weatherwiz

2 minutes ago, dendrite said:

Rain can stabilize things, but not always. Even if we’re “mixed” it’s going to be moist adiabatic with the high dews advecting in over the pack. It gets more difficult in the foothills and sheltered valleys where the latently cooled air can put up an easier fight, but there’s going to be a corridor just inland where the pack will go relatively quickly and the winds will be roaring off the deck with 59/59 at 2m. Idk...I can kinda see this going either way, but I feel like you’re getting a little Popeish here with the angry anti-wind posts and trying to pound your chest while going against the grain. I mean we get it, we know where you stand. But the NWS is hitting the concern pretty hard and some other mets too. Hey, I hope you’re right...we don’t need trees falling on travelers Christmas morning.

I'm just trying to bring perspective and lay out everything not go all balls out b/c some model maps are showing 60+ knot gusts. I' certainly not pounding my chest at all. I can see pockets of stronger winds for sure...but how many of these set ups in the past have been overplayed? There are virtually two scenarios here;

1) It pans out

2) It doesn't pan out

So what's the difference between the set ups that pan out and don't pan out? 

Also, just going through various bufkit profiles...it's very hard to find any locations yielding strong enough mixing to bring down 50+ knot gusts. 

6 minutes ago, CoastalWx said:

I will say this has a bit more of an inversion than other storms, but also a stronger LLJ. And maybe inversion is too aggressive......more like shitty low level lapse rates. I’m not sure how it shakes, but if those lapse rates steepen a tad....look out.

Also, there may be a quick one hour pulse of strong SW winds as we start to CAA. Right after the line of heavy rains and we get quiet for an hour or two. This probably happens more in RI and SE MA. 

bufkit soundings actually hint at this very well.

Also, it seems from past experiences that a stronger LLJ can often lead to a stronger inversion (especially if the strength of the WAA aloft exceeds the strength of WAA at the sfc). 

4 minutes ago, Ginx snewx said:

Hmmm

The guidance continues to beat the drum on potential for a high end,
potentially damaging wind event. As the parent low generates a
secondary low along the frontal boundary over the mid Atlantic a
very robust low level jet develops that would be unusually strong
for this time of year. We`re talking 75 to 85 kts at 925 mb and 85
to 95 kts at 850 mb. As mentioned by the previous forecaster, the
EPS and NAEFS ensembles continue to depict anomalies of >5 standard
deviations and maxed out percentiles! So, while historically these
southerly wind events struggle to mix down and modeled soundings
would indicate as much, the anomalous warmth that comes with it
should help to break that subtle inversion enough to mix down some
of those wind, and with that magnitude, even 50-60% would cause
scattered downed trees and power outages. Compounding that risk is
the heavy downpours and potential fine line of convection moving
through in the morning that would help to mix down the stronger
gusts

 

n additional concern is with strong to potentially damaging
winds Thursday night into early Friday morning. Models continue
to show 65 to 75 kt winds at 950 mb during this period. The core
of this low level jet is most likely to pass over Long Island
and southeast Connecticut. Forecast soundings indicate an
inversion around or just below these high winds and this is
typically a difficult forecast on how much will mix down to the
surface, but with models continuing to show signs of a potential
squall line or convective cold frontal band, this would enhance
the chances for stronger winds to mix down to the surface. If
this type of rain band/squall line materializes, the winds would
effectively weaken considerably once it passes, similar to what
occurred on November 15. Advisory-criteria winds could occur
for the inland areas. Strongest sustained winds and gusts would
be from late evening Thursday through around daybreak Friday.

If there is convection involved then we certainly would see high wind potential...in fact, we would probably see widespread damage and power outages. There is no doubt this LLJ is about as anomalous as you'll ever see, but we need to tap into that. It's always tough to gauging what percentage can be mixed down...sometimes its as high as 50%...other times it can be more around 30%. 

