February 12-13 Storm, Part III: Trilogy ends and then Obs thread soon!

[Wonderdog]

It's the exact same thing as saying you aren't confident...just more circuitously..anyway...I like your forecast

Yes, but admitting to "low confidence" in something is not how you would want to phrase it, imo.

[mosi76]

NC is getting hammered with the first phase of this storm.

 

RT @JimCantore One word: OVERACHIEVER Local Storm Report by NWS MHX: Bayboro [Pamlico Co, NC] social media reports SNOW of M10.0 INCH at 05:50 PM EST --

[twax1]

Winter storm warnings just went up southwest of Richmond. The US National Weather Service Baltimore/Washington is calling for 8-12 inches there. 

[yoda]

The everchanging LWX snow maps as of 645 for DC proper

 

~80% chance of 4"+

~50% chance of 8"+

~30% chance of 12"+

[cgillesp]

"For what it's worth, the NWS keeps pushing the rain forward without significant decline in totals. I know rain/sleet sucks, but a day off will certainly sweeten it. (this is NW DC)"

 

cgillesp,

 

What do you mean by forward?

What do you mean by "without significant declines in totals"? Declines in snow or rain? 

 

Also, what model is this based off of? 

Forward means sooner, that accumulation would be snow accumulation, and it's just the NWS's best guess, not any particular model AFAIK.

[Wonderdog]

There is still a fair amount of spread in handling the orientation of the trough and when (or if in the nam's case) the upper level low closes off. I don't feel like wasting time pulling snips together. It's easy to just look at the panels. Pull up 18z Thursday h5 vorticity panels. Each model handles it different. 

 

Euro op is the most aggressive still with closing it off and then going negative. This pulls the low into the chesapeake. It's easy to see why if goes from the nc sounds - jogs due nnw into the mouth of the bay (and stalls for a bit) and then continues its trek.

 

GFS is sloppy with the close but still has a good track. Deform never gets going strong for various reasons.

 

Nam remains open and neutral and has the best track and solution.

 

GEM is euro'ish but not as negative

 

RGEM is overdoing it imo. It's closed 3-4 contours and goes negative. That's probably the least likely.  

 

 

The spread in solutions isn't huge. Except for the rgem, i think they are all viable or anything in between. We'll see if the euro holds onto tucking the low into the bay @ 0z. I doubt it does. 

 

Front end is going to be juiced up and depending on the phasing of the energy prior to the precip getting here will determine how heavy we can get. I think it will be a pretty solid period. 

 

Like Matt said, after that, all bets are off. 

Bob, what do you think the EURO will show at 0z?

[yoda]

There is still a fair amount of spread in handling the orientation of the trough and when (or if in the nam's case) the upper level low closes off. I don't feel like wasting time pulling snips together. It's easy to just look at the panels. Pull up 18z Thursday h5 vorticity panels. Each model handles it different. 

 

Euro op is the most aggressive still with closing it off and then going negative. This pulls the low into the chesapeake. It's easy to see why if goes from the nc sounds - jogs due nnw into the mouth of the bay (and stalls for a bit) and then continues its trek.

 

GFS is sloppy with the close but still has a good track. Deform never gets going strong for various reasons.

 

Nam remains open and neutral and has the best track and solution.

 

GEM is euro'ish but not as negative

 

RGEM is overdoing it imo. It's closed 3-4 contours and goes negative. That's probably the least likely.  

 

 

The spread in solutions isn't huge. Except for the rgem, i think they are all viable or anything in between. We'll see if the euro holds onto tucking the low into the bay @ 0z. I doubt it does. 

 

Front end is going to be juiced up and depending on the phasing of the energy prior to the precip getting here will determine how heavy we can get. I think it will be a pretty solid period. 

 

Like Matt said, after that, all bets are off. 

 

Excellent discussion Bob and well written.  I believe the UKIE fits in the GGEM profile... or maybe the NAM

[Bob Chill]

Bob, what do you think the EURO will show at 0z?

