Jump to content
  • Member Statistics

    17,607
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

CAD storms thread.


dsaur

Recommended Posts

Ok, so things are trending drier below N VA. Why does the moisture look to be going North right into a high in PA. I always thought a High to close by would suppress the moisture South. I know that is what has happened several times here in NC in the past when a high was in VA the moisture would stay below NC in GA and SC.

 

Each setup is a bit different, but probably the primary reason is that the 850mb warm air advection providing the lift is centered just west of the Apps.  On the bottom left panel on this link you can see the low level wind max at 850mb run from northern Louisiana to West Virginia during hours 30 to 48...there's more precip along that axis.

 

http://www.meteo.psu.edu/~fxg1/AVN_0z/avnloopw.html

Link to comment
Share on other sites

  • Replies 994
  • Created
  • Last Reply

So now more questions arise for learning purposes.

 

Does the nam really mishandle short term precip? Did the Canadian really deserve all the praise? What happened to the other historic events right after this one on the Canadian? Did we just go through hell and back because we started this thread so early?

Link to comment
Share on other sites

So now more questions arise for learning purposes.

Does the nam really mishandle short term precip? Did the Canadian really deserve all the praise? What happened to the other historic events right after this one on the Canadian? Did we just go through hell and back because we started this thread so early?

No, just learn not to rely on the Canadian and NAM model. If the European model and GFS both agree somewhat, and are different from the other two, they are most likely right.
Link to comment
Share on other sites

The latest runs of the GFS and NAM seems to show less precipitation and less cold air around. I believe most of the heavier accumulations will be north into Virginia, so most areas of North Carolina will miss out on the heaviest ice from the storm.

Here is my call map for North Carolina:

Possible%20Ice%20Sunday%20Morning%202.gi

 

Up into Virginia, it will be a major ice storm. I am not complaining; however, because I absolutely hate ice.

Link to comment
Share on other sites

I think its better to bring bad news than for people to end up being disappointed in the long run. I want winter weather just as bad as most do. But sometimes the model riding is a bit much. I was spot on with all the big forecasters not even mentioning the 18z nam. I expect most of the Winter Storm Watches to be downgraded to Freezing Rain Advisories. Maybe a few (1-3) Ice Storm Warnings in NC if that.

Link to comment
Share on other sites

So now more questions arise for learning purposes.

 

Does the nam really mishandle short term precip? Did the Canadian really deserve all the praise? What happened to the other historic events right after this one on the Canadian? Did we just go through hell and back because we started this thread so early?

 

We started this thread due to the fact that our December discussion was being polluted with talk about this event and not about the overall pattern. It was NOT started too early...... Just because things are not going the way you want them to you have to find fault with something. Nobody made you read our forum. If you don't like what's being written here, then please leave. Midlo already gave you a warning. Take heed.

Link to comment
Share on other sites

We started this thread due to the fact that our December discussion was being polluted with talk about this event and not about the overall pattern. It was NOT started too early...... Just because things are not going the way yluyou want them to you have to find fault with something. Nobody made you read our forum. If you don't like what's being written here, then please leave. Midlo already gave you a warning. Take heed.

Cad, what's your thoughts on how much precip falls now? It's awful to come this far and it dries up on us. We know how hard it is to get winter precip here anyway. But having the rug jerked out from under you at the last minute hurts.lol.. We never know how long it's going to be before we have another chase?

Link to comment
Share on other sites

Cad, what's your thoughts on how much precip falls now? It's awful to come this far and it dries up on us. We know how hard it is to get winter precip here anyway. But having the rug jerked out from under you at the last minute hurts.lol.. We never know how long it's going to be before we have another chase?

 

Haven't had a chance to process any data this morning but I would like to see today's runs before throwing in the towel on this one. If the 12z suite continues the drier trend, then I would be concerned. The NWS has cut back precip totals, and in light of the recent runs, that appears to be the right course of action.... The high resolution models will be a very useful tool today and I know that everyone will be following them closely. Let's see how it all unfolds.

Link to comment
Share on other sites

A safe call would be to warn for up to .25. (.1 to .2) is what's more likely to verify in the Ice Storm Warning areas I think. Far cry from the  (.25 - .75) range earlier suggested by models.

 

Downgraded here in Hickory. 

 

Freezing Rain Advisory:
Link to comment
Share on other sites

I think its better to bring bad news than for people to end up being disappointed in the long run. I want winter weather just as bad as most do. But sometimes the model riding is a bit much. I was spot on with all the big forecasters not even mentioning the 18z nam. I expect most of the Winter Storm Watches to be downgraded to Freezing Rain Advisories. Maybe a few (1-3) Ice Storm Warnings in NC if that.

