Snow for Parts of Texas This Week.

An area of low pressure in the upper atmosphere associated with very cold air aloft will move across the state of Texas early this week. Out ahead of this low pressure copious amounts of Gulf Moisture will spread across East Texas. Rain will begin to develop late Tuesday and could be heavy at times Tuesday night.



While heavy rain breaks out across our area Tuesday night, under the actual upper low across west Texas, heavy snow could develop. There are winter storm warnings out for much of west Texas and southern New Mexico where up to 6 to 8 inches of snow could fall. As this area of low pressure moves east, the core of upper level cold air will move with it bringing a threat of snow mixing in with rain across much of west Texas Tuesday night and Wednesday morning.

Will this threat of snow move into East Texas? Although I can’t rule it out completely, there are a few things going against us getting any snow. The main obstacle preventing snow is the fact that our elevation is much lower in East Texas.

Below is an image of the forecast 850mb temperatures. We usually need these temperatures to be below freezing for snow to fall, which they are, running -2 to -4 degrees Celsius.



Below is an image of the forecast surface temperatures Wednesday Evening. Temperatures are forecast to be between 35 and 40 degrees. In this range snow could reach the surface.



The final image is the accumulated 6 hour precipitation. This image shows the heaviest wrap around precipitation north of I-30, some of which could be snow. If you look at the surface temperature map again you will see areas north of Mt. Pleasant where temperatures are below 35. This could allow for a light dusting if this verifies on elevated surfaces.



The mid and upper levels of the atmosphere will be plenty cold enough for snow to develop but the depth of above freezing temperatures near the surface is just too great to allow the snow to reach the surface. There are a few areas in East Texas where the elevation is over 700’ and in these locations, it is possible a few wet flakes could reach the surface. If this area of low pressure is slightly stronger than forecast then there could be heavier precipitation under the core and this would drag the colder temperatures aloft to the surface which could lead to a better chance of snow. Many surprise snow events have happened with these upper lows including the snow on Easter of 2007 here in East Texas and the heavy snow event on Christmas Eve of 2004 along the Gulf Coast. So this will need to be watched closely.

One thing is certain. Behind this low, the coldest air of the season will move into East Texas. Temperatures by Thursday morning could be in the upper 20s to lower 30s area wide bringing the first widespread freeze to East Texas.

Remembering Dr. Fujita

Eleven years ago today the world lost one of the great contributors to the science of meteorology, Dr. Tetsuya Theodore Fujita. Dr. Fujita’s tornado research would later lead to what is now known as the Enhanced Fujita Scale, or EF scale. His original scale of tornado intensity, known as the Fujita Scale, ranged from F-0 to F-12(as seen below).



Through further research based on his findings, this scale was later enhanced and implemented in February of 2007.



Dr. Fujita also studied downbursts and microbursts which eventually lead to a better understanding of how these phenomenons can cause air disasters. He studied two of the most noted airline crashes caused in and around thunderstorms, the 1975 crash of Eastern Airlines flight 66 which crashed at JFK airport killing 122 people and the 1985 crash of Delta flight 191 at Dallas-Fort Worth killing 135 people. It was shortly after Delta flight 191 the Dr. Fujita published is work on the study of microbursts and downbursts which has more than likely saved countless lives.



For more on Dr. Fujita please read the tribute from Stormtrack.org here.

Warm weather comes to an abrupt end next week

So far the month of November has been warm and dry giving us a chance to dry out from October’s deluge. Normally by now many areas of East Texas would have already experienced their first frost but this November we have been above normal temperature wise delaying the onset of frost and freezing temperatures. It looks as though this spell of mild weather will come to an abrupt end next week. A strong cold front in association with an area of low pressure will bring a chance of showers and thunderstorms late Sunday into Monday followed by much cooler weather. Right now it appears the area of low pressure will stall to our northeast Tuesday keeping cloudy and windy conditions and maybe even a sprinkle or two. The big story will be the temperatures behind the front. High temperatures Tuesday will struggle to reach the middle 50s thanks to lingering cloud cover. As the low finally moves away from the area Tuesday night, clouds should decrease and winds will die down. This is the perfect set up for what we call radiational cooling, were the Earth’s heat is able to escape the atmosphere causing rapid cooling after sunset. Right now it looks as though in our normally cooler locations, temperatures will be able to drop into the lower to middle 30s. This would produce frost in these areas for the first time this year. Right now we are calling for temperatures in the upper 30s to low 40s but looking at the raw data coming late this morning, a frost appears likely for some areas next week. So get ready for some big changes across East Texas.

Sesame Street Visits Good Morning East Texas

Clint, Jennifer, and I had a lot of fun this morning. Here are a few shots of the gang.

Remembering one of the worst tornado outbreaks in East Texas

Sunday will mark the 22nd anniversary of one of the biggest tornado outbreaks in the History of East Texas. On this day, four long track F3 tornadoes moved across parts of East Texas and a total of 50 tornadoes occurred over a 48 hour period from the Southern Plains to the Southeast United States. One of the most noted tornadoes was the F3 that caused considerable damage to Palestine in Anderson County. This tornado was on the ground for 11 miles and unfortunately claimed one life and injured 59 other people.

The most tragic tornado of the day tracked through Cherokee and Smith counties through Jacksonville, Mixon, and Whitehouse. This tornado was on the ground for 33 miles, claimed 4 lives, and injured an additional 81 people. Based on times and tracks , this tornado appears to be the second tornado in East Texas and fourth overall produced by a single supercell thunderstorm that developed along a dryline in Central Texas. This storm appears to have gone on to produce a total of eleven tornadoes including another F3 tornado in Cass County near Marietta, making a total of four F3 tornadoes from a single thunderstorm.

Later, in the early evening hours, another supercell developed near Lufkin and moved to the northeast. This storm would go on to produce a long track F3 tornado near Center in Shelby County and continue northeast through southeastern Panola County into Louisiana. Thankfully this tornado caused no deaths in East Texas but it did injure 15 people.

Unfortunately since this event happened before the internet age, there is very little information. A matter of fact, this may be one of the largest tornado outbreaks with very little research or information available. I would like to change that. Over the next few weeks I plan on researching this event to find out as much information as possible. For one thunderstorm to produce eleven tornadoes is a very unusual and extreme event. If you have any images or stories of this event you would like to share, please email them to me. With your help, we can learn more about the environment that lead to such a tragic event.

email: gdade@kltv.com

The November 11th Blue Norther of 1911

On November 11th, 1911, an intense area of low pressure developed over the Midwest leading to extreme weather across a good deal of the nation. Many areas of the country saw record warmth late that afternoon only to be shocked by the intense arctic blast to follow hours later. In Oklahoma City, a record high of 82°F was set in the afternoon before a cold front raced through the area. Just before midnight, the temperature was 16°F establishing a new record low for the same date. Other Cities such as Springfield, MO set record highs in the 80s that afternoon followed by record lows in the teens just before midnight.

Take a look at some of these temperature extremes from highs on the 11th to lows on the 12th:

Oklahoma City 82°F/14°F
Amarillo, TX 70°F/10°F
Palestine, TX 82°F/28°F
Springfield, MO 80°F/8°F
Fort Worth, TX 86°F/20°F

So why the big difference in temperatures? The image at the top shows the weather map for the morning of November 11th, 1911. You will notice an intense area of low pressure developing across northwest Missouri at this time. This low brought with it a large amount of warm moist air that would lead to severe thunderstorms, as I will discuss farther down, but also brought with it dry air as winds blew down the front range of the Rockies causing a dryline to form from Oklahoma down into Texas. The air mass behind this dry line was still out ahead of the main cold front so temperatures were allowed to soar. Much of southwestern Missouri, Oklahoma, and Texas were in this warm dry air mass with temperatures soaring into the 80s to near 90 in a few locations. Shortly after sunset the arctic front raced through these same areas causing temperatures to plummet, as much as 30°F in one hour. It was the unique combination of warm dry air ahead of a fast moving cold front which allowed such a large range of temperatures to occur on the 11th.

In addition to the significant temperature change, an outbreak of severe weather occurred across parts of the Midwest. Numerous tornadoes were reported across Indiana, Illinois, Michigan, and Wisconsin. An F2 tornado hit Waterloo, IN and 2 people were killed in Michigan with tornadoes. The strongest tornado was in Jamesville, WI where an F4 tornado killed 9 people. Less than an hour later blizzard conditions with wind chill temperatures near 0°F were hampering the cleanup efforts.

