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Pattern Failbruary Thread

SD said:
What the gfs has late in its run is probably a once in a decade plus perfect setup
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Yeah what the GFS has at the end of its run is quite rare looking, but would be fun. Arctic boundary pushes south, then west to east overrunning into the cold dome.

Just for fun, the closest I can find to that type of setup is from Jan 1962 (1st image here is from the GFS, then the next 2 are from Jan 1962)

sCdKU7z.png


hfxzRSH.gif


wY2plSQ.png



Also, there are some similarities to the first of the 2 big snows in Feb 1989 (incidentally, that date was one of the CPC analog dates shown for this run of the GFS for days 8-14, centered on day 11)

KsAYdxL.gif


lIoaaTw.png


HlfA3Rh.gif
 
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HRRR showing a nasty squall line with potential for spin up tornadoes. All the way up to central Alabama and central Mississippi. CAPE has really increasedHRRRSE_prec_radar_048.pngHRRRSE_con_3kmhel_048.pngHRRRSE_con_uphly_048.pngHRRRSE_con_cape3km_048.pngHRRRSE_con_sbcape_048.png
 
griteater said:
Yeah what the GFS has at the end of its run is quite rare looking. but would be fun. Arctic boundary pushes south, then west to east overrunning into the cold dome.

Just for fun, the closest I can find to that type of setup is from Jan 1962 (1st image here is from the GFS, then the next 2 are from Jan 1962)

sCdKU7z.png


hfxzRSH.gif


wY2plSQ.png



Also, there are some similarities to the first of the 2 big snows in Feb 1989 (incidentally, that date was one of the CPC analog dates shown for this run of the GFS for days 8-14, centered on day 11)

KsAYdxL.gif


lIoaaTw.png


HlfA3Rh.gif
Click to expand...

Per history, the frequency of big snow/sleetstorms for the SE as a whole including deep SE peaks around mid Feb after a quieter early Feb:

1. Dates of ATL 3.5"+/1.5"+ individual SN/IP storms:

DEC: 4 TOTAL 2, 3-6, 11-13, 29

JAN: 15 TOTAL 1, 2-3, 7, 7-8, 9, 9-10, 12, 18, 18-19, 22, 23, 23, 26, 28, 29-30

FEB: 14 TOTAL 10, 11-12, 11-12, 12, 12-13, 14-15, 15, 15, 15-16, 17-18, 21, 23, 24-25, 26

MAR: 6 TOTAL1, 2, 11, 13, 14, 24

So, ATL peak 7 day period looks like Feb 10-16 with 9 storms.



2. Dates of RDU 6"+ individual SN/IP storms:

DEC: 8 TOTAL 2-3, 9-10, 11, 12-13, 17, 25-26, 27-28, 29

JAN: 13.5 TOTAL 2-3, 7-8, 7-8, 9-11, 13, 17-18, 18-19, 19, 24-25, 25-27, 26-27, 26-28, 28, 31 (this one continued til Feb 1)

FEB: 16.5 TOTAL 1 (this one continued from Jan 31), 6, 6-7, 9, 9-10, 10-11, 11-13, 14, 15-17, 17-18, 17-18, 18-19, 21-22, 26, 26, 26-27, 28

MAR: 8 TOTAL 1, 1-2, 2, 2-3, 9, 10, 24, 24

APR: 1 TOTAL 3

So, interestingly enough, RDU peak period is later, Feb 26-Mar 3.
 
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griteater said:
Yeah what the GFS has at the end of its run is quite rare looking, but would be fun. Arctic boundary pushes south, then west to east overrunning into the cold dome.

Just for fun, the closest I can find to that type of setup is from Jan 1962 (1st image here is from the GFS, then the next 2 are from Jan 1962)

sCdKU7z.png


hfxzRSH.gif


wY2plSQ.png



Also, there are some similarities to the first of the 2 big snows in Feb 1989 (incidentally, that date was one of the CPC analog dates shown for this run of the GFS for days 8-14, centered on day 11)

KsAYdxL.gif


lIoaaTw.png


HlfA3Rh.gif
Click to expand...
That 1989 storm came in a day after widespread 70s and close to 80 in the Piedmont and Sandhills…. Then was followed a few days later by a significant snowstorm for the the eastern 2/3rds of the Carolinas
 
GaWx said:
I don’t disagree with any of what you’re saying. It all makes sense. Regardless, I looked in my files and actually found an analysis I did of RDU 6"+ SN/IP and posted here back in 2017. I just added 1/17-18/2018 and 12/9-10/2018 to complete the list.

(2/24-26/2015 and 1/13/14/1982 were both not included since both of those periods' snow were actually from two different storms with the heaviest at 5". 2015 would have counted as +NAO and 1982 neutral)

Here's the NAO for the 21 Raleigh 6"+ SN/IP storms since 1950. (I'm calling neutral NAO to be from +0.25 to -0.25):

-1/19/1955: -NAO

- 12/11/1958: neutral NAO

- 3/2-3/1960: neutral NAO

- 3/9/1960: neutral NAO

- 2/26/1963: neutral NAO

- 1/25-7/1966: -NAO

- 2/9/1967: +NAO

- 3/1/1969: -NAO

- 1/7-8/1973: -NAO

- 2/18-9/1979: neutral NAO

- 3/1-2/1980: +NAO

- 3/24/1983: neutral NAO

- 2/6/1984: +NAO

- 1/7-8/1988: +NAO

- 2/17-8/1989: +NAO

- 1/24-5/2000 (“Crusher”): -NAO

- 1/2-3/2002: -NAO

- 2/26-7/2004: -NAO

- 12/25-6/2010: -NAO

- 1/17-8/2018: +NAO

- 12/9-10/2018 +NAO



Tally:

-NAO: 8

Neutral NAO: 6

+NAO: 7

Though 2000-2010’s four big storms including the Crusher were all during -NAO, this shows a pretty even split through the entire period and the sample size isn’t small. Note that the last two were during +NAO as well as very notable storms like 3/1980 and 1/1988.

