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Significant Ocean Storm March 5-7 2013 Discussion Part II


earthlight

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one positive is that Steve D is saying a lot of rain for us

 

Final-Snow-Map.png

I think the "storm surge up to 8 feet!" is irresponsible, without explaining what that means.  Yes, tides will likely be 8 feet above the mean low tide level, but high tide is usually 5 feet above low tide and the 8 feet being referred to is relative to mean low tide, meaning the "storm surge" is really 3 feet above mean high tide, which is what people care about.  Nobody cares if the high tide is normal - they care how much higher it will get than a normal high tide.  Here's what the NWS said in the AFD...

 

OUR LOCAL IN HOUSE TIDAL DEPARTURE PROCEDURES

ARE GIVING US A TIDAL DEPARTURE OF AROUND 2.5 FEET WITH THE STARTING

WEDNESDAY AFTERNOON HIGH TIDE CYCLE. THIS WAS USING A 50/50 NAM AND

GFS BLEND. NOTING THAT THE "NORTHWARD" DRIFT OF THE MODELS HAS NOT

STOPPED AND USING A STRAIGHT (NORTHERNMOST FOR THIS RUN) GFS

SOLUTION WOULD TAKE US CLOSE TO MODERATE TIDAL FLOODING THRESHOLD

WITH THE WEDNESDAY AFTERNOON HIGH TIDE.

 

A 2.5-3.0 foot storm surge above mean high tide is considered minor to moderate and is in line with many past nor'easters and a completely different animal than the 10-12 foot storm surge seen for Sandy - lots of people out there already freaking out about how these numbers are reported in the coastal flood advisory by the NWS (where they report 8 feet above mean lower low water, which is the same as mean low tide, really) - way too confusing for laypeople (and Steve, obviously). 

 

 AT...SANDY HOOK... NEW JERSEY... HIGH TIDE WILL OCCUR AT 258

  PM WEDNESDAY WITH A FORECAST TIDE LEVEL OF 7.5 TO 8.0 FEET

  ABOVE MEAN LOWER LOW WATER. HIGH TIDE WILL THEN OCCUR AT 331

  AM THURSDAY WITH A FORECAST TIDE LEVEL NEAR 8.0 FEET ABOVE

  MEAN LOWER LOW WATER.

 

 

The NWS briefing package deck shows this in a nice graphic in the 6th slide. 

 

http://www.erh.noaa.gov/er/phi/briefing/packages/current_briefing.pdf

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at 42 the 1 in line is through most of NYC save for the bronx and basically follows the north shore of LI. 1.25 up to SI. Still snowing. Cold. freezing line very far east compared to earlier runs

 

Could the reason why it is so cold be due to the fact that there is now more northern stream interaction than previous runs? I remember several days ago when we were discussing about this interaction needing to happen to get a colder scenario for our region. What a beautiful run.

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Don't buy the NAM, it does this every storm...do not fall for it :)

 

 

It does but I remember for Blizzard it Did show Ridiculous amounts for NJ/NY one or Two runs but for Most part showed the 2-3 inch QPF totals over Conn and NE which is what really happened. 

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I think the "storm surge up to 8 feet!" is irresponsible, without explaining what that means.  Yes, tides will likely be 8 feet above the mean low tide level, but high tide is usually 5 feet above low tide and the 8 feet being referred to is relative to mean low tide, meaning the "storm surge" is really 3 feet above mean high tide, which is what people care about.  Nobody cares if the high tide is normal - they care how much higher it will get than a normal high tide.  Here's what the NWS said in the AFD...

 

OUR LOCAL IN HOUSE TIDAL DEPARTURE PROCEDURES

ARE GIVING US A TIDAL DEPARTURE OF AROUND 2.5 FEET WITH THE STARTING

WEDNESDAY AFTERNOON HIGH TIDE CYCLE. THIS WAS USING A 50/50 NAM AND

GFS BLEND. NOTING THAT THE "NORTHWARD" DRIFT OF THE MODELS HAS NOT

STOPPED AND USING A STRAIGHT (NORTHERNMOST FOR THIS RUN) GFS

SOLUTION WOULD TAKE US CLOSE TO MODERATE TIDAL FLOODING THRESHOLD

WITH THE WEDNESDAY AFTERNOON HIGH TIDE.

 

A 2.5-3.0 foot storm surge above mean high tide is considered minor to moderate and is in line with many past nor'easters and a completely different animal than the 10-12 foot storm surge seen for Sandy - lots of people out there already freaking out about how these numbers are reported in the coastal flood advisory by the NWS (where they report 8 feet above mean lower low water, which is the same as mean low tide, really) - way too confusing for laypeople (and Steve, obviously). 

 

 AT...SANDY HOOK... NEW JERSEY... HIGH TIDE WILL OCCUR AT 258

  PM WEDNESDAY WITH A FORECAST TIDE LEVEL OF 7.5 TO 8.0 FEET

  ABOVE MEAN LOWER LOW WATER. HIGH TIDE WILL THEN OCCUR AT 331

  AM THURSDAY WITH A FORECAST TIDE LEVEL NEAR 8.0 FEET ABOVE

  MEAN LOWER LOW WATER.

 

 

The NWS briefing package deck shows this in a nice graphic in the 6th slide. 

 

http://www.erh.noaa.gov/er/phi/briefing/packages/current_briefing.pdf

I guess apparently even some mets don't get the difference between storm tide vs. storm surge. In Sandy, a nearly 8 foot storm surge generated a nearly 11 foot storm tide for this area, and nearly 14 feet for Battery Park from a 9 foot surge. The difference maker then was unfortunately that it was nearly high tide when the max surge arrived. The level shown for this storm could generate some flooding along the highly vulnerable shores but it doesn't look serious.

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Hr 54 the norlun is a tad northeast of where you want it, but the precip never ended. Instead as the main low moved out the norlun filled everything in. NW burbs changing back over to snow after a brief period of a lighter mixed bag. Hour 57 light snow from the city on NW. Through hr 57 the 1.00" line is sitting right over the Sussex/Morris County border. 85% plus of this is snow for the western burbs.

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