Tornado Test

What happened to Beryl? Beryl never regained tropical storm status. The trough that accelerated the storm out of the Southeast decoupled the low level circulation from the convection activity. The storm transitioned to extratropical status. The well defined surface circulation is still visible but the lowest surface pressure has become very elongated, almost like a trough. The storm has been defined as post-tropical.

Cells favored most tomorrow for severe weather; tornado damage number is low, suggesting either very few tornadoes, short lived tornadoes, or weak tornadoes.

Storm Prediction Center's region most likely to see severe weather on Thursday

Cells favored most Friday for severe weather; tornado damage number still on the low (higher than the cells on Thursday), suggesting few tornadoes, short lived tornadoes, or weak tornadoes (some combination of those three).

Storm Prediction Center most likely area for severe weather Friday

This is a test update on my tornado index. Note that these forecasts are not purely derived from my new index (still unreleased, patent pending). Rather, it is the hope that the new tornado index is implemented to augment pre-existing forecasts. Note that for both days and for all cells the numbers I am getting are quite low (for tornado damage potential). Even using conventional techniques we are most likely to see severe thunderstorms with hail, damaging winds, but a small percentage for tornadic activity.

How come the cell containing the High Country is not included? Although there is a high potential for severe thunderstorms being near the area, conditions are not favorable enough for significant tornadic activity. Note that this index does not place much weight on squall line induced tornadoes and weighs longer tracking, more violent, and more frequent tornadoes more heavily than isolated events.

Using a conventional forecast, I have come to a similar conclusion; although storms may be severe near and around the High Country, the Piedmont and eastern Piedmont will get the lions share of the severe weather.

Beryl Visible Satellite

Well, Beryl shook off its dependency on the upper level low and passing over the Gulf Stream has induced deep convection over the system. The dry air that was penetrating the core yesterday has been walled off today. Beryl will likely be a strong tropical storm by landfall late tonight.

Ridiculous Outflow Boundary

Ridiculously long outflow boundary from a cluster of thunderstorms earlier. Thunderstorm genesis is still occurring along the outflow boundary.

Same observation. You can see the start of the sea breeze, the convergence along the coast that triggered the initial flareup of thunderstorms, and then the enhancement of the outflow boundary into the eastern Piedmont. By the way, we are starting to get a more mature phase of the cyclone. Comma head appearance still suggests there is frontal components to this.

05/25/12 forecast and a neat story

Before I start with the forecast, I want to share a story. As I was driving up to the High Country, I stopped at a rest stop just east of Wilkesboro. An old man says to me "I like your shirt" (referring to the NC State logo I had on it). I told him I have been out in the real world for 10 days and he tells me "I graduated in the class of 58 as an engineer. Where are you heading?" I tell him and he says "Ohhh I used to live up in Boone, moved up there in the fall of 59. I just couldn't handle the winters up there." I quickly put two and two together and realize why he was saying that. His first year he had to deal with the 1959 - 1960 winter, the same winter that dropped 105" of snow in Boone (83" fell AFTER Valentines Day). He told me a story where his truck got stuck in a snow drift on Rivers Street, and how by the time the plow had gotten to him, the truck was completely buried in a snowdrift. He left the High Country in 1963, because apparently during that winter, it got so cold slush refroze between his brakes and his tires, rendering his front wheels inoperable. He ended up being towed to a dealership to chip the ice off of his brakes.

Please, if you have any winter stories, feel free to share!

Infrared - Water vapor (experimental, from CIMSS). Yellow = upper level divergence. Note the complete lack of outflow west of the circulation (because of shear). This divergence is where the exit region of the southerly jet is located.

Upper level winds. Note that the yellow rings from the previous animation are where there is a decrease of upper level winds (and is to the right of this decrease). The surface low is also located downstream of the upper level low, meaning it's not ready to be listed as a named tropical system yet!

