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patrick7032

Alaska/Western Canada obs and discussion

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Started this thread to see how many people would be interested as we approach the winter storm season where HURRICANE FORCE WIND WARNINGS are not all that uncommon. I have also noticed that when we get a seasonally deep 500mb low dropping southeast up here as it tends to eject into the lower 48 active weather usually follows with decent severe weather outbreaks .

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I see the GFS is progging the return of the 0 degree 850mb isotherm to southern Alaska. Nobody wants to see termination dust around here yet!

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I see the GFS is progging the return of the 0 degree isotherm to southern Alaska. Nobody wants to see termination dust around here yet!

Termination dust?

I see some DCVA by CD3 progged by the EC/GFS for day 3.5+. Looks pinwheelish.

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I see the GFS is progging the return of the 0 degree 850mb isotherm to southern Alaska. Nobody wants to see termination dust around here yet!

Yeah will post the data in a few....only have 256k speed here so may take a few to load images.

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Looks like the GFS has backed off the -2 to -4 C 850 mb temps it was outputting yesterday.

post-1451-0-51509300-1312224191.png

Not surprising considering the ridging/warm 850 T's (+12 C extending up into the Beaufort Sea) to the northeast cutting it off from any reinforcing cold air and a warm southwest flow behind the north Pacific ridge. Strange to think of a system being "cut-off" when it is on the polar side of the jet. This type of a pattern seems to favor climatology with a mean trough centered over western Alaska and the Bering Strait. You can see the July/Aug mean 500mb geopotential height pattern isn't too far off from what is happening now.

climo

post-1451-0-56527300-1312224443.png

current

post-1451-0-71702300-1312225808.gif

The major difference I see is the high latitude block over Greenland which has acted to shift the polar vortex toward the Chukchi/Beaufort Seas. This developing pattern is depicted well in the ensemble mean forecasts of several teleconnectors....

post-1451-0-87067000-1312225991.png

The progged positive PNA makes sense with the deepening low and embedded disturbances moving south into the Bering Sea will act to build the heights downstream over the intermountain west though I think the + phase is more related to the negative height anomalies over the Aleutians.

post-1451-0-61931400-1312226071.png

The negative NAO at the same times shows the developing positive height anomolies over Greenland.

post-1451-0-44245700-1312226674.gif

All of these factors make for a cooler wetter period for southern Alaska. I am no teleconnector guru by any means, but just my take on the current pattern.

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Thanks for starting this thread...good stuff.I hope you're both enjoying life in Alaska.

Thanks Beavis....I expect this thread will get a lot busier once the winter storms hit and we get HURRICANE FORCE WIND WARNINGS with 60+kt sustained zone forecasts with seas 30 feet plus. Until then will try to post few times a week with met data.

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Looks like the GFS has backed off the -2 to -4 C 850 mb temps it was outputting yesterday.

post-1451-0-51509300-1312224191.png

Not surprising considering the ridging/warm 850 T's (+12 C extending up into the Beaufort Sea) to the northeast cutting it off from any reinforcing cold air and a warm southwest flow behind the north Pacific ridge. Strange to think of a system being "cut-off" when it is on the polar side of the jet. This type of a pattern seems to favor climatology with a mean trough centered over western Alaska and the Bering Strait. You can see the July/Aug mean 500mb geopotential height pattern isn't too far off from what is happening now.

climo

post-1451-0-56527300-1312224443.png

current

post-1451-0-71702300-1312225808.gif

The major difference I see is the high latitude block over Greenland which has acted to shift the polar vortex toward the Chukchi/Beaufort Seas. This developing pattern is depicted well in the ensemble mean forecasts of several teleconnectors....

post-1451-0-87067000-1312225991.png

The progged positive PNA makes sense with the deepening low and embedded disturbances moving south into the Bering Sea will act to build the heights downstream over the intermountain west though I think the + phase is more related to the negative height anomalies over the Aleutians.

post-1451-0-61931400-1312226071.png

The negative NAO at the same times shows the developing positive height anomolies over Greenland.

post-1451-0-44245700-1312226674.gif

All of these factors make for a cooler wetter period for southern Alaska. I am no teleconnector guru by any means, but just my take on the current pattern.

Yeah we even had a few sunny days this week and looks like a few more next week. Talk about a nice short wave ridge (see images). Will be interesting to see if one of these 500 lows head SE to the lower 48.

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A moist southwest flow and compact potential vorticity anomaly is continuing a climatologically wet pattern to south central Alaska today. The dynamic tropopause (1.5 PVU surface) extends down to almost 550 mb with the stratospheric intrusion bringing some very dry air close to -80 C dew point. Doesn't look like much at first glance.

post-1451-0-32817000-1312895438.png

Doing some QC on the incoming data I figured I had a faulty hygristor when I first saw the dew point tank. After looking at the upstream sounding from Bethel (PABE) from 00z and the recent 12Z it appears as if it is good data.

