Wednesday, November 16, 2011

Severe Thunderstorms in North Alabama


8:47 a.m., 11/16/11, Decatur, Alabama (Taken on my Droid phone)


8:50 a.m., 11/16/11, Decatur, Alabama

There were several reports of severe weather across Alabama today. Preliminary reports of possible tornadoes are coming in from Central and South Alabama. In North Alabama, reports so far have been confined to straight-line wind damage resulting from a severe thunderstorm in Madison County. The picture above was taken of the storm in Decatur that later caused the damage in Huntsville and Madison County.

The National Weather Service in Huntsville did a good job warning for the storm. At 8:42 a.m. a Severe Thunderstorm Warning was issued for portions of Morgan, Limestone and Madison counties. At 9:15 another Severe Thunderstorm Warning was issued for central portions of Madison County until 9:45.

Reports so far include the following:

8:27 am, 2 NE of Chalybeate: roof blown off porch, trees down, & awning blown off mobile home.
9:07 am, 4 miles north of Madison: trees and power lines down
9:15 am, Providence area: two reports of 55-65 mph wind gust reported
9:15 am, 911 Call Center in Huntsville: reported 74 mph wind gust
9:25 am, tree reported down on home and power lines down in N Huntsville.

Video as the storm approached Decatur and the first warning was being issued:




Radarscope capture by Chris Palmgren

Video of velocity loop on radar from Chris Palmgren:



Straight line winds knocked a tree on Pulaski Pike and power outages were reported on Shady Lane Drive. In Rutledge Heights, a tree was blown onto a car, and Johnson High School's marquee was blown off the frame.

Phoros from WHNT 19


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Thursday, September 15, 2011

Huntsville Lightning 9/15/11


12:22 Columbus Nexrad


Lightning photo taken at Oak Park in NE Huntsville, Alabama at 12:21 a.m. 9/15/11.

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Wednesday, September 14, 2011

Rocket City Weather Fest



If you live in North Alabama and have in interest in the weather, or have children interested in science, consider attending the secon annual Rocket City Weather Fest this Saturday, September 17, 2011 at UA Huntsville's Shelby Hall from 11 a.m. until 4 p.m.

The event is free and open to the public. Find out all of the details at www.rocketcityweatherfest.com.

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Monday, August 15, 2011

August 16, 1985 Hurricane Danny Tornado Outbreak


2:10 p.m. 8/16/85 Jasper, Alabama tornado. Photo taken by Douglas Pearson of the Daily Mountain Eagle newspaper. Source: Obsevations of the Hurricane Danny Tornado Outbreak of 16 August 1985, by Eugene McCaul, Jr.


4:37 p.m. 8/16/85 Redstone Arsenal Airfield tornado, Huntsville, Alabama. Photo by Andrew Junkins, Avionics Supervisor. Source: Obsevations of the Hurricane Danny Tornado Outbreak of 16 August 1985, by Eugene McCaul, Jr.


4:38 p.m. 8/16/85 Redstone Arsenal Airfield tornado, Huntsville, Alabama. Photo by Andrew Junkins, Avionics Supervisor. Source: Obsevations of the Hurricane Danny Tornado Outbreak of 16 August 1985, by Eugene McCaul, Jr.

In a very very interesting paper authored by Eugene McCaul, Jr. about the tornadoes that struck Mississippi, Alabama, and Tennessee on August 16, 1985, he describes the atmospheric conditions that led to an unusually violent tornado outbreak for a land-falling tropical system. These tornadoes were spawned by the remnants of Hurricane Danny, which had made landfall on the Louisiana Coast the previous day. This article includes photographs of two of the hurricane-spawned tornadoes, the first such documentation to be published, showing that the tornadoes displayed multiple-vortex structure and formed beneath wall clouds.

Account by Eugene W. McCaul, Jr. and Dave Gallaher in Storm Track:
Their account is about two thirds of the way down the page on the link, but here are some excerpts.

It was at 11AM CDT, right during my seminar, that the first Alabama tornado (an F2) struck Parrish, a small town about 80 miles southwest of Huntsville. Shortly thereafter, the town of Jasper was hit by an F2, and before the day was over some 53 other communities had reported tornado damage in Alabama, Tennessee and Mississippi. The radio station I listened to on my way to and from lunch didn't say anything (!) about the storms, at least while I was tuned in, so I didn't know anything about the remarkable goings-on to my southwest. In fact, I was beginning to wonder whether Huntsville would even get a decent rain that day.

After lunch, the rain finally got cranked up to moderate, with big drops of the kind you see in thundershowers; but there wasn't any thunder or lightning. I was working in my windowless, interior office in one of the huge NASA warehouse-type labs at 3:30, when I heard a gust of wind on the roof above me. Still, there was no thunder, so I didn't give it a second thought." At this point, Dave Gallaher was watching a just formed tornadic storm, from 4-5 miles to its east...


I wedged my way through the crowd of 30 co-workers, standing at the North Entrance of our building to get a look at a magnificent wall cloud with a multiple vortex tornado just about three miles northwest, moving north. To the north, there was a very ominous band of low clouds extending east from the wall cloud, but at first, I couldn't tell if the band represented the mesocyclone's pseudo-warm front or gust front. Since the storms were moving north and there was no evidence of a gust front to the west, I surmised that the low cloud band was probably the gust front--and that it had caused the winds I had heard a few minutes earlier. Cloud bases under this band were ragged, almost blurry looking and very low, perhaps only 300 feet above the ground while to the south was about 1,500 feet. A moderate shower of large raindrops continued to fall, accompanied by a 10-15 knot south-southwest wind, but there was still no thunder or lightning. 'Does anyone have a camera?' I pleaded, but nobody was listening.

