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E PA/NJ/DE Fall 2018 OBS Thread


Rtd208

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11 hours ago, Birds~69 said:

Really wish we had something wintry to "track". That Nov snow got my blood flowing, now nothing. Withdrawal?

36F

Not a ton of support right now but some mixed signals being tossed around on guidance for Dec 5 give or take a day. Wave may try and slide under the region if we can time it properly with some ridging up North. 

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3 hours ago, Ralph Wiggum said:

Not a ton of support right now but some mixed signals being tossed around on guidance for Dec 5 give or take a day. Wave may try and slide under the region if we can time it properly with some ridging up North. 

Hey Steve to my eyes the period from the 5th to 12th looks mighty interesting....stay tuned

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1 hour ago, ChescoPaWxman said:

Hey Steve to my eyes the period from the 5th to 12th looks mighty interesting....stay tuned

I agree and hopefully we can cash in during this with another 'bonus' event before the mid month advertised PAC air regime overwhelms N America. That might be a break before winter truly starts in earnest later in the month. Starting to finally see a few positive signs anyway. Cheers. 

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3 hours ago, Ralph Wiggum said:

I agree and hopefully we can cash in during this with another 'bonus' event before the mid month advertised PAC air regime overwhelms N America. That might be a break before winter truly starts in earnest later in the month. Starting to finally see a few positive signs anyway. Cheers. 

Agreed! Hey I notice in your winter stats you have snow and sleet separate...any reason for that? They should be combined as total snow correct?

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1 minute ago, ChescoPaWxman said:

Agreed! Hey I notice in your winter stats you have snow and sleet separate...any reason for that? They should be combined as total snow correct?

No reason other than personal for my own log purposes. End of season I guess I can pad the snow stats and include sleet in a separate column. I will also pad with fall snow and spring snow ;)

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6 hours ago, ChescoPaWxman said:

Agreed! Hey I notice in your winter stats you have snow and sleet separate...any reason for that? They should be combined as total snow correct?

 

6 hours ago, Ralph Wiggum said:

No reason other than personal for my own log purposes. End of season I guess I can pad the snow stats and include sleet in a separate column. I will also pad with fall snow and spring snow ;)

Its a good thing we don't run the NWS cooperative data program. Nobody would trust the data with a 13.3" per annul bias! hehe

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Liking the 9th-12th period much more than the 5th but that is based on the NAO returning to negative like the ensembles are hinting. There is a ton of variance though after the rise up to positive and even though the mean shows it going negative, I am not sold yet because the last few years we've seen a -NAO at day 10 get delayed after a few days. Seems the models have no clue whether it is going to stay positive and it's making the OP's pretty much useless after D 7. When you look at the trend since august, it is not encouraging for the NAO staying negative.. just my opinion though. AO looks to be negative for the foreseeable future though so at least that should signal cold air nearby or in place. Another good thing we have going is the PNA looks to stay positive which should translate to troughing in the east. We've scored a ton without a -NAO harder to do so in early December. I think the period will be active but progressive... no real sustained cold or warmth. we'll need to luck out on timing if the NAO stays positive in the LR.

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Have been watching the period between the 8th and 11th rather closely as there are back to back shortwaves moving thru the region. EPS took a large step forward irt the overall pattern evolution and the GEFS are starting to merge towards a coastal LP scenario with cold enough air around for a potential frozen event. 

However, while not overly enthused, we shouldn't look past Dec 5th too quickly. With the pattern being so fast changing right now guidance is still flopping around from run-to-run irt the handling of 500mb energy which is forecast to pass under the region. Again, flow is fast and doesnt really allow the subsequent trof to turn negative but this has the looks of a possible short range surprise minor event as a surface low tries to spin up while the UL energy swings thru. 

 

icon_mslp_pcpn_frzn_us_fh138-150.gif

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3 hours ago, Ralph Wiggum said:

Have been watching the period between the 8th and 11th rather closely as there are back to back shortwaves moving thru the region. EPS took a large step forward irt the overall pattern evolution and the GEFS are starting to merge towards a coastal LP scenario with cold enough air around for a potential frozen event. 

