Hurricane Sandy

[HoarfrostHubb]

Minimal rain north of central NJ.

Yeah, quite the cutoff. In winter we would be cryin'

[dendrite]

That is a beast LLJ.

[CoastalWx]

NAM pretty much identical to 18z. Right near Sandy hook area, just south of SI NY.

[HoarfrostHubb]

That is a beast LLJ.

Highest winds for NH coast?

[CoastalWx]

Highest winds for NH coast?

It pivots up from the south. Earlier is was down by the Cape. Just goes to show you how strong winds may be.

[Cold Miser]

Proving what fools the NHC is if they don't hoist hurricane warnings. Bloomberg seems to be the first example of people not taking this seriously enough.

lol. Bloomberg should just stick to being a business man first, and a Mayor last. Weather predictions should not even be part of his Shtick, even if it that portion is written by others.

[Cold Miser]

Minimal rain north of central NJ.

...It's all about the wind.

[Bostonseminole]

11 pm update from NHC up

000

WTNT43 KNHC 280246

TCDAT3

HURRICANE SANDY DISCUSSION NUMBER 23

NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012

1100 PM EDT SAT OCT 27 2012

SATELLITE IMAGERY SHOWS THAT THE CENTRAL CONVECTION ASSOCIATED WITH

SANDY HAS INCREASED DURING THE EVENING. IN ADDITION...DATA FROM AIR

FORCE RESERVE AND NOAA HURRICANE HUNTER AIRCRAFT INDICATE THAT THE

CIRCULATION AT 10000-12000 FT IS STRONGER THAN 24 HOURS AGO...AND

THERE ARE INDICATIONS OF AN INNER WIND MAXIMUM NEAR THE CONVECTION.

HOWEVER...THIS HAS NOT YET RESULTED IN ANY INTENSIFICATION...AND THE

INITIAL INTENSITY REMAINS NEAR 65 KT. THE AIRCRAFT-REPORTED

PRESSURE IS ABOUT 960 MB.

SANDY HAS MOVED A LITTLE TO THE RIGHT DURING THE PAST SEVERAL

HOURS...WITH AN INITIAL MOTION OF 040/12. OTHER THAN THAT...THERE

IS NO CHANGE TO THE TRACK FORECAST PHILOSOPHY. SANDY IS EXPECTED

TO MOVE GENERALLY NORTHEASTWARD FOR THE NEXT 24 HOURS OR SO...

STEERED BY A DEEP-LAYER TROUGH MOVING INTO THE EASTERN UNITED

STATES. AFTER THAT...A DEVELOPING MID/UPPER-LEVEL RIDGE OVER

NORTHEASTERN CANADA AND INTERACTION WITH THE U. S. TROUGH SHOULD

CAUSE THE CYCLONE TO TURN TOWARD THE NORTH...NORTHWEST...AND

EVENTUALLY WEST-NORTHWEST. THIS MOTION SHOULD BRING THE CENTER

INLAND OVER THE MID-ATLANTIC REGION BETWEEN 48-72 HOURS. AFTER

LANDFALL...SANDY IS EXPECTED TO MERGE WITH THE U. S. TROUGH TO FORM

A LARGE DEEP-LAYER LOW PRESSURE AREA...WITH THE RESULTING SYSTEM

MOVING NORTHWARD AND NORTHEASTWARD AFTER 72 HOURS. AS NOTED IN THE

PREVIOUS ADVISORY...IT IS STILL TOO SOON TO FOCUS ON THE EXACT

TRACK...BOTH BECAUSE OF FORECAST UNCERTAINTY AND BECAUSE THE

IMPACTS ARE GOING TO COVER SUCH A LARGE AREA AWAY FROM THE CENTER.

SANDY REMAINS IN AN AREA OF STRONG UPPER-LEVEL DIVERGENCE CAUSED BY

A TROUGH TO ITS SOUTHWEST. THIS IS LIKELY HELPING TO SUSTAIN THE

HURRICANE DESPITE SIGNIFICANT VERTICAL WIND SHEAR. WHILE THE

INTENSITY FORECAST SHOWS LITTLE CHANGE IN STRENGTH FOR 36 HOURS...

