It looks like we’re in for a little an unnecessary amount of snow on Wednesday:

TAF CYOW 270238Z 2703/2724 06012KT P6SM BKN180 OVC200
FM271300 07015G25KT 2SM -SN OVC020
FM271700 07020G30KT 1/2SM -SN BLSN VV005 
  PROB30 2717/2724 3/8SM SN BLSN VV004
RMK NXT FCST BY 270600Z=

And you can already see it on the radar:

Ick.

It’s cold in Ottawa today:

So, I decided to throw a cup of boiling water off my balcony:

The incoming warm front I wrote about earlier can be seen on the edge of the composite radar image for Ontario:

So, I see from the Weather Office’s website that Ottawa is under a freezing rain warning for tomorrow afternoon. Judging by the TAF, it’s not going to arrive until noon, and even then it’s only showing as a 40% probability from noon until 1PM (the end of the forecast period).

TAF CYOW 101738Z 1018/1118 29012KT P6SM FEW040
BECMG 1020/1021 30005KT
FM110000 VRB03KT P6SM SKC
FM111200 09005KT P6SM OVC200
FM111700 10010KT P6SM -RA SCT020 OVC050 PROB40 1117/1118 6SM -FZRA BR BKN020 OVC050
RMK NXT FCST BY 102100Z=

You can see the warm front passing through based on the wind directions in the various periods in the forecast. At the beginning, it’s out of the northwest at 5 knots, becomes variable at 3 knots at 0000Z (7PM) and then is out of the east at 5 knots early tomorrow morning. So, in about 12 hours it flips around almost 180 degrees. Fun.

We’ll get freezing rain if the air being overrun by the incoming warm air is sufficiently cold enough to cause the rain drops condensing at the boundary between the warm and cold air to be supercooled so they freeze instantly on contact.

The next TAF should clarify how long the freezing rain is going to go on for tomorrow, but any way you slice it, it looks like my plans for snowshoeing on Saturday are probably going to be a bust, as you can surmise from the graphic.

I have been looking forward to going snowshoeing this weekend with a bunch of friends for a while now, but having just looked at the long-range forecast for this weekend, I’m not at all confident that’s going to be possible.

As you can see from the graphic I clipped from the Weather Office’s website, there’s probably going to be freezing rain on Friday, which will put a crust on the snow. Then it’s supposed to go up to 11°C on Saturday, which is going to make the snow really sticky, and that sucks when you’re snowshoeing.

Nuts.

And this is going to set the canal back quite a bit, too.

Nuts again.

Air temperature is an important factor in how hot or cold you feel, but it’s not the only one. A few months ago, I posted a piece about how to calculate humidex, but given that it’s winter here in Ottawa, it’s highly unlikely that you’re going to have to worry about high humidex days for a few months. Wind chill, on the other hand, is something that you are almost certainly going to have to contend with in the next few months.

So, what exactly is wind chill and how is it calculated? (more…)

I was checking out the aviation forecast for Ottawa and saw this:

TAF CYOW 201438Z 2015/2112 31006KT P6SM FEW030 TEMPO 2015/2022 BKN030 BECMG 2016/2018 06005KT
FM202200 06012KT P6SM FEW015 OVC090
FM210200 08015G25KT 4SM -SN BKN030 OVC070
FM210500 08015G25KT 1SM -SN BLSN OVC010 PROB40 2105/2107 3SM -FZRA BR
FM210700 08015G25KT 1/2SM SN BLSN VV005 PROB30 2107/2110 2SM -PLSN -FZRA BR
FM211000 07018G28KT 1/4SM +SN BLSN VV002
RMK NXT FCST BY 201800Z=

Apart from the fact that it’s fairly disgusting weather in general with gusting winds, snow, blowing snow and the possibility of freezing rain and snow pellets, it also shows that it’s supposed to be very windy with excessive amounts of snow and blowing snow starting at 1100UTC, which you can see in red.

The Mayan calendar purportedly indicates that the world is supposed to end at 11:11UTC tomorrow morning and the forecast period doesn’t extend past 12:00UTC tomorrow morning (highlighted in fuchia). Coincidence or proof? (Hint: It’s a coincidence.)