The Psuhoffman Storm

[BaltimoreWxGuy]

Say what you want about Tombo but he says Baltimore is at least .50 frozen on the backend based on 850's and that it should dynamically cool the surface cause of the CCB

[Ian]

I imagine it's mostly rain for LYH?

At least the NE gets hammered.

you might get a flurry at the end.

2' for ct blizz

[CarolineWx]

What would make them cold enough for snow if Baltomre is toasty in a driving rain? There's no HP to the north.

It is looking like there will be HIgh to the north once the storm gets into the northeast

[Ian]

Say what you want about Tombo but he says Baltimore is at least .50 frozen on the backend based on 850's and that it should dynamically cool the surface cause of the CCB

most models are advertising snow with the ull passage. it's hard to get here but it's possible.

[ravensrule]

Say what you want about Tombo but he says Baltimore is at least .50 frozen on the backend based on 850's and that it should dynamically cool the surface cause of the CCB

Not doubting Tombo but that is highly unlikely to happen.

[ravensrule]

most models are advertising snow with the ull passage. it's hard to get here but it's possible.

If we get 5" of snow with ull passage i will give you a lap dance at the next convention .

[Ian]

Not doubting Tombo but that is highly unlikely to happen.

i think he's being generous with precip as well

[kurtstack]

Any hope for snow here is that temps crash as the low gets northeast of us and and convective band forms over us for a few hours. That's pretty much what we're looking for at this point. Top end probably 2-3 inches of slushy wet snow if things work out just right.

[insanegrenade]

EURO :

78hrs: 988mb SLP offshore from NJ.

Showing heavy snow for DCA. why is everyone saying all rain? not true. might start off as rain but it will snow eventually.

[Fozz]

Not doubting Tombo but that is highly unlikely to happen.

So is a foot of snow in Philly while Baltimore gets all rain.

[ravensrule]

i think he's being generous with precip as well

He always is, plus as has been said numerous times the back end snow almost never works out around here. Unless something changes tomorrow we are likely to see heavy rain to a bit of back end non accumulating snow.

[Ian]

Any hope for snow here is that temps crash as the low gets northeast of us and and convective band forms over us for a few hours. That's pretty much what we're looking for at this point. Top end probably 2-3 inches of slushy wet snow if things work out just right.

we have pretty solid agreement among the best globals that you get almost a perfect 500mb track and slp track. it's early, but they've been spitting out similar more often than not for many runs now. still need help in d.c. but if i was west of 95 my excitement level would be moving upward more quickly.

[BaltimoreWxGuy]

So is a foot of snow in Philly while Baltimore gets all rain.

This...If Philly gets something like that to happen, I would think we get some snow too..I know Philly is further north, but we are also further west than Philly...I would think 850's crash here first before they would....

[BaltimoreWxGuy]

He always is, plus as has been said numerous times the back end snow almost never works out around here. Unless something changes tomorrow we are likely to see heavy rain to a bit of back end non accumulating snow.

Back end snow with a frontal passage or west to east low is a lot different than backend snow from a Dynamic coastal storm...I think its possible.

[ravensrule]

So is a foot of snow in Philly while Baltimore gets all rain.

I agree, but in this winter there is always NADS.

[real]

I think the threat of a crippling 1 foot plus Philly to New York storm, while certainly is possible, is no where near as certain as they currently think. They are banking on very rapid and dynamic cooling -- kind of like what we would hope for in a big March storm when the temperature starts out at 38. Very well could occur, but if I was making a forecast for the public I would throw in a lot of caution before over-promising.

[ravensrule]

Back end snow with a frontal passage or west to east low is a lot different than backend snow from a Dynamic coastal storm...I think its possible.

True also but it is still not a highly likely scenario. Even from a dynamic coastal there is not likely to be much accumulation. I hope im wrong.

[BaltimoreWxGuy]

True also but it is still not a highly likely scenario. Even from a dynamic coastal there is not likely to be much accumulation. I hope im wrong.

Im not saying its a highly likely scenario, Im just saying its somethign we have to watch, and Id bet that it would be mentioned in NWS's discussion later tonight.

[Dr No]

If things hold constant, this is a branch-snapper for me and Ji. It's going to be very tricky p-type issues and depends precisely where the ULL tracks. Someone had mentioned Dec 5 2009 in a post yesterday, and this might not be that bad of a thermal comparison.

[MDstorm]

I think given the probable intensity of the storm and the copious amount of moisture likely with this storm, the backlash will over-perform and will save the storm form being a complete washout for DC/BWI area. I would bet that Philly sees a good bit of rain before any change over. But both Philly and DC/BWI areas should see a good back end thump.

MDstorm

[insanegrenade]

I have a question. I am hearing about this 1024 high dropping down on the Euro, just in time for the storm. That means cold air. Does that mean things change around here to all snow or am I wrong?

[psuhoffman]

most models are advertising snow with the ull passage. it's hard to get here but it's possible.

its not really THAT rare, but we do not remember them because 90 percent of the time when we get snow from a good H5 track we also get snow from the associated surface system and so its all blended together. Last year we got deform snows from the passage of the H5 low in all 3 major snowstorms for DC last year. But no one remembers the wraparound because it just became part of the larger whole event. What is rare here is getting snows from the H5/H7 lows after not getting any snow from the surface system. Its rare that we get "wraparound" snows after not getting snow from the front end. THe reason that is rare is because a good H5 track usually also promotes a good slp track. Here our issues are not the track of the storm but the lack of a high. This lack of a high also tends to lead to the disjointed nature of the precip. With a strong high you get better WAA precip ahead of the storm because there is more resistance to the surge of warm air and thus more lift. The disjointed nature of the precip is partly due to the lack of cold air. This seems common with similar systems. I do not find it that far fetched that we get some snow from the passage of the upper level low because most guidance has suggested it would be a good track for us from a week ago. The front end of this storm is not working out because it has trended slower, and the high has trended weaker and faster to leave. That combo killed our chances for a MECS/HECS down here. We still have a shot at a SECS if we can get that H5 to stay strong and pass right south of us, should crash heights and cool the column pretty fast and a quick thump of wet snow could happen.

[psuhoffman]

Not doubting Tombo but that is highly unlikely to happen.

areas just west of Baltimore got 5" with the passage of the upper low in the March 2009 storm after we were fringed by the front end precip. Its not as rare as everyone thinks...

[psuhoffman]

we have pretty solid agreement among the best globals that you get almost a perfect 500mb track and slp track. it's early, but they've been spitting out similar more often than not for many runs now. still need help in d.c. but if i was west of 95 my excitement level would be moving upward more quickly.

I think we see eye to eye right now (very scary). I am fairly excited for my area that this is going to be a heavy wet snow event. This is looking like a more classic type of storm where more elevated west and north suburbs get significantly more snowfall then the cities. We have not seen many of these in recent years but there are plenty of historical examples to guide us as to what locations are likely to do well in this type of event.

[BaltimoreWxGuy]

I think we see eye to eye right now (very scary). I am fairly excited for my area that this is going to be a heavy wet snow event. This is looking like a more classic type of storm where more elevated west and north suburbs get significantly more snowfall then the cities. We have not seen many of these in recent years but there are plenty of historical examples to guide us as to what locations are likely to do well in this type of event.

Trip to Manchester? If I could just get a solid 3-6" on the backside I would be pretty satisified...I think its a legit possibility, we'll see.

[MidlothianWX]

areas just west of Baltimore got 5" with the passage of the upper low in the March 2009 storm after we were fringed by the front end precip. Its not as rare as everyone thinks...

You mentioned the disjointed nature of precip - what was the reason for such a large gap during the March 2009 event? Although we had cold air and precip with the front end of that one down here, there was a noticeable break between that and the ULL.

[psuhoffman]

You mentioned the disjointed nature of precip - what was the reason for such a large gap during the March 2009 event? Although we had cold air and precip with the front end of that one down here, there was a noticeable break between that and the ULL.

I was kinda busy that week with personal things, but from what I can remember of that event, the surface storm never really bombed or reached full potential. TO get precip back to the west of a storm the surface has to develop a CCB that is phased up with the upper features and creates good moisture transport back to the west of the low. THe storm that time did not. It was disjointed with most of the precip streaming northeast and never wrapping around west. I do not know why, there could have been several culprits. The storm simply got out ahead of its upper level support. Usually this is a model error due to feedback but sometimes it does actually happen. The trough might not have had the right axis until too late. I don't know what the reason was from memory but I do know the original precip from the surface system was gone and to our east and then the upper level low swung through and dropped 4-6" across the area early the next morning.

[ORH_wxman]

This...If Philly gets something like that to happen, I would think we get some snow too..I know Philly is further north, but we are also further west than Philly...I would think 850's crash here first before they would....

Philly doesn't get a foot of snow on the Euro...maybe a few inches as the deformation band at the end flips to snow before ending. They are pretty much all rain (and a lot of it) through 78h on the Euro.

[notvirga!]

Where is the r/s line per euro?

[tombo82685]

Say what you want about Tombo but he says Baltimore is at least .50 frozen on the backend based on 850's and that it should dynamically cool the surface cause of the CCB

the stuff i said in the phl thread is all based upon 850 temps, cause i dont have soundings and frz temps dont get within 30 miles of the cities, so its all dynamics. My statement was if we are basing it on 850s balt is prob close to .5. Its hard to tell. hr 72 has the 850 line by hgr. hr 78 has the 850 by dov with .25-.5 falling, so i took half that qpf, then hr 84 the area gets another .1-.25, but your just south of the .5 line, so i assumed .4-.5