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January 2019 General Discussion & Observations


Rtd208

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3 hours ago, LibertyBell said:

You didnt like the Jan 2016 blizzard?  That one certainly made up for what Jan 2015 lacked and exceeded even Jan 1996.

I lived in Norwalk for 96 and had 27 inches of snow. Most in my lifetime. 2016 I lived in Easton and only had 11.5. Even my old town of Norwalk (which is only 2 towns SW) had 16 (much less than 96) 2016 was basically further south than 1996.

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15 hours ago, donsutherland1 said:

As the first weekend in January approaches, growing signs of the long-heralded pattern change are now beginning to appear on the guidance, including the EPS.

In terms of various indices that delineate the global pattern, the SOI has gone negative. It has now been negative for 5 consecutive days. Today's figure of -20.30 is its lowest reading since November 17 when it stood at -25.26. This development is consistent with the progression of the MJO and historic experience. The three December El Niño cases that had a positive SOI average all had a January SOI average below -10.00.

On January 3, the MJO was in Phase 6 with an amplitude of 1.808 (RMM). That amplitude is down from the 1/2-adjusted figure of 2.016. The MJO will likely approach and then reach Phase 7 in the January 5-9 period at a high amplitude.

While the MJO remains in Phase 6, the Arctic Oscillation (AO) will very likely remain mainly positive. However, as the MJO approaches and then moves into Phase 7, the AO will likely go negative. The AO's going negative will be the next significant domino to fall in paving the way for a return of winter.

Before then, milder conditions will prevail consistent with the MJO's being in Phase 6 at a high amplitude during El Niño January cases and an SOI-/AO+ combination. January 9-15, 2007 offers a representative example. Mean temperatures for select sites during that period were:

Atlantic City: 45.4°
Boston: 36.4°
Bridgeport: 38.1°
Harrisburg: 39.4°
Islip: 39.9°
New York City: 41.2°
Newark: 40.1°
Philadelphia: 43.4°
Richmond: 49.1°
Washington, DC: 46.2°

10 days later in January 2007, a sustained much colder than normal pattern had developed.

This year, the second half of January could feature the development of a predominant PNA+/AO- combination. Such a combination has been present for most of the region's big January snowstorms. As a result, a month that featured unseasonable warmth during its first week could turn cold and snowy.

The risk of a moderate or significant snowfall will increase from a very low probability for the first 7-10 days of January once the MJO moves into Phase 7. That probability will increase even more once the MJO moves into Phase 8.

2006-07 averaged 36.5 for met winter...30 straight days averaged 25.8 from late Jan to late Feb...that means the other 60 days averaged 41.8...two sleet storms yielded almost 8" of snow and sleet...if those storms were snow NYC would have seen 25"...

edit...1984-85 averaged 36.4 for met winter...there were 30 consecutive days that averaged 27.5...the other 60 days averaged around 40.8...in contrast 2007-08 averaged 36.4 but the coldest 30 day period averaged only 35.7...that means the other 60 days averaged slightly 36...

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In the fwiw department; BANDING...well modeled days in advance, particular the ECMWF.  If you wish to eyeball what I think is fairly classic banding signature, look at the EPC 500mb pattern for 12z today and 00z/6.  Note where we are located with respect to the 500 flow---deformation and banding (check later morning radar in NJ/PA).  Pretty big rains are occurring ne PA and far nw NJ.  We had 0.27 "prior to 8am EST,  now at 0.74 as of this writing.  I won't be able to reply to any comments for several hours but just wanted to pass on something that I think we could already see back around Dec 29 in the guidance 500 MB pattern.  GFS/JMA were constantly again tooo far south with this event, handled much better overall by the GGEM/ECMWF (EPS especially). 1038AM 1/5.  Also reposted NJ pcpn comments on 2018 annual and will be verifying daily the Dec 26 post. 

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there's a pretty cool ~850mb feature over northern jersey producing some heavy downpours in the region. 

1881508660_850vort.thumb.png.8dc75aa3e825cc2f3595953d1fd66266.png

with favorable synoptic support in most of the eastern mid-atlantic and southern new england, it now just comes down to the multiple, smaller areas of lift that rotate around the deepening, complex low. i think some of the heavier precip that has yet to develop should focus near the trowal (trough of warm air aloft) this afternoon. most of the hi-res seem to favor areas just s and e of the city for the deeper convection, including parts of the jersey shore and long island.

trowal.thumb.png.874f5f1c9a7798448f393e2dab701b75.png

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2 hours ago, EastonSN+ said:

I lived in Norwalk for 96 and had 27 inches of snow. Most in my lifetime. 2016 I lived in Easton and only had 11.5. Even my old town of Norwalk (which is only 2 towns SW) had 16 (much less than 96) 2016 was basically further south than 1996.

Oh yeah there was a sharp cut off, it was the typical moderate-strong el nino coastal (like Feb 1983).  There was a west to east straight line of 30+ inches from Allentown to JFK (which are at the same latitude.)  The same area had the heaviest snows in Feb 1983.

 

 

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1 hour ago, purduewx80 said:

there's a pretty cool ~850mb feature over northern jersey producing some heavy downpours in the region. 

