CAD storms thread.

[NCCatawba]

euro hr162 snowfall...these are the areas for the best wintry accumulation and points north. This is the start of the event btw.

 

[ouamber]

Will do Dsaur!! I live in Tulsa, they are saying about 4-6 inches here...we'll see:) I have family in Roanoke and Salem VA so I try to stay up on the weather around that area for them! I'm not sure what a CAD is, but I hope you guys reel a good one in:)

[GaWx]

euro hr162 snowfall...these are the areas for the best wintry accumulation and points north. This is the start of the event btw.

 

With 0C 850's well to the north of this area, I don't know why this is showing snow there. I'm confused. And with that, nighty night, folks. Great job, Mr. T!

[Shawn]

Will do Dsaur!! I live in Tulsa, they are saying about 4-6 inches here...we'll see:) I have family in Roanoke and Salem VA so I try to stay up on the weather around that area for them! I'm not sure what a CAD is, but I hope you guys reel a good one in:)

CAD is cold air damming.  It's when a stronger high to our north forces cold air down into areas of the south east.

[Shawn]

With 0C 850's well to the north of this area, I don't know why this is showing snow there. I'm confused. And with that, nighty night, folks. Great job, Mr. T!

 

Might be seeing "ice" as snow on the Wundermaps.  My first thought when I saw it.

[NCCatawba]

With 0C 850's well to the north of this area, I don't know why this is showing snow there. I'm confused. And with that, nighty night, folks. Great job, Mr. T!

 

Yea more like wintry accumulation. These maps are much more accurate than the paid Weatherbell maps that constantly hammer us with bogus amounts of snow.

[Shawn]

Yea more like wintry accumulation. These maps are much more accurate than the paid Weatherbell maps that constantly hammer us with bogus amounts of snow.

 

You have to use the 0.125 resolution maps on wxbell to get a better overall look.  The first/fast ones I learned not long ago.. show poop.

 

EDIT:  I just looked at them on wxbell.. it does seem a bit overdone even on those maps for even CLT type areas as snow.

[dsaur]

Will do Dsaur!! I live in Tulsa, they are saying about 4-6 inches here...we'll see:) I have family in Roanoke and Salem VA so I try to stay up on the weather around that area for them! I'm not sure what a CAD is, but I hope you guys reel a good one in:)

Cold air dams up against the flanks of the Appalachian Mts. and it funnels down sometimes all the way into Alabama.  We often get over running of moisture up from the gulf, and if the air is cold enough, we can get frozen stuff.  Many times it will bring in Atlantic moisture, and sock us in with clouds and drizzle.  It's hard to scour out, hard to predict how it will act, and always welcome

[Shawn]

Cold air dams up against the flanks of the Appalachian Mts. and it funnels down sometimes all the way into Alabama.  We often get over running of moisture up from the gulf, and if the air is cold enough, we can get frozen stuff.  Many times it will bring in Atlantic moisture, and sock us in with clouds and drizzle.  It's hard to scour out, hard to predict how it will act, and always welcome

 

And to add on this great explanation.. it is sometimes referred to as a "wedge".  Here is some reading material about it:

 

http://en.wikipedia.org/wiki/Cold_air_damming

[NCCatawba]

Might be seeing "ice" as snow on the Wundermaps.  My first thought when I saw it.

 

It is when looking at the 2 meter above ground temps.

 

...Now by 168 the euro makes the CAD stronger...accumulation maps go a tick higher. If you're not in the dark blue area of NC consider yourself in the fringe area on this run. Many more runs to go.

[NCCatawba]

This is what I wanted to see. Great example of how powerful the euro is with CAD situations over the other models we are using. Notice the circle over the Hendersonville area (GSP prone area for ice that had a Winter Storm Watch several days ago). Anyway, as we can see the CAD has departed to the heavy CAD areas only by hr174. Good run by a good model. EURO to depict this best until the NAM and other short range models come into play.

 

[NCCatawba]

DT seems to be a bit less impressed with the euro, fwiw-probably not much...

 

 

Wxrisk.com

about an hour ago

*** new 0z monday euro model... STILL HAS SIGNIFICANT ICE STORM but less snow even for western VA western MD and WVA because the cold air wedge over VA NC is less strong .. the Euro Develops a Low over the TN valley then tracks it into OH. This solution is BS IMO... BUT need sleep will post maps monday am

[ncskywarn]

DT seems to be a bit less impressed with the euro, fwiw-probably not much...