First, lets have a look near Florida. We have a disturbance here, which has a medium chance of becoming a subtropical or tropical storm, especially when this southern trough decays. Because of  strong wind shear, thunderstorm activity is east of the center. There is still an upper level low component to this, which is not over the center due to the shear. The low is sitting just downstream of a low level jet (the southern storm track). This jet is weakening: this should be conducive enough for a weak subtropical storm.

Infrared satellite image with vorticity contours (plot from CIMSS)

Visible satellite with shear (yellow contours) and upper level wind flow (white). Plot from CIMSS

300mb winds for today (from weather.unisys)

1000mb temperature and pressure contours for tomorrow (from unisys)

300mb winds for tomorrow (from weather.unisys)

The two blue/purple plots are upper level winds (this afternoon and tomorrow afternoon) with pressure contours and the plot on the right is a surface temperature plot (tomorrow afternoon). I would be really surprised to see a tropical cyclone designation before tomorrow. The decay of steering currents  slow down this surface low and eventually the tropical low will drift into the Florida/Georgia coast. This is an area that needs the precipitation!

To our forecast:
Today: We are on the backside of a decaying trough, which will inhibit thunderstorm chances. Tomorrow and Sunday the southern component of the jet stream decays over the Southeast (the jet actually merges over Mexico/Southwest United States, which is very visible on the bottom plot). We are underneath an upper level ridge but high surface instability, particularly near the mountains, will inevitably allow for scattered pop-up thundershowers tomorrow afternoon. Between the upper level low (what may soon become a tropical cyclone) and the upper level ridge there will be slight upper level convergence over the Piedmont tomorrow, which will hinder thunderstorm formation there. I do think the inhibiting factor will be weak enough to allow for a stray pop-up storm here as well. Sunday will be mostly clear with a chance of an isolated showers (from the onshore flow from the tropical low). The isolated shower activity will be contained to east of the mountains and the eastern portions of the mountains. Note that the shower activity will be near stationary for both days.

Forecast 05/22/12

Well, we will be singing our swan song for Tropical Storm Alberto. Wind shear has been displacing the convection away from the warm core surface low and the upper level component has detached from the surface low. This storm is on its way out the door and the surface low will soon lose its identity. Lets have a moment of silence for this storm.

Water vapor imagery from CIMSS.

So what's the swirl over Alabama/Georgia? That is actually the soon to be upper level low, forming at the base of the trough.

Palmer Drought Index (from U.S. Drought Monitor).

Let the rainfall commence...well, not really. We do not need anymore rainfall. In fact, the High Country and the immediate surrounding regions are completely out of drought conditions. The rainfall is more welcome farther south, which has been relatively dry except for sporadic thunderstorms. While the High Country has gotten both steady rain events and short "burst" convective thunderstorms, areas farther south have gotten just the latter. That's not a good thing when all of the water runs off before the soil has sufficient time to absorb the water!

Convective Available Potential Energy (CAPE) for tomorrow afternoon (from twisterdata.com)

As expected, thunderstorms peaked early today and remained semi-stationary over the mountains, aggravating the already rain soaked regions. Today is the peak day for thunderstorms this week. Tomorrow thunderstorms and showers will still be present in the afternoon but the spatial coverage will be slightly less than today. I think the proximity of the front (just east of the Blue Ridge) will keep showers nearby. In this very broad trough (in the southern storm track) we will have a weak upper level low form tomorrow. The next few maps are from www.weather.unisys.com.

300mb winds for tonight. The trough in the southern jet stream is in its peak phase

Tomorrow 300mb level (winds). Notice the trough has become more broad, with an upper level low over the Mid-Atlantic and another zone of vorticity over the Gulf.

This upper level segment of the trough (image above) for tomorrow, along with the proximity of the stationary front (just east of the Blue Ridge) will again fire up showers and thunderstorms in the afternoon. Again I think the rain chances will be high (higher than 50%) but the areal coverage of rainfall will be lower (not as much green covering the weather map).

Thursday 300mb winds.

Notice on Thursday that the upper level portion that was over us Wednesday has degenerated. We will look at a lower level to show this. The heaviest precipitation will be across Florida. Sporadic showers will still be around our area.