Ida Now A Tropical Storm

Ida moved back into the warmer waters of the Caribbean Sea late Saturday and re intensified to a hurricane yesterday. Ida reached its peak intensity yesterday at 6PM when the top winds reached 105 mph, making Ida a category two storm. Ida's top winds continue to decrease now as it enters the northern Gulf of Mexico where water temperatures are much cooler. As of this update top winds were 70 mph making Ida a strong tropical storms before making landfall along the north central Gulf Coast. Some continental, drier air will also wrap into the system causing Ida to lose her tropical characteristics. Very heavy rain and isolated tornadoes can be expected along the central Gulf Coast over the next couple of days along with very gusty winds. The current forecast track is below and will update as new advisories are released.

Ida Could Be Heading For The Gulf.

The 2009 Hurricane season does not want to end just yet. Our ninth named tropical system has now made landfall in Nicaragua as Hurricane Ida. In the process, Ida became one of the fastest developing tropical systems on record becoming a hurricane in just 24 hours. The fastest system to develop from depression to hurricane occurred two years ago off the Texas Gulf coast, Hurricane Humberto.

Now that Ida has made landfall, she will rapidly decrease in strength over Nicaragua and Honduras and will more than likely become a depression tonight. By Friday afternoon we expect Ida to move back into the Caribbean Sea and once again reach tropical storm status. Notice the current forecast track. The center of Ida comes very close to hitting the Yucatan Peninsula by Monday morning. If Ida remains over warm water, she could once again become a hurricane as she enters the Gulf.


The good news for Texas, it looks as though a cold front that will move through the area Monday will help steer Ida of to the east. Areas along the Gulf Coast from Alabama to the Florida Keys should pay very close attention to Ida as this appears to be the most likely area of landfall next week.

South Carolina Colors

Heavy Rain/Storms Possible Tonight

The above image shows the forecast rainfall for the next 48 hours. With plenty of lift and moisture in place, heavy rain appears likely overnight tonight into tomorrow morning. Because of this, most areas north of I-20 in East Texas are under a flash flood watch.

Another concern, although it is very small, is that there is a chance of mini supercells across the region tonight into tomorrow morning. A mini supper cells have mini characteristics of a classic supercell but on a much smaller scale. A few of the storms tonight have been showing signs of low level rotation indicating a mini mesocyclone, hence, a mini supercell.

Below are a few images of the forecast across East Texas at 7AM tomorrow. The 1st image is of the lifted index. Any value below 0 shows there is buoyant surface are that could lead to surface based convection. LIs around East Texas are in the -2 range tomorrow morning.


The second image shows the amount of SBCAPE, or energy available for thunderstorm updrafts. The values are very low, less than 500 in most areas. However, most of this CAPE if found in the lowest layer of the atmosphere which will be encountering lots of spin. This will help lead to a few storms having low level mesocyclones. The image below the SBCAPE shows the amount of CAPE between 0-3km. This low level CAPE is enough to help in tornadogenesis.




The next image shows the amount of 0-1km SRH in the atmosphere. This value is approaching 200 over much of East Texas. Again, this value would allow for tornadoes to develop.



The chances of a tornado developing tonight is less than 2% this evening and overnight but, we will have to watch the storms closely.

An El Nino Winter Ahead

So what does that mean for East Texas? If you look at the average weather for an El Nino year you will see we usually see wetter and cooler conditions. This is due to the storm track being placed across the Gulf Coast States keeping cloud cover and precipitation in the area. Will the cooler and wetter conditions combine to see more winter precipitation across East Texas? With the storm track farther to the south, the chances of winter weather would seem to be greater. I will give a more detailed look at what i expect this winter in the up coming days. Below are images showing what we normally expect in an El Nino winter.

Wild Cold Weather Across The Country

Photo credit: L.M. Baker with the MHA Times, New Town, North Dakota.

Over much of the Northeast and Midwest, temperatures this summer were cooler than normal. Many areas setting record lows for the coolest summer months on record. This cool weather seems to be setting the stage for what could be a fairly cold winter across much of the United States. Cold temperatures have already been seen across much of the northern states so far this October and record snowfalls amounts have fallen across the Plains. One of the most interesting features I read about with this current outbreak of cold weather was the development of a waterspout over a lake in North Dakota during snow showers. We normally think of waterspouts be a tropical phenomenon but they can occur anytime there is an area of low level instability. The following is a report from the National Weather Service in Bismarck, ND:

A waterspout formed over Lake Sakakawea, near New Town, around 10 AM CDT Friday morning, October 9, 2009. The National Weather Service received several reports of a waterspout and other funnel clouds over Lake Sakakawea Friday morning. L.M. Baker, a reporter with MHA Times of New Town, took pictures of the spout and forwarded them to local broadcast media and the National Weather Service. In the pictures it is evident that the spout is over the lake, is in contact with the water surface, and that water is being lifted into the air. The spout was visible for several minutes and dissipated before reaching land. Other funnel clouds were reported over the lake. It was reported that they did not touch the water surface.

