Ryan Snoddon - CBC Newfoundland & Labrador

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BLOCKING HIGH BREAKS DOWN

May 7, 2012 6:31 PM

Well, what a weekend in St. John's and across parts of the NE Avalon and even up the Northeast Coast of Newfoundland. At YYT, dozens of delays, cancellations and flights diverted. It was Friday, just before Noon when the Fog ramped up and for the next 3 days it was pea soup thick in parts of Metro. In the end, we had 49 hours with visibility under 800 feet and about 60 hours with visibility under 1 km. But it wouldn't be Spring if we didn't have a few days of R-D-F right? Right?

Here are the main points for the next few days...

-That NE wind onshore flow setup, is slowly breaking down, as the same blocking Greenland High, actually sinks South and clears us out over the next 24 hours or so!

-Winds will continue in from the Northeast tonight and through Tuesday along the Northeast Coast of the Island, as a result, we'll see fog patches developing again across much of Northeastern Newfoundland tonight. However things will clear through the day on Tuesday.

-A solid Tuesday across most of Labrador as well, however watch for Rain to move into Lab West on Tuesday afternoon and spread into Eastern Labrador on Wednesday.

-Wednesday is the day of change across the Island. Winds will finally become Southwesterly ahead of a system moving in and temperatures will be on the rise.

-However Wednesday and into Thursday, that system off to our Southwest will finally start to move into Newfoundland, with clouds and showers.

-Again, the good news, despite the increasing clouds, showers & even rain for some. Temperatures will be into the double digits and even teens for many across the Island Wednesday through Friday.

-This will be a system to watch for the West & Southwest Coast this week. From Wednesday through Friday, some forecast models are flirting with up to 50+ mm of Rain for parts of Western and Southwestern Newfoundland. The GEM Canadian model below, is one that supports this idea. I'll keep you posted on this.

-And yes, it's still Spring in NL. There's a good chance of seeing Snow mixing in along the Northern edge of this system. You folks in Labrador, could see some of the white stuff, late Wednesday into Thursday and even into Friday.

LONG RANGE

Some good news. Based on the long range forecast models, it appears that the "Greenland Block" setup, shouldn't be re-appearing any time soon. Both the long range European & American forecast models are leaning towards a more West to East setup through next week. The latest NOAA outlook for the NAO (North Atlantic Oscillation) also shows consensus that we are now coming out of the negative NAO phase (which promotes blocking patterns) and into a more neutral, or even positive phase into next week.

Ryan

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