Cold Air Delayed a Day

These images will update every time you load the page. The trough I mentioned on Friday will be moving through today. The radar will show a line a showers that will develop as the final push of cold air moves in. Typically showers will persist in the mountains of PA, WV and western MD after the cold air settles in. For most of central MD however, it will be the trough itself that will most likely bring us showers. As you can see, at least as of Sunday morning, the truly cold air was lingering just north on the other side of the Appalachians. There is a shot of snow mixed in back west, but I do not see it for us now. Since the cold air will be delayed a day, it will have a chance to modify before reaching us. However, if we get some convective storms to develop this afternoon- small hail is possible. That is because the freezing layer is pretty low, so it would not take much vertical lift to reach this. In fact, most showers in the spring and summer do have hail, but tends to melt before reaching the ground so you would never know it. That is a minor factor though. Plan on a much colder than normal pattern into Wednesday. There may be a dramatic warm up beyond that- but I will look into that tomorrow.

Blinded By The Light

"Go-cart Mozart, was checking out the weather chart To see if it was safe outside.."
That's a Manfred Mann tune, which often gets misquoted, but seemed to fit here:
"Blinded by the light, revved up light a deuce, another runner in the night."
Deuce= car
There has been a tremendous amount of buzz about a storm at the end of this week. For time sake I refer you to Mr. Foot's blog who did an extensive analysis of the La Nina, North Atlantic Oscillation, etc.. this past weekend. He may be a little more optimistic than me at this time. The excitement by many may be compounded by a lackluster Maryland winter, and the 5 year anniversary of our #1 snow- record Presidents Week storm in 2003. There are a tremendous amount of pictures and information on the internet of this storm, and I wanted to focus on something different today. Click here for the Feb 17, 2003 radar. Here is a general storm breakdown and comparison.
Anniversary of more big storms:
Among the top 11 snowstorms in Baltimore- 6 have occurred in mid February:
#1: Feb 16-17 2003 28.3"
#3: Feb 11-12 1983 22.8"
#6: Feb 11-14 1899 21.4"
#7: Feb 18-19 1979 20.0"
#8: Feb 15-16 1958 15.5"
#11: Feb 11-12 2006 13.1" (Many have forgotten about this recent storm)

For the regular readers of my blog, you know two main things about me: First- I LOVE SNOW! Second, and most important- I don't like to push the panic button too soon. I have learned a lot in my nearly 2 decade career. Bias can burn you! As good (for those of us that want snow) as something may look 5 days out, things can change. Models change, and all of the ingredients that go into forming a storm may not line up as needed. The more you want snow, you may be blinded by the real data or few models that indicate otherwise. That is my hesitation for Thursday -Saturday's event.
First: the step down in temps will provide a few shots of snow. If you have seen my 7 Day forecast (click the TV Graphics tab above), it looks much more impressive than what will play out.
Tuesday:
Two surface trough shows a step down in temperatures. They may not show up a true cold fronts on the weather map, but these kinks in the isobars will in mark a wind shift and temperature drop.
The 850mb temps(cooling at 5,000Ft) show a drop back to -10C and colder.
The 500mb vorticity max= a spin in the upper levels to help enhance the chance of showers as the cold air builds back in...









Friday Morning:
I am not a one model forecaster, but here is the same GFS model for Friday. For space limitations- I am just showing this one projection... as it does indicate what we will be dealing with. Arctic high may be passing overhead or just north. While that would help with the cold air, it will also be be dry and suppress the phasing branches of the jet stream to our south. Right now it looks like an over running event. That means it could be an extended period, but not an organized blockbuster for us. Over running is when warm moist air ride aloft, and cold air stays at the ground level. That can mean either virga (drying up before hitting the ground) or mixed sleet and freezing rain. This is just a snapshot of the potential, not a guaranteed forecast. Again, I don't like to jump the shark this early until I see how the players are playing. So in the next few days, here are a few things to watch:

1. How cold will it get here. This will show the strength of the new air mass. If we stay in the 30s (BWI) on Wednesday- that is colder than my forecast and a sign it might stay colder.
   
2. Where will the High will be positioned? I see it very close to MD on Thursday. If the center can stay north, or slides past sooner, thigh might allow this storm to slip up the back side and bring in more moisture.
3. When will the High pass? When will the southern branch develop it's Lows? Timing is crucial with this southern branch. If it acts up sooner than Thursday- then it could all pass well to our south. If it develops later than Friday morning, then #1 and #2 will have to be asked differently.

You can also throw in a Full moon on Thursday- and test my hypotheses of enhanced storms thanks to gravity flux. This will be a guarantee to influence coastal regions with above normal high tides. Tomorrow I will start to look at how some other models are handling this event.
"Faith in the flakes."

Something Blowing in the Wind

Wind Advisory Today- Gusts to 50mph
My Morning Headlines are now posted at the right. Click on the image for a full view. Also, reminder, my full web site is now ready. Click the link and you can find "My Blog" posted there in addition to much more local weather images.
I had a little ice yesterday morning, but since I live up north - I knew it was isolated. Soon we will all get to share a scene of winter. As the storm winds up in New England, a very potent Polar Air Mass moves in. The transition will result in damaging winds today. But as we jump ahead to Wednesday, the indication now is that we may repeat 4 of the last 5 years. December 5th tends to be our first day with snow in Baltimore - (More on tomorrow). Here is some of the model support:
First: My favorite for winter events is the Canadian. Here you can see the clipper in central Ohio on Wednesday afternoon. I highlighted the potential snow line in yellow, as the precipitation moves in during the afternoon hours. This type of system does not often have a lot of moisture with it, but this quick move and path likely overhead or just to our south, will give us it's full punch. Early bet on 1" accumulating or more. The real indication of the amount begins about 60 hours before the event, which would be this morning's package. If i see anything significant, I'll update it here.
Either way, the support for cold air is seen here on the GFS. A nice trough in the 850mb level showing the cold air aloft to our north continues to flow in. This map shows the important freezing line south of central Maryland. So even though high temperatures will be above freezing at ground level, cloud level support for snow is there with temperatures -4C to -6C.
Behind this, another quick moving system will reach us on Friday with wintry mix. Looks like winter is here, and glad I finished my new web site just in time. Please see the link above and surf around. If there is something more you would like to see- contact me.