I noted the time on my watch, 3:42PM CDT, rushed back to my office, put up the 'gone fishin' ' (i.e. chasin') sign, and took off for my apartment to get a camera. As I tore out of the building, the loudspeakers in the halls declared: 'Warning! A tornado has been sighted on Redstone Arsenal. All personnel take cover in designated areas until further notice.' Of course, at that point, there was no longer any danger from this particular storm--at least not to the Arsenal. - - - It was early rush hour as I departed, and rush hour in Huntsville is not a pretty sight--even on a dry day. I made several unauthorized U-turns in order to get home 'efficiently,' and the native Alabamans seemed to be impressed; a couple of them even honked their horns at me. When I got to my apartment, the other tenants were all outside, looking to the northeast at the departing storm. The radio crackled with tornado warnings for Madison and Limestone Counties. I grabbed my camera and headed west.


Now away from the traffic, the radio was starting to issue tornado warnings on another round of storms, moving up from Cullman and Morgan Counties --and there was a report of a tornado on the ground south of Decatur, which is about 20 miles southwest of Huntsville. I headed northwest on Route 72 toward Athens, hoping to intercept the mesocyclone, which I figured was moving through Decatur at that time. The radio was remarkably free of static.

After a few miles, I encountered a very heavy rainshower -with visibility down to a quarter-mile and figured the storms were already on me. I found a spot on the side of the road, where there was an open view to the south, and waited for the rain to stop. A bright line appeared on the southern horizon and another band of low clouds swept over, but behind this gust front there was no evidence of a wall cloud to the west. However, now the view to the east, back towards Huntsville, looked promising, so I headed back towards town.


To the east, there were several purplish bands of north-south ragged low bases, with one especially dark base behind Rainbow Mountain a 400 foot hill that was scraping the cloud bases just to my southwest. There was rotation almost everywhere in the low clouds, and I noted on my tape recorder that I expected to see a tornado any minute. As I continued to race east toward the presumed well cloud, a small break appeared in the stratiform deck above me, giving me a brief glimpse of big gray towers -leaning sharply to the north and penetrating the mid-level clouds higher up. In hopes of catching e tornado, I blew off picture options and headed north on a road named, appropriately, Wall Highway.


The dark base to my southeast emerged from behind Rainbow Mountain, but to my disappointment I could see no tornado; and the wall cloud was losing its shape as it elongated along a north-south axis. Comparing notes the next day with the obs taken by NWS observers at Huntsville Airport, which was about seven miles south of me, I found that they had observed a tornado for eight minutes from this particular base at the very same time that Rainbow Mountain was blocking my view!...


I believe the key to the potency of the Danny outbreak was the development of a narrow dry intrusion, which showed up clearly in Danny's southwest quadrant in the satellite photos. This is something to look for in preparing for a hurricane tornado chase...Most importantly, don't leave your camera at home in favor of an umbrella. That way, if you get lucky, you'll have something of your own to show for it!"

My memories of the day:


As the center of Danny travelled through Mississippi, North Alabama was in a prime location for rotating storms. I was in Huntsville at the time and as I recall there was a lot of light rain and not too much (if any) thunder with these storms. My Dad witnessed the Redstone Arsenal tornado shown above while standing outside of his office in Huntsville's Research Park.

I remember standing outside on that day watching the clouds. I don't know why I didn't go look for the storm. I don't think we had very good access to radar then and my parents would have had a fit if they knew I was out doing that. I did, in fact, tape the coverage on local television stations out of Huntsville and Birmingham.

Here are some videos of the television coverage from that day which I uploaded that capture the event well.


WAAY 31 TV Huntsville Coverage - Gary Dobbs, Part 1


WAAY 31 TV Huntsville Coverage - Gary Dobbs, Part 2


8/16/85 The Weather Channel Coverage - John Hope, et. al.

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Tuesday, August 09, 2011

Early Morning Lightning in Huntsville, Alabama


4:52 a.m., 8/9/11, Northeast Huntsville, Alabama
This lightning caused a power outage in the area.


4:51 a.m., 8/9/11, Northeast Huntsville, Alabama


4:20 a.m., 8/9/11, Northeast Huntsville, Alabama

In the top picture, I was at the Shell Gas Station on US 72 East and Moore's Mill Road in Huntsville, Alabama. It was raining, so I parked under the awning. After running in to buy a couple of bags of peanuts (and letting the clerk know what I was doing), I set up my camera on the tripod, facing west. I clicked it and went back in the car to wait 60 seconds for the exposure time to elapse. That kept me safer as it seemed the lightning was getting closer. To capture these images, I usually set my camera's shutter to stay open 60 seconds so that it captures any light that occurs during that time. That way, if there are multiple lightning strikes, I can capture them all and don't have to worry as much about timing. The interesting thing about the top image is that these strikes occurred basically all at once (not multiple strikes over the entire 60 seconds). It occurred right before the shutter closed. I am learning that lightning photography requires some skill, even more patience, and quite a bit of good luck!

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Thursday, August 04, 2011

August 3, 2011 Lightning in Huntsville, Alabama


The above radar capture was posted by Bill Murray on Alabamawx.com.

The following images were captured on the east side of Chapman Mountain in Northeast Huntsville, Alabama between 11 p.m. and Midnight on August 3, 2011.














