A lot of the deaths appear to boil down to a few factors, but even those seem skewed. People who took the proper action died, and people that took no action lived. Therefore, there is no real finger pointer that wins here. The hope is that by better structuring the tornado warning process, people will be more likely to respond. However, one such speaker at AMS really captured my attention. Kim Klockow, a PhD at the University of Oklahoma really hit hard with what she said. (When the link comes from the AMS talk, I’ll be sure to post it). Klockow said that the first thing we need to do is to stop trying to control the people under a tornado warning. We cannot force them to act a certain way, no matter how hard we try, because it’s their right to act on their own free will, tornado or no tornado. This conclusion came about in her study of interviewing tornado victims and asking about their experience in the warning process. Almost all of the people Klockow interviewed took action, but the interesting thing was the train of verification it took for them to take action (again, the slides will make this easier to see when they come out). Several people only took action after verifying the tornado warning with 3 or more sources; some took an indirect action towards the tornado warning. For example, if the warning was issued and the person heard sirens, they would go inside, turn on the TV to the news station, and get their shelter area prepared and then wait for their warning to be verified on the TV. Klockow argues that this decision process of incremental action is natural, and the people that did this survived.

Therefore, my point to this post is to emphasize what Kim Klockow said in her presentation; it is not right of meteorologists to try to control a person’s actions to achieve a desired outcome. This sounds sinister, but it isn’t. Most meteorologists have very good intentions – they want to save lives in the warning process. However, if we acknowledge that people are smart enough to make their own decisions, then it changes our job from “how do we get people to respond?” to “how do we give people the most accurate and timely information so that they can make critical decisions?” THAT, right there, should be the core focus of the coming discussions about tornado warning effectiveness. In its current state, tornado warnings are good, but not effective enough. We’ve come a long way, but now it is time to go further yet. Hopefully you found this post intriguing, and I hope to get the slides up soon.

As far as my explanation, I am at the American Meteorological Society conference in New Orleans, LA. The image above (this morning’s sounding by LIX) is the fruit of this conference; Patrick Marsh released his new sounding analysis program called SHARPPy. I’ve been here since last Friday, attending talks, meetings, presentations, and the whole lot. I got to meet Reed Timmer, the now retiring Director of the National Hurricane Center, and Dr. Josh Wurman of the Doppler on Wheels (DOW). In other words, I’m in weather nerd heaven and having a great time. I return home Saturday and will be able to resume normal life, if life permits.

No severe weather is expected for the Middle Tennessee area over the next few days.

(LEFT: Surface Theta-E from a cold front on December 5th at 18z)

The decoder:

• New approach going from list indexing to loading data into dictionaries. This brings about an incredible speed boost in sifting through thousands and thousands of lines of METAR data.
• Several decoder bugs worked out while sifting through data
• NEW DATA SOURCE: Now reading data from http://metfs1.agron.iastate.edu/data/text/sao/ - This also speeds up the decoder because international stations like Iraq are not in these files, speeding up the sifting process.

GRIDMAKER:

• This new module handles ALL grid making processes, simplifying the plotting process and making the syntax more uniform.
• NEW GRID TYPES: 3 hour tendency (change over time) grids for all scalar outputs, new special grids (divergence, vorticity)
• NEW SCALAR GRIDS: Theta, Theta-E, Mixing Ratio, Relative Humidity, LCL Height in meters, SLP (Sea Level Pressure), wind speed scalar, wind chill, dewpoint depression, 3 hour tendencies of all of the above, and two new special grids: divergence and vorticity, including their 3 hour tendencies.

New Output Grid:

• Changed from a uniform 0.5 degree grid to the RUC 40km grid, the same grid used by the SPC’s mesoanalysis pages (Thanks again Patrick Marsh!)

