April 2016 discussion/obs

[Allsnow]

Amazing how normal to slightly above normal temps are talked as a cool shot..same refrain the last few weeks and ive seen very warm days in this period

After Wed it will be normal to slightly below with chilly nights

[bluewave]

Yet another desert SW low Dew and RH day around the area.

 

KENNEDY INTL.................... 62 14 15

PHOENIX .............................75 20 12 

[donsutherland1]

12z gfs warmer now again...either way temps look to drop quickly into the 40's by later at night...This is for Tuesday.

All of that looks more reasonable than on the 6z run. Given the deep blocking, I wouldn't be surprised if the first 7-10 days of May winds up not far from normal. Afterward, things could warm up.

[Stormlover74]

Ewr hit 72 with 13% humidity. Forecast high was 64

[bluewave]

Ewr hit 72 with 13% humidity. Forecast high was 64

 

Concord, NH takes the dry prize for today.

 

CONCORD SUNNY 58 -3 8

[bluewave]

Euro only gives NYC .50 of rain for the rest of April. This would allow NYC to finish

in the top driest March-April slot. The Euro holds the decent rainfall potential

until the first week of May. That would be fitting since most consecutive dry

months recently in NYC were answered with a change to wetter in the third month.

 

NYC.....2.49  through today

 

Top 5 driest  MAR/APR for NYC

 

...3.09...1885

...3.32...1985

...3.54...1894

...3.55...1995

...3.63...1966

[uncle W]

Euro only gives NYC .50 of rain for the rest of April. This would allow NYC to finish

in the top driest March-April slot. The Euro holds the decent rainfall potential

until the first week of May. That would be fitting since most consecutive dry

months recently in NYC were answered with a change to wetter in the third month.

 

NYC.....2.49  through today

 

Top 5 driest  MAR/APR for NYC

 

#1...3.32...1985

#2...3.55...1995

#3...3.63...1966

#4...3.83...1915

#5...4.01...1935

before 1900, 1885 had 3.09"...1894 had 3.54"...

[bluewave]

before 1900, 1885 had 3.09"...1894 had 3.54"...

 

Thanks for that update from the late 1800's. I am hoping that the 2010's third month rebound in rainfall 

for May works out. I put together all the two months of the 2010's which had below 4 inches of

precip and the third month with a rebound in rainfall.

 

2015..APR/MAY....3.94....JUN....4.79

2014..AUG/SEP....3.46....OCT....5.77

2013..SEP/OCT....3.31....NOV....3.15

2012..FEB/MAR...2.33....APR.....3.56

 

2.49 through today Euro forecast .50 more for April

 

Top 5 driest  MAR/APR for NYC

 

...3.09...1885

...3.32...1985

...3.54...1894

...3.55...1995

...3.63...1966

[donsutherland1]

The deep blocking Bluewave has highlighted, has occurred during the 4/23-5/7 timeframe in 10 cases following El Niño winters. Although it has often resulted in cool anomalies across parts of the eastern half of the CONUS during spring (with some exceptions), there was often a pattern reversal that led to a warm summer overall.

 

 

During such cases, the likelihood of cases during which there were 25 or more 90° days was 30% vs. the 21% figure for the entire 1950-2015 period for New York City. The latest JMA still points to a warmer than normal summer.

 

In short if the blocking develops as modeled, it likely does not indicate that the probability of a warm or perhaps very warm summer has diminished. It might even be a reaffirming signal if some of the past cases including 1995 and 2005 are representative.

 

Finally, the lowest AO reading during the above-mentioned timeframe is -3.081, which occurred on April 25, 1995.

[bluewave]

Great post Don. If the GEFS are correct, we may be able to rival the strongest 

4/20-4/30 drop of -3.533 set on 4/20/89. The -AO is making a much better showing

recently after the more positive phase stretch from April 2013 into 2015.

The impressive plunge last July may have been a precursor to the strong

drop in January and the continued more -AO overall this year.

 

1989 4 20 -3.533

 

 

 

[doncat]

Euro only gives NYC .50 of rain for the rest of April. This would allow NYC to finish

in the top driest March-April slot. The Euro holds the decent rainfall potential

until the first week of May. That would be fitting since most consecutive dry

months recently in NYC were answered with a change to wetter in the third month.

 

NYC.....2.49  through today

 

Top 5 driest  MAR/APR for NYC

 

...3.09...1885

...3.32...1985

...3.54...1894

...3.55...1995

...3.63...1966

Have had 3.08" here since 3/1...We'll see how we do in May, my driest spring was in 1995 with 6.47".