However, while not overly enthused, we shouldn't look past Dec 5th too quickly. With the pattern being so fast changing right now guidance is still flopping around from run-to-run irt the handling of 500mb energy which is forecast to pass under the region. Again, flow is fast and doesnt really allow the subsequent trof to turn negative but this has the looks of a possible short range surprise minor event as a surface low tries to spin up while the UL energy swings thru. 

 

icon_mslp_pcpn_frzn_us_fh138-150.gif

With how fast the pattern is and will continue to be for the forseeable future imo, these kind of storms are how we can score this pattern. The problem is we need to rely on perfect timing but once things get clearer and nearer, we'll have a better idea. I wouldn't be confident and anything past day 4 right now. Really nice signal though developing day 10... if blocking isn't as strong as projected or is delayed, that high will slide out to sea and it will be snow to rain scenario for most. honestly, this is the most likely outcome in this pattern. PHL averages ~ 2" and ABE ~ 4" in December for a reason. Most of the time, you need a pretty textbook pattern to see a significant storm and I'm not sure the upcoming pattern fits that bill. Light events like the one above are our best shot imo..

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Dec 5th thread fizzled....DOA it seems.

Dec 8-11 period still bears watching....long way out there obviously. Latest op guidance clustering around a tucked look with coastal slp onshore or very near onshore around DelMarVa. Nao ridge nonexistent and allows HP to move out and storm to come n and w. Ens are mixed between sliders and another cluster of tucked lows. We were able to cash in back in Nov so we will see. Things to keep an eye on are the pieces of STJ energy moving across the US, the nao and if it can pump a ridge at the right time, and the WAR which is trying to foul things up. Very typical Nino look imo. 

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4 hours ago, Ralph Wiggum said:

Euro just woofed for the Dec 8-11 potential. However it also hasn't exactly been "the King" at this range since the upgrade. Solid signal for tracking potential though.

I'll take it even if it's false hope...just something to somewhat track for the time being.

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Storm next weekend starting to show more potential. Signals still mixed due to weak ridging at high lat and interaction or lack of between STJ and PJ. EPS are a mix of Southern hits, direct hits, and I95 mix with NW burbs hits. Majority are South, the others are basically a mix of NW hits and 95 hits. Here are a few of the i95 hits

us_model-en-087-0_modez_2018120100_216_505_215-1.png

us_model-en-087-0_modez_2018120100_216_505_215-1.png

us_model-en-087-0_modez_2018120100_216_505_215-3.png

us_model-en-087-0_modez_2018120100_216_505_215.png

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The GFS sucks I know that and it's been flipping every run, but what it showed at 6z is my biggest concern. The energy up in SE Canada is suppressing the flow enough to not allow the storm to gain latitude and gives DC a hecs. 

gfs_z500_vort_us_35.png

Not to mention the strong high pressure system north of the storm. This MSLP look is classic for an east coast snow storm. But is the press going to be too much?

gfs_mslpa_us_35.png

Now the models are going to be flipping every run up until we're 2 days out. But the suppression risk is REAL. One thing I hate sometimes when we're tracking is the ignorance to possible setbacks. I understand why we try to ignore the shortfalls in a storm we're tracking, but it can get us in trouble when we assume a storm "must" trend north but in reality the pattern doesn't fit it. Right now our biggest issue, verbatim, would be suppression. From now up until about 84 hours, we need to look at why the storm WON'T be affected, per say, by the suppression. However, just like the Jan 16 storm, sometimes even at 84 hours the models will be clueless. But the synoptic pattern set forth almost guaranteed that the storm (Jan 16) wouldn't be as south as modeled. I know that I'm going to be on the lookout for trends in the high pressure in the great lakes, the 50/50 low, and the possible nuisance energy in SE Canada suppressing the flow. Remember trends can go BOTH ways, good and bad for a storm threat. Don't get me wrong, the overall hemispheric pattern suggests a significant east coast storm. What I'm suggesting is why does it have to be a Philly to NYC storm? This storm is the real deal and I hope we all cash in next weekend.