A waterspout is, in simple terms, a tornado over the water. Waterspouts are not common in North Dakota, and this one did not form from a thunderstorm.

Several factors contributed to the formation of this waterspout. Low pressure over the state was already producing upward motion and large scale circulation in the atmosphere. Cumulus clouds, associated with a cold front passing through the area, were producing snow showers. The combination of very cold air, in the upper 20s, and relatively mild water, near 60 degrees, caused significant instability in the lower several thousand feet of the atmosphere over the lake. This instability enhanced the instability associated with the low pressure and snow showers and changed atmospheric conditions over the lake. Strong surface winds interacting with the terrain around the lake may have formed a small vortex (rotating air) that translated onto the lake. This vortex may have been stretched vertically by the updraft (rising air) of the snow showers, leading to the waterspout forming. The spout dissipated quickly as it neared land as conditions from the land surface up through the atmosphere over it were more uniform than those over the lake.

This is a good example of the land – water – atmosphere interactions that drive our weather.


The following is snowfall from Nebraska this past weekend:

Snowfall Location County
17.0 8 WNW North Platte Lincoln
16.0 6 NNE North Platte Lincoln
15.0 North Platte - Third and Maple Street Lincoln
15.0 North Platte Lincoln
15.0 Paxton 6 W Keith
15.0 Sutherland 1 N Lincoln
14.0 Mason City Custer
14.0 5 E Westerville Custer
14.0 12 W Callaway Custer
13.0 3 E North Platte Lincoln
12.0 15 NNE North Platte Lincoln
11.8 North Platte - Southwest side of town Lincoln
11.0 Ogallala Keith
10.0 20 S Arnold Custer
10.0 Lewellen Garden
10.0 10 NE Lemoyne Keith
9.6 9 WSW Wallace Perkins
9.0 7 NW Madrid Perkins
8.0 Arthur Arthur
7.0 10 NE Oshkosh Garden
6.2 Grant 3 S Perkins
6.0 Tryon McPherson
6.0 Stapleton Logan
6.0 Grant Perkins
0.5 Mullen Hooker

Crazy winter weather for so early in the season.

Cass County Storm

Numerous reports of wind damage, including a report of 20 homes damaged west of Linden, were reported across East Texas this morning. Above is an image of velocity data taken from the storm as it moved through Cass County. Along the gust front three areas of rotation are seen including a strong TVS (tornado vortex signature). This was the only indication of rotation across East Texas through the entire event. Below is a radar loop of the storm as it moved across the county. If you look closely you will notice an inflow notch were the strong TVS is located in the velocity data above. We will see what hit Cass county after the weather service completes a survey.

Heavy Rain, High Winds, and Isolated Tornadoes Possible!

A strong cold front will be moving into East Texas Early Friday morning and along and ahead of this front, there is a chance of severe storms, including isolated tornadoes. The image above is of a forecast radar image for 7AM tomorrow morning. Instead of seeing a straight line of storms we see more of a wavy pattern. This is called a line echo wave pattern and in many cases this type of storm system will produce very gusty winds and isolated tornadoes. Many East Texas tornadoes occur in patterns such as the one moving through East Texas tomorrow morning.

In addition to a slight risk of severe weather, heavy rain will be a concern. The amount of moisture available for thunderstorms is unusually high for this time of the year thanks to a strong southerly flow off the Gulf this afternoon. As the cold front moves into East Texas, it will force this warm moist air up and over the front producing widespread heavy rain behind the main line of storms. Some places, mainly north of I-20, could see 2 to 4 inches of rain tomorrow. The image below shows the storm total precipitation that is forecast. Notice the heavy rain forecast across the northwest counties of East Texas, where flooding was a problem in September. We also see a bulls eye of heavy rain across our southeastern counties however, we have not seen as much rain here over the past 30 days so flooding is not as great of a concern.




