I love storms, so I headed out to Bate Island in the middle of the Ottawa River this evening a few minutes before the storm arrived to take some pictures.

It was a big storm, as evidenced by the fact that I had to paste together five photos to capture some of it:

If you browse through these photos, you can see the wall of rain crossing the river upstream near Britannia before it arrived where I was. What you can’t see in the pictures are the bolts of lightning that were hammering things on both sides of the river.

VIEW SLIDE SHOW

I just took a look at the Franktown weather radar to see where the incoming weather is and saw this:

Ick.

And the forecast looks equally wonderful:

TAF CYOW 230238Z 2303/2324 04010G20KT P6SM BKN040 OVC180 TEMPO 2303/2305 P6SM -RA
FM230500 04015G25KT 6SM -RA BR OVC025 TEMPO 2307/2309 3SM -SHRASN OVC010
FM230900 04020G30KT 1/2SM SN VV005 TEMPO 2309/2314 3SM -SNPL SCT005 OVC012
FM231400 03015G30KT 1SM -RA BR OVC004
FM232100 36007KT 2SM -SHRA BR BKN005 OVC010
RMK NXT FCST BY 230600Z=

I’m driving to a meeting early Monday morning and it looks like I could be driving in sleet or snow, possibly with pellets mixed in for good measure.

I hate this climate.

So, Spring arrived yesterday, at least temporarily. The warm front I wrote about a couple of days ago passed through Ottawa around 9am Wednesday morning, as can be seen from this graph:

The blue line represents the wind direction. Leading up to 9am on March 7th, it was coming from between NE (45°) and E (90°). Between 9am and 10am, you can see the direction changed to come from roughly SSE (160°), which is basically when the front passed through.

I’ve been watching the weather forecasts the last couple of days in anticipation of the +10C (or higher) that we’re supposed to see in Ottawa tomorrow. I looked at the Ontario radar a few minutes ago and you can see the line of precipitation escorting the warm front, which I’ve marked in red in this screen capture.

What causes this line of weather is the less dense warm air over running the more dense cold air, condensing as it rises and causing precipitation, which you can see in the diagram I drew:

The diagram isn’t quite to scale as the clouds tend to form around 8000′ AGL, while the top of the CN Tower is roughly 1800′ AGL. Clouds at higher altitudes form in advance (to the right in my diagram) of the clouds that have the precipitation. But, you get the idea. 🙂

So, in the next few hours we can expect to see some precipitation and the winds changing directions significantly as the front passes through. And looking at the terminal area forecast (TAF) for CYOW, you can see that it’s going to happen between 0200Z and 1200Z (9pm and 7am):

TAF CYOW 062038Z 0621/0718 10010KT P6SM BKN070
FM070200 12008KT 2SM -SN BKN020 OVC040
FM070500 08008KT WS015/20030KT P6SM BKN060
FM071200 20012KT P6SM SCT060
RMK NXT FCST BY 070000Z=

Before 9pm, we can see the clouds are around 7000′ AGL (that’s the BKN070), but the precipitation won’t have arrived. At 0200Z (9pm), the precipitation preceeding the front  is forecast to start falling in the form of snow from lower altitude clouds at 2000′ and 4000′ (BKN020 OVC040). This band of weather passes through in about 3 hours, as by 0500Z, the winds are forecast to be 8 knots (about 15 km/h) from the 080 (almost due east) with some windshear about 1500′ AGL where the wind will be blowing at 30 knots (55 km/h) from 200 (almost southwest). From a pilot’s point of view, that will make for a bumpy ride as they pass through 1500′ AGL. In my diagram above, this would be where the red-blue line meets the top of the CN Tower. By 1200Z (7am), Ottawa will be behind the front and the winds at the surface will be 12 knots (22 km/h) from the southwest.

And if the weather office is correct, it will be about +12C in Ottawa tomorrow. 🙂

It’s days like today that make me particularly grateful that I can walk to work, particularly when the traffic layer on Google Maps shows this:

If you’re unfortunate enough to be out on the roads, drive safely!

I have to head out at lunch so I thought I’d check the radar to see when it’s going to start to snow.

Apparently, it’s about to start.

In fact, in the time that it took me to grab that image from the Weather Office’s website and type this, it started snowing in Tunney’s Pasture.

It would be great if I could capture a snowflake like this, but sadly they only seem to show up when I’m on my way to work: