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April Discussion


IsentropicLift

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Ugly pattern progged to develop post April 19th-20th through the end of the month, which should seal the deal on a slightly cooler than normal April in the Northeast IMO. The -EPO will probably rebuild, except this time, height rises in the NAO domain could coincide with Alaskan ridging. I'm a bit more inclined to buy into the negative NAO trend as compared to this past winter given we've finally killed off the stratospheric vortex (zonal easterly winds at 10hpa/60N now), in conjunction w/ renewed phase 2 MJO forcing. So we're clearly in an El Nino atmospheric regime at this point, and it may be difficult to shake the -EPO signal, especially considering the extremely robust +PDO. Apparently the Euro monthlies have a fairly potent -EPO depicted from May right through this autumn. Not ready to make any comments on this summer yet, but my early thoughts are another "temperate" warm season could be on the way.

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It looks fairly certain from the long range pattern that this will be only the third April of the

2000's so far with no 80 degree readings in NYC. The two other years were 2014 and 2000.

I don't think they've hit 70F either yet.

I don't see how this month will average below normal. The next 7-10 days look somewhat above normal where as of yesterday we were already on the plus side.

That means the last week of April would have to be significantly below to pull off a negative departure.

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The GGEM also likes the amplified pattern for early next week or late this upcoming weekend. It would be nice if one of these worked out for once. 

 

f174.gif

 

 

Without phasing, that looks like a repeat of the past 60 days. Confluence will push things south as we get closer.

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It looks fairly certain from the long range forecast that this will be only the third April of the

2000's so far with no 80 degree readings in NYC. The two other years were 2014 and 2000.

We have a good shot at setting the April monthly lo max for the 2000's since we should

come in under the April 2014 high of 77 and the April 2000 high of 75 degrees.

the record latest 80 degree temp in NYC is early June 1924...two second year el nino analogs are 1969 and 1987...Both years had a max of 97 in late May...1977 was another second year el nino and it was hot...1958 and 2003 had cool damp springs and a average Summer...so far with spring half way over there is no sign of early heat...don't be fooled by that because other analogs had a cool May but hot Summer...1966 was one of those...

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I don't think they've hit 70F either yet.

I don't see how this month will average below normal. The next 7-10 days look somewhat above normal where as of yesterday we were already on the plus side.

That means the last week of April would have to be significantly below to pull off a negative departure.

 

 

 

GFS ensembles are quite chilly relative to normal for April 21st-30th due to the development of blocking:

 

303ls2o.png

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the record latest 80 degree temp in NYC is early June 1924...two second year el nino analogs are 1969 and 1987...Both years had a max of 97 in late May...1977 was another second year el nino and it was hot...1958 and 2003 had cool damp springs and a average Summer...so far with spring half way over there is no sign of early heat...don't be fooled by that because other analogs had a cool May but hot Summer...1966 was one of those...

 

 

 Agree. In fact, I think there's a tendency for hotter summers following cool May's rather than vice versa. May often has an inverse correlation to JJA.

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Without phasing, that looks like a repeat of the past 60 days. Confluence will push things south as we get closer.

The energy ejects from a closed low. You're going to be pretty hard pressed to get the northern stream to phase in during late April. Hopefully the northern jet is too far North and gets out of the way.

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 Agree. In fact, I think there's a tendency for hotter summers following cool May's rather than vice versa. May often has an inverse correlation to JJA.

You can't "often" have an inverse correlation.  Correlation does not mean what you think it means.

 

That being said, IIRC, the best approach to warm season forecasting is persistence (in part, IIRC, because of the soil moisture effect).

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You can't "often" have an inverse correlation.  Correlation does not mean what you think it means.

 

That being said, IIRC, the best approach to warm season forecasting is persistence (in part, IIRC, because of the soil moisture effect).

 

What?  You can have an inverse (negative) correlation.  The correlation coefficient is between -1 and 1.

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You can't "often" have an inverse correlation.  Correlation does not mean what you think it means.

 

That being said, IIRC, the best approach to warm season forecasting is persistence (in part, IIRC, because of the soil moisture effect).

 

 

Yes, you can. You're not correct here. Inverse correlation simply means that there is a negative relationship between two variables, namely, as one variables increases, the other decreases, and vice versa. In this case, I was applying it to May-JJA temperatures. Cooler than normal temperatures in May have often preceded hotter than normal summers. That would be considered an inverse correlation. Obviously there's no 100% of the time guarantees; I was simply making an observation that there tends to be a negative relationship between May temperatures relative to normal and the ensuing JJA temperatures relative to normal.

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The overnight guidance moved to making Saturday the warmest day of the month so far 

with NYC finally getting above 70 on a warm downslope flow. We'll see if the later runs

follow through on this idea. We had a few overperforming downslope days earlier this

spring.

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The overnight guidance moved to making Saturday the warmest day of the month so far

with NYC finally getting above 70 on a warm downslope flow. We'll see if the later runs

follow through on this idea. We had a few overperforming downslope days earlier this

spring.

Alot of news stations are calling for 70 today. I don't it will happen. You think it could hit 70 today?

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The overnight guidance moved to making Saturday the warmest day of the month so far

with NYC finally getting above 70 on a warm downslope flow. We'll see if the later runs

follow through on this idea. We had a few overperforming downslope days earlier this

spring.

Anyone in nyc (other than the park/lga) get to 70 yet Staten Island , bklyn, queens etc? Just curious.

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Looking like my third 70 plus day coming up...should be gorgeous

Posts like this just made me realize how boring the weather would be living in Southern California. 99% of the posts everyday would be like this.

I don't really see cool weather end of month, just seasonable which would solidify April being above average especially given we should be well above normal today through Saturday.

The cooler weather is around the Midwest/Great lakes region.

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