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Friday, July 15, 2011

July 14, 2011 Lightning in Huntsville, Alabama

These images were captured looking west over the City from Chapman Mountain in Northeast Huntsville.












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Friday, June 17, 2011

Huntsville Lightning 6/17/11

These images were taken between 12:49 and 1:03 a.m. from High Mountain Road in Northeast Huntsville, Alabama, looking to the west.













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Monday, May 09, 2011

Forecasting the 4/27/11 Tornado Outbreak in Alabama

This is a look back at excerpts from some forecast discussions in the days leading up to the historic outbreak of tornadoes in Alabama on April 27, 2011. Forecast models indicated the possibility of severe weather over a week in advance. Local media and National Weather Service offices in Huntsville and Birmingham did an outstanding job alerting us to the potential severity of the event. Following are some samples of their work...

The video below includes excerpts from ABC 33/40 Birmingham Chief Meteorologist James Spann and Meteorologist Brian Peters Weather Xtreme Videos which were produced in the week leading up to the historic and tragic April 27, 2011 tornado outbreak in Alabama. The video begins with an excerpt from April 19th and takes us all the way through April 26. These are weather forecasting model discussions, not necessarily the forecast that was published officially on those days. This video was made to focus on discussions about the 27th, both at long range and as the event became imminent. I have excluded most other parts of the original discussions so that the viewer can focus on information related to April 27th. 



Tuesday 4/19 AM Weather Xtreme Video, James Spann:
"Wednesday the 27th, that could be a pretty active period, maybe, for strong or severe storms. We'll be watching developments toward the middle of next week. Hey, this is April in Alabama, when things like that can happen and often will."

Tuesday 4/19 PM Weather Xtreme Video, James Spann: Toward the middle of next week we could have some issues with severe weather."

Wednesday 4/20 AM Weather Xtreme Video, James Spann: "Very significant severe weather outbreak moves in here...Clearly late Tuesday and Wednesday next week severe weather is on the board here.

Wednesday 4/20 PM Weather Xtreme Video, James Spann: "Clearly a chance of severe weather Tuesday night or Wednesday of next week."

Thursday 4/21/11 NWS Birmingham AFD: THE SECOND SURFACE LOW WILL DEVELOP FARTHER SOUTH AND BRING INCREASING CHANCES OF SEVERE STORMS TO ALABAMA ON WEDNESDAY.

Friday 4/22 PM Weather Xtreme Video, James Spann: "Look at Wednesday (the 27th)! That's a pretty good looking severe weather setup for April in Alabama. Digging trough to the west, difluent flow aloft, surface low near Memphis - 996 mb. In fact it doesn't get more classic than that. That would suggest a chance of supercell storms Wednesday afternoon with the possibility of tornadoes, and a squall line Wednesday night.

Friday 4/22/11 NWS Birmingham AFD: THE BIG EVENT IS STILL SHAPING UP FOR TUESDAY AND WEDNESDAY. THERE IS FAIRLY GOOD MODEL CONSENSUS WITH REGARD TO TIMING AND POSITION OF SURFACE FEATURES. THERE STILL APPEARS TO BE TWO WAVE OF STORMS THAT WILL AFFECT THE AREA. THE FIRST WAVE MAY BE MORE OF A HEAVY RAIN EVENT...AS FIRST LINE OF STORMS SLOWS WEAKENS AND BECOMES STATIONARY OVER NW ALABAMA ON TUESDAY. THERE WILL BE ENOUGH INSTABILITY AND SHEAR FOR THE POSSIBILITY OF SEVERE STORMS...BUT BETTER FORCING AND SHEAR WILL HAPPEN ON WEDNESDAY AS UPPER LOW AND SURFACE LOW DEEPENS UPSTREAM OF ALABAMA.

Friday 4/22/11 NWS Birmingham HWO: CONFIDENCE HAS INCREASED FOR WEDNESDAY...WHEN THERE MAY BE A THREAT OF TORNADOES. SPOTTER INFORMATION STATEMENT...ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT MAY BE NEEDED NEXT TUESDAY AND WEDNESDAY DUE TO THE POSSIBILITY OF SEVERE STORMS.

Friday 4/22/11 NWS Huntsville AFD: BUT THE MAIN STORY WILL STILL BE WITH THE MAIN TROF AXIS AS IT LEADS TO RAPID LEE CYCLOGENESIS OVER THE ARK-OK-TX REGION ON WEDNESDAY. THIS WILL BE THE STRONGER OF THE TWO SYSTEMS THIS COMING WEEK AND LIKELY DEVELOP STRONG TO SEVERE CONVECTION ACROSS MS/TN/AL LATE WED MORNING INTO THE EVENING HOURS. THE GFS IS MUCH MORE BULLISH IN THE DEEPENING OF THIS SECOND LOW AND INDICATES A VERY STRONG LL JET DEVELOPING AHEAD OF THE SYSTEM. THE ECMWF STILL LOOKS FAVORABLE FOR STRONG TO SEVERE DEVELOPMENT ON WEDNESDAY BUT PAINTS A SLIGHTLY WEAKER LL JET /50KTS AS OPPOSED TO 75+KTS JUST TO OUR N WED AFTERNOON/. SVR WX PARAMETERS SPIKE ARND 18Z WED WITH CAPE VALUES IN EXCESS OF 1000 J/KG AND A NICELY CURVED HODOGRAPH...BUT A SIGNIFICANT CAP IS IN PLACE WED MORNING AT ARND
750-800MB.