Now most of the dynamic energy needed for severe weather will move north of our area but there are a few features that jump out at me that could lead to gusty winds and isolated tornadoes. The image below is from a short range high resolution forecast model which shows the amount of instability available as the line of storms enters East Texas tomorrow. Most of East Texas is colored in pink which indicates surface based lifted index values less than -6°C. This is more than enough instability for intense thunderstorm updrafts.



The next image shows there will be lots of moisture available as the dark blue colors indicates dew point temperatures in the low 70. You will also see a couple of small low pressure areas, or mesoscale lows, indicting areas of backed winds leading to low level rotation. With the amount of moisture available, cloud bases will be very low increasing the threat of isolated tornadoes.



There will also be moderate amounts of energy to help with thunderstorm development. The image below shows the amount of surface based CAPE. A large area of East Texas has CAPE values over 2000 J/kg out ahead of the storms, providing additional energy for thunderstorm updraft. What is not shown is much of that energy is confined to the lowest levels of the atmosphere, where there is more spin available. This could help in developing low level mesocyclones which could produce an isolated tornado.



In the final image, the amount of 0-1km storm relative helicity, or the amount of low level spin in the atmosphere, is shown. Most of East Texas is at or above 160 which is enough when you combine the amount of CAPE to produce an isolated tornado. You can also see areas of enhanced 0-1km helicity near the mesoscale low pressure areas. This could really enhance the possibility of isolated tornadoes as the line moves through.


So as this line of storms moves through tomorrow morning, we could see some wind damage and isolated tornadoes. Overall I believe the main threat will be flooding rains but we will be monitoring the situation very closely.

Today's Severe Weather Threat

A strong cold front will move into East Texas this afternoon and evening bringing with it the possibility of strong to severe thunderstorms. Right now the main threat of severe weather appears to be strong gusty winds and hail up to the size of pennies. This morning, a layer of warm air just above the surface is putting a lid on thunderstorm development until immediately behind the front. This trend will continue until temperatures this afternoon reach the middle to upper 80s across East Texas. Once these temperatures are reached we will see air lifted ahead of the cold front increasing thunderstorm development. Winds throughout the atmosphere ahead of the cold front are out of the southwest limiting the amount of turning of the winds with height, a big factor needed in tornado development. However, with any additional daytime heating this afternoon, enough instability could form to compensate for the lack of vertical wind shear so we can’t rule out an isolated tornado, especially over the northeaster parts of East Texas.

In addition to severe weather, parts of East Texas today with come close to having dangerous heat index values. Tremendous amounts of Gulf moisture are in place across East Texas and as temperatures approach 90 degrees, especially across our southwestern counties, heat index values will range between 100 and 105 degrees this afternoon. Across most of East Texas heat index values will reach the middle to upper 90s, something we have not experienced in a while across East Texas. Please use caution later this afternoon with any strenuous outdoor activities.

Thursday's Storms

Well, as forecast a line of strong storms developed out ahead of a fast moving cold front Thursday evening. The severity of the storms was not quite as strong as I thought they would be but none the less, most of East Texas was given a spectacular lightning display with heavy rain and gusty winds. Yours truly drove all over East Texas with my chase partner Paul Lachowsky looking for places to take lightning photos. Unfortunately from all the angles we approached the storms, the lightning was hidden from us by very heavy rain and small hail. We got hundreds of illuminated sky capes but very little in the way of actual lightning bolts. A few of our viewers had better luck just staying at home. Tim Ogrodnik was again lucky in capturing a few lightning shoots and was kind enough to send them my way. The shoot of the actual bolts is from him, I need to take lessons.

For the most part the severe weather remained west of our viewing area last night however, there were many large trees blown down and power outages reported across western Upshur County. As for hail, I can vouch for pea size hail in a few locations as the loud ting of hail hitting Paul’s truck greeted us in a few locations.

A couple of interesting photos I took last night included a look at the back edge of the storms with clear skies immediately behind the line. I love seeing the back edge of a thunderstorm with stars all around.



The second photo was a tree that was struck by lightning last night in front of Bullard High School. The tree was still smoldering as you can see the orange glow of the trunk and the rest of the tree smoldering on the ground to the left. Wish I could have seen the bolt hit.