Aug 9th 12Z for Anchorage (PAFC) and Bethel (PABE)

post-1451-0-43207000-1312895471.png

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A moist southwest flow and compact potential vorticity anomaly is continuing a climatologically wet pattern to south central Alaska today. The dynamic tropopause (1.5 PVU surface) extends down to almost 550 mb with the stratospheric intrusion bringing some very dry air close to -80 C dew point. Doesn't look like much at first glance.

post-1451-0-32817000-1312895438.png

Doing some QC on the incoming data I figured I had a faulty hygristor when I first saw the dew point tank. After looking at the upstream sounding from Bethel (PABE) from 00z and the recent 12Z it appears as if it is good data.

Aug 9th 12Z for Anchorage (PAFC) and Bethel (PABE)

post-1451-0-43207000-1312895471.png

Nice maps. Got to love our awesome hygristors. Nice catch though, looks legit, and it makes sense with that type of deep tropopause that stratospheric mixing is occurring.

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For those of you that wonder if tornadoes occur in Alaska, yup they do. This location is in my zone and have been told by the locals that funnels occur at times in Cold Bay. It's also amazing how high the surge can get if the earthquake occurs "in the right spot". These images were taken from material I'm reviewing which I received from co-workers.

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For those of you that wonder if tornadoes occur in Alaska, yup they do. This location is in my zone and have been told by the locals that funnels occur at times in Cold Bay. It's also amazing how high the surge can get if the earthquake occurs "in the right spot". These images were taken from material I'm reviewing which I received from co-workers.

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Termination dust?

I see some DCVA by CD3 progged by the EC/GFS for day 3.5+. Looks pinwheelish.

Termination dust is the Alaskan term which describes the first snow to fall on the peaks of the mountains outside of town and which actually sticks for good. It signals the last days of summer before the long Anchorage winter.

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Termination dust is the Alaskan term which describes the first snow to fall on the peaks of the mountains outside of town and which actually sticks for good. It signals the last days of summer before the long Anchorage winter.

Is this C.C.?

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Termination dust is the Alaskan term which describes the first snow to fall on the peaks of the mountains outside of town and which actually sticks for good. It signals the last days of summer before the long Anchorage winter.

Anchorage, AK doesn't even seem like it has that bad of a winter historically speaking..Not any worst then say a place like Duluth,MN.

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Anchorage, AK doesn't even seem like it has that bad of a winter historically speaking..Not any worst then say a place like Duluth,MN.

Winters are milder than places in the Upper Midwest but also much longer. Anchorage's climate is much milder than locations just a few miles away in the southern interior. Sitting on a broad peninsula that juts out into Cook Inlet certainly has an advantageous effect. It is also rather dark most of the day, with November and December usually featuring overcast skies so that even when there is daylight, it is still rather gloomy. The white of frequent fresh snowfalls from mid-November through late December does mitigate a lot of the darkness though.

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SXAK78 PACD 121156

RERCDB

RECORD EVENT REPORT

NATIONAL WEATHER SERVICE COLD BAY AK

356 AM AKDT FRI AUG 12 2011

...RECORD HIGH TEMPERATURE SET...

AT 4:59 PM AKDT THE TEMPERATURE AT THE STATE AIRPORT AT COLD BAY REACHED

67 DEGREES. THIS BREAKS THE RECORD OF 65 DEGREES SET IN 2001.

$$

JAP AUG 11

Believe we were close to a record during Friday too....I'm checking on this now....when I flew out to Anchorage Thursday it was definitely "toasty"....which 67 doesn't sound like much to people back in the lower 48, and sure there is acclimation involved, but with the high sun angle that felt like 77....could take another day or to like that....:)

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Rather than make a long post here, I blogged about some local terrain effects. I struggled with going between technical/non-technical for non-met types so it's kind of in a grey area in between.

http://mtlawsonwx.wo...cts-of-terrain/

Nice post. Interesting features that stick out in the PABE sounding is the strong above mountain top inversion (around 850 hpa) which probably enhanced the trapped wave mode, but probably too high to incite strong downslope winds given the height of the range. I am assuming no major downslope winds?

The other interesting feature is the model cross section which seems to be simulating a vertically propagating mode given the back tilt of the wave w/height. Do you guys have any higher res x-sections? I found the x-section tropopause uniquely flat...also neat to see how the model simulates (actually probably parameterizes) the dampening of the wave as it reaches the tropopause.

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