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March 2018 Model Discussion


WeatherFeen2000

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1 hour ago, EastonSN+ said:

Thanks Jay.

Bridgeport which always under reports had 5.5 in the last storm with temps at 35. Heavy rates of course. Could this not be an all snow event for coastal CT as well? I am 1 town inland from the coast and received 9.5 in the last storm. Coastal CT never changed over.

Too early for details. Map just highlights my preliminary thoughts. Right now I think it's mostly rain inside 95. But my thoughts can change based on future guidance. I'll probably refine again on Sunday/Monday unless something dramatically changes on guidance before then...

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13 minutes ago, jbenedet said:

I'm concerned about the 925 to 850 mb warmth. And I think surface temps will be above freezing.

Obviously this is still 5 days out so this isn't a high confidence forecast at this point - just a "best guess".

Nice forecast

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13 minutes ago, NJwx85 said:

Just some preliminary thoughts - risk area for warning criteria snowfall

Light blue, slight risk

Dark blue, significant risk

Red - greatest risk

sketched_5aabc0ff0d863.png

Finally you have me in the Red area... geez only took you all winter!!.... I think mayb we get a thread going for this now? what you guys think?  and NO WeatherFeen u can't start it because you will probably jinx it with a 1-2 foot blizzard call LOL :P

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7 minutes ago, jbenedet said:

Too early for details. Map just highlights my preliminary thoughts. Right now I think it's mostly rain inside 95. But my thoughts can change based on future guidance. I'll probably refine again on Sunday/Monday unless something dramatically changes on guidance before then...

Thanks

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1 hour ago, bluewave said:

This could be our first storm this month where the heaviest precip axis is DC to NYC. The EPS mean is seeing higher pressure than just a few days ago to the north. The EPS/Euro/ NAM generally do much better than the GFS when strong high pressure is present over SE Canada.

New EPS

ecmwf-ens_mslpa_us_6.thumb.png.341424fa826a30d6321cf9bbf49df25a.png

 

 

 

 

 

Oooh boy :o

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24 minutes ago, gravitylover said:

Oooh boy :o

The great typhoon tip posted some interesting stuff in NE forum for next week here take a look.... FROM TYPHOON TIP.....

So anyway... the basic storm track in a -NAO is off the M/A ... Overly exert the -NAO, and it ends up too far S.. But just in the right measure? It's downright Bench Markian!

That's the problem sort of in a nut shell I have with the "too much reliance" on the negative phase state of the NAO.  The last two or three weeks of this thing have been a charmed state of affairs for us - though the first storm chapter in the series was cold starved.. The NAO was west based, but it wasn't predominating the flow that suppressing extent.  This will undoubtedly get the masses into a ready and willing state to re-embrace the NAO too much.  That's fine - it's a frustration I'll have to live with...

But that's a different annoyance for a different time.  In the here and now... with the NAO being if anything even less exerting (because it is weakening in all agency prognostics..) I don't see how ...more importantly, 'why' that has to mean suppression is favored.   It seems to me that individuals may be seeing squashed appearance in the pressure pattern offered up by various operational runs and running with that as a suppressed system. That's not the same.  I don't perceive the larger sort of 'canvas' of bigger scoped players really dictating suppression.  

What that is next week is a middling wave structure trying to overcome a lower tropospheric polar high. That's what's causing that dammed cold look with the 'split' in the cyclone evolution. That's not really the same as large scale circulation suppression.  If the -NAO was suppressing in that nature, you'd see a compressed height field in the east with lot of lines and screaming mid level wind velocities outside of local-scaled jet maxes.  

If anything, this system really is like a placeholder in the atmosphere and all it really needs is some bit of N/stream mechanics to dump in ...or maybe a more proficient total stream sampling... whatever, and that turns into probably into the biggest storm this month - yes, that includes the last.  It would be bigger because those prodigious snow totals would be more pervasively realized, as well...have bigger water content contained, as well, ... a slower moving ordeal.  

Until that happens, we have this weird bag of vorticity jetlets rattling around in a big bag of medium gradients up underneath a fairly strong negative SD thickness tapestry/polar high.