Saturday 4/23/11 NWS Birmingham AFD: AS THE DEEP LAYER JET FIELDS ROUND THE BASE OF THE UPPER TROUGH AND ENTER THE WARM SECTOR...IT IS LOOKING BETTER FOR SUPERCELLS FOLLOWED BY A DECENT BROKEN SQUALL LINE. I TEND TO FOCUS ON SEVERAL ITEMS THAT COULD BE CONSIDERED SYNOPTIC TO GET SOME IDEA OF STORM MODE. FIRST IS THE 0 TO 6 KM BULK SHEAR...MAGNITUDE AND ORIENTATION. THE VECTOR ORIENTATION IS AT AN ALMOST PERFECT 45 DEGREE ANGLE WITH THE SURFACE FRONT AND INCREASING TO 55 TO 65 KTS INDICATING SUPERCELL DEVELOPMENT BETWEEN 18 AND 21Z WEDNESDAY...BUT IT DOES BACK MORE SOUTHEAST AS IT GETS CLOSER TO SUNSET...SUGGESTING THAT A SQUALL
LINE IS MORE LIKELY WITH TIME OR ALONG THE FRONT. NEXT WOULD BE THE 0 TO 8 OR 10 KM BULK SHEAR...WHICH IS INDICATIVE OF LONGER TRACKED SUPERCELLS.AND IT IS AN IMPRESSIVE 75 KTS FROM 18 TO 00Z. SO THE SHEAR DOESN`T SEEM TO BE MUCH OF AN ISSUE AT THIS POINT.

Sunday 4/24/11 PM Weather Xtreme Video, Brian Peters: "The trough really digs in...as it comes across Arkansas...then it moves to the vicinity of Memphis midday Wednesday...that's going to be our big day...probably tornado watches on Wednesday in the afternoon and evening hours."

Sunday 4/24/11 NWS Huntsville AFD: WE MAY NEED TO RAISE THE POTENTIAL FOR +RA GIVEN AMPLE MOISTURE INFLUX ASSOC WITH THE LLJ. SUPERCELLS MAY BE PSBL AS WELL...SPCLY W OF I-65 ALONG WARM FRONT GIVEN A GOOD COMBO OF ML-CAPE/6KM BULK SHEAR. 0-1KM SRH VALUES INCREASE ABOVE 300 M2/S2 SUGGESTIVE OF A TORNADO THREAT AS WELL LATE TUE NIGHT. WED LOOKS TO BE A HIGH IMPACT WX DAY...PERHAPS CONTAINING AN ONGOING MORNING EVENT...FOLLOWED BY A WDSPRD SQLN WED AFTN/EVNG. WINDY CONDITIONS ARE LIKELY WED GIVEN A VERY TIGHT PRESSURE GRADIENT...THE NAM SUGGESTS THE WARM FRONT AND OVERNIGHT CONVECTION SHOULD LIFT N OF THE AREA BY 12Z. THIS IS STILL A QUESTION MARK THOUGH. THE GFS PROGS A LARGE MCS MOVG INTO MIDDLE TN AND PSBLY CLIPPING NRN AL AS WELL. SOMETHING TO WATCH CLOSELY IN FUTURE SHIFTS AS IT COULD CERTAINLY INCREASE OUR +RA/FLOOD THREAT. IN ANY EVENT...MODEL SOUNDINGS INDICATE A LOW CLOUD LAYER BENEATH A STRONG CAPPING INVERSION THRU THE MORNING HRS. THIS SHOULD PROHIBIT PRE-FRONTAL CONVECTIVE REDVLPMT AND ALLOW FOR DECENT HEATING DURG THE AFTN. A 5H JET ACCELERATES TO 90-100KT BY MIDDAY INTO THE AFTN...CREATING VERY STRONG DEEP LAYER SHEAR. WITH A STRONG SHORTWAVE/-DIV Q PROVIDING AMPLY FORCING ALONG THE COLD FRONT...CONDITIONS APPEAR FAVORABLE FOR A LONG-LIVED SQLN TO DVLP WED AFTN/EVENING. DAMAGING WINDS AND MESO-VORTICES / QLCS TORNADOES WL BE CONSIDERABLE THREATS.

Sunday 4/24/11 NWS Birmingham AFD: WEDNESDAY...WE WILL RAPIDLY CHANGE AS ANOTHER DECENT COLD CORE SPOKE DIGS WAY SOUTH AND QUICKLY NEGATIVE TILTS TO OUR NORTHWEST. AS IT DOES SO...THE HEIGHT FALLS QUICKLY DEEPEN A SURFACE LOW FROM LITTLE ROCK TO DETROIT. HERE IN LIES THE FIRST SIGNIFICANT DISAGREEMENT INTO EXACTLY HOW LOW WE WILL GO. I`VE SEEN EVERYTHING FROM 996 TO 985...AND ALL NUMBERS IN BETWEEN. THIS WILL MAKE AN OBVIOUS SIGNIFICANT DIFFERENCE IN THE WIND FIELDS...IN PARTICULAR...THE LOWEST 1 KM HODOGRAPH TURN. DON`T WANT TO GET INTO THAT MUCH MESOSCALE THIS EARLY...BUT IT IS A LITTLE TROUBLING TO HAVE THAT MUCH VARIATION AS WE ARE GETTING WITHIN THE 3 DAY WINDOW. REGARDLESS...I AM STILL IMPRESSED WITH THE 0 TO 6 KM AND 0 TO 8 KM BULK SHEAR SPEED AND VECTOR ORIENTATION. IT STILL SHOWS ISOLATE LONG-LIVED SUPERCELL FAVORABLY INTO WEDNESDAY AFTERNOON...ESPECIALLY WEST OF I65...BUT DOES HINT AT QUICKLY TRANSITIONING AND BECOMING COLD POOL DOMINATED AS IT ACCELERATES ACROSS THE STATE...IN THE MEAN TIME...THE CAPE PROFILES CONTINUE TO IMPRESS...

