1/28 - 1/30 Storm Thread II

[Poimen]

GGEM looks good from the Triangle east.I'm guessing ~.50 qpf makes it to that far west.

[rduwx]

On 12z cmc 5h map you can see a little of the southern energy being sucked into the northern energy at hr 18.  It's not going to be a full phase but we'll see if it helps some.

[Disc]

Weatherkid#27, on 27 Jan 2014 - 11:27 AM, said:

Is the GEFS out yet? Interested to see if they came NW at all.

Not yet. They're out around 12 or so.

[Cheeznado]

Here in GA the trend is slightly down for qpf on most models. Another factor is the really dry surface air, virga will eat up some of the snow methinks. A trace to none northside, 1" or less downtown and up to 2-3" far southside seems like a safe forecast. Not as good as the Carolinas, but if I do get an inch I will take it.

[Stebaney]

At this point I would be surprised if they didn't raise WSW regardless of what the EURO says.

They do have WSW now. 

Winter Storm Watch

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE RALEIGH NC

351 AM EST MON JAN 27 2014

...WINTER STORM POSSIBLE FOR ROUGHLY THE SOUTHEAST HALF OF CENTRAL

NORTH CAROLINA LATE TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON...

[El Kabong]

A pretty amazing rollercoaster ride the past 24 hours, which is to be expected when it comes to winter weather in the Southeast.  Had the 18z GFS solution held, I don't know if the AMWX server would have survived!  It looks like a conservative, middle-of-the road solution appears to be where most of us west of the Carolinas are headed.  The extreme totals that the NAM and GFS were hinting at appear to be off the table, nevertheless it should still be at least a moderate impact event in parts of central and south Georgia.  Still hard to tell just how far north the precip will extend, but as Robert said, there are likely to be some surprises.

 

IP accumulations will cut down on our overall totals, but if that helps us avoid the dreaded ZR, I'm all for it!  A blend of the models should give us 1-2" of sleet topped off with 2" of snow if we can get the transition to take place early enough...otherwise, it might be a central Georgia sleetfest.  Tony, wax up your sled and head down this way!

 

Looking forward to updated thoughts from Delta and Candyman.

[Poimen]

They do have WSW now. 

Winter Storm Watch

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE RALEIGH NC

351 AM EST MON JAN 27 2014

...WINTER STORM POSSIBLE FOR ROUGHLY THE SOUTHEAST HALF OF CENTRAL

NORTH CAROLINA LATE TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON...

 

I'm sorry I meant winter storm warning.

[Cold Rain]

You RDU folks should take you .5 and run. Im sitting here hoping for a dusting! Y'all are about to get .5 and complaining. C'mon. It was looking like nothing a couple of days ago. But I suspect a good snow for most. Especially how bad models are handling it! Good luck everyone.

 

Not complaining...just commenting on the trend and how it seems counter to what some of the other guidance is showing.  5 inches of snow would be awesome!  More would be great, but nobody's complaining about 5 inches.

 

Thanks to all who weighed in with context!

[BadTrends]

Here in GA the trend is slightly down for qpf on most models. Another factor is the really dry surface air, virga will eat up some of the snow methinks. A trace to none northside, 1" or less downtown and up to 2-3" far southside seems like a safe forecast. Not as good as the Carolinas, but if I do get an inch I will take it.

 

Yea, it doesn't look great for us in AL/GA unless you are in the southern sections. Now, if the s/w can kick east under the northern stream (which has to dig more west) things could get a little better.

[FLweather]

Are we still acting on the assumption of 10:1 ratio here? I would assume a little higher based on the overnight temps when the bulk of the snow falls. If we do get a lot that heavy wet stuff could be a problem. I already lost a ton of trees on my property from the severe storms a few weekends ago.

 

Yup. Sounds right. Its hard to get 15:1. At most the SREF members doing about 11:1 here.

[lj0109]

Here is the 11AM updated forecast map from WIS-TV here in Columbia.  Thanks to everyone for all the great contributions to this thread.  It has been full of great information and analysis over the past few days!  

[Brick Tamland]

NWS Raleigh ‏@NWSRaleigh 13 mins

Morning model runs also showing a westward shift in snow. We're taking a look and will be updating the forecast early this afternoon

[WxJordan]

Here is what I am thinking at the moment....

 

 

The area in blue stands the best chance to see accumulating snow, and it may be a lot. I would not be shocked to see some areas receive 10 inches of snow from this set-up.

The area in white will see accumulating snow; however, it will not be as high as the area in blue.

The light blue shading is where we need to see the westward shift trend continue. This is definitely possible given the small features that will be affecting the pattern. The pieces of energy over the southwest United States may eject differently than what the models are showing, so there will be changes.

 

I did decide to go on the conservative side with this map.

 

I have a full update on my website and I go a little more in depth there. I am still not sure if this will be the final outcome. This is just what I have to go with at the moment. I will continue to post updates through out the day.

[beanskip]

If the RAP is to be believed, that southern stream energy is trending west -- not east. The 15z RAP has it ending up west of the 12z NAM's position. 

[Shawn]

Guys, this is going to be a "look at the radar" and "look at where the 850 lines is setup on the RAP model" deal. This could be 1973 for Southern GA, Coastal FL, Coastal SC, Midlands of SC. Or this could end up in the crapper really quick. I don't think we are going to know until the event is actually happening.