 

 

Wxrisk.com

about an hour ago

*** new 0z monday euro model... STILL HAS SIGNIFICANT ICE STORM but less snow even for western VA western MD and WVA because the cold air wedge over VA NC is less strong .. the Euro Develops a Low over the TN valley then tracks it into OH. This solution is BS IMO... BUT need sleep will post maps monday am

He is definitely not buying into the idea that it shows a low cutting from Tennessee into Ohio

[CAD_Wedge_NC]

IT APPEARS THAT THE CANADIAN HIGH
TO OUR NW WILL SLIDE SE AND SET UP SOME SORT OF CAD PATTERN FOR THE
END OF THE WEEKEND AND EARLY NEXT WEEK WITH THE POSSIBILITY OF
FROZEN/MIXED PRECIP TYPES OVER PORTIONS OF THE CWFA.

 

From GSP this morning....

[ncskywarn]

Better make it a 5 loafer and 2 kegger now

[DaculaWeather]

GL tony bring it home for us.  Put me down for week without power

Make it two...

[DaculaWeather]

http://www.daculaweather.com/4_hpc_extended_disco.php

 

THIS SUPPORTS WRAP-BACK SNOWS WITH THE LOW AND A FULL BLOWN ARCTIC OUTBREAK
ACROSS MUCH OF THE LOWER 48 IN THE WAKE OF LOW PASSAGE INTO ERN
CANADA AS A TRAILING FRONT DIGS IN. THIS FRONT SHOULD PROVIDE A
WELL DEFINED FOCUS LATE WEEK INTO NEXT WEEKEND FOR MOISTURE AND AN
AXIS OF HEAVY RAINFALL FROM ROUGHLY THE SRN PLAINS/LOWER MS VALLEY
STATES NEWD THROUGH THE MID-ATLANTIC. THE VERY COLD AIRMASS
SUBSEQUENTLY SETTLING IN PLACE BEHIND THE FRONT WILL ALSO THEN
PROVIDE A LINGERING BASE FOR MESSY OVERRUNNING SNOW/ICE
UNSEASONALLY SWD AS IMPULSES RIDE OVERTOP IN PROGRESSIVE SW FLOW.

 

Also a lot of uncertainty with the models right now:

http://www.daculaweather.com/4_hpc_model_diag_disco.php

[FallsLake]

RAH long range discussion last night continues to mention the CAD for next weekend. They are still not saying anything about ptypes but this is still too far out. One thing that is good, they're not saying this should be rain. Usually they will state that the system looks too warm for anything but rain. With them saying nothing, they don't know; which is good. 

 

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
 

-- Changed Discussion --

AS OF 315 AM MONDAY... A TRANSITION OF THE UPPER LEVEL PATTERN WILL LEAD TO WEST- SOUTHWESTERLY FLOW ALOFT OVER THE SOUTHEAST US AND MID-ATLANTIC STATES...WHICH WILL PERSIST THROUGH THE END OF THE WEEK AND POTENTIALLY INTO EARLY NEXT WEEK. LOW-LEVEL MOISTURE WILL SLOWLY INCREASE WEDNESDAY THROUGH FRIDAY AHEAD OF A SLOW MOVING FRONTAL ZONE THAT WILL REMAIN WEST OF THE MOUNTAINS UNTIL FRIDAY NIGHT OR SATURDAY. SHALLOW ISENTROPIC LIFT FOCUSED ACROSS WESTERN NC MAY SUPPORT ISOLATED SHOWERS OR SPRINKLES WEDNESDAY AND THURSDAY NIGHTS ...THOUGH MOISTURE IS FORECAST TO REMAIN RELATIVELY SHALLOW UNTIL THE DEEPER MOIST AXIS SHIFTS EAST ON FRIDAY. DESPITE MOSTLY CLOUDY SKIES THROUGH THE PERIOD...SOUTHWESTERLY FLOW WILL HELP WARM HIGHS FROM INTO THE UPPER 60S TO EVEN MID 70S BY FRIDAY AS LOW LEVEL THICKNESSES SURPASS 1380M. CONFIDENCE IN THE TIMING OF THE FRONTAL PASSAGE FRIDAY NIGHT OR SATURDAY IS RELATIVELY LOW DUE TO SOME RUN- TO-RUN INCONSISTENCY IN THE GFS AND ECMWF...THOUGH THE LATEST RUNS BOTH FAVOR AN EARLY FRONTAL PASSAGE FRIDAY NIGHT. THE SLOW MOVING NATURE OF THE FRONT...ALONG WITH THE POTENTIAL FOR A COUPLE WAVES OF LOW PRESSURE MOVING ALONG THE FRONT...FAVORS AN ANAFRONTAL PRECIP STRUCTURE AS IT SLIPS SOUTH ACROSS CENTRAL NC. COLD AIR DAMMING THEN LOOKS TO BE POSSIBLE EARLY NEXT WEEK AS PRECIP SPREADS BACK ACROSS THE FRONTAL ZONE AND SURFACE HIGH IN THE WAKE OF THE COLD FRONT...LEADING TO TEMPS BACK BELOW NORMAL.