[donsutherland1]

Great post Don. If the GEFS are correct, we may be able to rival the strongest 

4/20-4/30 drop of -3.533 set on 4/20/89. The -AO is making a much better showing

recently after the more positive phase stretch from April 2013 into 2015.

The impressive plunge last July may have been a precursor to the strong

drop in January and the continued more -AO overall this year.

 

1989 4 20 -3.533

Thanks. It will be interesting to see whether the AO approaches or surpasses that mark. There seems to be solid agreement about a figure at or below -3.000. On another note, the 12z NAM and GFS are still far apart on tomorrow's high temperature for NYC (NAM MOS: 71° and GFS MOS: 59°). I still think we'll get into the lower 60s and maybe Thursday or Friday would offer the better bet of a sub-60° high.

[uncle W]

The deep blocking Bluewave has highlighted, has occurred during the 4/23-5/7 timeframe in 10 cases following El Niño winters. Although it has often resulted in cool anomalies across parts of the eastern half of the CONUS during spring (with some exceptions), there was often a pattern reversal that led to a warm summer overall.

 

 

During such cases, the likelihood of cases during which there were 25 or more 90° days was 30% vs. the 21% figure for the entire 1950-2015 period for New York City. The latest JMA still points to a warmer than normal summer.

 

In short if the blocking develops as modeled, it likely does not indicate that the probability of a warm or perhaps very warm summer has diminished. It might even be a reaffirming signal if some of the past cases including 1995 and 2005 are representative.

 

Finally, the lowest AO reading during the above-mentioned timeframe is -3.081, which occurred on April 25, 1995.

April 1995 was the last time NYC got below 25 degrees...This year was close with 26 degrees earlier in the month...August and September could climax a very hot summer...

[donsutherland1]

April 1995 was the last time NYC got below 25 degrees...This year was close with 26 degrees earlier in the month...August and September could climax a very hot summer...

Summer 1995 might well be a viable scenario for how things will play out this summer, especially as it preceded the onset of a La Niña winter.

[forkyfork]

We could really use a slow moving cutoff low in the East like the ensembles hinting at

to increase rain chances for the first week of May.

 

ecmwf-ens_z500a_nhem_11.png

the eps has gfes support for a deep trough and slow moving low. i think this is our first real shot of a 2" or greater rain event since february 

[dmillz25]

the eps has gfes support for a deep trough and slow moving low. i think this is our first real shot of a 2" or greater rain event since february

This is for when?

[Stormlover74]

This is for when?

First 4-5 days of May

[HailMan06]

Surprised no one's posting on the storm at the moment. The thunder is so loud it woke me up.

[NycStormChaser]

Surprised no one's posting on the storm at the moment. The thunder is so loud it woke me up.

lots of lightning too

[dmillz25]

Surprised no one's posting on the storm at the moment. The thunder is so loud it woke me up.

Yeah it woke me up too

[weathermedic]

Line weakened (as usual) as it made it's way here. I guess the marine layer had something to do with that. Did have a gust front come through just prior to the rain. Gusted to 33 mph at my station here in Sheepshead Bay

[weathermedic]

Long Beach, Lido Beach and eastern Nassau looks like they are getting hit pretty good now.

[nzucker]

Yeah it woke me up too

Me too in the Bronx, Pelham Bay area. Torrential rain, vivid lightning, intense thunder. Definitely putting a dent in the drought.

[ForestHillWx]

Agreed, there was one flash with a canon blast of thunder following it.

[Cfa]

Decent storm that was, torrential rain and quite a bit of lightning although the thunder wasn't particularly loud.

[dmillz25]

First 4-5 days of May

Hopefully it's gone by May 5th which is my birthday although we could use the rain.

[NycStormChaser]

SPC outlook looks interesting for us later today.

[uncle W]

this April could have one of the lowest monthly AO number since 1950...most of those years had 90 degree heat in May...

[bluewave]

Looks like only the 3rd time that the -AO reached -3 or lower during the 4/20-4/30 period.

 

1989 4 20 -3.533

1995 4 25 -3.081

 

 

[donsutherland1]

Looks like only the 3rd time that the -AO reached -3 or lower during the 4/20-4/30 period.

 

1989 4 20 -3.533

1995 4 25 -3.081

 

ao.obs.gif

The dates I have are:

 

4/20/1989 -3.533

4/21/1989 -3.509

4/22/1989 -3.223

 

4/25/1995 -3.081

 

4/26/2016 -3.455 (preliminary) -- the old record for 4/26 was -2.683, which was set in 1960.