I may be right, for the wrong reason...

A few days ago, I mentioned that we had a pattern shift and a chance that the weekend storm might bring snow or a mix. Here is the temperature map of the 850mb level (above 3,ooo ft) for Saturday. The wind flow is still NW, and our numbers are around -6C. This (cloud) level and number are important for wintry precipitation. The problem is that it will be clear early Saturday. But it does set the stage for the approaching storm.


The models have been all over the place - especially the GFS. Initially it had a Low passing to our west in the Great Lakes, Tuesday night it shifted the track closer to us due to the strong cold air mass and developing trough. Last night, it went back west. This time of year I would expect that track. Here is the same GFS model for Sunday morning. While the storm will be a mean wind and snowmaker for MN, it will push a wind shift to the south for us. As the cold air gets pushed out, the warmer air is forced up and over developing 'over running' clouds and wintry mix. The pink is that precip, while the yellow line shows the likely freezing line. However, that upper level temperature will be cold enough that the first round might be snow or sleet early Sunday. When the real 'stuff' gets here, it should be rain. This is the type of situation where temperatures warm overnight. As the storm passes, the colder air has a chance to bring some Lake Erie snow showers here on Tuesday. Still 4 days out, and the models may shift again....

New Nasa Images

This is the Ferrar Glacier, Antarctica. This past month, NASA, the U.S. Geological Survey, and the British Antarctic Survey jointly developed this accurate image of the 7th Continent. The Full Story from NASA's Earth Observatory can be found here.
If you want to see the 3D movie view, click here or on the image.
This is independent of the recent stories that have been released expecting a mild winter. The Climate Prediction Center is building it's forecast off of the La Nina in the Pacific which historically brings milder temperatures to much of the US . I am not a big fan of this- besides my love of snow. They are limited by their computer models, and restrictions of data out of the Pacific. Recently they mis-identified the position of the El Nino, which led to a bad forecast. Besides, how often does a 3 month forecast work out. It's not any better than the 7 Day I show no TV. I would venture to say that because they are saying mild, we have a better shot of it turning out cold. We have to watch the storm this weekend to see how the pattern will set up. But at this time- we may have a better shot of over running light snow on Sunday if it arrives early enough. The wrap around snow for the east will depend on the path of the Low. This path will likely produce a modest snow storm - but for whom. Best bet now would be Detroit and Chicago.
I will have more on this tomorrow, with a few model outlooks.

Birthday of a weather legend:
Anders Celsius: 1701-1744
astronomy was his passion, but he made a major contribution to science with a simplified temperature scale. Instead of the Fahrenheit scale which ranges from freezing of 32F to boiling at 212F, Celsius developed his scale based on 100 degrees. He did attempt to turn things around, and use 0 for boiling and 100 for freezing, but this was reversed back to the way we know after he died.
From a scientific standpoint, this makes the math much easier working with the metric system (based on 10).
In terms of weather, the rest of the world uses Celsius except the USA. Perhaps we are stubborn to change, but the wider variation of numbers does make it easier to explain a range of conditions. It sounds odd to think a warm day in the summer would be 30 degrees C, instead of 86 degrees F. Yet having freezing at 0C does make sense. All upper level data is measured in Celsius and used for all mathematical computer models.
Locally, our rain was a disappointment. At least officially. BWI measured only .16", yet northern sections of Carroll County picked up much more. Manchester recorded 1.28", and is only about 30 miles from BWI. Today will be a reversal of fortunes. The warm air surged in last night, and we were still at 62F at midnight. As the strong winds shift to the northwest, we should stay in the 50s or get colder this afternoon.

I Like What I See

First it was flurries - last night. It's a little early to get excited about snow, even though some ski areas are open. Our below normal temperature pattern is holding, yet this is just a balance of the heat we had in October and early this month. We are now just about normal at BWI as it stands today.
This pattern change however is showing promise. Here is the early week storm as seen by the Canadian model. Here you can see over 1 inch of rain for the south- including Atlanta, GA. Definitely a pattern change for them. This storm is coming from the southern branch of the jet. A sign of a winter pattern, one that will tap into Gulf of Mexico moisture. This is a signal for improvement in the dry south US. Nothing surprising here with our La Nina pattern. So what you see next is somewhat expected...


Looking longer range, I have posted the 5 day GFSx. This is the upper level 500mb flow. The spots highlighted are vort maxes, or pieces of energy that are ingredients for building storms.
The closed Low off of the southern California coast will open up and develop the next southern branch Low. While I highlighted a ZONAL flow for the eastern US, the jet itself should be located just south of the Great Lakes. So this time, there will be colder air in place. The pattern for La Nina would have these developing Lows ride west of the Appalachians. That means snow for midwest, and rain for the B'more and the rest of the I-95 cities. But if the cold air holds like we have now, then a slight push east with the next storm could shift snow and ice potential east as well. No Guarantees! But it is something to watch. Note: December 5th has been the 1st major snow event for Baltimore 4 of the last 5 years. It is about that time....