 

Your call for 1-3 ice storm warnings isn't working out so well. Why is that?

Link to comment
Share on other sites

A safe call would be to warn for up to .25. (.1 to .2) is what's more likely to verify in the Ice Storm Warning areas I think. Far cry from the  (.25 - .75) range earlier suggested by models.

 

No..... in order for a warning to be issued,  the forecasters expect warning criteria to be met. That is .25 or greater of ice accumulation.

Link to comment
Share on other sites

The Raleigh AFD is also inline with my .1 to .2 thinking. Is .25 warning criteria for them?

 

Forecast remains on track with potential for a tenth to two-tenths of an inch of ice across the far northwest/northern Piedmont of North Carolina late tonight through Sunday evening. 

 

 A watch is upgraded to a Warning when 4 or more inches of snow or sleet is expected in the next 12 hours, or 6 or more inches in 24 hours, or 1/4 inch or more of ice accretion is expected.

 

This is the criteria for the NWS Raleigh.

Link to comment
Share on other sites

No, just learn not to rely on the Canadian and NAM model. If the European model and GFS both agree somewhat, and are different from the other two, they are most likely right.

 

WTF Are you talking about? The NAM outside of like two runs showed drier. So if anything the Euro and GFS have caved to the NAM *IF WE END UP DRY* which leads to more credence that it should be used in the short term. It also had and still has a better handle on the cold air filtering in. The bottom line is you don't rely on any one model. People haven't been. You use the strengths of each model. In this case it's perfectly fine to rely on the NAM for dynamics and strength of CAD.

Link to comment
Share on other sites

I think its better to bring bad news than for people to end up being disappointed in the long run. I want winter weather just as bad as most do. But sometimes the model riding is a bit much. I was spot on with all the big forecasters not even mentioning the 18z nam. I expect most of the Winter Storm Watches to be downgraded to Freezing Rain Advisories. Maybe a few (1-3) Ice Storm Warnings in NC if that.

 

An advisory is not a downgrade from a watch. The watch only points toward potential accums/impacts. Watches have more uncertainty than advisories/warnings, which in contrast are deterministic in nature. 

Link to comment
Share on other sites

So now more questions arise for learning purposes.

 

Does the nam really mishandle short term precip? Did the Canadian really deserve all the praise? What happened to the other historic events right after this one on the Canadian? Did we just go through hell and back because we started this thread so early?

 

 The Euro from a number of days out tends to make sfc highs in/near the NE Us too strong. I commented on the 12Z 12/1 run where it made it ~1044 mb in far southern Quebec. Consequently, it had the mother of all CAD's extending all of the way to Atlanta despite 850's that were too high for ZR per history. Then it started gradually weakening that high. Now it is only ~1036 mb. or 8 mb weaker/more ordinary. As a result, the CAD isn't nearly as strong as then progged. That's 0.24" weaker within 6 days of runs. Be wary of the Euro when it has a stronger NE high vs. consensus. The GFs never had that strong a high and will verify pretty well in that way. I will remind readers about this in the future if similar situations get progged.

Link to comment
Share on other sites

An advisory is not a downgrade from a watch. The watch only points toward potential accums/impacts. Watches have more uncertainty than advisories/warnings, which in contrast are deterministic in nature. 

 

I have seen it used interchangeably by the NWS as either downgraded, canceled, or transitioned. This morning they said it was "canceled" for Hickory. Yesterday they said they might "transition" it to a advisory. I don't have the AFD to back up the downgrade usage not sure when and where I picked up that misconception. Thanks for the info.

Link to comment
Share on other sites

I have seen it used interchangeably by the NWS as either downgraded, canceled, or transitioned. This morning they said it was "canceled" for Hickory. Yesterday they said they might "transition" it to a advisory. I don't have the AFD to back up the downgrade usage not sure when and where I picked up that misconception. Thanks for the info.

 

Some forecaster may have said that, but I doubt it. Our SOO would cringe if he heard or read that word in that context...and we'd hear about it!  

Link to comment
Share on other sites

WTF Are you talking about? The NAM outside of like two runs showed drier. So if anything the Euro and GFS have caved to the NAM *IF WE END UP DRY* which leads to more credence that it should be used in the short term. It also had and still has a better handle on the cold air filtering in. The bottom line is you don't rely on any one model. People haven't been. You use the strengths of each model. In this case it's perfectly fine to rely on the NAM for dynamics and strength of CAD.

Just a few pages ago you guys said the NAM was notoriously bad with QPF and good with surface temps. I'm pretty sure you said the GFS and Euro caved to the NAM because they were showing wetter solutions while the NAM was showing a drier solution outside of two runs. So then that means that it really isn't that bad with QPF and that was only said because it didn't give as much precip as some would have liked.
Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...