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Wow

The Big One - Forecast & Discussion

1,993 posts in this topic

The first thread is getting too large for the database to handle...

 

It's looking pretty likely that we've got a big storm on our hands. Let's continue the discussion here.

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Got supplies and the sleds. I think we cash in on this one. 18z GFS looked good. Real modeling begins tomorrow as energy is being sampled. I'm sure they will be sending some recon flights out tonight or tomorrow if this looks like it's going to slow crawl up the east coast. 

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Got supplies and the sleds. I think we cash in on this one. 18z GFS looked good. Real modeling begins tomorrow as energy is being sampled. I'm sure they will be sending some recon flights out tonight or tomorrow if this looks like it's going to slow crawl up the east coast.

I thought the energy would be sampled for tonight's 0z runs?

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WOW.  The EPS members are way up!  Mean is up 2.25" in GSO alone to 10" as of the 12z run!  All 51 members show >2" and only five show less than 6".  It's the best EPS run yet without a doubt and the second improved run in a row.

 

Totals (this is probably mostly or all snow further north and west, but ice further south and east):

 

GSO: 10"

HKY: 9.5"

CLT: 11.5" (mixing?)

AVL: 10.25"

RDU: 9.75" (likely some mixing)

MWK: 8.75"

RWI: 7.75" (likely mixing)

PGV: 5.75" (definitely mixing)

FAY: 10" (definitely mixing)

DAN: 10"

CAE: 10" (obviously not snow, but IP and/or ZR) -> NO snow here... you're probably looking at 1" ZR and/or 1" ZR/IP

GSP: 11.5" (probable mixing?)

ATL: 5" (probably not much snow)

AHN: 9.75" (mixing, I'd presume)

RMG: 4" (mixing)

DNN: 4.25" (mixing)

 

If you want to know more locations, you can ask in the banter thread.

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BMX says there could be snow on Wednesday Night in Eastern AL.

 

THE POTENTIAL FOR RAPIDLY FALLING
TEMPERATURES IN THAT LAYER OVER THE NORTHERN HALF OF THE CWA.
THIS COULD RESULT IN A TRANSITION TO SLEET AND SNOW WEDNESDAY
AFTERNOON AND EVENING. WE WILL HAVE TO MONITOR THIS SITUATION
CLOSELY FOR THE POTENTIAL DEVELOPMENT OF A DEFORMATION BAND AND
DYNAMIC COOLING LEADING TO AT LEAST SOME CHANCE OF ACCUMULATING
SNOW...ESPECIALLY OVER EAST-CENTRAL AND NORTHEAST ALABAMA.

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WOW.  EPS members way up!  Mean is up 2.25" in GSO alone to 10" as of the 12z run!  It's the best EPS run yet without a doubt and the second improved run in a row.

 

Totals (this is probably mostly or all snow further north and west, but ice further south and east):

 

GSO: 10"

HKY: 9.5"

CLT: 11.5"

RDU: 9.75"

MKW: 8.75"

DAN: 10"

CAE: 10" (obviously not snow, but IP and/or ZR)

GSP: 11.5"

Do you have enough info to determine totals for only the periods where snow is falling?

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Should someone recap the current modeling for historical and verification purposes? It would be great to have at the top of this new thread.

 

day2_psnow_gt_04.gif

day3_psnow_gt_04.gif

sig west shift from the 7z products

 

& 15z SREF prob of >1/2" ZR

post-382-0-05548100-1391987322_thumb.jpg

 

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Do you have enough info to determine totals for only the periods where snow is falling?

 

Unfortunately, no.  I do believe the ensemble mean is east of the operational, though, so there might be less mixing.  I'm not sure.

 

BTW, I added Asheville.  I knew I forgot someone.

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Unfortunately, no.  I do believe the ensemble mean is east of the operational, though, so there might be less mixing.  I'm not sure.

 

BTW, I added Asheville.  I knew I forgot someone.

Alright, I'll just go in for what I want: how much snow for RDU?

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ECMWF ENS mean for RDU is now 10 inches!

Looks like CLT is around 11.5 inches.

Again keep in mind it isnt all snow, takes ice into account.

I know this has been discussed, but I want to make sure I understand it:

If these snowfall maps show 10 inches, and presumably some of that is IP/ZR, does that mean if you stick a ruler in the ground, you'll measure 10 total inches of SN+IP+ZR or does that mean it's more likely that you'll measure something like 4 inches of SN+IP+ZR?

I think it's the latter because the model is counting ANY frozen/freezing precip as snow.

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I know this has been discussed, but I want to make sure I understand it:

If these snowfall maps show 10 inches, and presumably some of that is IP/ZR, does that mean if you stick a ruler in the ground, you'll measure 10 total inches of SN+IP+ZR or does that mean it's more likely that you'll measure something like 4 inches of SN+IP+ZR?

I think it's the latter because the model is counting ANY frozen/freezing precip as snow.

 

It's the latter.  I think what it's saying is that RDU, for example, gets 1" QPF of wintry precipitation (thus, 10:1 ratios = 10" of snow).  RDU probably mixes, so I doubt the actual mean is 10".  Given the ensemble mean is apparently east of the op, places like CLT, GSO, HKY, DAN, and MWK might escape with all or almost all snow, though (just a guess), and RDU would probably get more snow than the op, as well.  That's just speculation, though.

 

That's also how you get it showing 10"+ in CAE when, in reality, that's almost certainly IP and/or ZR.

 

I am curious if the StormVista (?) maps that DT posted for the EPS mean are more accurate when accounting for mixing.  Does anyone know?

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Interesting, I live 50 miles due east of Charlotte and news 14 saying mostly ice and heavy snow North and West of Charlotte. not sure I agree

all depends on the track, the models as of now. That sounds about right

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GEFS has RDU about 1.25" of QPF, Euro Ens is about 1.3" and GGEM Ens is about 1", pretty good agreement.  Now we just need to hope the sleet can hold out over the frzn or even rain.

 

The 18z GEFS run is the wettest yet.

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CLT & NW South Carolina has 90% probability of equal to or greater than 6" based on the Euro EPS probabilities on WxBell. Entire state of NC has 90% chance at >1" and much of the state save east of I-95 has 90% chance at > 3"

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