Thursday 500mb level VORTICITY map. This is not a wind map, but a map that shows absolute spin in the atmosphere.

Question that may get asked: Why is this map disproportionately covered in positive values?
Answer: Absolute vorticity = relative spin + planetary spin. The farther north one goes, the greater the planetary spin effects weather systems. This is the same reason why we do not get tropical cyclones forming along the equator. Tropical cyclones need some input from planetary spin (coriolis).

See the yellow off the coast of New Jersey? This is what is left of the upper level low that will be over the area tomorrow. Shower chances decrease to a moderate level on Thursday. The trough quickly accelerates away from the Southeast coast, giving us clear weather on Friday - Sunday, as a ridge builds to our southwest. It will be VERY warm this weekend, however I think the hottest weather will be to our west.

I blame Pete Soule (professor at Appalachian State) for my frequent use of weather.unisys. This site is run by several guys over at Purdue and in terms of making weather map products that are easy for the common person to read, this is it. We will save the more complex variables for another day!

05/21/12 Forecast

Hey everyone! Let me start by saying this: we have more low pressure centers across the Southeast than Starbucks has coffee sizes. Lets start with a water vapor image.

And below is a fixed image with the centers located. This image comes from CIMSS Tropical Cyclone analysis page (along with the above animation).

All four low pressure systems are entirely different.
Low #1 (over Tennessee/Kentucky) is a frontal low associated with a building trough in the northern branch of the jet stream. This low is forming in the zone most favorable, which is slightly downstream of the trough axis.
Low #2 (near Virginia) is responding to a mid-level disturbance (from a very broad trough)
Low #3 (over Atlantic, east of the SC coast) is a frontal low associated with a trough in the southern branch of the jet stream.
Low #4 is a warm core tropical low, also known as Tropical Storm Alberto

So no wonder we have that continuing shower threat for this week! What do we have lined up for this week.

Today - thunderstorms will pop up rapidly this afternoon and evening. Weak winds even high aloft will limit damaging winds and storm longevity. The outflow from these storms are likely to fire up new storms nearby. Expect heavy rain and some hail today.

Tuesday - Wednesday - amplified split of the storm track (northern branch vs southern branch). We won't be seeing the northern branch very often this summer but the southern branch (subtropical jet) will be a nuisance for us this summer. This is typical for a neutral ENSO or an El Nino summer. A stronger subtropical jet brings more frequent southern tracking (weaker) storm systems to our area. This somewhat diminishes the chance of a powerhouse ridge forming over our area.

Upper level vorticity for Tuesday afternoon (from weather.unisys)

I don't see this upcoming cold front making it very far past the Blue Ridge before it stalls. This keeps rainfall nearby for Tuesday and Wednesday, but does put the High Country in a slightly more stable air mass. This means severe thunderstorms less likely. The building trough will accelerate the tropical storm away from the coast and lead to its demise.

Thursday - the strengthening trough in the northern jet "pinches" off the trough in the southern branch. This will leave behind a weak, broad upper level low for Thursday, which keeps showers in our area. The GFS has the upper level low being too strong but at least is on the right track of the areas of precipitation. We will just have some scattered showers then.

Friday - A ridge behind the southern branch of the jet stream will make it mostly clear and dry. There may be isolated showers along the coast due to a synoptic reinforced onshore flow. This won't be around Saturday. The ridge will force the southern branch far south of our area and will be weaker, thus keeping the weather drier for the weekend. It will be WARM this weekend

Ski Beech Geospatial Model

THIS WEBSITE AND THE FORECASTS ARE THE INTELLECTUAL PROPERTY OF JOHN L'HEUREUX AND L'HEUREUX'S WEATHER. NOTHING CAN BE REPRINTED, REPOSTED, OR USED WITHOUT PERMISSION.

I am making these "GIS analysis" when I can, but I will be going at about 1-2 resorts per week. Appalachian Ski Mountain is on my portfolio but will be copied to this blog (as it is easier/quicker to modify than using Dreamweaver). For this entry I will be covering the highest ski resort on the east coast, Beech Mountain.