More Data Observations:

• Canadian METAR sites
• Mexican METAR sites
• Caribbean METAR sites
• Cuban METAR sites

UI Improvements:

• Constructed a command-line UI – GEMPAK veterans need not worry; the command line syntax is based off of the GEMPAK model. I didn’t want to fix what wasn’t broken. This familiar syntax will help seasoned meteorologists and new users alike to be able to easily navigate the program without too much hassle.
• Plans for an improved GUI

And that’s just what has already been done – I haven’t even touched on what I have planned! Things like frontogenesis, advection of scalar quantities, and upper air maps are in the process of being planned out. I also have not forgotten about the meteogram plots; even though no new development has taken place on this program, a lot of the improvements in the mapping program will apply to the meteogram program. How interesting would it be to have meteogram plots of conserved quantities like mixing ratio and theta-e? Or meteograms of values like the lcl height? Could be very interesting!

All of this post is to say, some exciting progress has been made. I figured it would be good to post and update since the last post drew so much of a positive response. However, one VERY important part of the program remains unfinished – THE NAME! I was thinking that in honor of AWIPS/GEMPAK, I would name it PyWIPS: Python Weather Interactive Processing System. It sounds cool, but I don’t think the name makes that much sense. Perhaps I should turn to the interwebs for help! What do you think the program should be named? (RIGHT: Surface Vorticity from December 5th at 18z. Values are multiplied * 10 to the 5th)

So what is Python? Well, I won’t go into too much detail, as any Google search could probably enlighten you better than I. Regardless, Python could be summarized as just another programming language. However, that would not be the truth. The truth is that Python is a very powerful programming language. Confused? Google. They use Python!

So what am I doing with Python, and how is it weather related? Well, I’m doing a lot, actually, and it could be very useful data if the community so desires it. At first I decided to write a program to simply decode METAR (weather station) data from the internet, but then I realized I could do more with that data. So, I am attempting to write a full fledged surface data analysis suite that will include meteograms, contoured plots, station plots – you name it! How is this useful? Well, as far as I am aware, there is no program that shows the raw (contoured) station data on a map (station plots are a different story) – most data you see is from a model analysis, save for some programs that will show the METAR station data, but won’t visualize that data beyond an ordinary plot. The second reason that this is useful is because there is only one program that can come close to doing this kind of stuff, called GEMPAK, which I use often. However, it is a pain in the butt to build, is extremely complex, cumbersome, and quite “buggy”. Where it does succeed is in its high level of customization and its diversity in showing a large array of products. What I am hoping to do with this program is provide a lightweight, fast, and functioning alternative to GEMPAK while keeping that customization intact. Python just happened to fit the bill!

Obviously I am not starting ENTIRELY from scratch here. The only “from scratch” part is the program that gathers and interprets the data. The rest of it is made possible with MATPLOTLIB via ENTHOUGHT. Matplotlib is what I am using to visualize the data and does a lot of heavy lifting.

So what do I have so far? The two major ones are meteograms and surface contours (with wind barbs). An example of the meteogram can be found above: It’s bare bones right now, only taking in temperature, dewpoint, and wind data. In the future, however, it will also support pressure data and possibly precip. Meteograms are great for viewing data over time for a particular station. The one above is quite interesting, for station KOUN (Norman, Oklahoma), and if you look closely, denotes the passage of a cold front. The other plot I have completed is contouring the surface data on a map. This proved to be quite a challenge. Thankfully I had a bit of help from Patrick Marsh, so a big thanks to him! I won’t get too detailed, but the data is interpolated onto a lon (x) lat (y) grid (like a graph) and then plotted on a map via Basemap, a part of MATPLOTLIB. This is an example image output to your right (the program supports all major image outputs – PNG, GIF, JPG, PS, PDF, etc.). Quite visible in the map is a surface cyclone with a trailing cold front. Again, this is ALL RAW METAR DATA. No model analysis. Pretty cool, huh? The best part is, the program supports interactive viewing, with pan and zoom functions available. However, the user interface is primitive, at best.

So what now? Well, it may look like a lot is done, but this is only the bare guts. The next step (which I am in the process of doing) is to optimize the code and make it faster. After that, the user interface will need to be built, followed by plenty more code revisions. Another huge step is to make it more interactive with the user, taking in options that the user can specify. As you can see, there is a ways to go! But, because the foundation has been lain, I figured it was time to make this public. If you are all intrigued and would like to know more, you are more than welcome to email me or message me on facebook/twitter/google+. I’m going to refrain from posting any code online, but if you’d like to ask questions or even make suggestions (help is always appreciated), give me a holler.