Here is another reference to 1973.. just look at how the precip axis setup and where we are at currently. I think we are relying on the weather models too much to guide us this time around... and if the models were where they are now and we used today's computers back in 1973, I bet you they would have never honed in on the actual event correctly either. I think Robert wrote an excellent discussion basically saying the models were wrong.

 

EDIT: Check out Jordan's map above.. and this.. wow

 

[rduwx]

Any word on how the cmc came in? My map is stuck at hour 36 and hasn't moved in 30 mins.

[Cheeznado]

The FFC snow total map is odd. It has 2" for Atlanta and only 3-4" max in central GA. That is way too loose a gradient IMO. If we get 2" someone south of here will probably get 5-6" easy.

[packfan98]

Any word on how the cmc came in? My map is stuck at hour 36 and hasn't moved in 30 mins.

Big NW trend.  Gets to the MA and NE coast!

[Lookout]

Here in GA the trend is slightly down for qpf on most models. Another factor is the really dry surface air, virga will eat up some of the snow methinks. A trace to none northside, 1" or less downtown and up to 2-3" far southside seems like a safe forecast. Not as good as the Carolinas, but if I do get an inch I will take it.

I agree with your amounts for the metro area. Will also probably see a bit more the further east you go.

 

I think if we somehow get more than expected it will be from the initial over running starting a few hours earlier than what is currently expected. Others have noted the fact the models will often under estimate the precip in situations such as this. The evidence of a good amount of moisture and degree of over running is the nam's and it's cousins showing a ton of virga initially. If that moisture can consolidate into one primary band, (which some do), those underneath it could get the snow to reach the ground a number of hours sooner than expected.

 

Overall, the models show me with around 0.25 to 0.40 liquid. Ratios don't look as high as they were in earlier runs when it was showing colder temps throughout, so 10:1 is probably about right.  So a 2 to 4 inch amount looks like a reasonable expectation for my neck of the woods. Although I would lean toward the 2 or 3 inch amount. I think athens will see 1 to 3 inches. There is such a sharp cutoff that it's really hard to nail down exactly how much everyone should expect. That cutoff line is probably not going to be resolved until a few hours before hand or even as it is happening. So although we can say in general terms where it could or will be right now, it certainly is not set in stone. So i'm taking my own thoughts on accumulation with a grain of salt. Very easily could be less or more...with a greater chance of it being less.

 

And it goes without saying the slightest move northwest or southeast can make a huge difference. As gsp noted, a single county could see a wide range of accumulation from a dusting to a few inches...which is pretty incredible when you think about it. But if you see those reflectivity images, you can see why.

 

Btw, about that virga. I see people subtract from a models accumulations to account for the virga/evaporation. But IIRC, from what I've been told in the past the amounts you see on a model does include evaporation. In other words, if a model shows 0.10 then 0.10 is actually what the model is showing reaching the ground..no deduction for virga is necessary. It's been awhile so I hope I'm remembering correctly. But I think you can see that really when the nam is showing tons of precip on it's reflectivity images but show no accumulations underneath that virga.

[strongwxnc]

With the MA and NE coast coming into play now, I assume late off shore development is occurring here

Big NW trend.  Gets to the MA and NE coast!

 

 

[superjames1992]

Holy crap, the GGEM is way west. A decent event for the western Piedmont. Almost gets to DC.

EDIT: Lookout posted the maps on the previous page.

[Buddy1987]

Hey guys I consider myself somewhat knowledgeable in regards to interpreting and reading the models. Do have a quick question however. When looking at the 700RH maps and seeing the moisture being advected and having it read in the green "90" is that a good indication that we may be able to get some overruning into the area as the atmosphere is moistening up? Just curious because looking at the 12Z nam at around hours 27-36 it shows even my area getting into the best RH

[rduwx]

Big NW trend.  Gets to the MA and NE coast!

 

 

 

Thanks packfan!  I could tell at the beginning of the run it looked decent. Some of the energy from the southern system was tapped into and the trough looked sharper to me.

[RaleighWx]

Any word on how the cmc came in? My map is stuck at hour 36 and hasn't moved in 30 mins.

CMC sometimes puts out the gribs later in the run and not sequentially. My script is designed to run sequentially so it is waiting on hour 42 to come out, should be soon.

[burrel2]

The ukmet, CMC, and NAVGEM have all come in significantly west. 

[strongwxnc]

This is a great example of a post that needs as image or a link

Thanks James

Holy crap, the GGEM is way west. A good storm for the western Piedmont.

[FLweather]

Hey guys I consider myself somewhat knowledgeable in regards to interpreting and reading the models. Do have a quick question however. When looking at the 700RH maps and seeing the moisture being advected and having it read in the green "90" is that a good indication that we may be able to get some overruning into the area as the atmosphere is moistening up? Just curious because looking at the 12Z nam at around hours 27-36 it shows even my area getting into the best RH

 

Between that and the 850 rh will give you a good indication where precip is.

[packfan98]

The ukmet, CMC, and NAVGEM have all come in significantly west. 

I was thinking that every model has come at least a little west or northwest on their most recent run except for the gfs which lined up with the 6z run.  Did any other model not tick nw?

[RaleighWx]

Here was 12z JMA by the way. 72 hour QPF

[rduwx]

CMC sometimes puts out the gribs later in the run and not sequentially. My script is designed to run sequentially so it is waiting on hour 42 to come out, should be soon.

 

Thanks for the info Allan!