Ski Beech Proposed. Description is below.

I have skied at Beech Mountain and this resort has some great potential. Sitting at a base elevation of 4700' (that's not a typo) and a peak elevation just under 5500', Beech Mountain's elevation CLEARLY passes my GIS test of both being on a peak above 5000' and having a resort base above 3500'. The peak elevation minimum of 5000' ensures that there is sufficient orographic uplift for a Northwest Flow Snowfall. Now, this peak elevation is not an essential. Poga Mountain barely tops out at 4300' yet still racks in heavy upslope snowfall. A big part of this is having nearby peaks that are above 5000' (Snake Mountain, Roan Mountain, Sugar Mountain, Beech Mountain). 

Since orographic snowfall can constitute up to 50% of a season's snow content, every tangible factor which increases this snowfall total is critical. Since Beech Mountain is on the western periphery of the Appalachian Mountains, the moisture content is undiluted and thus maximizes in orographic snowfall. Areas east of here receive far less snowfall, with Deep Gap (just 20 miles away) receives far less snow from an upslope flow. This is because upslope events have little moisture to work with and with this being a stable air mass, vertical uplift is unlikely to occur past the initial windward slopes. For a perspective, there is often a capping inversion between the 725mb and 750mb levels. Above this layer the relative humidity sharply decreases. That is shallow my friends. And that's during peak conditions. I have seen a moisture layer as shallow as the 850mb level (4700') that STILL produced measurable snow. Northwest Flow Snowfall however does not have a very high liquid to water content, so this snow compacts and melts faster than a southerly tracking system. We have had Northwest Flow Snow events range from a 10:1 snow ratio to an outrageous 70:1 ratio (70" of snow to 1" of rain water). I can sweep that off my deck for crying out loud!

With a low density like that, this snow type is likely to have snow drifts associated with it if there is any significant wind. This is a disadvantage for Beech Mountain, as some of the snow is simply blown off the slopes. They tried really hard to make every slope face northward to decrease sun exposure, but this is a case where it takes away another benefit. Had the resort oriented its runs towards the Northeast instead, like Hawksnest, then snow blown off the summit would actually be deposited on the resort side. This happened at Poga Mountain where a rotor kept the highest winds above our research station and actually helped to keep our snow around. The same snow blown off of the summit of Beech is deposited in the town of Beech Mountain.

Another disadvantage to making every slope face north - sometimes the mountain slope is not quite oriented towards the north. Many of Beech Mountains main runs have a double fall line where the left side of the slope is 15' higher than the right side of the slope. Ouch.

Beech Mountain has clear advantages over the other resorts. Higher elevation = cooler and enhanced Northwest Flow Snowfall = more snow. Wide runs give skiers more room to work with and having a high speed quad is really nice.

But has anyone tried to come up here in a bus? Not only do you have to drive up to the summit, you have to go down the other side as well. The other side has much sharper curves and is somewhat sheltered from the wind, increasing snow drift chances. The images I have below are Google Earth derived and are not actual plans but a "what if" scenario.

Proposed Beech Mountain. Red = new lodge/village, gray = parking lot (proposed), purple = new terrain, black = reclassified ski run

Wait a new lodge? Did I really just propose moving the entire base area and parking lots? Yes, I did. Why? This shortens the distance one has to drive to the resort and makes it much easier to get there. No longer does one have to go down the other side of the mountain on really tight, steep curves and the new area is much more bus accessible. But imagine this: instead of a ski in/ski out village, what about a ski in/ski out TOWN. Right next door is the sledding hill, town center, Fred's Merchantile, and other convenience stores. A new lift on the old terrain park (nearest lodge) would serve as the new beginner area. Honestly this terrain was a little too flat to support a park but half of the slope could still support a progression park. A new triple lift replaces the Shawneehaw lift and has a mid station. Another lift replaces the fixed grip lift that used to be here and could also be a triple lift. A defunct slope cutting across the mountain would serve as an advanced beginner run from top to bottom, while the new run on the backside would give a lower intermediate/upper beginner run to funnel more traffic to this lift. To eliminate the difficult double fall line on Robin's Run, the bottom half of the slope curves towards the northeast. The old "lower Robin's Run" would serve as the intermediate/advanced terrain park. The pitch is perfect and the new triple lift nearby funnels park traffic to this area instead. The original base village can still exist: remember that there are residents living on the backside of the mountain. I don't think they need all of the buildings but rather could possibly add another reservoir down here for the town water supply.