Sunday Afternoon 4/24/11 NWS Birmingham AFD: THINGS WILL REALLY GET TO ROCKIN` AND ROLLIN` ON WEDNESDAY, AS A STRONG LOW PRESSURE SYTEM DEVELOPS OVER ARKANSAS AND LIFTS INTO NORTHERN KENTUCKY BY 00Z/THU. STRONG DYNAMICS ASSOCIATED WITH THIS SYSTEM WILL CREATE THE POTENTIAL FOR A SIGNFICANT SEVERE WEATHER EVENT FOR THE MID STATE, INCLUDING THE POSSIBILITY FOR ISOLATED TORNADOES. A STRONG FORECAST 850MB JET, OF 60 TO 65 KTS, COUPLED WITH 0-3KM STM RELATIVE HELICITIES NEAR 500 M2/S2 COULD SET THE STAGE FOR THE BEST POSSIBILITY FOR ISOLATED TORNADOES THAT WE'VE SEEN SO FAR THIS SEASON.

Monday Afternoon 4/25/11 NWS Birmingham AFD: LOOKING AHEAD TO WEDNESDAY...SOME OF THE SYNOPTIC PARAMETERS ARE LOOKING DOWNRIGHT DANGEROUS. IF THINGS GO ACCORDING TO THE NUMERICAL OUTPUT...THE CAP SHOULD CONTINUE TO GROW AND DEVELOP DURING THE EARLY MORNING HOURS...WHILE ENERGY BEGINS TO BUILD AS BREAKS OF SUN HEAT THE SURFACE THROUGH MUCH OF THE MORNING AND EARLY AFTERNOON HOURS. CAPE VALUES ARE SIGNIFICANT AS THEY LOOK TO RANGE ANYWHERE FROM 1000 TO 3000 J/KG. THE CAP IS RATHER WEAK AND CONTINUES TO TREND WEAKER WITH TIME SUGGESTING THAT IT WILL EASILY BE BROKEN BETWEEN 1 AND 3 PM. THAT IS ABOUT THE SAME TIME THAT THE JET MAX BEGINS TO NUDGE IN FROM THE WEST...OR AS THE 0 TO 6 KM AND THE 0 TO 8 KM BULK SHEAR VECTORS INCREASE TO GREATER THAN 60 KTS...AND MORE IMPORTANTLY THEIR ANGLE OF ATTACK SUGGESTS SUPERCELLS AND LONG-LIVED ONES AT THAT. MY FINAL QUESTIONS SURROUND THIS LOWEST SHEAR LAYER FROM 0 TO 1 KM. SYNOPTICALLY...WOULD LIKE TO SEE MORE CONSISTENCY BETWEEN MODELS AND INDIVIDUAL RUNS ON EXACTLY HOW MUCH VEERING WITH HEIGHT WILL EXIST. THIS IS DIRECTLY RELATED TO THE MESSY SURFACE PRESSURE FROM THE DOUBLE HELIX LOW AND FROM VARYING DEGREES OF THE STRENGTH OF THE LOW. ADD TO THAT...EVEN MORE UNCERTAINTY OF WHETHER THIS FRONT BEGINS TO GO LINEAR. OVER THE
PAST SEVERAL FORECASTS...WAS THINKING THAT WE START SUPERCELLS THROUGH MUCH OF THE AFTERNOON AND EARLY EVENING ONLY TO TRANSITION LINEAR AFTER SUNSET...BUT A RE-EXAMINATION OF THE VECTOR ANGLES SHOWS THAT IT MAY NOT HAPPEN UNTIL FURTHER EAST INTO GA AND NORTH FL. SO...WHILE IT MAY BE A LINE...IT MAY ACTUALLY BE A BROKEN OR MORE CELLULAR LINE AS THE EVENT TRANSLATES EAST OF I65. REGARDLESS...MY BEST FORECAST IS THAT THE GREATEST OPPORTUNITY FOR SUPERCELLS AND TORNADOES WILL LIKELY BE ALONG AND WEST OF I65 FROM 1 UNTIL 6 PM WEDNESDAY. PLEASE STAY TUNED TO THE WEATHER EVENTS THROUGH WEDNESDAY EVENING. THISIS A DANGEROUS SITUATION THAT WARRANTS ATTENTION. DO WHATEVER IS NECESSARY TO PROTECT LIFE AND PROPERTY...NOW IS THE TIME TO REVIEW SAFETY RULES AND PLANS AS IT MAY SAVE YOUR LIFE!

Monday 4/25/11 ABC 33/40 Forecast Discussion, James Spann: "SPC, in their day three convective outlook, already has much of North Alabama under a moderate risk. Sure looks like all of the ingredients will be there; a surface low will form north of Memphis, which will give very favorable low level shear, and it looks like the capping inversion should break by mid-afternoon with scattered supercells forming over North and Central Alabama, which will have potential for large hail, damaging wind, and a few tornadoes. Based on the forecast parameters, a few strong, long track tornadoes will be possible Wednesday afternoon and Wednesday evening, so it will be yet another day on which you will need to be close to a good source of severe weather information. If you read this blog, we don’t worry about you, but be sure and pass the word along."