-- End Changed Discussion --

 

[NCCatawba]

So correct me if I am wrong...the strength/track of the low from TN to OH may act to destroy our CAD faster limiting the severity of the winter weather. The weaker/more east track will enhance the CAD.

 

This is going to be a long week.

[Marion_NC_WX]

So correct me if I am wrong...the strength/track of the low from TN to OH may act to destroy our CAD faster limiting the severity of the winter weather. The weaker/more east track will enhance the CAD.

 

This is going to be a long week.

 

 

That's partially correct...the surface low track will determine where temps aloft (850mb) will surge above freezing creating a freezing rain profile. If the low track can continue to slide south and east, the less warm nose that appears.

 

You also have to remember, if the cold air is dense enough and the high pressure is strong enough across the Lakes Region/New England it will force the low track farther south...I think that's why some dismissed this morning's Euro because it sent a Miller-B into the heart of the cold air source...which does not make Meteorological sense.

[tnweathernut]

Sure there is a big high present, but we need serious confluence or blocking to keep the 850's from surging.  I wouldn't be so quick to dismiss the Euro's depiction of a low from TN to the OH valley, which would harm even you guys chances of severe icing on the other side of the mountain.  I have seen low pressures track into big highs before.  I think that option is greater than anyone will give credit to at this point.  I think the GFS has been trending that way over the last couple of days.  Time will tell.

[SnowNiner]

This is what I wanted to see. Great example of how powerful the euro is with CAD situations over the other models we are using. Notice the circle over the Hendersonville area (GSP prone area for ice that had a Winter Storm Watch several days ago). Anyway, as we can see the CAD has departed to the heavy CAD areas only by hr174. Good run by a good model. EURO to depict this best until the NAM and other short range models come into play.

 

 

 

Maybe it's because it's still 6 days away, and it seems like the best case scenerio here is ice (blah) but I'm not in to this storm at all for CLT.  A low tracking west of the Apps depending on 2 m tempatures CAD doesn't get me excited.  Especially looking at 850s up in northern virginia.   Plus the EURO map above doesn't even show the zero line making it down to CLT. 

 

Bit of a MBY post but I would think this is going to be a cold rain right now for CLT south.  Maybe I40 north will be more interesting if you like ice.  We'll see what happens in future runs, but the "underdoing the cold" discussion is like your favorite team losing and you hang your hat on "the average fan doesn't know how good that team was" argument.  Makes you feel better but it's still a loss. 

 

I have a feeling though it's going to be fun reading the PBPs this week...

[NCCatawba]

That's partially correct...the surface low track will determine where temps aloft (850mb) will surge above freezing creating a freezing rain profile. If the low track can continue to slide south and east, the less warm nose that appears.

 

You also have to remember, if the cold air is dense enough and the high pressure is strong enough across the Lakes Region/New England it will force the low track farther south...I think that's why some dismissed this morning's Euro because it sent a Miller-B into the heart of the cold air source...which does not make Meteorological sense.

 

I'm looking at the 6z GFS here...is it really worlds apart from the euro? From these maps it appears to be trending toward the euro with the low track. I have seen this before as tnweathernut mentioned...this can often screw us over and there is plenty of time for it to do just that. Something to watch over the next few days I guess. I hope you are right tho with a track more south it does make sense...but stuff just tends to happen to screw us over these days.

 

Even with the imperfect track, I still see something for i40 north tho.

 

[tarheelwx]

Sure there is a big high present, but we need serious confluence or blocking to keep the 850's from surging.  I wouldn't be so quick to dismiss the Euro's depiction of a low from TN to the OH valley, which would harm even you guys chances of severe icing on the other side of the mountain.  I have seen low pressures track into big highs before.  I think that option is greater than anyone will give credit to at this point.  I think the GFS has been trending that way over the last couple of days.  Time will tell.

Excellent point. I have seen it happen before as well, even as other "experts" dismissed it as a meteorilogical impossibility. I think one thing to keep in mind here is that with a fairly strong hp from such cold sources parked in PA/NY, ice is highly likely. Couple that with the tendancy for models to scour out and underplay the low level cold air, and I believe a major ice storm is on the table. A couple of things that could save some folks would be more sleet than freezing rain, or if the temp can stay above 30 degrees while 850's get very warm. If 850's are very warm and the temp is 31 or 32, it will be difficult to have major icing (though not impossible). I think something else to consider is that the long/light duration of this event is consistent with major icing.

