bristolri_wx

7:10 BOX DISCUSSION:

Details... Friday night through Saturday night... ***A Strong Winter Storm will impact southern New England Saturday*** After a jog east with the 12Z/18Z guidance yesterday, this evening`s 00Z models have ticked back west; a windshield wiper effect we often see in computer models leading up to these events and why you don`t want to hang your hat on one deterministic model run. This remains a decidedly chaotic forecast with decent run-to-run consistency in some models/ensembles, but large model-to-model discrepancies. One of the biggest struggles is how to resolve the upper air pattern with northern and southern stream energy that may phase leading to a more volatile system. The biggest outlier is the GFS which continues to depict a track well southeast of the 40/70 benchmark, while the NAM/Canadian/ECMWF are further northwest (if much slower, in the NAM`s case). For now the forecast continues to go with a blend of guidance, more or less in line with the ECMWF run which is a compromise between the GFS east and UKMET west. Ultimately the evolution of the parent 500 mb trough that digs into the Ohio and Tennessee valleys Friday night and Saturday will help to determine the track of the surface low. Confidence is high that this low will strengthen rapidly as it moves up the east coast, likely undergoing bombogenesis, meaning its central pressure drops at least 24 mb in 24 hours. This will bring the threat for significant snow, potentially damaging winds, and coastal flooding. Thinking this morning is that the significant snowfall threat will be centered over southeast Massachusetts, diminishing to the northwest. Given QPF of nearly 1.5 inches toward eastern MA and a cold column leading to snow-to-liquid ratios greater than 10:1, snowfall totals of 12 to 18 inches are possible; greater beneath any deformation band that sets up somewhere northwest of the low. A Winter Storm Watch has been issued for eastern and central MA as well as eastern CT; this is where we have the highest confidence of significant snowfall. Strong, potentially damaging winds are also a significant hazard with this system given a 60 to 70 kt low level jet overhead thanks to the explosive deepening of the low. Bufkit soundings indicate a well mixed boundary layer, up to 850 mb on the southeast coast Saturday and Saturday night. The strongest winds will be over Cape Cod and the islands. Coastal flooding is the final threat we`re concerned about. This would be during both high tide cycles on Saturday, but moreso in the evening. Though the astronomical tide is higher in the morning, winds and seas won`t fully ramp up until later. Thus, we continue to expect a 1-2 ft surge leading to minor coastal flooding on the east coast Saturday morning. For the evening high tide that surge will be more like 3+ ft. Factoring in the 20-25 ft seas just offshore, widespread minor coastal flooding is likely with pockets of moderate. Again, timing will be crucial for us to realize this upper end of flooding potential, if the max surge can coincide with the high tide.

6 minutes ago, WxWatcher007 said:

I get it, but we have to remember these are just tools. There have been big individual misses or caves by the other models and even the ensembles—I’ve seen this particularly in tropical genesis/track/intensity forecasting. Obviously different than mid latitude cyclone forecasting, but this is why it’s important to not get too high or low on the specific runs and understand each model’s relative strengths/biases.

I totally understand everything you're saying and this stuff isn't easy by any means.  It just seems silly to me that US models aren't as good at some types of US weather than other agency's forecast systems.  We should strive to do better for our own backyards, especially when its a pretty densely populated area, and their own mission is "provide weather, water and climate data, forecasts, warnings, and impact-based decision support services for the protection of life and property and enhancement of the national economy."

2 minutes ago, PhineasC said:

I can't get over the shift the CMC and UKMET made from 12z. Just a totally different look. Garbage to MECS without blinking an eye. These shifts are pretty wild.

In a way, I have to give the GFS credit for hanging tough even if it's wrong. These other models are just crazy.

The GFS has two extra runs per day to make it look like it's "hanging tough".  If you compare 0z to 12z it looks just as crazy.  QPF went from 1.1" to .10" at my location.  That's garbage.

8 minutes ago, Typhoon Tip said:

I’ve bitched about this before but situation like this really underscores my complaint… Why did they discontinue the model diagnostic division- … now would be a good time to see if there were data ingest/ initialization issues. 

 

In all seriousness, if the GFS ends up being out to lunch on this one, someone at NCEP/WPC needs to take a look at why and get this solved.  While US East Coast cyclones might not be the focus of the CMC, Euro, UK because of their own missions and priorities, the US models should have this as one of their strengths, not weaknesses.  1/3 of the US population lives on the East Coast.  It should be a priority to get the accuracy up on these scenarios.  The GFS and NAM going back and forth is embarrassing inside the 5 day window.

4 minutes ago, ineedsnow said:

might be  from a death band to the west?

