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3/20-21 Potential Winter Storm


anthonyweather

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Mixing issues on the 12z NAM at LGA

 

150320/1700Z  29  13006KT  32.4F  SNOW   14:1| 0.2|| 0.00|| 0.00|| 0.012   14:1|  0.2|| 0.00|| 0.00|| 0.01   90|  0| 10
150320/1800Z  30  10006KT  33.3F  RASN    0:1| 0.0|| 0.00|| 0.00|| 0.019   14:1|  0.2|| 0.00|| 0.00|| 0.03   81|  0| 19
----------------------------------------------+----++-----+-------------++--------------++-------------++-----------+---+---
150320/1900Z  31  09004KT  33.5F  RASN    0:1| 0.0|| 0.00|| 0.00|| 0.025   14:1|  0.2|| 0.00|| 0.00|| 0.06   81|  0| 19
150320/2000Z  32  06005KT  33.0F  RASN    0:1| 0.0|| 0.00|| 0.00|| 0.044   14:1|  0.2|| 0.00|| 0.00|| 0.10   84|  0| 16
150320/2100Z  33  05006KT  32.6F  RASN    0:1| 0.0|| 0.00|| 0.00|| 0.059   14:1|  0.2|| 0.00|| 0.00|| 0.16   88|  0| 12
150320/2200Z  34  05007KT  31.9F  SNOW   13:1| 0.8|| 0.00|| 0.00|| 0.057   13:1|  0.9|| 0.00|| 0.00|| 0.22  100|  0|  0
150320/2300Z  35  05009KT  31.2F  SNOW    7:1| 0.3|| 0.00|| 0.00|| 0.041   11:1|  1.2|| 0.00|| 0.00|| 0.26  100|  0|  0
150321/0000Z  36  05009KT  30.8F  SNOW    9:1| 0.1|| 0.00|| 0.00|| 0.016   11:1|  1.4|| 0.00|| 0.00|| 0.27  100|  0|  0
----------------------------------------------+----++-----+-------------++--------------++-------------++-----------+---+---
150321/0100Z  37  06009KT  30.8F  SNOW   10:1| 0.0|| 0.00|| 0.00|| 0.005   11:1|  1.4|| 0.00|| 0.00|| 0.28  100|  0|  0
150321/0200Z  38  06008KT  30.8F  SNPL    6:1| 0.0|| 0.00|| 0.00|| 0.004   11:1|  1.4|| 0.00|| 0.00|| 0.28   63| 37|  0
 

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A few quotes 30 hours out March 4  

Same people , same awful mode hugging . 

I  hid the names but can be found in the 4- 5 thread . . 

 

BTW 6 to 10 fell 

 

Per the nam most people are no where near 6 inches and many are 2 -3 tops. even parts of central and south jersey.

 

Seems as though this becoming a non event for NENJ. 

 

Correct and hopefully this is just the nam being the nam. It was a terrible run all around

 

This looks like 2-3 for nyc and 1-2 north of the city imo 

 

3 yes, 6? Very Seriously doubt it 

 

This looks like 3 to 5 , not the 1 to 2 on the NAM . ( Once again this will correct ) 

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A few quotes 30 hours out March 4  

Same people , same awful mode hugging . 

I  hid the names but can be found in the 4- 5 thread . . 

 

BTW 6 to 10 fell 

 

Per the nam most people are no where near 6 inches and many are 2 -3 tops. even parts of central and south jersey.

 

Seems as though this becoming a non event for NENJ. 

 

Correct and hopefully this is just the nam being the nam. It was a terrible run all around

 

This looks like 2-3 for nyc and 1-2 north of the city imo 

 

3 yes, 6? Very Seriously doubt it 

 

This looks like 3 to 5 , not the 1 to 2 on the NAM . ( Once again this will correct ) 

 

Not sure why people rely on the NAM when it has such a poor track record compared to the Euro and GFS

beyond day 1. Its real value is picking out 6-12 hr trends on the same day of the storm.

 

Here are the precip scores from the HPC.

 

http://www.wpc.ncep.noaa.gov/html/hpcverif.shtml

 

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Not sure why people rely on the NAM when it has such a poor track record compared to the Euro and GFS

beyond day 1. It's real value is picking out 6-12 hr trends on the same day of the storm.

Here are the precip scores from the HPC.

http://www.wpc.ncep.noaa.gov/html/hpcverif.shtml

509ge3036.gif

I think it is because of the 3hr increments, and more widespread availability. I think people trust what they can see, rather than what must be regurgitated from another's perspective (euro)

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FWIW, some notable late-season snowstorms have occurred with an AO+/PNA-. The April 1982 blizzard and 1997 April Fool's Day snowstorm are the biggest ones.

 

 

LOL we've had a positive NAO and AO all winter...EPO is king, when that folds up shop, then we're done

 

Pazzo has a point tho...The AO/NAO parameters, and really any/all parameters that produce anomalous cold, becomes increasingly important to be all in our favor later and later in the season. I know what Don pointed out about those prolific storms and what the  ao/nao numbers said then, but this is not a +NAO on 4-6-82 ... 