1881508660_850vort.thumb.png.8dc75aa3e825cc2f3595953d1fd66266.png

with favorable synoptic support in most of the eastern mid-atlantic and southern new england, it now just comes down to the multiple, smaller areas of lift that rotate around the deepening, complex low. i think some of the heavier precip that has yet to develop should focus near the trowal (trough of warm air aloft) this afternoon. most of the hi-res seem to favor areas just s and e of the city for the deeper convection, including parts of the jersey shore and long island.

trowal.thumb.png.874f5f1c9a7798448f393e2dab701b75.png

My sister was driving through NW NJ talking about how bad I-80 is and the flooding happening there and wondering why the forecasts called for only 0.5-1 inch of rain, she said it's at least 3 inches of rain on the roads.

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1 hour ago, uncle W said:

2006-07 averaged 36.5 for met winter...30 straight days averaged 25.8 from late Jan to late Feb...that means the other 60 days averaged 41.8...two sleet storms yielded almost 8" of snow and sleet...if those storms were snow NYC would have seen 25"...

edit...1984-85 averaged 36.4 for met winter...there were 30 consecutive days that averaged 27.5...the other 60 days averaged around 40.8...in contrast 2007-08 averaged 36.4 but the coldest 30 day period averaged only 35.7...that means the other 60 days averaged slightly 36...

And one of those storms wasn't even in the late Jan to late Feb period!  It was on St Paddy's Day in March!  Was that late Jan to late Feb period the coldest 30 day period of the winter?  I remember the cold didn't actually get here until the second week of February and the first three weeks of April were colder than the first three weeks of January!  So perhaps the February-March period was even colder!

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8 minutes ago, LibertyBell said:

Oh yeah there was a sharp cut off, it was the typical moderate-strong el nino coastal (like Feb 1983).  There was a west to east straight line of 30+ inches from Allentown to JFK (which are at the same latitude.)  The same area had the heaviest snows in Feb 1983.

 

 

1983 was still in Norwalk had 16.

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7 minutes ago, LibertyBell said:

My sister was driving through NW NJ talking about how bad I-80 is and the flooding happening there and wondering why the forecasts called for only 0.5-1 inch of rain, she said it's at least 3 inches of rain on the roads.

I am completely sick of all this rain. If its not gonna snow bring in 60s and sun

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1 minute ago, sussexcountyobs said:

We've gotten alot more rain than was forecasted for today here. Already 1.30" with heavy rain still falling and 38°. NWS forecast discussion this morn said they lowered precip amounts to .5 - .75". Guess they got it wrong?

Yes and there was flooding on I-80.  Imagine if this was a snow or ice bust lol.

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convective precip this afternoon is mainly driven by the 500mb jet nosing into areas south of montauk and the islands - both left front quad dynamics and diffluent flow are contributing to lift. thunderstorms really took off out there as a result and robbed the metro area of moisture and the overall best conditions. there is an mcv south of kmtp that is part of the broader low and mid-level circulations. 

mcv.thumb.png.0484c7b6b9bc90797f9b23e6bfcf7dd0.png

today is a good example of how mesoscale features can steal the show with some of these coastal lows. very few if any models consistently nailed the two-max precip; occurring well nw and se of the city. communicating how important nowcasting is over model-hugging can be a huge part of a meteorologist's job, despite the push to make operational decisions sometimes days in advance.

perhaps this is somewhat moot today since it's far too warm for snow. as the pattern becomes more favorable for colder air invading in the medium range and beyond, we should all keep in mind the myriad of reasons why there can be huge differences in snow amounts across the city and northeast in general with nor'easters and other coastal storms. 

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9 minutes ago, purduewx80 said:

convective precip this afternoon is mainly driven by the 500mb jet nosing into areas south of montauk and the islands - both left front quad dynamics and diffluent flow are contributing to lift. thunderstorms really took off out there as a result and robbed the metro area of moisture and the overall best conditions. there is an mcv south of kmtp that is part of the broader low and mid-level circulations. 

mcv.thumb.png.0484c7b6b9bc90797f9b23e6bfcf7dd0.png

today is a good example of how mesoscale features can steal the show with some of these coastal lows. very few if any models consistently nailed the two-max precip; occurring well nw and se of the city. communicating how important nowcasting is over model-hugging can be a huge part of a meteorologist's job, despite the push to make operational decisions sometimes days in advance.

perhaps this is somewhat moot today since it's far too warm for snow. as the pattern becomes more favorable for colder air invading in the medium range and beyond, we should all keep in mind the myriad of reasons why there can be huge differences in snow amounts across the city and northeast in general with nor'easters and other coastal storms. 

This is a good lesson though for future coastal storms that might be snow.  It's not a coincidence that even in all snow scenarios the southwest part of Nassau County seems to be in a bad spot for high snow totals, we dont usually get the convective snows here and end up in an area of subsidence.  Our best snows happen when there is less banding or there is a changeover area just to our south and then we get our largest ones like the ones we've been talking about- Feb 1983, PD2 and Jan 2016.  In Jan 2016 the changeover line was just to the south of LI and we ended up with 30"+ just 5-10 miles north of it.

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