Hopefully this post wasn’t too terribly boring, but I wanted to share the project with the interwebs. You’ll be seeing more posts and photos about this in the future as things continue to progress. It’s really coming together quite nicely.

Generally speaking, in the last 2 years we have had at least 1 significant tornado risk during fall severe weather season. If this trend continues, it is likely that we will see at least one significant risk this year. However, the atmosphere does not like to be put in a box. Therefore, at this point we can only assume what will happen. Based on long range modeling, however, it looks like Tennessee will experience above average temperatures over the next month. We cannot guarantee a lot of things from this alone, but one can guess a few…

Warmer temperatures do not guarantee more moisture, but it certainly increases our chances of getting that moisture. With the jet stream in better position, warmer temperatures in place, and the potential for good moisture could indicate an active season for the Southeast. Will this actually come to pass? We won’t know until it happens.

Until that happens, however, enjoy the lovely weather! Things should stay cool and dry through the next week and rain free. Though not my favorite kind of weather, I know the rest of the world enjoys it, so enjoy it while it lasts! I’ll be happy when fall severe weather comes around .

Also, keep checking back for updates, as I am planning on making a trip to Norman, OK, for the National Weather Festival. I’ll post about it if it comes to pass!

As said above, a strong mid-level jet is currently situated around a cutoff low, perfectly positioned to provide copious amounts of wind shear through the atmosphere. These strong winds extend through the lower atmosphere, and there is even a 40-50kt low level jet forecast to take place after dusk, bringing plenty of moisture out of the Gulf. By my limited understanding, if this takes place, surface instability will continue into the evening and allow for a better chance of severe thunderstorms, mainly across northern portions of Mid-TN. If this is the case, the strong, shearing winds in the upper-air profile to the right will provide an environment favorable for severe weather. However, most of this is speculation, and the models are inherently imperfect. The challenge is knowing how to sift through the data. Unfortunately I do not have much more to add, but through the afternoon and early evening, I am going to continue to monitor the weather and try to further analyze the situation. Even though severe weather isn’t staring us in the face (yet), be prepared for some storms to be severe tonight. The National Weather Service is saying that places West of I-65 have the best shot; I’m going to say West of I-65 and North of I-40.

I’ll keep updating the website as things change. Thank you for reading, and don’t forget to check for updates on Facebook and Twitter!

Irene is forecast to become a category 4 hurricane at it’s peak, which would be approximately 2 AM friday. A category four hurricane has *sustained* winds between 131-155 MPH. Irene is currently a category 2 hurricane (96-110 MPH), forecast to be a category 3 (111-130 MPH) hurricane by tomorrow. Infra-red satellite imagery shows that Irene has begun to intensify quite a bit over the last 12 or or so hours, and is really about to kick it into high gear! Irene is moving over very warm waters with a relatively unobstructed intake of that heat, which will result in further intensification. Because of this, it is completely within the realm of possibility for Irene to become even stronger more quickly. Irene needs to be watched very closely, because she could become quite strong and may even make landfall as a category 4 hurricane instead of the forecast category 3.

Irene has not yet developed a well defined eye wall (see left image), which is interesting. I am not well versed in hurricane forecasting, this is a first for me, so I am not quite sure what this indicates. However, I would guess that this means that Irene is not a “mature” hurricane yet. The fact that it is not fully organized might have to do with the fact that portions of Irene are over the Dominican Republic. Once Irene moves out into the bahamas, I expect we will see an eye wall develop on satellite and it will probably correspond with the category 3+ conditions. If you look at this visible satellite image from this morning, you can see the lack of a well defined eye wall. However, you can also see a very intense updraft and the further strengthening of Irene.

I’ll close this off with the forecast text from the National Hurricane Center. If you are in the path of Irene, you need to start getting prepared! If you are chasing Irene, I wish you the best of luck. Stay safe!