This is just a proposal using geospatial analysis. The beautiful thing about using GIS and Google Earth is the ability to quickly render a map of almost any variable. One can quickly use these tools to find the most favorable locations for ski runs on a mountain, and use the tools to classify the ski rating for the terrain (based on slope).

Tropical Storm Alberto

Google Earth image of Tropical Storm Alberto

For those of you who have been in the North Carolina area for a while, a tropical storm forming off the coast during the month of May should not be a surprise. Statistically, one storm forms during the month of May every other year, and those that form off the coast of the Carolinas during this time of the year can form from a backdoor cold front. Before we go any farther, I would like to introduce you to Subtropical Storm Andrea.

Subtropical Storm Andrea visible satellite, source Wikipedia

Subtropical Storm Andrea water vapor, source Wikipedia

This storm and the current tropical storm have a remarkable amount in common. Both formed from a backdoor cold front and both were originally attached to a cold core upper level low. Both went through a process of a burst of convection underneath the upper level low. This is not atypical: cold core upper level lows that either detach from the upper level trough or are still attached to the trough and move towards the tropics steadily lose the cold/dry air contained within it. Convection that occurs nearby the cold core low can actually moisten the environment around the low, making it more conducive for thunderstorms to form closer to the center. Prior to a subtropical storm forming, you will see a scattered band of convection displaced from the center of circulation.

But what is a subtropical storm? A subtropical storm is a storm that has some characteristics of a tropical storm, but may not fully meet the criteria (weak surface low, still attached to upper level low, still transitioning from a cold core to a warm core system). A subtropical storm does need to lose most if not all of its frontal characteristics.

If the surface circulation becomes better identified, has the strongest convection near the center, and is a true warm core low, then it will become a true tropical storm, such as Alberto. This never happened with Andrea; Andrea had too much dry air disrupting thunderstorm formation near its center. The next four images below are from SRRS and show how both Andrea and Alberto formed from backdoor cold front systems.

Prior to Subtropical Storm Andrea, May 7th, 2007

Formation of Subtropical Storm Andrea (May 9th, 2007)

Prior to the formation of Tropical Storm Alberto

Alberto losing its frontal characteristics and becoming more tropical

Forecast for 05/19/12

A building ridge will keep the High Country warmer and drier for the weekend. A weak upper level disturbance will keep some shower activity around for the South Carolina and North Carolina coast. High moisture content and enough instability allowed for the isolated thunderstorms today: those variables are in much less abundance tomorrow. There is an outside chance for a rogue shower for southwest North Carolina but that chance is very low.

Weak upper level low meandering over Southeast keeps precipitation chances around.

Sunday will be clear and even warmer for the High Country. The low off the coast continues to hang around and weaken, keeping the thunderstorms around the coast. There is a slight chance of a thundershower Sunday night and again on Monday, from the meandering (and weakening) low. An approaching cold front Monday night/Tuesday morning puts the High Country at a moderate chance for showers/thunderstorms. Tuesday will have moderate showers/thunderstorms. Tuesday night becomes more clear as the system starts to depart.

Soon to be commentary on Sugar Mountain on my portfolio. Purple runs = proposed runs, red lines = fixed grip lifts, pink lines = high speed quad

 

Let me take the opportunity to post my online video of Appalachian Ski Mountain. I may do another resort as time goes on, however there are time restraints with other current projects going on.

http://www.youtube.com/watch?v=X_KMQVXoFDM