stormy weather

Hydro Therapy · Apr 16, 2018

Where getting blasted with rain and wind at this moment here in N.J. Between the storm surge and rain off my dock lines are tighter then guitar strings.

rgranger · Apr 16, 2018

Is the 28.1 in mmHg (bars) ?

justsomeguy · Apr 16, 2018

I'm betting inches of mercury.

rgranger · Apr 16, 2018

justsomeguy said:
I'm betting inches of mercury.

Yeah maybe. 28.1 inches would be 0.94 atmospheres. I don't really have a lot of perspective. Is a 6% drop in air pressure a big drop? Intuitively that does not seem like a huge gradient to me but I really don't have a basis to gauge with. 30 inches Hg is about one atmosphere.

kappykaplan · Apr 16, 2018

rgranger said:
Is the 28.1 in mmHg (bars) ?

28.1 inHG = 951.6 millibars, so it's a pretty intense low!

justsomeguy · Apr 16, 2018

rgranger said:
I don't really have a lot of perspective.

Superstorm Sandy was 27.76 inches.

rgranger · Apr 16, 2018

Thanks ... that helps.

dlochner · Apr 16, 2018

jon hansen said:
the great lakes got April showers this last weekend. 28" of 'wet, mashed potatoes' at my summer house on sturgeon bay, wis. over 2" of rain here in toledo.
the good news is this is how we keep the great lakes full. for twenty years the lakes had been dropping. now they are filling. i prefer deep keels on sailing vessels. my houses sit on high ground. i'm a happy camper.

there is a storm in the north atlantic right now with a double eye, that is 28.1 " at it's center. WOW! is that a hurricane? it is HUGE!

Ireland is taking it on the chin today
https://www.windy.com/?42.618,-62.446,4,i:pressure,m:e7radAL

Jon, I'm glad the upper Great Lakes have water in them. However, would you please keep the water in the upper lakes, we have more than enough water down here. Last year you didn't and this is what happened to my marina.

Pirate Dave · Apr 17, 2018

Shoot, I thought Stormy Weather was going to be about Stormy Daniels and te Donald !!!! I feel cheated !!!!

Justin_NSA · Apr 17, 2018

We're heading in to tornado and hail season. Yippee!

Allowishish · Apr 17, 2018

we are having winds in the low 30's with gust to the 50's out here today.

There are a few bout on my dock that do not use a spring line... with todays wind direction that is really going to suck for them.

JamesG161 · Apr 17, 2018

Katrina landfall 27.4 inHg
Camille land fall 27 inHg
1935 labor day Hurricane 26.3 inHg
I have a video of my rolled vinyl kitchen flooring "ballooning" as Katrina eye passed.
My ears popped too.
Jim...

Roland5048 · Apr 17, 2018

JamesG161 said:
I have a video of my rolled vinyl kitchen flooring "ballooning" as Katrina eye passed.

How about posting it? I bet that would look interesting, if not downright eerie.

rgranger · Apr 17, 2018

Thanks @JamesG161

And everyone else. This post has been a real education. I've always measured pressure in units of atmospheres so looking at inches of Hg does not give me an intuitive feel.
In order to calibrate my head.. I did some conversions. For the rest of you who do not think in inches of Hg here are some conversions that I made for myself.

Normal Air Pressure

1 Atm = 29.92" Hg = 1013.25 millibar

1935 Labor Day = a 12% pressure gradient

0.88 Atm = 26.3" Hg = 892 millibar

Camille land fall = 9.8% pressure gradient

0.902 = 27" Hg = 914 millibar

A 10% Gradient

0.9 Atm = 26.93" Hg = 912 millibar

Katrina land fall = 8.4% pressure gradient

0.916 Atm = 27.4" Hg = 928 millibar

It seems like most weather maps use millibar. As I was reading up on this I ran across the following rule

Isobar lines may only pass through pressures of 1000 + or - 4. In other words, allowable lines are 992, 996, 1000, 1004, 1008, and so on.

Some questions that remain in my mind are.. how close do two lines need to be in order to create a approximate 10 mph breeze? or a 20 mph breeze? etc. I think if I had that info in my head, I could look at a weather map and make much better predictions about wind speed in an area.

anybody here know this info?

rgranger · Apr 17, 2018

Think I found it

If you are interested in learning to read isobar maps check this site out

http://about.metservice.com/our-company/learning-centre/how-to-read-weather-maps/

Bottom line... if the isobars are spaced by about 2 deg. lat, then expect a breeze between 17-21 knots. The closer they get, the faster the wind will blow.

JamesG161 · Apr 17, 2018

Roland5048 said:
How about posting it?

I will look for it.
When my Katrina adjuster was here for my really Minor home Katrina damage <$20K, I showed him the video and he nearly freaked out.
I lost my office entirely , just a clean slab and bent building structural steel warehouse.
Here is a picture of my office 2 days after Katrina. Yes that was a iMac from my office too.

Before, I couldn't not see the Water Tower. See the 2x4 on the floor, that is where my desk was.

Notice NO MUD... almost like it was pressure washed.
Zero leaves in the trees.
Waveland MS was the real ground zero.
Jim...

JamesG161 · Apr 17, 2018

For the weather buffs, 1000 milliBars = 1 standard Atmosphere at sea level, is used for all hurricane and storm forecasting.
They search out 800 millibars and 500 millibars for the Hurricane Hunter's fly throughs. Then they zig zag at that pressure, not altitude.

The real key is the diameter of the LOW pressure. That gives a big Area of pressure reduction.
Three things for all ship's watches.
1) Time
2) Celestial position
3)BAROMETRIC pressure CHANGES...

Fast falling... LOOK out
Slow Rising... clear sailing.
Jim...

PS: I was Sandy's diameter and the lack of Hurricane standard building codes that caused the major damage.