THE SHIPS MODEL AND THE DYNAMICAL MODELS SUGGEST THE POSSIBILITY

THE SHEAR COULD DECREASE DURING THIS TIME...AND IF THAT HAPPENS

SANDY COULD STRENGTHEN A LITTLE AS A TROPICAL CYCLONE. AFTER 36

HOURS...THE DYNAMICAL MODELS ALL FORECAST THAT INTERACTION WITH THE

U. S. TROUGH SHOULD CAUSE SOME INTENSIFICATION ALONG WITH

EXTRATROPICAL TRANSITION...WHICH IS FORECAST TO BE COMPLETE BY 48

HOURS. IT SHOULD BE NOTED THAT THIS TRANSITION WILL HAVE LITTLE

EFFECT ON THE SIZE AND IMPACTS OF THIS LARGE AND VIGOROUS SYSTEM.

AFTER LANDFALL...THE FORECAST AGAIN CALLS FOR THE CYCLONE TO

STEADILY WEAKEN.

AS ALSO NOTED IN THE PREVIOUS ADVISORY...IN ORDER TO AVOID THE RISK

OF A HIGHLY DISRUPTIVE CHANGE FROM TROPICAL TO NON-TROPICAL

WARNINGS WHEN SANDY BECOMES POST-TROPICAL...THE WIND HAZARD NORTH

OF THE TROPICAL STORM WARNING AREA WILL CONTINUE TO BE CONVEYED

THROUGH HIGH WIND WATCHES AND WARNINGS ISSUED BY LOCAL NATIONAL

WEATHER SERVICE OFFICES.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 30.9N 74.3W 65 KT 75 MPH

12H 28/1200Z 32.2N 72.9W 65 KT 75 MPH

24H 29/0000Z 34.1N 71.4W 65 KT 75 MPH

36H 29/1200Z 36.3N 71.1W 65 KT 75 MPH

48H 30/0000Z 38.7N 72.4W 70 KT 80 MPH...POST-TROP/EXTRATROP

72H 31/0000Z 40.5N 77.0W 45 KT 50 MPH...POST-TROP/EXTRATROP

96H 01/0000Z 43.5N 77.0W 30 KT 35 MPH...POST-TROP/EXTRATROP

120H 02/0000Z 47.5N 75.0W 25 KT 30 MPH...POST-TROP/EXTRATROP

$$

FORECASTER BEVEN

[PhineasC]

...It's all about the wind.

It will be interesting to see which airports record the highest gusts and sustained. With 8 inches of rain it won't take much to uproot trees down here.

[Bostonseminole]

Just amazing:

Hurricane force winds extend outward up to 105 miles. Tropical storm force winds extend outward up to 520miles

[radarman]

Maybe one of the Mets can chime in on what the wind potential is in W MA. in the lower elevations. The hill towns are more likely to get the higher gusts but I'm not sure what the higher end wind potential is in the Ct Valley where most of the population is. The hills East of the valley (ORH, and the high points just W of the Quabbin) are over 1000' that may knock down the winds just a bit?

I don;t know enough meteorology to say how it will mix down into the valley.

I still think W. MA, especially N of I-90 is the least effected area of SNE, relatively speaking.

Considering the massive N-S pressure gradient, I would think the isallobaric component may yield a pretty stout inversion in the low spots initially, and prevent significant mixing. God knows from my time in Northampton (*cough* Boxing Day) downsloping east winds should seriously cut into precip totals relative to the east slope as well. But the Masslive article referencing 'normal thunderstorm type winds' is out to lunch I think. Even 40kts is not too common, and I could see 30g45 definitely. Still fully expecting to be out of power for multiple days.

I live on a hilltop at about (only) 750' but it's off the valley floor enough that I think it should definitely help with higher stuff. Like Will said, not too many have seen 65kts in their lives. I believe I have once with a large tree snapped off as evidence, but I'll be shocked to approach that and don't really want to.

[bobbutts]

Wind maps from wunderground

12z Euro:

18z GFS:

0z NAM

[free_man]

I live on a hilltop at about (only) 750' but it's off the valley floor enough that I think it should definitely help with higher stuff. Like Will said, not too many have seen 65kts in their lives. I believe I have once with a large tree snapped off as evidence, but I'll be shocked to approach that and don't really want to.

The 2010 windstorm changed my opinion of this. Also live on a very exposed (highest point until you hit Derry 10 miles east) hilltop within valley. I don't remember the exact gusts, but the trees were obviously 100% defoliated. 65-70 mph? people should be! careful with that underestimation, because 75mph gusts will take down large trees and cause huge problems.

[weatherwiz]

Even if we were to only see widespread 40-50 mph winds...just like with Irene it's the duration of the winds that are going to make for serious issues. Now you add in the potential for several hours of gusts >60-70 mph

[HIPPYVALLEY]

Even if we were to only see widespread 40-50 mph winds...just like with Irene it's the duration of the winds that are going to make for serious issues. Now you add in the potential for several hours of gusts >60-70 mph

Really can't be over emphasized.

