Snow before Thanksgiving?

Possible Snow for Richmond Nov 26th

This week is shaping up to be an interesting one for Richmond, VA! First, temperatures will keep climbing from a low of about 35-36 tonight all the way up to the mid 70s on Monday!!

This is in response to a potent 500mb shortwave that is abnormally far south. At least I can't ever remember a time when a shortwave in the Southern stream had so much energy and intensify like this one will. Here is the 11/22 NAM 12z initialization.




At the surface, a low pressure center is forecast to form in the lee of the Rockies. Another low that has already formed in Alberta will move down into the upper plains and combine with the Rockie low. It looks like this low will rapidly intensify by the time it moves over the Great Lakes by forecast hour 48 (12Z 11-24). The GFS has the low below 972mb! This will provide plenty of warm air advection for us in the warm sector, giving us the near 75 degree highs on Monday. As the warm front moves through on Monday, the NAM has Richmond getting over an inch of rain, but the GFS is only showing ~1/4 of an inch.

Snow!!!

The big excitement for me is the possible snow on Wednesday.

After that shortwave moves through, the GFS is showing a second shortwave moving throught the bottom of the main trough. A low pressure is forecast to form off the Carolina coast and moving quickly up the Eastern shore. This low may also bomb out off the coast of Newfoundland. As it bushes past Virginia, wrap around moisture, and a column that looks like it can support freezing precip, and a surface right 34-35 could be our first snowstorm and our first big snowstorm.

If it verifies, I just hope it doesn't cause any trouble for my Dad who is coming to visit us for Thanskgiving. He gets here Thurday morning!

My Weather Station

My Davis Vantage Pro2

I finally got my weather station up-and-running and reporting to the Weather Underground!
URL: http://www.wunderground.com/personal-weather-station/dashboard?ID=KVAHENRI14

I wanted it to be more than just a way to check the outside temperatures. Also, I didn't want to have a full computer running all the time to gather the data (The Davis WeatherLink software only runs on Windows). So I decided to buy a rabbery pi.(http://www.raspberrypi.org/): a $35 mini-computer the size of a credit card.

How cool is this little thing!!!

The little dongle sticking out is a USB Wireless adapter. Which actually works amazing on the Rasbery Pi!!! All I had to do was plug it in and press the WPS button on it and my router. Then, it was connected!!! As for an Operating System, I choose Raspian: http://www.raspbian.org/. I liked it MUCH better than Arch Linux. I tried Arch first, but man, I had to configure every little thing manually - like DHCP settings. Raspian seems like it is basically Dabian, but smaller and built for the Pi. It has been working perfectly for me!!!

As for the software, there are these amazing people over at WeeWX: http://www.weewx.com/. They have software that will interface with almost any personal weather station and its built for Linux! It's really easy to set-up, just follow their directions. They also have a large user group which actively posts on the forum and answers many technical questions. They only thing I did wrong (and it took me almost two weeks to figure out) is that you have to see up a MySql database first to store your weather data. I assumed their code would do it for me (dumb of me). However, even I was able to download MySQL, set up a database, a table, a user (weewx) and set a password. 

Somehow, I finally did it! I am very proud of my weather station (counsel pic below). Thanks to my AMAZING husband for buying it for my birthday!!! LOVE you babe!!

Cold front

7-16-14 Cold front

We had a nice cold front come through Richmond yesterday. It came through around 7am in the morning. It was fun to watch the cold air advection fight diabatic heating. The temperature barely changed at all until after 10 am. The real change was the dew point!!! It dropped almost five degrees in 30min!

The GFS is drunk!!!

I fell for the GFS's drunken blunder!

So, last time I posted, I was all excited for the major land-falling hurricane that the GFS was forecasting 5+ days out. I should have known better because:

1) The GFS is drunk

2) The GFS always showed the hurricane forming at the same time, regardless of run time. (No matter what run of the GFS you look at over the past five days, it shows the hurricane forming at the same forecast hour.

3) The Euro model was showing no development at all. 

Finally yesterday, I came to my senses and started to do some research on what is going on. It turns out that the with the GFS's convection characterization, it tends to overestimate large areas of thunderstorms. 

Here is Dr. Masters (a man much smarter that I) in his blog yesterday:

"We know that the GFS model gets in trouble when making predictions of heavy thunderstorm activity via a problem called "convective feedback." Basically, the model sometimes simulates that an unrealistically large area of thunderstorms will develop, destabilize the atmosphere, and cause an area of low pressure to form that will draw in more moisture and create more heavy thunderstorms. This vicious cycle can snowball out of control and generate a bogus low pressure area that can then modify the upper level winds, reduce the wind shear, and allow a tropical depression to form."

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2700

He goes on to say that there is an update to the GFS that will come out later this summer that should fix what I'm going to call a "Bug." He also states that he still gives it a 10% chance that a storm will form in the Carribean late next week. However, I'm not holding my breath!!

First Tropical Depression could also be the first land-falling hurricane of the Season!

6/13/2014 6Z GFS

For the past couple of days, I have been watching as the GFS has put an interesting feature developing South and East of the Yucatan Peninsula. Yesterday's morning's run had the tropical system slamming first into the Yucatan, then Florida, and then out to the middle of the Atlantic Sea. Then, the feature disappeared completely for a couple of runs. However, this morning, the feature re-appeared and the GFS has it tracking much closer to the Eastern coast, potentially affecting Florida, North Carolina, and here in Virginia! 

GFS surface Hour: 312

GFS surface Hour: 348

Discussion

Now, it is of note that this is the GFS fantasy-land and this is two weeks out. Also of note, none of the other models I have looked at have this system (Euro, CMC). But, what makes this at least a little exciting is that it has shown up in a couple of runs now of the GFS (most notably the 6/12 6Z run) with relatively the same track. Also, the GFS is forecasting it to be a tropical storm before 192 (the switchover to fantasy-land)