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17 minutes ago, Newman said:

The GFS sucks I know that and it's been flipping every run, but what it showed at 6z is my biggest concern. The energy up in SE Canada is suppressing the flow enough to not allow the storm to gain latitude and gives DC a hecs. 

gfs_z500_vort_us_35.png

Not to mention the strong high pressure system north of the storm. This MSLP look is classic for an east coast snow storm. But is the press going to be too much?

gfs_mslpa_us_35.png

Now the models are going to be flipping every run up until we're 2 days out. But the suppression risk is REAL. One thing I hate sometimes when we're tracking is the ignorance to possible setbacks. I understand why we try to ignore the shortfalls in a storm we're tracking, but it can get us in trouble when we assume a storm "must" trend north but in reality the pattern doesn't fit it. Right now our biggest issue, verbatim, would be suppression. From now up until about 84 hours, we need to look at why the storm WON'T be affected, per say, by the suppression. However, just like the Jan 16 storm, sometimes even at 84 hours the models will be clueless. But the synoptic pattern set forth almost guaranteed that the storm (Jan 16) wouldn't be as south as modeled. I know that I'm going to be on the lookout for trends in the high pressure in the great lakes, the 50/50 low, and the possible nuisance energy in SE Canada suppressing the flow. Remember trends can go BOTH ways, good and bad for a storm threat. Don't get me wrong, the overall hemispheric pattern suggests a significant east coast storm. What I'm suggesting is why does it have to be a Philly to NYC storm? This storm is the real deal and I hope we all cash in next weekend.

More concerned with the inevitable North trend over the next 7 days especially in a Nino pattern. I cant really recall a specific time in a setup like this where it shifted hard South. I really like where we sit at this range especially given the eps members that are NW hits and the trends n already on the GEFS and GEPS. 

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The other thing is, this isn't a Nina pattern where pieces are moving around at the speed of light and bouncing around from run to run. Last year for example we struggled with forecasts 72 hours out irt even whether there would be a big storm or no storm whatsoever. Not saying this year will be easy but I am much more comforted in knowing there is really strong agreement already 7 days lead time. Yes I expect shifts and changes still. But I also dont expect this to go from where the majority is at this time to say a cutter or a total whiff like we saw numerous times last year. I think the spread is shrinking between a classic i95 rain/snow line dca-nyc type of event to a richmond-philly special. Yes we are right inside the window for both and yes I feel good we see wintry weather in the region next weekend. Hope that is transparent enough without anyone having to read between the lines. Major or minor tbd.

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I figured I'd share this.

I made a list when reading Kocin and Uccellini's Northeast Snowstorms book of "Ingredients to get the Big One" and here are some (not all) similarities right now with this storm to other greats:

 

1. "West Coast ridge and downstream trough increasing in amplitude and decreasing in wavelength". Check. 

gfs_z500a_namer_37.png

2. "Vorticity Maxima passing between NC and NJ, heading northeast". Check.

gfs_z500_vort_us_37.thumb.png.50d4881170b6f190bcff869db53937ca.png

3. "Possible southern and northern stream energy mergers". Check.

gfs_z500_vort_us_33.thumb.png.0a9b2e814cf8693b8d55068d7dc99f28.png

4. "High latitude blocking over Greenland trapping a 50/50 low, resulting in confluence over SE Canada". This one is little trickier. It's not like there's a huge NAO but the confluence is there that we need.

 

5. "Large increase of wind speed in upper-level jets upwind of trough axis and along the downstream ridge crest. Entrance region of upper-level jet streaks in NE US or SE Canada". This is a big player in the overall solution. How strong and how far north can we stretch that 250mb Jet.?

gfs_uv250_us_33.png

6. "Heaviest snows occur 50-300km north of the 850 hPa path". It's close.

gfs_z850_vort_neus_36.png

As you can see. This one has the looks of a truly classic snowstorm. 

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