HURRICANE IRENE DISCUSSION NUMBER 12

NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011

500 AM EDT TUE AUG 23 2011

SMOOTHING THROUGH ALL OF THE AIRCRAFT FIXES SINCE IRENE MOVED OFF THE COAST OF PUERTO RICO MORE THAN 18 HOURS AGO YIELDS A LONG TERM MOTION OF 295/10 KT…WHICH IS USED FOR THIS ADVISORY. THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK REASONING. THE 23/00Z G-IV JET AIRCRAFT AND AIR FORCE C-130 DROPSONDE DATA APPEAR TO HAVE SETTLED DOWN THE MODELS…AND THERE IS CONSIDERABLY LESS DIFFERENCE AMONG THE VARIOUS MODEL SOLUTIONS NOW. THE OVERWHELMING CONSENSUS IS THAT IRENE WILL GRADUALLY TURN NORTHWESTWARD OVER THE NEXT 2-3 DAYS AND THEN MOVE NORTHWARD THROUGH A DEVELOPING BREAK IN THE SUBTROPICAL RIDGE OVER THE SOUTHEASTERN UNITED STATES. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY AND LIES VERY CLOSE TO CONSENSUS MODELS TVCN AND TVCA.

AN EARLIER RECON FLIGHT INDICATED THE PRESSURE HAD ONLY FALLEN BY 2 MB DOWN TO 978 MB…AND THE OVERALL APPEARANCE IN SATELLITE IMAGERY HAS CHANGED LITTLE SINCE THE PREVIOUS ADVISORY. AS A RESULT…THE INITIAL INTENSITY IS BEING HELD AT 85 KT…WHICH COULD BE GENEROUS. IRENE IS FORECAST TO REMAIN IN A RELATIVELY LOW VERTICAL WIND SHEAR ENVIRONMENT AND OVER SSTS NEAR 30C. THAT COMBINATION…ALONG WITH EXPANDING OUTFLOW IN ALL QUADRANTS…SHOULD ALLOW FOR IRENE TO BECOME A MAJOR HURRICANE WITHIN THE NEXT 24 HOURS ONCE THE CYCLONE CLEARS THE EFFECTS OF HISPANIOLA…AND PROBABLY MAINTAIN MAJOR HURRICANE STATUS THROUGHOUT THE REMAINDER OF THE 5-DAY FORECAST PERIOD. THE INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND CLOSELY FOLLOWS A BLEND OF THE HWRF AND GFDL MODEL INTENSITY FORECASTS…AND CONVERSION OF THE SURFACE PRESSURES DEPICTED IN THE GFS AND ECMWF MODELS.

WIND RADII WERE EXPANDED BASED ON A BLEND OF RECON FLIGHT-LEVEL WINDS…SFMR WINDS…AND SURFACE OBSERVATIONS.

IRENE IS FORECAST TO BECOME A LARGER THAN AVERAGE HURRICANE. IT IS IMPORTANT TO REMIND USERS NOT TO FOCUS ON THE EXACT FORECAST TRACK…ESPECIALLY AT DAYS 4 AND 5…SINCE THE MOST RECENT 5-YEAR AVERAGE ERRORS AT THOSE FORECAST TIMES ARE 200 AND 250 MILES… RESPECTIVELY.

These thunderstorms will be coming from the north, heading south (due to the upper level high pressure’s circulation altering the jet stream) and the storms will be lined up from west to east. Convective Available Potential Energy (CAPE) will be well over 5,000 even into 6,000 j/kg due to our very warm environment, with low level lapse rates already over 8.5c/km! For a quick crash course, CAPE is the amount of potential energy available to a storm, and a lapse rate is how fast the atmosphere cools with height. 8.5 degrees celsius for ever kilometer is considered nearly extreme! In other words, this damaging wind setup is beginning to really take shape, and it will be interesting to see what these storms do. The atmosphere is already primed, all we are waiting on is for the front to pull the trigger. The image to the right is the experimental High Resolution Rapid Refresh (HRRR) model showing simulated radar reflectivity, and is confirming the chance for thunderstorms this evening. Even though there is a margin for error, it is looking increasingly likely that we will see storms tonight.

