Tuesday, April 27, 2010

Yesterday's Central Texas Chase

A few lightning shots from a severe storm over Temple Texas Yesterday afternoon.

Wednesday, April 21, 2010

Severe Storms appear likely Friday

As we move closer to the weekend it is appearing more likely that a severe weather event will occur across Parts of East Texas Friday afternoon and evening. The Storm Prediction Center currently has a large area of the Plains and Midwest under a slight risk of severe weather Friday, including all of East Texas. It looks as though parts of East Texas could be upgraded to at least a moderate risk of severe weather, mainly north of I-20.

Severe weather will begin to break out this afternoon across the Texas Panhandle as a strong storm system begins to take shape. This storm system will move to our north on Friday dragging a dryline and a cold front into East Texas. Right now the atmosphere is forecast to be conducive for very large hail, larger than golf balls, gusty winds, and isolated tornadoes. The forecast hodograph for Friday afternoon shows a tremendous turning of the wind with height. The large clockwise turning is favorable for tornadoes however, in the lowest 1km of the atmosphere; the turning of winds is not as great. So I do believe we will see an isolated tornado or two but right now it does not look as though we are looking at a major tornado outbreak. I will add many times with an atmospheric set up like we will have Friday, storms will move slightly faster and more to the right than forecast. This will greatly increase the low level clockwise curvature of the winds increasing the tornado threat.

Right now it appears the greatest threat of severe weather will be large hail. By looking at the forecast sounding for Tyler Friday afternoon, a lot of ingredients are coming together to produce large hail. There is a large amount of positive buoyant energy, CAPE, which will allow for robust updraft strength. There is also a cap in place, an area where the temperature increases above the earth’s surface holding back initial thunderstorm development. This will allow daytime heating to reach its peak before explosive thunderstorm development occurs. Also the sounding shows a large amount of the buoyant energy is in the hail growth region, between -10°C and -30°C. This tells me we will see some very large hail. When you combine this with strong wind shear, golfball size hail seems very likely with the possibility of baseball size hail occurring in a few storms.

Overall this does appear to be a significant severe weather threat. Both the hodographs and soundings are very similar to the event which occurred April 9th last year. If you don’t remember, this event produced 5 tornadoes in East Texas and 87 tornadoes across the Southern Plains and Southeast.

Tuesday, April 20, 2010

Severe Weather Possible Friday

So far the severe weather season of 2010, other than January 20th, has been very quiet. A continued intrusion of cold air over the late winter and early spring weeks have suppressed the Gulf moisture needed for strong storm development well to the south. This is about to change, at least for the end of this week. Currently we are watching a strong upper air disturbance along the Pacific Northwest coast which will move to the four corners region by Wednesday afternoon. As this system moves out of the Rockies in to the Southern Plains, a dryline will develop across west Texas and move its way towards our area. Right now it appears we will see some severe storms develop Thursday Afternoon from the Eastern Texas Panhandle south towards West Texas. These storms will move east and lose some of their strength Thursday night into Friday morning. This dryline will still be out to our west Friday afternoon giving East Texas plenty of time to warm into the lower 80s. This will set the stage for severe storms to develop out to our West late Friday afternoon and move east into East Texas Friday evening and overnight. At this time it appears there will be plenty of instability and wind shear to keep these storms at severe levels through the overnight hours. The atmosphere will be conducive for very large hail, strong gusty winds, and isolated tornadoes. Remember we are still four days away from this developing storm system and a lot could change between now and then. Severe weather outbreaks require many ingredients to come together at once. Any difference in timing could cause these storms to be weaker or stronger. Below is an outlook for severe weather on Friday. This is NOT an official forecast. The Storm Prediction Center does have most of East Texas outlooked for a 30% or greater chance of severe weather Friday. The outlook below is based on the 0Z model runs and can and probably will change between now and Friday. For those used to SPC outlooks, do NOT use the colors on this outlook to determine slight, moderate , and high risk areas. I have enhanced an area in red where I feel the greatest risk of severe weather will take place on Friday. I do believe we will see a moderate risk of severe weather issued for Friday.