[N. OF PIKE]

i would be on alert thru central new england and perhaps even north central new england to this beast turns from NW to wnw in a couple days. you never know

[BeauDodson]

Even if we were to only see widespread 40-50 mph winds...just like with Irene it's the duration of the winds that are going to make for serious issues. Now you add in the potential for several hours of gusts >60-70 mph

If I remember correctly the ground conditions were very wet before Irene. Seemed like that help bring down even more trees. Not sure what ground conditions are like now - in most areas. Could balance out the difference - somewhat.

[weatherwiz]

If I remember correctly the ground conditions were very wet before Irene. Seemed like that help bring down even more trees. Not sure what ground conditions are like now - in most areas. Could balance out the difference - somewhat.

That is a fantastic point...have to check the maps but I know as of late we've been on the wet side.

[weatherwiz]

Precip departures over past 90 days

[wxmanmitch]

Considering the massive N-S pressure gradient, I would think the isallobaric component may yield a pretty stout inversion in the low spots initially, and prevent significant mixing. God knows from my time in Northampton (*cough* Boxing Day) downsloping east winds should seriously cut into precip totals relative to the east slope as well. But the Masslive article referencing 'normal thunderstorm type winds' is out to lunch I think. Even 40kts is not too common, and I could see 30g45 definitely. Still fully expecting to be out of power for multiple days.

I live on a hilltop at about (only) 750' but it's off the valley floor enough that I think it should definitely help with higher stuff. Like Will said, not too many have seen 65kts in their lives. I believe I have once with a large tree snapped off as evidence, but I'll be shocked to approach that and don't really want to.

I would tend to agree with this. The northerly flow and inversion may inhibit strong winds from reaching the valley floor early on. The strongest winds for the Pioneer Valley will probably occur after the storm has moved inland into NJ and turn more southerly due to funneling up the valley. An east or southeast flow can actually get forced into the south in the valleys. The southeasterly flow on the east side of the circulation will likely allow for greater mixing as well, especially if we can dry slot and lapse rates steepen a bit.

I think topography will play a much larger role with this compared to most weather systems in terms precip amounts as well since the usual mid-level processes (i.e. frontogenesis) will take a back seat to the LLJ and upsloping/downsloping. The heaviest totals will likely be on the east slope areas and back west toward the crest. If there is some spillover, areas like me just to the west of the crest may get on it as well.

Winds will likely be the worst at 2K+. I fully expect these areas to gust near hurricane force at times.

[bobbutts]

The 2010 windstorm changed my opinion of this. Also live on a very exposed (highest point until you hit Derry 10 miles east) hilltop within valley. I don't remember the exact gusts, but the trees were obviously 100% defoliated. 65-70 mph? people should be! careful with that underestimation, because 75mph gusts will take down large trees and cause huge problems.

One thing to remember is that the ground was like wet slop when those winds hit. For me all the trees that fell were in an area near a stream except for one sickly tree in the front yard. Although it looks rainy I don't think it will be quite as easy to uproot trees this time.

2010 imby

[radarman]

The 2010 windstorm changed my opinion of this. Also live on a very exposed (highest point until you hit Derry 10 miles east) hilltop within valley. I don't remember the exact gusts, but the trees were obviously 100% defoliated. 65-70 mph? people should be! careful with that underestimation, because 75mph gusts will take down large trees and cause huge problems.

Well you bring up a good point about the defoliation. When I suspect I saw 65kts it was May 31st 2008. The appearance of large oak trees in full bloom with those kind of winds is pretty terrifying, and the leaves probably 'add' 10 kts of damage potential at least. But are you expecting winds of that magnitude? I mean it should be bad, but allowing for at least a token regression to the mean, I feel a little uncomfortable expecting anything more than 50 maybe 55kts in Western MA. If it's truly exceptional and we see widespread 65kts it would be a disaster.

[Typhoon Tip]

Will be curious to see how the water levels compare historically with other events in the New York City area.

Reading from Mayor Bloomberg

“Although we’re expecting a large surge of water, it is not expected to be a tropical storm or hurricane-type surge. With this storm, we’ll likely see a slow pileup of water rather than a sudden surge, which is what you would expect with a hurricane, and which we saw with Irene 14 months ago.

“So it will be less dangerous – but make no mistake about it, there will be a lot of water and low-lying areas will experience flooding."

He doesn't sound as concerned as during Irene.