I also agree, the llvl warmth here plus the dews is something you certainly want to see when looking for wind potential...but the issue here is the distribution of warmth in the lowest say 4-5km is just too even...hence the crappy lapse rates. Sure this warmth will help to mix somewhat, but due to clouds and precipitation (you'd have to figure lots of showers ahead of the main line) that mixing is going to be very limited...and the best mixing would occur well prior to the core of the LLJ.

If the core of the LLJ was ahead of the main rain rain then there would certainly be a window for very damaging winds. However, given it coincides with the timing of the heaviest rain, we are likely going to be rather stable and probably have a tough time mixing even close to 1,000'.

Even looking at bufkit soundings for BDL...you have to change the mixing depth to a 20 to even get big gusts. 

2 minutes ago, Great Snow 1717 said:

I

 

It is just too bad that your met degree and years of experience pales in comparison to the knowledge that some individuals  have acquired on the internet........

Well too be fair school is like 95% math and not a ton of forecasting. forecasting is really more about experience and applying knowledge and someone who has been doing that for day 20 years will probably outforecast someone who just freshly graduated. 

1 minute ago, Ginx snewx said:

Models can't handle low level lapse rates in these low top convective situations.  You have downplayed winds pretty much everytime while we end up with power loss and trees in houses. Think out of the box you have put yourself in.

I've played up the past several wind events..didn't downplay any of them. 

This isn't a low topped convective situation either. Outside of the intense forcing this is very little instability to work with aloft...certainly not enough for any convective elements. And that whole "models can't handle low level lapse rates" thing made zero sense. Low-level lapse rates are going to be garbage...all you have to do is look at the thermal profile in the lowest 10,000 feet.

Torrential rainfall is not going to mix winds down, in fact, torrential rainfall will help to induce an inversion. This is not a big wind setup. Sure...winds at 925 and 850 are off the charts, but that means nothing at the surface is they can't be tapped into. Sustained winds will be the most impressive (20-30 mph) with gusts 40-50 and the typical spots that get above 60 will do so. But this isn't a region wide 60+ gust setup

I still think it's going to be tough to generate widespread (or region wide 50-60 knot) winds. The core of the LLJ still looks to coincide with the timing of the heaviest rainfall. Not good when looking to draw down big winds. Yes, any inversion looks weak to "non-existent" (I don't totally buy a non-existing inversion in these setups) but you still have to get some mixing going and those llvl lapse rates are a joke. It seems we do better wind wise when they start exceeding 6.5 C/KM...they're pretty meh here. 

I wish there was a stronger signal for convection. Oh well...another 6 weeks to go until our annual February event 

1 minute ago, OceanStWx said:

What inversion on the GFS? No real hint of one on soundings until about 800 mb.

ahh yeah you're right. Now I am not totally sure I buy that...otherwise they are in for some big trouble. 

Here's BOS on the GFS

that's quite impressive actually...but you gotta draw that down. That is probably pretty close to the inversion too. 

2-6km lapse rates do look better over eastern sections. 

Let's look at the wind potential from the following perspectives:

We can "handle" wind events where we gust 40-50 mph.

• Will this result in some damage? Of course.
• Will this result in widespread damage? No. 
• Will this result in power outages? Yes
• Will this result in widespread power outages? No

Now, if we get gusts in the 50-70 mph range, well then the answers to all the above are yes. 

So, what's the likelihood of a 40-50 mph gust event vs a 50-70 mph gust event? Let's assess...

What are some of the differentiators between each?

• Low level lapse rates:
  • In our higher end wind events, there are typically steeper low-level lapse rates present. The steeper the low-level the lapse rate, the greater the depth and strength of mixing. This of course results in stronger momentum transport and tapping into stronger winds. 
  • In this event low-level lapse rates likely will be less tan 5.5 C/KM...if even that. This isn't going to get the job done. 
• Convection: 
  • The best way to drawn down strong winds is via convection. Outside of the impressive forcing, the signals for convection are very weak. No sfc-based instability, virtually no elevated-instability (or certainly not enough to indicate convection) due to very poor mid-level lapse rates and saturated profile. 
• Dry punch:
  • In these setups, the strongest winds ALWAYS occur outside of the heavier rain. Heavy rain stabilizes the atmosphere and limits mixing. Rain itself does not result in momentum transfer unless there is convection involved. A dry punch (or whatever you want to call it) can help with steepening lapse rates and also enhance mixing. 

