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Coastal Storm September 25-26th.


IsentropicLift

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With the 00z ECMWF, 00z GGEM, 00z NAM, 00z GFS, 06z NAM and 06z GFS on board, we have fairly good agreement on a period of heavy rain associated with a weak surface low centered around the Thursday time frame. General impacts at this time look to be 1-2" of rain with cool temps and breezy conditions. Strong high pressure over New England will somewhat limit the northern extent of the precipitation shield but the trend has been north over the last 24 hours. The new 09z SREF has NYC in the 0.75"+ area with the 1.00"+ mark over Sandy Hook. The entire area is at least 0.75"+.

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Technically wouldn't this be the first nor'easter of the season?  

 

 

I thought about mentioning that but the surface low itself is weak and it's getting sheared apart as it comes north.

I was thinking the same thing and was going to start checking the dates on the nor'easter thread I started but I am really not sure if this one should qualify.

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Finally a rainstorm on the way :)

 

People take my ball breaking too serious on here :thumbsup:

 

Cue Weatherguy701 for a warm core prediction for this weak, but juiced up low/inverted trough...

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It's interesting to me that in this case 1020MB can be considered Low Pressure here, yet in other cases can be considered High Pressure. Someone educate me. Is it because 1020MB is the lowest pressure in the general area? BTW this somewhat reminds of last October where we had that Low that was bringing a lot of rain South of here, but it never reached here because of strong high pressure. I have a feeling there's decent bust potential here if that high proves too much. The Euro has been steady, as always, and I'd trust it first, way before anything the Nam, (my "favorite") CMC and probably even the GFS say.

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It's interesting to me that in this case 1020MB can be considered Low Pressure here, yet in other cases can be considered High Pressure. Someone educate me. Is it because 1020MB is the lowest pressure in the general area? BTW this somewhat reminds of last October where we had that Low that was bringing a lot of rain South of here, but it never reached here because of strong high pressure. I have a feeling there's decent bust potential here if that high proves too much. The Euro has been steady, as always, and I'd trust it first, way before anything the Nam, (my "favorite") CMC and probably even the GFS say.

 

I'd wait for the 12z Euro before saying you trust its drier forecast. If the GFS stays wet at 12z I highly doubt the Euro will stay at the same precip numbers.

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It's interesting to me that in this case 1020MB can be considered Low Pressure here, yet in other cases can be considered High Pressure. Someone educate me. Is it because 1020MB is the lowest pressure in the general area? BTW this somewhat reminds of last October where we had that Low that was bringing a lot of rain South of here, but it never reached here because of strong high pressure. I have a feeling there's decent bust potential here if that high proves too much. The Euro has been steady, as always, and I'd trust it first, way before anything the Nam, (my "favorite") CMC and probably even the GFS say.

I think it's relative to the surrounding pressure. High pressure has air that sinks and low pressure air that rises.
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You have an actual area of vorticy at 500mb that closes off southwest of here and spawns a surface low which is responsible for the precip. You don't have a real temperature gradient so the low isn't able to deepen much based on baroclinic instability. The strong high to the north is also helping to shear this out as it tries to come north. I wouldn't take the forecasted surface pressures too literally either.

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You have an actual area of vorticy at 500mb that closes off southwest of here and spawns a surface low which is responsible for the precip. You don't have a real temperature gradient so the low isn't able to deepen much based on baroclinic instability. The strong high to the north is also helping to shear this out as it tries to come north. I wouldn't take the forecasted surface pressures too literally either.

 

Why not?

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Why not?

Why not what? Take the forecasted pressures litteraly? Well for starters we're still 48-60 hours out and still well within the time frame of model error. Secondly, the strengh of the low itself is not the biggest factor. If the low was deeper the precip shield may have been more wrapped up and we might not even be discussing this storm.

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Broken record, but are there any analogs for this storm? My memory is wasted, I need something to compare this to. The 4knam is on board with the westward track, makes the GFS seem suspect.

 

http://mp1.met.psu.edu/~fxg1/NAMSFC4_12z/ptot60.gif

 

A classic noreaster is always frontal, this looks more mesoscale, and tbh NAM has surface temps peaking in the upper 70s down here. Seems more tropical than anything else.

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