What could prevent us from seeing this? Well, this whole forecast goes to pieces if the frontal boundary doesn’t show up, or shows up too late. We’ll have to keep an eye on whether or not that happens. Enjoy tonight’s storms, they should be quite fun!

..TN AND MID MS VALLEYS…

MORNING CONVECTION OVER PARTS OF KY/WV/VA HAS ERODED THE AREA WHERE STRONG INSTABILITY REMAINS…WITH GREATEST THREAT OF SEVERE STORMS REMAINING OVER PARTS OF KY/TN INTO SOUTHEAST MO. HOT /100F+/ TEMPERATURES AND MUCAPE VALUES OVER 5000 J/KG WILL PROMOTE STRONG UP/DOWNDRAFTS…ALTHOUGH VERTICAL SHEAR IS RATHER WEAK. LATEST STORMSCALE MODEL SOLUTIONS INDICATE POTENTIAL FOR UPSCALE GENERATION OF MCS SAGGING INTO NORTHERN MS/AL THIS EVENING. DAMAGING WINDS ARE THE MAIN THREAT WITH THESE STORMS.

Today, the atmosphere will be pretty unstable, with CAPE values well over 2,000 j/kg. Our initiation mechanism today will be an upper level shortwave trough making it’s way through Kentucky. This shortwave trough will continue to circulate around the upper level high pressure over the central US, eventually making it to Tennessee. Forecast models have this shortwave trough kicking off storms over the next few hours, and then storms should die down after the sun sets. This event isn’t expected to be anything major or anything complicated. Again, we have a lifting mechanism (shortwave trough), unstable atmosphere, and clear skies. The ingredients are in place, now we just have to see what happens.

Don’t be surprised to see a few severe thunderstorm warnings today if things do kick off. Also, heed them! Downburst winds can be just as strong as dangerous as tornadoes in some situations, do don’t take warnings likely.

Even though the National Weather Service and the weather community have been expecting this heat wave for the last week, it never really caught my attention until last night when I was drawing my own weather analysis map. When I saw how large this high pressure was, I knew we were in for it. This was confirmed with this morning’s weather map analysis, where the high pressure actually GREW overnight! Take a look at the image to the right. I’ll explain things a little. This is a 500 millibar map (millibars is a unit of pressure). Now, 500mb is just a pressure reading, and can be at varying heights above ground. So, we contour them (the black lines), or lines of a constant height. The higher the height (center of the map right now) the higher the pressure. The lower the height (Pacific Northwest) the lower the pressure. (Confused as to why this is the case? check out this link here.) Now, areas in blue are areas that dropped in height/pressure over the last 12 hours, while areas in orange are height/pressure rises. Now you can kind of get a picture of what the atmosphere has done. A low pressure off of the West Coast as brought the heights down a little bit, but not by much. Also, a Canadian low pressure dropped the heights a bit, but it is also leaving the area and will not affect us much. The high pressure, however, enlarged and grew in intensity, expanding to the Northwest. This and similar things will likely be the pattern for the next week. This pattern is called a Ring of Fire, because areas on the outer edges of the high pressure are unstable enough to support some summertime thunderstorms. The general storm motion tends to rotate clockwise around the high pressure.

So, just how bad is it going to get for us in the Southeast? Well, as early as Monday we can expect temperatures back in the mid and even upper 90s, but the overall likelihood of *excessive* heat isn’t quite like what’s going on elsewhere. The National Weather Service in Nashville doesn’t expect heat index values to head into heat advisory levels over the next week. So, although it will be hot, it shouldn’t get too dangerous. Most of the dangerous heat will be confined to the Central US for the time being, and maybe even the East Coast as the high begins to move out. Forecast models show this high pressure system beginning to move out sometime next weekend. One model says Friday, the other says Sunday, so it is unclear as to exactly when.

A friend of mine described to me the real danger of heat waves. He said, “The danger of heatwaves is not because of the heat during the day, but it’s the fact that the temperature does not easily drop during the night.  The body needs to have the opportunity to recover from the heat during the day.” Unfortunately, high dewpoints wont allow the temperatures to drop too low. So, stay cool if you are out in the Central US! Those of us in the Southeast are going to dodge this bullet… for now.