Tuesday 4/26/11 AM Analysis, Dr. Tim Coleman: "…MAJOR TORNADO OUTBREAK LIKELY IN SOUTHEAST OVER THE NEXT 48 HOURS…The morning model runs are in now, and it still looks like a significant severe weather outbreak will occur over the SE US today and tomorrow. I will primarily talk about Alabama here, but this is a large-scale event. The models disagree on the timing of this low, one moving it through Memphis early morning then into KY and OH, the other not until afternoon. That will be one key factor tomorrow, because the highest storm-relative helicity values will be closer to the surface low and low-level jet, making storm rotation more vigorous. Taking the average of the two, the largest storm-relative helicity, a very high 400 or more m2/s2, will be centered from northern MS into NW Alabama and middle TN by noon tomorrow. The thing that makes this event more worrisome is that we’re pretty deep into Spring now, with strong sunshine and a warmer Gulf. Dewpoints tomorrow will rise to near 70 degrees, and assuming we get sunshine, temperatures will rise into the 80s. With cold upper-level temperatures, this will cause very unstable air. CAPE will range from 2,000 to 4,000 J/kg over most of Alabama by early afternoon. With that combination of wind shear and instability, severe storms will develop, and in the areas of strongest shear, the storms will rotate vigorously and produce tornadoes. Pinpointing the exact areas that will be the most vulnerable is still tough at this time, since it will depend some on where clouds linger longer in the morning, where today’s storms leave boundaries, etc. But, the stage will be set most favorably for tornadoes over the northwest half of Alabama this time (it was the south half on April 15). We are talking about areas northwest of a line from Demopolis to Clanton to Anniston to Gadsden."

Tuesday 4/26/11 ABC 33/40 Forecast Discussion, James Spann: "All of the synoptic elements for a major outbreak are in place. A deep (sub-1000 mb) low west of Memphis, steep lapse rates, strong veering of the wind with altitude in respect to projected storm motion, strong wind fields at the surface and aloft, dry air in the mid levels, and a very deep, long wave upper trough that is somewhat negatively tilted enhancing diffluence aloft over Alabama. Projected soundings show the classic “loaded gun” look, meaning that a cap should keep storms at bay through the morning hours, but when that cap breaks early in the afternoon, storms will quickly become severe with all modes of severe weather possible. This means potential for large hail, damaging winds, and a few violent, long track tornadoes. This is dangerous weather setup. Of course, long time readers know that mesoscale features play a huge roll in the ultimate severity of a severe weather day, and we really won’t know about those until early tomorrow. TIMING: This is an event where it doesn’t make much sense to ask when storms will arrive in your county or home town; nobody knows since the initial storms will be cellular in nature. Just understand a severe storm is basically possible anytime from now through 3:00 a.m. Thursday. The storms tonight will mostly pose a threat of high winds and large hail, although an isolated tornado cannot be ruled out.Tomorrow, the main risk comes from about 12:00 noon to 12:00 midnight. Again, we can’t rule out morning storms, but the most intense and dangerous thunderstorms will come during the afternoon and nighttime hours. The severe storms should merge into a long squall line late tomorrow night, with the main threat becoming damaging straight line winds after 10:00 p.m. or so."

Tuesday 4/26/11 SPC Day Two Outlook: HIGH RESOLUTION MODEL DATA IS STRONGLY SUGGESTIVE THAT A SIGNIFICANT CLUSTER OF STORMS COULD BE IN PROGRESS WEDNESDAY MORNING EAST OF THE MIDDLE AND LOWER MISSISSIPPI VALLEY. IF THIS VERIFIES...IT IS UNCERTAIN WHAT INFLUENCE IT WILL HAVE ON SUBSEQUENT BOUNDARY LAYER DESTABILIZATION ACROSS THE OHIO/TENNESSEE VALLEY REGION. THIS UNCERTAINTY PRECLUDES AN OUTLOOK UPGRADE TO HIGH RISK PROBABILITIES AT THE PRESENT TIME. HOWEVER...MOST OTHER INDICATIONS ARE STRONGLY SUGGESTIVE THAT A MAJOR OUTBREAK OF SEVERE THUNDERSTORMS COMMENCING TONIGHT ACROSS PARTS OF THE OZARK PLATEAU/LOWER MISSISSIPPI VALLEY WILL CONTINUE AND EXPAND NORTHWARD AND EASTWARD TOWARD THE APPALACHIANS DURING THE DAY WEDNESDAY. THIS WILL INCLUDE THE POTENTIAL FOR LONG-LIVED SUPERCELLS CAPABLE OF STRONG TORNADOES...AND ORGANIZED STORM CLUSTERS CAPABLE OF STRONG DAMAGING WIND GUSTS.