 

post-402-0-93427600-1426783023_thumb.gif

 

The EPO becomes tougher and tougher to produce cold on its own later in the season, and less of a correlation as well...part of that is seasonal wavelengths shortening

 

post-402-0-32566900-1426783036_thumb.png

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Why wouldn't the snow stick to streets if the temps are 28-31 degrees with a thick cloud deck?

Thanks for the reply in advance.

(Obviously not talking about midtown Manhattan)

 

Also,

How did your 2"-4" call go for the March 5th 6"-10" storm??

 

Surface temps for anyone near the I-95 corridor will likely be within a degree or two of 32F, either direction.  Indirect late March sunlight should supply more than enough UV to warm paved surfaces a few degrees, leading to 1/4-1/2" melting rates during at least 10 am to 4 pm, meaning we'd need pretty good rates (1/2" per hour or more) to get accumulation on untreated paved surfaces; obviously melting rates are greater at 34F vs. 30F, but I'm just trying to be illustrative.  Traffic adds additional heat and increases the melting rate (as does salt).  Of course, once there is accumulation on roads, that melting rate goes to near zero at 32F, given the UV-reflective nature of snow, meaning snow would then start to accumulate much faster - many people don't understand that difference (snow falling on snow accumulates pretty easily).  

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Pazzo has a point tho...The AO/NAO parameters, and really any/all parameters that produce anomalous cold, becomes increasingly important to be all in our favor later and later in the season. I know what Don pointed out about those prolific storms and what the  ao/nao numbers said then, but this is not a +NAO on 4-6-82 ... 

 

attachicon.gif4-6-82.gif

 

The EPO becomes tougher and tougher to produce cold on its own later in the season, and less of a correlation as well...part of that is seasonal wavelengths shortening

 

attachicon.gifEP-np corr.PNG

We all agree that you will not  see the same  - anomalous  departures in March  like you do in Jan and Feb , so where  -EPO + PNA regimes can produced - 20 mid winter , you can still see - 10 departures later in the Season on into early March . 

 

At this point in the season what is 1 or 2 SD above normal in Manitoba can still be below normal into the NE .

What Pazzo misses is if you are - 5 or so at 850 ( even if that only translates to mid 40`s at the BL ) once LP is present you can easily wet bulb to 0 C with that profile  .

 

The mid levels , BL and Rates determine late season snowfall , not the calender or the sun . We never argued we would see temps in the teens , but just " cold enough " to snow . 

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We all agree that you will not  see the same  - anomalous  departures in March  like you do in Jan and Feb , so where  -EPO + PNA regimes can produced - 20 mid winter , you can still see - 10 departures later in the Season on into early March . 

 

At this point in the season what is 1 or 2 SD above normal in Manitoba can still be below normal into the NE .

What Pazzo misses is if you are - 5 or so at 850 ( even if that only translates to mid 40`s at the BL ) once LP is present you can easily wet bulb to 0 C with that profile  .

 

The mid levels , BL and Rates determine late season snowfall , not the calender or the sun . We never argued we would see temps in the teens , but just " cold enough " to snow . 

 

The storm track becomes an issue too though..need that nao to suppress the northern jet more and more as spring presses in...but yea, tack on a +PNA hooked up to a -epo then the cold will come in still... but you generally also need that nao upstream to cut off the system and allow a prolific precip maker, large storm and overcome any BL issues

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GGEM is now just a light accum on colder surfaces like the NAM? It sure seems like the models are going downhill for this event.

 

So **** what the Ukmet and GFS say at 12z?

Or what the Euro is about to show?

Calm down.

 

This is a 3"-6" snow event. Always has been and will remain that way. The range of emotions here is ludicrous. Especially after we have just had a historic Jan-March and another 50"+ season on the way for a NYC station (KLGA).

 

It will snow tomorrow. Whether it's 2"-4" or 3"-6", who cares.

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So **** what the Ukmet and GFS say at 12z?

Or what the Euro is about to show?

Calm down.

 

This is a 3"-6" snow event. Always has been and will remain that way.

 

 

I'm calm. Just pointing out that some models have gone downhill. Last night pretty much all models looked like significant snow. Today it has changed to a model battle. I'll feel better if the EURO still looks good.

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The storm track becomes an issue too though..need that nao to suppress the northern jet more and more as spring presses in...but yea, tack on a +PNA hooked up to a -epo then the cold will come in still... but you generally also need that nao upstream to cut off the system and allow a prolific precip maker, large storm and overcome any BL issues

 

And FWIW, I do feel snow in early April is a strong possibility this year

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Pazzo has a point tho...The AO/NAO parameters, and really any/all parameters that produce anomalous cold, becomes increasingly important to be all in our favor later and later in the season. I know what Don pointed out about those prolific storms and what the  ao/nao numbers said then, but this is not a +NAO on 4-6-82 ... 

 

attachicon.gif4-6-82.gif

 

The EPO becomes tougher and tougher to produce cold on its own later in the season, and less of a correlation as well...part of that is seasonal wavelengths shortening

 

attachicon.gifEP-np corr.PNG

the EPO has the biggest correlation in the upper midwest/plains. we can get months like july 2013 where the trough was far enough west to allow ridging to build from the east

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