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February mid to long range threats discussion


Ji

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Ensembles look decent at least. I sadly have no faith the models are even showing the right general scenario though. 

 

eta: most members under us, redevelop south of OBX. still oddly slow.. we pile up light precip for a long while. 

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Maybe 40/50 show the slow scenario. Still think think we need to be realistic and unslow this thing? What's slowing it down exactly? Is it just cut-off? 

yeah i doubt it's a 48 hour light event. not sure.. lumbering 500mb maybe. looking closer it seems there are a number of members that are just slower to get going overall and lag the main body as well so maybe that's part of it on the mean. 

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Not sure about the Euro ensembles, but the GEFS and Canadian ensembles show no big hits for DC.  Of course that could change, but there haven't been many solutions in the last 24 hours that have shown big snow south of Baltimore.

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Ensembles look decent at least. I sadly have no faith the models are even showing the right general scenario though.

eta: most members under us, redevelop south of OBX. still oddly slow.. we pile up light precip for a long while.

Yea, decent in a weird kind of way. Decent and who knows are interchangeable at this point.

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yea its a similar deal just everything is displaced north initially...the h5 ends up in the same place but gets there in a very different way. What is similar is the idea of waves along a boundary producing WAA precip over a cold airmass locked into the northeast. Problem is the high is just further north then we want it. Its actually pushing down the whole time but the trough axis starts so far east, we are on the back side, so the initial wave goes well north of us, everything retrogrades as the h5 vort digs into the mid atlantic but we need it to bomb out fast for it to work out since the surface is all messed up by the first wave.

Seems like we've been stuck in this little wave pattern. We need bigger waves. Maybe this is silly but I'm glad it warmed up a little today because it indicates maybe a slightly different pattern emerging. Today certainly doesnt fit the cold/dry verbiage.

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Seems like we've been stuck in this little wave pattern. We need bigger waves. Maybe this is silly but I'm glad it warmed up a little today because it indicates maybe a slightly different pattern emerging. Today certainly doesnt fit the cold/dry verbiage.

 

lol that's what I've ended up hoping... if mitch is right about a thaw reshuffling things, maybe today is the day? Or just wishful thinking since it's brief.

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One thing I noticed is that the temps are pretty bad on many of the ensemble members - even the ones with a good track. Surface temps scorching until maybe Monday 18z on many of them. And 850s don't drop below 0 for the District until Tuesday 00z. On the runs with good tracks (to our south), they don't really get good until we're to the NW of the low...backend flakes anyone?

 

I'm guessing that a low stalling there to our SW in TN for 24 hours isn't the greatest thing......it would be supremely irritating if this thing is a slow moving rainstorm.

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One thing I noticed is that the temps are pretty bad on many of the ensemble members - even the ones with a good track. Surface temps scorching until maybe Monday 18z on many of them. And 850s don't drop below 0 for the District until Tuesday 00z. On the runs with good tracks (to our south), they don't really get good until we're to the NW of the low...backend flakes anyone?

 

I'm guessing that a low stalling there to our SW in TN for 24 hours isn't the greatest thing......it would be supremely irritating if this thing is a slow moving rainstorm.

why not, we've had every other kind this year

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lol that's what I've ended up hoping... if mitch is right about a thaw reshuffling things, maybe today is the day? Or just wishful thinking since it's brief.

well, the thaw I was referring to was a complete pattern break down and then reshuffles to something different than pattern before the thaw

I don't think we get that by just today

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lol that's what I've ended up hoping... if mitch is right about a thaw reshuffling things, maybe today is the day? Or just wishful thinking since it's brief.

 

yea maybe it's the key...the ol' farmer's way of forecasting lol.  but yea, i think a lot of people would prefer warm/dry, cold/wet.  that's how denver does it, maybe we can sneak into that pattern (or more of it) this month.

 

http://forecast.weather.gov/MapClick.php?lat=39.739146640000456&lon=-104.98469734299971&site=all&smap=1#.VNKIhGjF-So

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One thing I noticed is that the temps are pretty bad on many of the ensemble members - even the ones with a good track. Surface temps scorching until maybe Monday 18z on many of them. And 850s don't drop below 0 for the District until Tuesday 00z. On the runs with good tracks (to our south), they don't really get good until we're to the NW of the low...backend flakes anyone?

 

I'm guessing that a low stalling there to our SW in TN for 24 hours isn't the greatest thing......it would be supremely irritating if this thing is a slow moving rainstorm.

The big thing is the circulation at around 500 feet is north of us. Look at where the 850 low is located at 108 hours, northwestern PA.  That helps place the strongest warm advection to our north.  Our winds at 850 are almost westerly, not great for getting heavier precipitation. To get the heavier precipitation we need to have the 850 low to our south. 