If you look at this setup, the strongest LLJ coincides with the heaviest rain. It will be very stable above the surface and that will make it very difficult to transport much of these winds. Sure even if we "only" tap into a little bit of it we would get crazy gusts but how can we do that in this case...convection. And there isn't much signals for convection. 

Bufkit (yeah kinda far out) is not very impressed with mixing (BDL). Have to change the value to 20 to really mix down stronger winds. The inversion actually isn't terribly strong though but it certainly doesn't take much of an inversion to prevent deep mixing. I still say we see gusts 40-50 inland. Bigger issue is going to be flash flooding. 

5 minutes ago, Cold Miser said:

Can someone help me understand "inversion" a bit better?

layer of the atmosphere where temperatures warm with height rather than cool with height. 

1 minute ago, tamarack said:

Slightly off topic, but this is what MSM does and it's frustrating.  Last night on the 6 PM news a respected news anchor was addressing the very real negative economic impacts due to COVID-19.  The example given was a woman who lost her job and took one for far less money, her income dropping from $6,000/month to $255/week.  Not $6,000 down to $1,385 or $1,105 down to $255.  The impact was huge but IMO the presentation was dishonest and makes one ponder whether other data  from that source is similarly spun. 

I know cold spell wasn't long, but any Hydro issues due to ice jams in the smaller rivers and streams?

I don't think there's enough ice - thickness nor extent - to pose a problem, at least in our area.

 

It's why media sucks. 

The goal is to draw people in at any cost possible. Viewers = money and when it comes to social media platforms likes/follows just equals a big ego. There is obviously nothing wrong with sharing forecast models online, however, the way it's done is just totally irresponsible. The idea should be to use something to emphasize or illustrate what you're trying to forecast. What gets me is when people will post like a snow map that shows 20-30'' and then say "here is one model showing 20-30''. doesn't mean it will happen, and this is only one model"...WTF is the point of the post then? there is no point other than to get views/likes/clicks. 

13 minutes ago, CoastalWx said:

Tossed that far inland I think. 

If there was convection involved I could see that potential but I really don't see much convection with this. 

I wonder what the algorithm is for that product. llvl lapse rates are also pretty junky...appears mostly around or below 5.5 C/KM. tough to really mix down winds when they're that garbage. 

The big problem with getting maximum wind gust potential with this is the core of the LLJ coincides with the heavy rain. Remember the strongest winds never occur with the heaviest rain. 

I don't get why people on social media always have to show a model prog which is the worst case scenario. Hey the GFS snow map shows 12-18'' but the NAM only shows 3-6''...let's share the GFS map b/c it shows the most snow and everyone gets aroused by hype so let's arouse them. euro showing max wind gusts of 75 mph...NAM only 55 mph...let's show the euro. NAM showing 5000 CAPE, GFS showing 2000...let's show NAM. Everything always has to be the most aggressive, most extreme output. IT's FOOKING RIDICULOUS. WTF IS THE POINT?? Oh here is a SHARPpy sounding that indicates PDS Tornado...I'm going to share that even though what's presented on the sounding is probably more indicative of straight-line winds with a bit of curvature but it's PDS tornado and I want to scare the crap out of people. OUTRAGEOUS. 

The Euro max wind gusts maps may actually be even worse than model snow maps  

8 minutes ago, CT Rain said:

Don't often see >40 knots of MOS around here. 

That is beyond impressive...wow. 

I'm still conflicted on the overall wind potential. My thinking is still gusts in the 40-50 mph range but there will probably see some higher gusts in the typical favored locations...but is that going to be the coast or higher elevations? 

