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Jan 26-27 light snows


ORH_wxman
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1 minute ago, Damage In Tolland said:


can you post Google?

From your boy Matt Noyes

 

First, what is a "Norlun Instability Trough?"  A trough is a weak disturbance in the atmosphere - in this case, near the surface - marked by lower surface barometric pressure that results from converging wind direction and speed.  Surface convergence of air results in rising air (afterall, air converging at the surface must go either up or down, and clearly can't go into the ground), and rising air produces clouds and precipitation.  Hence, troughs can focus locally heavier bands of precipitation.  It was noted by operational forecasters Steve NOgueiRa and Weir LUNdstedt (Nor-Lun) that these troughs, when inverted (extending northwest from a surface low) and beneath a middle and upper level atmospheric cold pool, could result in very strong, localized bands of precipitation.  On occasion, these narrow but intense bands of snow could produce in excess of one foot of snow, and largely were missed by computer guidance.  Mr. Norgueira and Lundstedt both worked to find methods of forecasting these events, even when computer modeling missed them.  Since their initial study in 1992, computer modeling has improved significantly, and these events often are projected in advance, though placement and intensity continues to be a challenge, especially in more complex setups.

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2 minutes ago, Sey-Mour Snow said:

From your boy Matt Noyes

 

First, what is a "Norlun Instability Trough?"  A trough is a weak disturbance in the atmosphere - in this case, near the surface - marked by lower surface barometric pressure that results from converging wind direction and speed.  Surface convergence of air results in rising air (afterall, air converging at the surface must go either up or down, and clearly can't go into the ground), and rising air produces clouds and precipitation.  Hence, troughs can focus locally heavier bands of precipitation.  It was noted by operational forecasters Steve NOgueiRa and Weir LUNdstedt (Nor-Lun) that these troughs, when inverted (extending northwest from a surface low) and beneath a middle and upper level atmospheric cold pool, could result in very strong, localized bands of precipitation.  On occasion, these narrow but intense bands of snow could produce in excess of one foot of snow, and largely were missed by computer guidance.  Mr. Norgueira and Lundstedt both worked to find methods of forecasting these events, even when computer modeling missed them.  Since their initial study in 1992, computer modeling has improved significantly, and these events often are projected in advance, though placement and intensity continues to be a challenge, especially in more complex setups.

Sounds like a lot of long winded verbiage for a wind shift to NW that causes enhanced precip 

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3 minutes ago, CoastalWx said:

It’s a special type of inv trough. What you guys are mentioning is more of an inv trough feature and not a NORLUN.  In any case, we’ll have to see how that sets up. Guidance is not totally in agreement which isn’t surprising. 

Are you actually related to mr. Norlun or is this a joke? Asking for a friend.

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20 minutes ago, CoastalWx said:

It’s a special type of inv trough. What you guys are mentioning is more of an inv trough feature and not a NORLUN.  In any case, we’ll have to see how that sets up. Guidance is not totally in agreement which isn’t surprising. 

Upper air cold pool being distinguishing feature of Norlun. Basically INVT meets Windex

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Just now, The 4 Seasons said:

oh nice thats cool, didnt know thought it could be a coincidence. Figured on here, you never know.

Lol I’m just messing around. He already mentioned further back in the thread that there was no relation. 

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Just now, CoastalWx said:

Something seems wrong with the NAM. It has holes in the sim reflectivity over areas that don’t move and make no sense at all from a meteorological standpoint. 

Dendrite pointed it out on one of the earlier runs too. It looks glitchy. 

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27 minutes ago, Ginx snewx said:

At some point Mets are going to bump it up. HRRR is warning level in many spots, snow growth looks pretty good to this untrained eye 

It looks really good, at least for your area with the initial push for about a couple hours then drops off like a rock and lift in the DGZ is awful. This is HR22 vs HR24.This is just one run of one model, outside of its normal run time but looking at the two big ones where i can see snow growth, NAM and GFS, are not too impressive. With that said, i do think 1-2 that OKX has is on the low side but right now i dont feel too comfortable going much higher than 2-5.

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