December 2020 Forecasts and Discussions

[hawk2]

Check again. That map is CM.

[Monty]

How often is the euro wrong?

It’s the best at this range. No doubt in my mind. But the accuracy differences between models are pretty insignificant at this range and they have all had failures. I think if this storm can strength to around 1000mb before it reaches the coast it’ll probably track pretty favourable for SW BC. If development is delayed and the storm is weaker it’ll be a miss to the south.

[Rubus_Leucodermis]

How often is the euro wrong?

Both Euro and GFS show the southern Island getting the goods. How often are both of them wrong, within 36 hours of the onset of the forecast event?

(They’re both favorable for me, too. Fun times!)

[PortKells]

Apparently port Angeles is the place to be? Wow

[NoahG]

Both Euro and GFS show the southern Island getting the goods. How often are both of them wrong, within 36 hours of the onset of the forecast event?

(They’re both favorable for me, too. Fun times!)

Heck yeah man!
Not often, just don’t love the fact that we lost most of the mesoscale support we had yesterday.

[Monty]

Apparently port Angeles is the place to be? Wow

There is definitely going to be some terrain issues with model resolution and the Olympics but if the flow turns NE with the heaviest precip the higher elevations around there will probably get hammered.

[Rubus_Leucodermis]

Apparently port Angeles is the place to be? Wow

They can really get hammered in the right conditions. Got two to four feet (depending on elevation) out of the February 2019 storms.

[Rubus_Leucodermis]

A word of caution is that the professionals seem skeptical of what many model runs are forecasting. From this morning’s forecast discussion from the Seattle office:

The upper trough and cold front will bring colder air. Some ensemble members show rain changing to snow for a few hours in the afternoon and evening for the lowlands but most solutions keep rain for the lowlands. The possibility for a little lowland snow will need to be monitored but for now the forecast will be for just rain with snow levels falling to 1000-1500 feet Monday afternoon and evening.

[wetcoast91]

Not surprised to see the GEM and RGEM go with mostly rain. The low has looked really disorganized, or even weakened to an open wave on some runs. Really limits adiabatic cooling under 700m and keeps it rain for everyone.

GFS/ECMWF actually intensify the low as it crosses over Puget Sound which draws some cooler drier air into the NE-N area.

[Esquimalt39]

Not surprised to see the GEM and RGEM go with mostly rain. The low has looked really disorganized, or even weakened to an open wave on some runs. Really limits adiabatic cooling under 700m and keeps it rain for everyone.

GFS/ECMWF actually intensify the low as it crosses over Puget Sound which draws some cooler drier air into the NE-N area.

Yeah the HRDPS though shows it as snow in the heaviest precipitation areas which I found weird.

What solution do you find more likely?

[Rubus_Leucodermis]

Not surprised to see the GEM and RGEM go with mostly rain. The low has looked really disorganized, or even weakened to an open wave on some runs. Really limits adiabatic cooling under 700m and keeps it rain for everyone.

It’s not really a gem. It’s just cheap glass costume jewelry.

[Monty]

Yeah the HRDPS though shows it as snow in the heaviest precipitation areas which I found weird.

What solution do you find more likely?

Heavy precip is going to be favoured for snowfall

[hawk2]

Is everyone prepared for the last minute rug pull?

[wetcoast91]

Yeah the HRDPS though shows it as snow in the heaviest precipitation areas which I found weird.

What solution do you find more likely?

Based on the trends? A weaker low with areas above 500m seeing snow. I don't trust the ECMWF in these setups.

Slight intensification of the low could change this.

[Rubus_Leucodermis]

Is everyone prepared for the last minute rug pull?

“It is never too late for a rug pull.” — Me