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2/13/2014 Major Coastal Storm Observations Part 2


Sickman

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The HRRR looks too far east with the most organized area of convective precipitation through the first several hours of its run. Looking at the radar from KLWX and KDIX, the most organized precipitation is forming near DCA and in that part of VA, while the HRRR had the steady precipitation over Delaware. 

 

We will have to see if this begins to pivot northeastward from the VA/DC region towards Delaware in the next hour or two. If it doesn't it could be a tip off that the HRRR and RAP are too far east with this activity. This would not be a terrible shock as we are cutting it close based on the track of the H7 and H85 lows anyway. 

 

I believe the models had the deformation banding too far east yesterday as well, showing it in upstate SC when in reality it set up in eastern TN.

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The HRRR looks too far east with the most organized area of convective precipitation through the first several hours of its run. Looking at the radar from KLWX and KDIX, the most organized precipitation is forming near DCA and in that part of VA, while the HRRR had the steady precipitation over Delaware.

We will have to see if this begins to pivot northeastward from the VA/DC region towards Delaware in the next hour or two. If it doesn't it could be a tip off that the HRRR and RAP are too far east with this activity. This would not be a terrible shock as we are cutting it close based on the track of the H7 and H85 lows anyway.

This is also what happened down south when sc was supposed to get plastered and it wound up 50 miles out further west.

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The HRRR looks too far east with the most organized area of convective precipitation through the first several hours of its run. Looking at the radar from KLWX and KDIX, the most organized precipitation is forming near DCA and in that part of VA, while the HRRR had the steady precipitation over Delaware. 

 

We will have to see if this begins to pivot northeastward from the VA/DC region towards Delaware in the next hour or two. If it doesn't it could be a tip off that the HRRR and RAP are too far east with this activity. This would not be a terrible shock as we are cutting it close based on the track of the H7 and H85 lows anyway. 

There's actually some pretty decent convection starting to pop up over DELMARVA and the nearshore waters now.

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Yea John I was just seeing the same thing, Our hope is that the second band becomes the main band not the one pivoting now

To me I think you are goin to see precip start blowing up E of AC and that band closes up

 

Think thunderstorms may start to pop out there

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Maybe someone can explain to me....on the RAP it has shown 3 areas of banding showing up/developing....one is south of our area that comes up into our area, more off the ocean. However, this seems to be something other than snow...the other area is well N and W of us that stays north...and the 3rd area is what is down south that lifts up NNE that I believe we would need to be further east to get into the best action. What are each of these bands of snow from exactly ?

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If you look at the RAP and HRRR

 

Yea thats what the HRRR has and it pulls the rest of it east...next our or 2 will be crucial

Look at the breath of both models - the .8 line on both has some pretty good distance from end to end  . The model can be off by 50 miles , but its telling you this is not localized .

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this looks like a pretty good match to me

VA_WV.rad.gif

1ref_t3sfc_f03.png

Yup positioning looks good but the 850 temps depiction was way off on the 19z. It had 850's all the way to the water gap I think and they were in actuality sitting south of KNYC at the same exact time as the HRRR depiction. We should wait to see the newer runs at this point anyway.

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UPTON

MODELS HAVE BEEN CONSISTENT WITH THIS BACKSIDE DEFORMATION

BANDING OVER THE LAST FEW DAYS...AND CONFIDENCE IS MODERATE TO

HIGH IN A SWATH OF HEAVY SNOW ACROSS THE LOWER HUDSON VALLEY...NE

NJ...NYC/LI METRO AND SW CT. TRAVEL WILL ONCE AGAIN NOT BE

RECOMMENDED TONIGHT IN THIS AREA...WITH SNOWFALL RATES OF 1 TO 3

INCHES...AND AS MUCH AS 4 TO 8 INCHES OF ADDITIONAL SNOW LIKELY

HERE. THERE IS A LOW PROBABILITY OF AN ADDITIONAL 8 TO 12

INCHES...PARTICULARLY N&W OF NYC. BLOWING AND DRIFTING SNOW IS

LIKELY AFT MIDNIGHT ACROSS THIS AREA AS WINDS BEGIN TO PICK

UP...WITH VSBY DROPPING TO QUARTER MILE OR LESS.

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1) The heaviest precipitation right now is inside the 700mb low. The precip will be pseudo-convective, so it might not be necessarily best to assume that only heaviest snow will be falling to the west of the 700mb low.

 

2) The mid-level centers will become very tightly compacted. This tends to mean that ageostrophic flow becomes a lot more compact, and precipitation can be compressed closer to the center, instead of displaced well to the west, especially given the track of the 500mb low.

 

That all being said, I still do echo some of John's concerns about the ability of the heaviest banding to shift east. But I think the above will help it at least get to Western Long Island. Also, it seems the HRRR has been verifying well so far. 

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