Joe D'Aleo mentioned this

STORM SURGE THREATS

Scott A. Mandia, Professor of Physical Sciences, SUNY Suffolk has put together an excellent page showing Long Island storm surge maps and animations here for various category hurricanes. From that site, the following

Hurricane storm surge causes approximately 90% of all storm deaths and injuries and much of the damage, therefore it is important for residents of Long Island, New York to be aware of the areas that will be affected by the storm surge. The southern shore of Long Island is most vulnerable to storm surge inundation because hurricane landfall will first occur there and the low elevation will allow sea water to move well inland.

The height of maximum storm surge is a function of storm strength, location of eye landfall, tidal time of landfall, elevation, and speed of storm. The images below represent the various regions of the southern shores of Long Island as well as the north and south forks as they would be affected by storm surge from various strength hurricanes. The images are derived from HURREVAC, a DOS-based software application that uses historical storm data and Long Island regional topography to estimate areas that would be inundated by water. (It should be noted that category 5 storm surges are not predicted by HURREVAC since there is little probability of such storms and no historical data exists for reference.) Each zone assumes landfall within that zone at normal tidal height. For high tide landfall, one would need to add 1/2 normal tide height to the predicted surge, while landfall at low tide would require a subtraction of 1/2 normal tide height from the predicted surge. The animated image was created using Microsoft GIF Animator and shows a loop of all maps within the zone with a five second interval between images.

Mmm This system may have rather sudden surge potential.

Bloomberg is taking this - probably because he's advised that way - as either strong nor'easter, or a hurricane. But this storm is neither. It's a hybrid upon impact with land - as modeled - and as we've painstakingly outlined in recent days, warn core seclusion dynamics don't fit and either or.

That aside, the combination of a core wind max combined with topographical aspects combined with astro-tides augment this, and a rather sudden insurgence of water rise is very plausible.

He's making a mistake. I don't see the use of 'People should be prepared to evacuate in short notice' in a situation such as this as entirely helpful. By the time a danger is registered in that vane, it's too late.

I've been hammering this hook scenario for days and days. This is pissing me off... We put people in charge in this culture that are not capable of making a scientifically objectified decision. I don't know what B's advisers are telling him, but the relay into a public statement doesn't lend much confidence that they are seeing this in the right way.

We'll see, and hopefully for the best.

[HIPPYVALLEY]

If I remember correctly the ground conditions were very wet before Irene. Seemed like that help bring down even more trees. Not sure what ground conditions are like now - in most areas. Could balance out the difference - somewhat.

SNE has been relatively rain free the past week so that is huge considering we are expecting more wind than rain concerns here. 2-3" qpf over hours will be nothing compared to Irene. Hopefully that helps considering the winds from Sandy will be higher and more prolonged than Irene.

This of course depends on the soil make up of any particular location. My neighborhood is very sandy (no pun intended) as opposed to much of Greenfield which sits on soil with a high clay ratio which causes more drainage issues.

[CoastalWx]

GFS identical to 18z through hr 42.

[CoastalWx]

Trough to the west a bit sharper and ridge to the NE a bit sharper, so end result is slightly SW of 18z through hr 48.

[CoastalWx]

Actually into central NJ this run. SO a shift south, towards consensus.

[yoda]

Trough to the west a bit sharper and ridge to the NE a bit sharper, so end result is slightly SW of 18z through hr 48.

Looks like that causes landfall between hrs 51-54 in C NJ, correct?

[Tropopause_Fold]

Someplace in w li sound is in trouble

[radarman]

I would tend to agree with this. The northerly flow and inversion may inhibit strong winds from reaching the valley floor early on. The strongest winds for the Pioneer Valley will probably occur after the storm has moved inland into NJ and turn more southerly due to funneling up the valley. An east or southeast flow can actually get forced into the south in the valleys. The southeasterly flow on the east side of the circulation will likely allow for greater mixing as well, especially if we can dry slot and lapse rates steepen a bit.

I think topography will play a much larger role with this compared to most weather systems in terms precip amounts as well since the usual mid-level processes (i.e. frontogenesis) will take a back seat to the LLJ and upsloping/downsloping. The heaviest totals will likely be on the east slope areas and back west toward the crest. If there is some spillover, areas like me just to the west of the crest may get on it as well.

Winds will likely be the worst at 2K+. I fully expect these areas to gust near hurricane force at times.

Very good post. If we had the accelerating NNW mover into Long Island ripping up the CT valley it would be sayonara, but the wide hook should keep winds out of the east through Monday night anyway. Still think the magnitude of the hook might end up overdone, but for all intents and purposes the general idea will be right.

As for the topography, you bring up an excellent point and I think I'll leave the ground clutter filter off on the UMass radar. Should make for an great topo case, at least until the power fails.