TW

[NCCatawba]

Excellent point. I have seen it happen before as well, even as other "experts" dismissed it as a meteorilogical impossibility. I think one thing to keep in mind here is that with a fairly strong hp from such cold sources parked in PA/NY, ice is highly likely. Couple that with the tendancy for models to scour out and underplay the low level cold air, and I believe a major ice storm is on the table. A couple of things that could save some folks would be more sleet than freezing rain, or if the temp can stay above 30 degrees while 850's get very warm. If 850's are very warm and the temp is 31 or 32, it will be difficult to have major icing (though not impossible). I think something else to consider is that the long/light duration of this event is consistent with major icing.

TW

 

That is something that also caught my attention on the wundermaps. Our previous spells of freezing rain was way too heavy...but still managed to accumulate on trees. This event looks totally different in terms of rates and duration.

[NCCatawba]

Maybe it's because it's still 6 days away, and it seems like the best case scenerio here is ice (blah) but I'm not in to this storm at all for CLT. Bit of a MBY post but I would think this is going to be a cold rain right now for CLT south.  Maybe I40 north will be more interesting if you like ice.  

 

Charlotte is in the fringe area for sure at this point in the game. However, you have (6) days to monitor 1-2 degree fluctuations still. Same for the people in Raleigh. 

 

I don't think the snow algorithms can handle this crucial 1-2 degree difference. 3-6" of snow for the mountains, foothills and Piedmont Triad from Allan Huffman's map (0z GFS).

[superjames1992]

Charlotte is in the fringe area for sure at this point in the game. However, you have (6) days to monitor 1-2 degree fluctuations still. Same for the people in Raleigh.

I don't think the snow algorithms can handle this crucial 1-2 degree difference. 3-6" of snow for the mountains, foothills and Piedmont Triad from Allan Huffman's map (0z GFS).

I wonder if the snow algorithms are picking up on sleet. I haven't checked.

[buckeyefan1]

Bro, the GGEM is lining up with what the GFS showed for the Midlands a couple days ago when I was flipping about a major ZR here... just slowly.  I do NOT want this.  I had just started feeling better seeing the GFS take it all away from us in SC.

 

So what does everyone think?  I've read that the Euro (previous runs) had something like the Canadian is trying to show now..?  Maybe even underdoing it?  Is the GFS too weak with this deal or?

 

I still would think we can't get cold enough down this way.

I don't see it getting this far south, but it's still a long way out  

 

He is definitely not buying into the idea that it shows a low cutting from Tennessee into Ohio

I was going to answer, but it was answered in the quote below...lol

 

That's partially correct...the surface low track will determine where temps aloft (850mb) will surge above freezing creating a freezing rain profile. If the low track can continue to slide south and east, the less warm nose that appears.

 

You also have to remember, if the cold air is dense enough and the high pressure is strong enough across the Lakes Region/New England it will force the low track farther south...I think that's why some dismissed this morning's Euro because it sent a Miller-B into the heart of the cold air source...which does not make Meteorological sense.

[NCCatawba]

I wonder if the snow algorithms are picking up on sleet. I haven't checked.

 

The sleet window looks too small to account for 3-6".

 

Special Weather Statements are going up in western Tennessee and a chunk of Mississippi now.

 

Statement as of 6:48 AM CST on December 02, 2013

... Significant winter weather impacts probable Thursday night into

Friday night... 

[burgertime]

Maybe it's because it's still 6 days away, and it seems like the best case scenerio here is ice (blah) but I'm not in to this storm at all for CLT.  A low tracking west of the Apps depending on 2 m tempatures CAD doesn't get me excited.  Especially looking at 850s up in northern virginia.   Plus the EURO map above doesn't even show the zero line making it down to CLT. 

 

Bit of a MBY post but I would think this is going to be a cold rain right now for CLT south.  Maybe I40 north will be more interesting if you like ice.  We'll see what happens in future runs, but the "underdoing the cold" discussion is like your favorite team losing and you hang your hat on "the average fan doesn't know how good that team was" argument.  Makes you feel better but it's still a loss. 

 

I have a feeling though it's going to be fun reading the PBPs this week...

 

 

Given the strong CAD signal...if the models are right you would get a major icing event for GSP as well. Don't underestimate how strong CAD can be especially for us. The big questions are, how strong is the high pressure and how much moisture is involved.