Thursday, April 15, 2010

Tornado hits India

You may have heard on the news that a powerful cyclone hit Northeast India Tuesday Night killing over 100 people. In actuality what appears to have hit this area of the world was a tornado. This area of the world is no stranger to severe weather and tornadoes, many times called cyclones in this part of the world. Based on archived satellite images it does appear a broken line of strong thunderstorms, possibly supercells, developed as moist southerly winds off the Bay of Bengal were forced vertically along the front range of the Himalayan Mountains. I do not know for sure if these were indeed true supercells as the nearest Doppler radar site is over 400 km away and I could not find any archived data. Based on the latest information from the Regional Meteorological Center in Alipore a tornado did indeed move across Northeast India from the northeast corner of the Bihar State into West Bengal. Top winds were estimated around 125 km/hr or78 mph which would be an EF-0 tornado in the U.S. Lack of warning and poor construction can be attributed to the loss of life, over 120 at last count, many of which lived in mud shacks.

Below is a satellite loop I made from archived images.

Friday, April 9, 2010

Remembering One Year Ago Today

One year ago today a tornado outbreak began across East Texas and proceeded to spread across much of the Mid South and Southeast. Before the outbreak ended, 87 tornadoes touched down causing 5 deaths and injuring 146 people.

The day began with a moderate risk of severe weather across parts of Arkansas and a slight risk across most of East Texas and Louisiana. Across East Texas, the threat was very conditional, meaning if the storms were to develop, they would rapidly become severe but there was still a chance no storms would form at all.

Well, the storms did develop and ended up producing large hail and 5 tornadoes across East Texas.
Tornado Tracks In Red.
Fortunately for us, very few injuries were reported and no fatalities occurred. It was a different story across other areas of the south where one tornado in Arkansas killed 3 people.

One of the most interesting aspects of this event was in Southwest Arkansas where an anti-cyclonic tornado struck near Centerpoint. This tornado was rated an EF-2 and had a damage path of up to a half mile, very large and strong for an anti-cyclonic tornado.
Now anti-cyclonic tornadoes are not unheard of, but what is interesting about this one was the unusually large size. The storm that produced this tornado began as a part of the supercell which produced three tornadoes in Cass County. This cell split and the left mover remained as strong as the right mover. The left mover showed anti-cyclonic circulation for around 30 minutes before the half mile wide tornado touched down.

You can read more about this event from the Nation Weather Service in Shreveport here.

Friday, April 2, 2010

Strong Gusty Winds, Hail, and Tornadoes Possible This Evening

Strong to severe storms are likely to develop across East Texas this afternoon and evening bringing the threat of large hail, strong gusty winds, and even an isolated tornado or two. A dryline, a front separating moist tropical air from dry continental air, is slowly moving east as of late this morning. Based on radar trends the dryline should be moving into our western counties from Greenville down to Palestine around 4PM. Out ahead of this line a few showers and storms have developed on the tail end of an upper air disturbance moving to our north. These showers should diminish in intensity over the next couple of hours. An area of sinking air on the right front side of a jet streak is currently moving into the area.

This could allow for addition heating this afternoon. By late this afternoon, East Texas will be in what we call the right rear our right entrance region of this jet streak. This will aid in lifting to increase the storms’ strength this evening. It still looks as though the greatest threat will be strong gusty winds and hail however, any additional surface heating will increase our chance of tornadoes. Current visible satellite image shows clearing skies over much of East Texas. This could allow temperatures to reach near 80 degrees again today and this will increase the instability needed for severe thunderstorm growth.

It still appears the best timing for these storms will be from 3PM in our western counties, 6PM in the Tyler area and 10 PM in our Eastern counties.

Thursday, April 1, 2010

Severe Storms Possible Tomorrow Evening

Spring time warmth has finally moved into the area and although many of us are glad to see it, it does have a downside. The warmer temperatures we have seen this week will aid in the development of strong to severe storms tomorrow afternoon west of Dallas. These storms will form into a squall line late tomorrow and race through East Texas during the evening hours. Right now it appears the main threat from these storms will be large hail and strong gusty winds. The atmosphere will be conducive for tornadoes tomorrow as well however, the tornado threat looks to be small. If we have any isolated storms develop out ahead of the squall line, these storms would have a chance to produce tornadoes so we will have to monitor this situation closely.

The best timing as of right now for severe weather is for the storms to enter our western counties late tomorrow afternoon or evening. The line of storms will probably make their way into the Tyler Longview areas around 9PM, and then exit East Texas around 1AM Saturday.