 

Hard to say. Definitely not the deform setting up close to deep creek lake. Same low track from nc sounds off of OC that it's been showing. Good front end thump. Then all bets are off. The easy part of this storm is the front. It's too complicated after that. It will be a developing situation. 

 

The march bust last year did some wild stuff with the upper level low. The slp jogged SE before moving up the coast. Ric got hit hard while we watched our front end stuff vanish overhead. 

 

When h5 closes off the dynamics are awful tough to nail down over a relatively small area. We're just going to have to wait and see. 

[Wonderdog]

Hard to say. Definitely not the deform setting up close to deep creek lake. Same low track from nc sounds off of OC that it's been showing. Good front end thump. Then all bets are off. The easy part of this storm is the front. It's too complicated after that. It will be a developing situation. 

 

The march bust last year did some wild stuff with the upper level low. The slp jogged SE before moving up the coast. Ric got hit hard while we watched our front end stuff vanish overhead. 

 

When h5 closes off the dynamics are awful tough to nail down over a relatively small area. We're just going to have to wait and see. 

If h5 closes off sooner rather than later, it will make the storm more dynamic, no? And with that stronger winds that could keep the upper levels colder. Is that something we want to key on?

[Kmlwx]

If h5 closes off sooner rather than later, it will make the storm more dynamic, no? And with that stronger winds that could keep the upper levels colder. Is that something we want to key on?

Though I believe if it closes off TOO soon it comes too far west and we get a too warm solution. 

[snowdude]

bad news on WSR...aircraft had fuel leak had to abort...got about 5 drops

CONSPIRACY!!

[TL97]

What do you guys think of totals around that of 1/26/11. Obviously the storm is different but could the totals look similar by the end?

[Bob Chill]

If h5 closes off sooner rather than later, it will make the storm more dynamic, no? And with that stronger winds that could keep the upper levels colder. Is that something we want to key on?

 

It's not really that simple. As kmlwx said, too soon = too close with slp. Orientation is important too. If it closes and goes quickly negative then it also pulls slp nw. 

 

Euro has already shown a near best case scenario with closing off in west TN but staying neutral so the closed low passes more under us than over us. 

 

H5 doesn't even have to close off to get a great hit. Sharp and neutral until the axis is east of us and then going negative would be solid. 

 

I wouldn't key on anything except hoping the closed/negative with the axis west of us doesn't happen. That's the worst case. 

[Ian]

CONSPIRACY!!

At least none of us will even notice the difference. Winter storm recon is the new snowmap.

[nj2va]

If h5 closes off sooner rather than later, it will make the storm more dynamic, no? And with that stronger winds that could keep the upper levels colder. Is that something we want to key on?

 

Great question...I'll be interested to see what Bob, etc says.  I think its one of those tricky balances to play...if its too early like the Euro is currently depicting, it brings it up into the Chesapeake Bay and we see mixing.  

 

ETA:  Nice explanation above by Bob!  

[Bob Chill]

Great question...I'll be interested to see what Bob, etc says.  I think its one of those tricky balances to play...if its too early like the Euro is currently depicting, it brings it up into the Chesapeake Bay and we see mixing.  

 

ETA:  Nice explanation above by Bob!  

 

 

Every situation is different. A vort can close off in south dakota and still get under us. Euro closed it off basically in the same place today but was even more amped up and aggressive so the trough went negative. Euro got close to 3 contours closing. Sucked everything west. 

 

Euro could be totally right but I wouldn't put all my chips on it. Slightly less aggressive phase with the 2 pieces of energy and you get a more progressive solution. We may not know how "part 2" of the storm plays out until this time tomorrow and even then. 

[feloniousq]

DT posted a final call without a final call map, but seems to hint that he really likes the RGEM and the NAM

[DSF]

I'm a pretty big noob, so you'll have to forgive me.

 

Is there a reason warnings are up in the Philly/Mount Holly area and in southwestern VA, but not in LWX's region?  Are they less convinced than the other offices?

 

I guess what I mean is, I can understand the areas to the SW getting warnings up now since the storm will obviously pass through there first, but I'm wondering why Philly already has warnings up and LWX doesn't.