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Looks like arctic front sets up just a little too far north on this run, starting to look like a pretty sweet overrunning event for areas to our north, maybe we can that high pressure to press a little more as we get closer to the event and get in the game.

 

 

Pretty unimpressive h5 evolution on 18z gefs. Less digging and phasing and more pos tilt in front.

 

We need the trailing vort to catch up, phase early and drag the whole system down....something similar happened for the Boston blizzard 48 hours out, so I suppose it is possible...otherwise we are taking our chances with the cold air bleeding down in time...we probably get 1-2" with this run...a lot of wasted potential...definitely a worse run than 12z

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We need the trailing vort to catch up, phase early and drag the whole system down....something similar happened for the Boston blizzard 48 hours out, so I suppose it is possible...otherwise we are taking our chances with the cold air bleeding down in time...we probably get 1-2" with this run...a lot of wasted potential...definitely a worse run than 12z

And it's just another run with a different outcome. There will be more.

Lead low has to pass south into central or southern wva. It's a very simplistic way to think about it but it's the key feature if you don't want to look at the upper levels.

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We need the trailing vort to catch up, phase early and drag the whole system down....something similar happened for the Boston blizzard 48 hours out, so I suppose it is possible...otherwise we are taking our chances with the cold air bleeding down in time...we probably get 1-2" with this run...a lot of wasted potential...definitely a worse run than 12z

The pattern has real potential.   Check out the 500 mb composite analogs.  At the lower right, check out the last analog:  02/05/1995.

This storm is in Kocin's book.

 

 

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Snow or mostly snow solution is looking like an extremely low probability event at this point.  Still worth watching at this lead, but a flawed cartopper or 1-2" of taint is still a decent possibility. There's always a chance the models are not bringing the frontal boundary far enough south, but I'm not really seeing a mechanism to bring that boundary south until the first shortwave exits, and by then it may be too late.  If there are two short waves spaced properly with the right timing, then I guess it's possible the first shortwave could bring the boundary south of our latitude before the other one arrives with the qpf, but that's a complicated setup and as Bob said, we generally don't do complicated, but we can thread the needle on occassion.  It's certainly been interesting to watch the models scramble around in this setup.

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I always used analogs only as a tool on whether a storm threat is real or not. I don't think it's a good idea to think that, for example, just because Blizzard of 96' is #1 analog, we should expect a blizzard. To me it just means a similar pattern once delivered a storm. Nothing more, nothing less. Just my personal opinion since no 2 patterns are ever perfectly similar. 

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On a cool note though, February 3-5 1995 was probably the storm that got me absolutely hooked on weather. You see that little area of 12+ over Philly? I was 8 years old. I recall waking up the clap of thunder, first time experiencing thundersnow. I could see that orange hue in the window that snowstorms love to give off. I looked out the window and it was absolutely pouring snow. It stopped in the early morning hours, but it was one helluva storm. 

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I always used analogs only as a tool on whether a storm threat is real or not. I don't think it's a good idea to think that, for example, just because Blizzard of 96' is #1 analog, we should expect a blizzard. To me it just means a similar pattern once delivered a storm. Nothing more, nothing less. Just my personal opinion since no 2 patterns are ever perfectly similar. 

The analog is at the 500 mb level.  Really, it is a signal that the pattern has potential.  I think of "7 days out" in terms of signals.

It just seems that for a couple of days centered around the 10th, there will be transient blocking, a ridge over the Rockies, some 500 mb vorticity swinging by and some available moisture.

 

We've realistically got about five weeks so lets milk the good signals for all they are worth.

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new sref has the first system way north with the heaviest precip axis way north of Boston and even north of NY state

I don't think any of the models showed that so far

not that it's correct, but maybe indicative of a continued north trend?

http://mag.ncep.noaa.gov/Image.php?fhr=087ℑ=data%2Fsref%2F21%2Fsref_namer_087_precip_p24.gif&model=sref&area=namer&param=precip_p24&group=Model+Guidance&preselected_formatted_cycle_date=20150204+21+UTC&imageSize=&ps=model

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The analog is at the 500 mb level. Really, it is a signal that the pattern has potential. I think of "7 days out" in terms of signals.

It just seems that for a couple of days centered around the 10th, there will be transient blocking, a ridge over the Rockies, some 500 mb vorticity swinging by and some available moisture.

We've realistically got about five weeks so lets milk the good signals for all they are worth.

I would milk anything that produces dendrite growth. ;) We all need 1 good one at this point. We're not asking for much are we?

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