For a more significant wind threat, I think I'd like to see the sfc low probably another 75-100 miles farther northwest. As currently modeled, I think it may be difficult to full swing the sfc warm front through a large part of the region. I could see it getting hung up around the MA Pike or maybe even a bit farther south. When you also get these highly anomalous LLJ's this time of year, it also usually indicates potential for a much stronger inversion (WAA aloft > WAA at the sfc). I guess it also depends too on how deep the inversion is but as we've seen it doesn't take much of an inversion to prevent big winds from mixing down. 

I also don't see much in the way of convection to aid in any transport. It looks quite stable throughout the column outside of some subtle unstable layers. Forcing is certainly enough to support convection but don't seeing much instability aloft. Having a fully saturated column doesn't help either. I also don't like the super heavy rain which is coincident with the max LLJ. This will further destabilize the column and lapse rates are very poor so mixing is going to be weak. 

I see sustained winds being strong (20-30 mph) but it might be tough to full gusts much above 40-50 mph with exception of the usual spots. 

The models seem awfully aggressive too with the sfc warm front. 

1) Snow pack

2) The main sfc low track is a bit too close to the region

3) multiple waves may develop along the cold front

I guess there are multiple layers to attack here...this is huge in assessing overall wind potential;

1) >60F well we would see quite a bit of wind damage/power outages

2) 55-60F probably a bit more than "scattered"

3) 50-55 more in the way of scattered

4) < 50 the steeple on Kevin's roof may get blown off but that's probably about it.

Will we see the widespread 55-60+ temperatures the models have...idk. 50-55 ay be more like it but best best is south (obviously). 

Hand drawing the sfc warm front with this would be fun. Too bad I sucked a drawing. 

That LLJ being forecast is one of the strongest I recall seeing; particularly on the GFS. However, I don't think that translates into a damaging wind event. We'll see strong winds for sure (from the pressure gradient alone) with winds sustained 15-25 mph and gusts 40-50 mph (usual suspects 60+) but a stronger LLJ = a stronger inversion...unless of course we are able to pop sfc temps into the 60's which I don't foresee happening. Anyways, the snow pack will certainly enhance any inversion. Convection could certainly aid in the transport of stronger winds to the sfc. In this event, forcing is significant enough to potentially yield some low-topped convection or convective elements, however, it just might be too stable, however, there might be a shallow unstable layer between H7-H6. Flooding alarms for sure though 

Just now, 40/70 Benchmark said:

I'm not sure how a la nina sesaon being front loaded is illustrative of your point.

Just speaking in general terms. But too many just solely rely and focus on ENSO for long-range and well...as years have gone on and strides continue to be made with research IMO ENSO is more a back seat kina state as opposed to the driver. I mean sure a super strong ENSO event will probably be a main driver but these weaker events...they aren't the driver or focus of the pattern/evolution as either they once seemed or once used to be. A big player in this is just oceanic heat content in general. For example, take a look at the 1981-2010 climo means compared to the previous base...some weak La Nina events then are literally like a "neutral now". I think there are a couple warm-neutral ENSO events that are now classified as weak NIno too

14 minutes ago, 40/70 Benchmark said:

I think we can now say with confidence that a 1975-1976 scenario is about the worst possible outcome.  You can essentially toss the wretched la nina analogs considering how the first half of December has evolved.

I know I've made some posts on this but it's becoming more evident that these 'ENSO analogs" we all used to live and die by have less merit and don't hold the weight they perhaps once did. There are numerous reasons for this I think and well...could actually be a fun idea for a thread some day. 

1 minute ago, 40/70 Benchmark said:

Would that be west-based?

depends on position of entry 

Just now, CoastalWx said:

Monday night.

ohhh...with that amplifying trough/ULL digging in? 

Just now, JC-CT said:

I'm excited for Tip's throbbing NAO

hopefully it's poking into the right region