The greatest threat of tornadoes appears to be over Northwest Alabama’s Lauderdale, Colbert, Franklin and Marion Counties, but these new numbers from the NAM increase the concern that tornadoes could be possible early in the evening over Central Alabama. The chance of hail is rather unclear now.

TIMING: Showers and thunderstorms will fire near the Mississippi River around noon on Tuesday. The line of storms should reach the Northwest Corner of Alabama between 6-8 p.m. It should reach Huntsville, Jasper and Tuscaloosa around 11 p.m. to midnight. It should reach Birmingham sometime around 1-2 am. and Anniston around 4 a.m. We will be watching for storms to form ahead of the main line during the late afternoon and early evening. These could also produce damaging winds and tornadoes.

HEAVY RAIN THREAT: The approaching system will be a relatively slow mover, with about 6-8 hours of moderate to heavy rainfall across Central Alabama. It now appears that rainfall amounts could approach 2 inches over that time period. It appears that most locations can absorb that quantity of arainfall without major concerns, but localized flooding will be a very real possibility.

REVIEW YOUR SAFETY PLAN: Go over your personal safety plan for your home and business. Have a way of receiving weather warnings reliably, even while you sleep. Know what to do wherever you might be if a warning is issued. And tell others who might not be interested in weather about the potential threat. Don’t be anxious, just be prepared in case.