One nice thing about that screw hole showing up now - it means it will probably end up somewhere else.  I've noticed over they years that most of the RI screw holes aren't forecasted on the models, they usually show up unexpectedly on radar when some good banding is going on elsewhere.

Just now, PhineasC said:

The what? Keep that weird model shit outta here, bro.

It's not that weird - the French worked with the ECMWF on a fork of the Euro for their needs.  Based on similar code.

1 minute ago, 40/70 Benchmark said:

Kev would love that...hours of useless snow

He also jackpots on the CMC Kuchera clown map... 29" lol...

Just now, The 4 Seasons said:

We're breakin' out all the weird ones tonight..we're the IBM and RPM

I don't think we're in the RPM range yet... lol...

1 minute ago, cleetussnow said:

Best comment.  One of these models is profoundly wrong.  I would be surprised if its the Euro, but the GFS has been relatively steadfast.  

It's been posted a few times that GFS is having a tough couple of weeks vs the Euro even on mundane 500mb verification in the northern hemisphere domain. GFS has been consistent - we've also seen it cave to the consensus many times on the coastals at the last minute.

This Kuchera Ratio map on Pivotal is kind of neat... not sure how accurate it is...

The last 3 runs are exactly why people say "but it's the NAM".  It's doing everything it normally does with coastal snow storms lol.  It's improved aloft, and totally reversed what it did at 18z.  Since we're depending on the 60-84 without the 3k to aid us, I'd call it a win.

Looks like the NAM is back on it's meds.   Needs to get that prescription on auto-fill so it doesn't have anymore 18z episodes...

17 minutes ago, CT Valley Dryslot said:

I don't understand why they use such big snow maps.

Literally no one in CT receives WCVB or WBZ over the air.

People who live in Boston do leave the city and travel west... rarely... 

5 minutes ago, CT Rain said:

Woof. That need A LOT of work.

Interesting that the majority of western solutions are stronger than the eastern solutions by a few mb...

6 minutes ago, CT Valley Dryslot said:

Does WPC still have a model diagnostic text discussion?

They do not:

https://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdhmd

...but their 4 PM extended forecast discussion and 3:30 PM snow discussions did not mention anything regarding the 18z models, or how awful the NAM is.  Mostly referenced 00z/06z/12z trends today.

https://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=qpfhsd

https://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdepd

Yeah tick east.  24" on Cape Cod, while Worcester gets an inch.  LOL... models...

12 minutes ago, TheSnowman said:

Wait wait wait Waaaait.  

 

You guys have been hyping this up to be like the grand puba's of 2005, 2013, 2015.... and I NEED TO GET HOME.....

 

And I'm projected to be 9"-16"????  With confidence Getting Lower by the run?  Baaahahaha.  OK.  I'll be in LA.  

Thanks for locking in a KU for us by staying in LA 

I would confidently toss this NAM considering how different it is from all other models.  Of course if the other 18z's come in similar trends then we worry.  This concludes my John Madden-like weather model commentary.

Keep the faith... modeling hasn't been good this season for us, for both hits and misses, even at this range.  GFS hasn't been good last couple of weeks according to multiple sources.  I feel like the trends tomorrow will be the important ones as better data comes in.  Right now its kind of the Euro against the other globals but who knows it might be on to something.  It was worrisome that some perfect scenarios showed up on the models YESTERDAY, which is a little far out to my liking.  Prefer those outcomes a little closer in knowing how models adjust closer to storm formation and arrival.

10 minutes ago, wxsniss said:

So far 0z suite trends:

GFS east, still solid hit for eSNE

GGEM west, huge hit for all of New England

NAM: looks to be in west camp, might even jack NJ/NY/CT/eSNE area

ICON: west

UK: very east, the worst run in days

We won't get much certainty tonight, but will be nice to see Euro hold

Out of curiosity, I went over to weather.us and looked at some of the other models available there.  The French, Chinese, Korean are on the eastern side of the guidance as well.  We know what the skill levels are there, but it does make you wonder what's making some of the models go east of the Euro/CMC...

The calm before the 0z GFS...

This was a torchy run of the GFS... lol...

3 minutes ago, JC-CT said:

omg dude I literally almost replied to him before you posted that. then was like...nah

He's also not a fan of the metric system.  Definitely going to follow him on Twitter now.

1 minute ago, JC-CT said:

admirable attempt. for future hahas, he is slightly northeast of that --- along or ever so slightly northeast of the blue dotted line

It's the best I could do in 60 seconds in Photoshop lol.  I had to eyeball it based  on two different maps. LOL