Today's Severe Weather Threat

We have been discussing the possibility of severe weather today since the beginning of the week and it looks as though everything will come together to produce a widespread, gusty wind event. A strong cold front to our northwest will move into East Texas along the I-30 corridor this evening and sweep through all of East Texas by Friday Morning. The main threat with this line of storms will be gusty winds however, temperature decrease a good deal in the mid levels of the atmosphere so I can’t rule out large hail with this line of storms, especially along and north of I-20. All of East Texas has been outline for a slight risk for severe weather with the greatest chance across North East Texas. Right now it appears the line of storms should form along the I-30 corridor around 7PM, enter the I-20 corridor around 10PM, and the Lufkin Nacogdoches area around 1AM. By Sunrise tomorrow the front should be through all of East Texas and drier cooler air will move in.


We could also see a few isolated storms develop this afternoon out ahead of the squall line. If temperatures can reach the middle to upper 80s we will see enough surface based instability for robust thunderstorm updraft development. Enough wind shear will be present this afternoon for any storm to take on supercellular characteristics. A south southwesterly flow at the surface will minimize the tornado threat but we could see large hail and high winds with these storms as well. So until the front moves through your neighborhood, severe weather is a possibility.

Thursday's Severe Weather Possibilties Tue PM Update

The GFS has slowed down the frontal passage (Fig 1) by about 150 miles and is coming more in line with the NAM and WRF (Fig 2). We still do not see a dry line forming on the GFS solution so we would be looking mainly at a squall line event Thursday evening. The NAM still shows a dryline and develops a secondary surface low, much like the GFS was hinting Monday morning, causing backing winds over north central TX and south central OK (Fig 3). This will aid in low level mesocyclone development which could lead to a tornado or two developing during storm initiation. I still like the northern target better for the possibility of tornadoes but the 12Z NAM has a better potential for tornadoes in the Southern Plains. Looks as though there could be a significant tornado or two late Thursady into Friday in eastern OK and north west AR but the chase terrain here is not the greatest. As of now I will probably head out Thursday after Midday and wait to see what happens.

Fig 1

Fig 2

Fig 3

Thursday's Severe Weather

We are still looking at a threat of severe weather developing Thursday across the Central U.S. but depending on which forecast model you go by, there is a very different result. The image above shows the forecast for Thursday evening at 7PM CDT. Notice the cold front is much farther east than the forecast for the NAM (see below). The scenario forecast by the NAM would be much more conducive for supercell and tornado development Thursday afternoon and evening so this will be the model of choice to discuss, since the GFS shows a fast moving squall line with mainly a gusty winds small hail event.



Looking at the forecast map for the NAM for 0Z Friday ( 7PM CDT Thursday Evening) you see an area of low pressure with a warm front extending east through central Illinois and a cold front draped across central Kansas and northwestern Oklahoma. Out ahead of the front a dryline sets up and would be the focusing mechanism for thunderstorm development if this scenario unfolds. There are two areas that seem favorable for supercell development which could lead to isolated tornadoes late Thursday.

The first area that seems likely a few supercells could develop is along and east of I-35 in central Oklahoma south into North Texas north of Dallas. A large area of low level helicity will combine with moderate instability and moderate CAPE across these areas. 0-1km storm relative helicity are between 100 and 250 from the Dallas Forth Worth area through the Eastern third of Oklahoma (Fig 1). This should provide adequate low level turning of height to help produce low level meso cyclones as thunderstorms develop. In the same area surface based CAPE is on the order of 1500 to 2000 J/kg (Fig 2), not extreme but enough to have robust updraft strength in this area of low level helicity. Finally the surface based lifted index is around -4 in this same area providing moderate levels of instability (Fig 3).

Fig 1

Fig 2

Fig 3


The second area of supercell development and in my opinion may be the big winner when it comes to tornado development is out ahead of the surface low across southeast Nebraska, southwestern Iowa, eastern Kansas, and northwestern Missouri. An area of higher instability, CAPE and strong low level helicity will combine for the development of scattered supercells along the dryline/cold front. The images below show the surface based lifted index and CAPE for 4PM CDT Thursday Afternoon. LIs approach -5 (Fig 4)with CAPE approaching 2000 J/kg (Fig 5) in southeastern Nebraska. This area will also be experiencing very strong low level relative helicity, approaching 250 (Fig 6). For chasing Thursday I really like the northern option out ahead of the surface low for tornado development.

Fig 4

Fig 5

Fig 6

Again the following forecast is based on the NAM forecast model. I feel the GFS may be bringing this system through too fast as the water vapor imagery shows the 500mb vort max is moving into the Pacific Northwest slower than the GSF advertised on the 0Z run. I will issue another update later this afternoon after analyzing the 12Z model runs.