Tuesday Afternoon 4/26/11 NWS Birmingham AFD: AND NOW FOR THE MAIN EVENT. A SIMILAR SETUP WILL EXIST FROM WHAT WE SAW BACK ON APRIL 15TH...AS SEVERAL WAVES OF ENERGY WILL BE MOVING INTO OUR AREA FROM THE ARKLAMISS WITH A 65KT 850MB JET DEVELOPING. WE WILL HAVE TO CLOSELY WATCH THE DEVELOPMENT OF THE LINE OF THUNDERSTORMS...AS THIS WILL HAVE A LARGE IMPACT ON THE DEVELOPMENT OF SEVERE THUNDERSTORMS LATE IN THE DAY. IF THE LINE HOLDS TOGETHER...SEVERE PARAMETERS WILL BE GREATLY REDUCED ONCE THE LINE PASSES. OUR CONFIDENCE IN THAT SOLUTION IS VERY LOW HOWEVER...AND WE ARE EXPECTING THE LINE TO BE GREATLY WEAKENED BY THE TIME IT REACHES OUR AREA...AND WILL ALLOW FOR A RAPID DESTABILIZATION OF THE ATMOSPHERE AFTER MIDDAY TOMORROW. AFTER TALKING WITH SPC...THE
UNCERTAINTY IN THE STRENGTH AND LOCATION OF ONGOING CONVECTION TOMORROW MORNING IS THE ONLY FACTOR THAT IS PREVENTING THE ISSUANCE
OF A HIGH RISK OF SEVERE STORMS AT THIS TIME. LOOKING AT THE LATEST FORECAST SOUNDINGS...NOT MUCH HAS CHANGED IN RELATION TO PARAMETERS THAT WE HAVE BEEN ADVERTISING OVER THE PAST FEW DAYS. ONE WORD COMES TO MIND AFTER LOOKING AT SEVERAL SOUNDINGS. DANGEROUS. A WEAK CAP SHOULD BE IN PLACE THROUGH THE EARLY MORNING HOURS...THEN RAPIDLY ERODE DURING THE LATE MORNING AND EARLYAFTERNOON. AMPLE TURNING OF THE WINDS WITH HEIGHT...DRY AIR ALOFT...AND STEEP LAPSE RATES WILL BE PREVALENT ACROSS ALL OF CENTRAL ALABAMA TOMORROW AFTERNOON. THE MOST UNSTABLE AREAS WILL BE GENERALLY ALONG AND NORTH OF INTERSTATE 20...BUT I MUST STRESS THAT ALL OF CENTRAL ALABAMA WILL BE UNDER THE GUN. MOST SEVERE WEATHER PARAMETERS ARE OFF THE CHARTS TOMORROW AFTERNOON. THE CRAVEN/BROOKS SIGNIFICANT SEVERE PARAMETER...WHICH INCORPORATES 100MB MLCAPE AS WELL AS THE 0-6KM SHEAR...IS BETWEEN 60000 TO 80000. USUALLY YOU WILL SEE SIGNIFICANT SEVERE EVENTS OCCUR WHEN THE VALUE IS ABOVE 20000. THAT ON TOP OF ALMOST 3000J/KG OF SBCAPE IS A VERY DANGEROUS MIXTURE. 0-6KM SHEAR OF 60-80KTS...WITH VECTORS SUGGESTING SUPERCELL DEVELOPMENT REMAINS IN PLACE AHEAD OF THE FRONT. ALONG THE FRONT...SHEAR VECTORS CONTINUE TO INDICATE THE DEVELOPMENT OF SUPERCELLS UNTIL LATE IN THE EVENING AS THE FRONT APPROACHES EASTERN ALABAMA. THE SHEAR VECTORS THEN BECOME SLIGHTLY MORE PARALLEL TO THE FLOW...INDICATING A MORE LINEAR DEVELOPMENT...BUT TORNADOES ALONG THE LINE WILL CONTINUE TO BE POSSIBLE. ONCE AGAIN...THE DEVELOPMENT OF STORMS TONIGHT WILL HAVE A MODEST IMPACT ON THE MESOSCALE MORROW...AND HOW THE EVENT PLAYS ITSELF OUT. I MUST ALSO STRESS THAT NOW IS THE TIME TO REVIEW YOUR SEVERE WEATHER PLAN TO PROTECT YOUR LIFE AND PROPERTY...TOMORROW WILL BE TOO LATE!

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Monday, April 18, 2011

Central Alabama Chase Account - 4/15/2011


Chase Map


INTRODUCTION


Friday April 15, 2011 will go down as one of the most productive and intense Alabama storm chases that I have experienced. As of 4/21/11, 23 tornadoes have been confirmed by the NWS Birmingham and 11 have been confirmed by the NWS Mobile for a total of 34 in the State of Alabama. There may be a few more confirmed when surveys are completed. The highlights of the trip included seeing a very photogenic "textbook" mesocylone with a wall cloud east of Uniontown, Alabama, witnessing and reporting a rain-wrapped tornado in southern Tuscaloosa, quarter-sized hail and trees down in Bibb County, and witnessing a wall cloud and possible funnel at dusk on the Chilton-Autauga County line.




PLANNING AND PREPARATION





SPC SREF Significant Tornado Parameter 36 hours







This event first appeared to be potentially significant with the model runs from Tuesday night/Wednesday morning. I listen to James Spann’s Weather Xtreme video regularly, usually while I get ready for work in the morning or sometimes I pick it up on my phone. He does a very good job describing the model output. In addition, I looked at all of the model output for the usual severe weather parameters (instability, shear, composite indices, etc.) numerous times Wednesday and Thursday. I like to use Earl Barker’s model page, the College of Dupage model page, and the SREF data from the Storm prediction center site. Everything seemed to be in place for a major severe weather event. The only ingredient that seemed questionable was instability. The models were pretty consistent. However, the area of highest instability seemed to stay roughly south of Interstate 20 and it seemed to be maximized over the Alabama-Mississippi state line.


With all of the parameters seemingly coming together, Wednesday I asked for and was approved to take leave on Friday. I did later get a scare when some circumstances changed and I almost did not get to be off work. Through some help from a co-worker, the good graces of my boss, and a little prayer, I was finally able to obtain approval to be on leave.