[Kmlwx]

I'm a pretty big noob, so you'll have to forgive me.

 

Is there a reason warnings are up in the Philly/Mount Holly area and in southwestern VA, but not in LWX's region?  Are they less convinced than the other offices?

 

I guess what I mean is, I can understand the areas to the SW getting warnings up now since the storm will obviously pass through there first, but I'm wondering why Philly already has warnings up and LWX doesn't.

This has been discussed even within the past few pages of this thread. Winter storm warning is for within 24 hours of an event. We are just starting to touch that now - NWS also discussed confidence levels. We aren't being skipped over - all NWS offices operate somewhat differently. 

[mappy]

I'm a pretty big noob, so you'll have to forgive me.

 

Is there a reason warnings are up in the Philly/Mount Holly area and in southwestern VA, but not in LWX's region?  Are they less convinced than the other offices?

 

I guess what I mean is, I can understand the areas to the SW getting warnings up now since the storm will obviously pass through there first, but I'm wondering why Philly already has warnings up and LWX doesn't.

Most likely confidence. LWX seems to be in a tricky spot since there is a chance of mixing Thursday which will reduce snow amounts. They may wait until the 00z runs before going forward with warnings.

[Bob Chill]

This should help some people. Euro last night had us in tears of joy. It was a perfect progression @ h5. Great phase - close - track. We basically had the bowling ball over us with a neutral look. Here's 18z thurs panel from last night:

 

 

 

 

 

And then here's the same period from today's run:

 

 

 

 

 

They don't even really look all that different but a little means a lot here. Euro could go back to a version of last night or it could hold serve. And even then it's just a model. Dynamic upper level storms will always confuse, frustrate, and annoy everyone. Even if the euro goes hog wild again tonight it won't mean it can't punch us in the face tomorrow. 

[Deck Pic]

Rap should be in range later this evening and I'll get my fix every hour!!

[DCAlexandria]

Thanks bob

[Ian]

The closed 500 low thing is less important than a proper pass. If it closes early it tries to run too far west and messes up the flow. A close as it passes is good but not necessarily because it's closed but that can often be around when a storm is bombing. Closed lows can also suck as they tend to show up with vertically stacked storms.. Fine in winter if you've already been pounded I guess as it'll probably be occluding etc.. But a long term closed low in svr wx season is usually less fun than a non closed counterpart in the same spot.

[Bob Chill]

Ian made great points. We don't have to have h5 close off to have a great storm. We need it to close in a perfect location and time for us to have an epic storm. 

[DSF]

This has been discussed even within the past few pages of this thread. Winter storm warning is for within 24 hours of an event. We are just starting to touch that now - NWS also discussed confidence levels. We aren't being skipped over - all NWS offices operate somewhat differently. 

Sorry, I looked back a page or two and didn't see anything, I guess I just didn't look back far enough.  Just got home from work and doctor.

 

I did see mention of the 24 hour guideline, but by 7PM I thought we were inside of that.  Anyway, my real point was that whenever the storm comes it'll hit us before Philly, so they must not be using the same 24 hour guideline.  

 

I can accept that the offices just run differently.  Just didn't know if there was anything more to it than that.

[DCAlexandria]

Ian I think bobs overall point that 4"-14" is still in the cards. I stand with Bob.

[Interstate]

Anyone notice that DT made a last call but never showed a map or really made a last call for the mid atlantic?

[Wonderdog]

The closed 500 low thing is less important than a proper pass. If it closes early it tries to run too far west and messes up the flow. A close as it passes is good but not necessarily because it's closed but that can often be around when a storm is bombing. Closed lows can also suck as they tend to show up with vertically stacked storms.. Fine in winter if you've already been pounded I guess as it'll probably be occluding etc.. But a long term closed low in svr wx season is usually less fun than a non closed counterpart in the same spot.

But doesn't the h5, closed or not, affect the pass?

[Ian]

But doesn't the h5, closed or not, affect the pass?

Yeah to a degree depending on the flow. In this case if it closes early it's generally not good IMO. Not always the case especially if we have a good block.