 

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EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

221 AM EDT FRI MAR 16 2018 VALID 12Z MON MAR 19 2018 - 12Z FRI MAR 23 2018

...LATE-SEASON WINTER STORM FOR PORTIONS OF THE MID-ATLANTIC/NORTHEAST NEXT WEEK... ...SPRAWLING SYSTEM TO PUSH INTO THE WEST LATER NEXT WEEK... ...OVERVIEW... EAST... WINTER WILL NOT GO OUT QUIETLY IN THE EAST AS A COMPLEX EVOLUTION BRINGS A SERIES OF SURFACE LOWS OVER THE SOUTHERN APPALACHIANS TO REDEVELOP OFF THE NORTH CAROLINA COAST AND LIFT NORTHEASTWARD NEXT TUE-FRI. THE MODELS HAVE HAD A TOUGH TIME WITH HOW (AND WHERE) THE MANY PLAYERS IN THE FORECAST INTERACT BUT THE ENSEMBLE SIGNAL REMAINS QUITE LOUD FOR AT LEAST AN INTERIOR AND HIGHER ELEVATION HEAVY SNOW THREAT TO THE MID-ATLANTIC (AND SOUTHERN APPALACHIANS) INTO THE NORTHEAST OVER THE COURSE OF SEVERAL DAYS.

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7 minutes ago, allgame830 said:

EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

221 AM EDT FRI MAR 16 2018 VALID 12Z MON MAR 19 2018 - 12Z FRI MAR 23 2018

...LATE-SEASON WINTER STORM FOR PORTIONS OF THE MID-ATLANTIC/NORTHEAST NEXT WEEK... ...SPRAWLING SYSTEM TO PUSH INTO THE WEST LATER NEXT WEEK... ...OVERVIEW... EAST... WINTER WILL NOT GO OUT QUIETLY IN THE EAST AS A COMPLEX EVOLUTION BRINGS A SERIES OF SURFACE LOWS OVER THE SOUTHERN APPALACHIANS TO REDEVELOP OFF THE NORTH CAROLINA COAST AND LIFT NORTHEASTWARD NEXT TUE-FRI. THE MODELS HAVE HAD A TOUGH TIME WITH HOW (AND WHERE) THE MANY PLAYERS IN THE FORECAST INTERACT BUT THE ENSEMBLE SIGNAL REMAINS QUITE LOUD FOR AT LEAST AN INTERIOR AND HIGHER ELEVATION HEAVY SNOW THREAT TO THE MID-ATLANTIC (AND SOUTHERN APPALACHIANS) INTO THE NORTHEAST OVER THE COURSE OF SEVERAL DAYS.

TWC already calling for 3 to 9 for CT coastal towns. Obviously large spread due to uncertainties.

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Just now, ZeeTwentyFour said:

Is this saying the city could get 12" plus another 14+? Or is it a total of 14+ inches over both days?

Sent from my SAMSUNG-SM-G930A using Tapatalk
 

It's the storm total to that point in both maps, i.e., through 12Z Weds in map 1 and through 12Z Thurs in map 2.  This is a model projection, not anyone's forecast, especially since the 2-low scenario is definitely an oddball one (although not unprecedented).  I posted them to show the potential not to say this is going to happen.  

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41 minutes ago, Brian5671 said:

classic archembault event here...

Edit: I had it backwards - looks like this is not an Archambault Event, since the NAO is going from neg to positive.  Funny thing is I could swear I've read elsewhere that when the -NAO is going to positive is when we have a chance at big snows.  Fuzzy memory I guess...didn't change my original post below, though.  

 

Certainly looks like it based on NAO projections going from fairly negative to just about positive as the storm approaches and according to the abstract that's the only regime transitino associated with more frequent NE storms (as per the part I bolded).  FYI, here's the abstract from her paper, which I just looked up, as I was curious...

This observational study investigates statistical and synoptic–dynamic relationships between regime transitions, defined as a North Atlantic Oscillation (NAO) or Pacific–North American pattern (PNA) index change from at least a 1 standard deviation anomaly to at least a 1 standard deviation anomaly of opposite sign within 7 days, and cool-season (November–April) northeastern U.S. (NE) precipitation. A statistical analysis is performed of daily cool-season NE precipitation during all NAO and PNA transitions for 1948–2003, and a composite analysis and case study of a major cool-season NE precipitation event occurring during a positive-to-negative NAO transition are conducted. Datasets used are the 0.25° NCEP Unified Precipitation Dataset, the 2.5° NCEP–NCAR reanalysis, and the 1.125° 40-yr ECMWF Re-Analysis (ERA-40).

Results of the statistical analysis suggest that cool-season NE precipitation tends to be enhanced during positive-to-negative NAO and negative-to-positive PNA transitions, and suppressed during negative-to-positive NAO and positive-to-negative PNA transitions. Of the four types of regime transitions, only the positive-to-negative NAO transition is associated with substantially more frequent major cool-season NE precipitation events compared to climatology. Results of the composite analysis and case study indicate that a surface cyclone and cyclonic wave breaking associated with the major NE precipitation event can help produce a high-latitude blocking pattern over the North Atlantic characteristic of a negative NAO pattern via thermal advection, potential vorticity transport, and diabatic processes.

https://journals.ametsoc.org/doi/abs/10.1175/2010MWR3362.1

GFS North Atlantic Oscillation Outlooks

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