I don’t know. I’m admittedly a bit surprised the numbers are this balanced. Perhaps some of this is due to how the NCEP based NAO is defined/calculated. I mean I think you can still have good blocking near Greenland and it not officially be calculated as -NAO. What do you think?

By the way, I also did a similar analysis for the NAO five days before each storm and the result didn’t change much with any -NAO advantage still small.
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That's good data to have. Thanks for posting it. Do you have any sense, particularly for the neutral NAOs, whether or not we were coming up out of a period of -NAO? It's often said that we see some of the larger storms ascending out from -NAO regimes. I haven't researched it for RDU specifically. I remember people in the mid-Atlantic forum talking about this frequently.
 
Rain Cold said:
That's good data to have. Thanks for posting it. Do you have any sense, particularly for the neutral NAOs, whether or not we were coming up out of a period of -NAO? It's often said that we see some of the larger storms ascending out from -NAO regimes. I haven't researched it for RDU specifically. I remember people in the mid-Atlantic forum talking about this frequently.
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You're welcome. Great question. Check this out for the 6 that were during neutral NAO::

- 12/11/1958: neutral NAO; 5 days before -1.168 (-NAO)

- 3/2-3/1960: neutral NAO; 5 days before -0.740 (-NAO)

- 3/9/1960: neutral NAO; 5 days before +0.107 (neutral NAO)

- 2/26/1963: neutral NAO; 5 days before -0.245 (neutral NAO)

- 2/18-9/1979: neutral NAO; 5 days before -0.616 (-NAO)

- 3/24/1983: neutral NAO; 5 days before +1.009 (+NAO)

So, for the 6 neutral NAO 6"+ RDU snowstorms since 1950, 3 were coming off of a -NAO, 2 had been neutral awhile, and only 1 was coming off of a +NAO.

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While I'm at it, I might as well add the same stats for the -NAO and +NAO storms:

-NAO: 8
-1/19/1955: -NAO; 5 days before -1.214 (-NAO)

- 1/25-7/1966: -NAO; 5 days before -1.739 (-NAO)

- 3/1/1969: -NAO; 5 days before -0.681 (-NAO)

- 1/7-8/1973: -NAO; 5 days before +0.347 (+NAO)

- 1/24-5/2000: -NAO; 5 days before -0.723 (-NAO)

- 1/2-3/2002: -NAO; 5 days before -0.736 (-NAO)

- 2/26-7/2004: -NAO; 5 days before -0.095 (neutral NAO)

- 12/25-6/2010: -NAO; 5 days before -0.740 (-NAO)


So, for the 8 -NAO 6"+ RDU snowstorms since 1950, 6 had been -NAO for awhile, 1 had just been neutral, and only 1 was coming off of a +NAO.


+NAO: 7
- 2/9/1967: +NAO; 5 days before +0.735 (+NAO)

- 3/1-2/1980: +NAO; 5 days before +1.108 (+NAO)

- 2/6/1984: +NAO; 5 days before +1.045 (+NAO)

- 1/7-8/1988: +NAO; 5 days before +0.953 (+NAO)

- 2/17-8/1989: +NAO; 5 days before +1.792 (+NAO)

- 1/17-8/2018: +NAO; 5 days before +0.836 (+NAO)

- 12/9-10/2018 +NAO; 5 days before +0.691 (+NAO)

So, for the 7 +NAO 6"+ RDU snowstorms since 1950, all 7 had been +NAO for awhile.
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From this, the tally for all 21 for 5 days before:

-NAO 9
neutral NAO 3
+NAO 9
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One more interesting thing:

- 1955-1966: all 6 either -NAO or neutral NAO
- 1955-1979: only 1 of the 10 was +NAO
- 1979-89: none of the 6 -NAO
- 2000-2010: all 4 -NAO
- 2018: both +NAO
 
If nothing else tonight, wind gusting good here. Reaching 30+.
 
JHS said:
Yep February 1989 has to be one of wildest months I can remember for weather in the Carolinas.
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You’re right… I would imagine that some areas across the NC/VA border that received 15-20” of snow that month also ended up being 3-4 degrees above average on temperatures
 
Bruh. Both cams are showing kidney beans. A uptick in severe probability coming?? 12z HRRR comes out in a bit. Eagerly waiting to see if the 12 HRRR prints these kidney beans and continues a ragged line wrf-arw2_ref_uv10m_seus_47.pngwrf-arw2_ref_uv10m_seus_46.pngwrf-arw_ref_frzn_seus_46.pngwrf-arw_ref_frzn_seus_45.png
 
Mega Frost morning:
Man we need to start getting some moisture in the ground. I see less than an inch qpf totals on the 10 and 15 day ops. I'm afraid we are going to have a very dry growing season/ summer. Hopefully that's not the case. But you don't want to be running a deficit as mid March approaches. Things can escalate quickly with the higher sun angles, low spring DPs. Next thing you know its summer and it seems you never catch up then.
 
NCSNOW said:
Mega Frost morning:
Man we need to start getting some moisture in the ground. I see less than an inch qpf totals on the 10 and 15 day ops. I'm afraid we are going to have a very dry growing season/ summer. Hopefully that's not the case. But you don't want to be running a deficit as mid March approaches. Things can escalate quickly with the higher sun angles, low spring DPs. Next thing you know its summer and it seems you never catch up then.
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Shetley? That you??
 
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