Thursday night my partner, John Brown and I had a phone briefing around 9:30. We decided meet in Birmingham and head west, perhaps to Meridian , Mississippi to set up. I met John late Friday morning and our initial decision was to drive to Tuscaloosa and then decide whether we wanted to go west or south from there



DALLAS MESOCYCLONE







Dallas/Perry County Mesocyclone Time Lapse





While heading west out of Birmingham we decided to turn south at the West Blocton (Alabama Highway 5) exit and attempt to intercept some cells that were moving out of Mississippi. We decided that we had plenty of time to get in a safe position to intercept one or two of those cells. We took Highway 5 all the way down to the US 80 corridor, west of Selma . That was a great choice for several reasons. First, the land was flat and there weren’t many trees, which is a rare viewing opportunity in Alabama . In addition we were able to watch a textbook mesocyclone produce a wall cloud. The video and pictures from that particular storm may be of use for future storm spotting training purposes. While we did not see a tornado with that storm, the structure itself made that a good decision. Around that time, tornadoes were being reported in Mississippi by Greg Nordstrom’s Mississippi State chase team and others. We would have liked to have gone west and intercepted those cells, but we would have had to have left earlier. We were also a bit concerned about committing too far west and missing anything in Alabama .



TUSCALOOSA TORNADO









Tuscaloosa Tornado Video by John Brown


Next we decided to go north. John debated about west at Marion , towards Greensboro . I was concerned that we didn’t have enough time to get in position to see that storm safely. We decided to go north toward Centreville, and then northwest towards Tuscaloosa . We knew we had plenty of time to intercept a cell that had a history of tornado reports and damage reports. We stopped for a long time in Duncanville , southeast of Tuscaloosa . For a while it looked as if the tornadic circulation was headed directly at us but then it appeared to be make a bit of a turn to the left, or north of our location. We finally decided to go north, slowly, on US 82, as we were hearing reports of a tornado to our west on Alabama Highway 69. As we drove in to southern Tuscaloosa, we saw transformers exploding within approximately a half-mile, to our north and some obvious indications of a rain-wrapped tornado directly in front of us. I reported that tornado on the ABC 33/40 Skywatcher instant message chat and Meteorologist Jason Simpson immediately used that report on the air. In fact, we were on the outer circulation of the tornadic rotation. At one point we stopped, as the winds suddenly increased. We were concerned that the tornado may have been growing and “back-building” toward us. We stayed in a safe position, relative to the storm, but as we drove north we saw tree debris along US 82, just south of Skyland Boulevard. As we turned right (east) on Skyland, we saw where the tornado crossed, blowing out some signs and more tree debris. This storm took a northeast path from there and we were no longer able to keep up with it.


BIBB COUNTY LIGHTNING, HAIL, AND TORNADO DAMAGE










Next we decided to go back toward West Blocton and possibly intercept a cell that was taking aim on the area just south of West Blocton. That storm was producing a reported tornado near Demopolis. As we traveled down Alabama 5, south of West Blocton, we were too late to witness the tornado. However we did experience quarter-sized hail, witnessed a 200-300 yard path with trees and power lines down, and had a lightning bolt explode a tree within feet of John’s truck as we were traveling down the highway. I reported the trees down and that report was immediately relayed my meteorologist Jason Simpson at ABC 33/40. While we were there, we met storm chaser Brett Adair who showed me video of a tornado he captured earlier in the afternoon.



CHILTON-AUTAUGA WALL/FUNNEL





From there we drove south and intercepted a storm near the Chilton-Autauga county line on US Highway 82 just after sunset. We found only one small area with any viewing potential. Everything else was obscured by trees and hills. We found a spot on a ridge with a view to the northwest. John and I saw a wall cloud and a possible funnel. This storm had previously produced a report of a tornado. ABC 33/40 meteorologists James Spann and Jason Simpson used John’s live stream in their coverage of this warning. This was going to be our last storm of the day, but then we decided to drive to Prattville to get in position for another tornado-warned supercell.




PRATTVILLE TORNADO WARNING/CG LIGHTNING




We took Highway 22 from Maplesville over to Clanton and then we turned south on I-65. This storm was producing an amazing amount of lightning to the west. By the time it got to our location, we were not able see any indication of a wall cloud, funnel, or tornado. I am still looking at footage to determine if we may have captured some good lightning images.




THE RIDE HOME




After that, it was a long drive back to Birmingham and then Huntsville . John and I were a bit giddy by this point and we laughed as we listened to ourselves react to the close lightning strike. I listened to my footage all the way from Birmingham to Huntsville . After I arrived home, John texted me the bad news that fatalities were reported in Autauga County , in a tornado that moved through there after we left. I stayed up until after 3 a.m. editing footage.


That was definitely an adventure to remember.


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ABC 33/40 Coverage...

Tuesday, April 12, 2011

4/11/11 Severe Weather

This severe thunderstorm was observed at the Huntsville (AL) International Airport, 2.3 miles south of I-565 on County Line Road. I reported an estimated wind gust of 60 mph to the NWS Huntsville at 6:30 p.m. Take a look at the video. It was hard to estimate wind speed without many trees nearby. The wind created a loud roaring sound that lasted for about 10 minutes. Storm reports from the NWS Huntsville.


6:34 Columbus Nexrad - My location was at the green triangle southeast of Athens and southwest of Huntsville.


6:34 Columbus Nexrad velocity image.


Short, edited version of my video from the storm.













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