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April 2020


donsutherland1
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Tomorrow will see abundant sunshine, but the respite from rain will be short-lived. Another storm will bring a general 0.50"-1.50" rain to much of the region later Sunday into Monday.

Temperatures will likely average generally below normal across the Middle Atlantic and southern New England regions through most of the remainder of the month. Warmer than normal conditions could return near the end of the month or just afterward.
 
Past cases that saw the NAO average -0.750 or below during April 1-5 with warmth in the East, as occurred this month, saw the development of a trough in the East after April 10. That trough typically persisted in the means for 1-2 weeks.

Looking ahead to May, 73% of cases that saw one or more days where the NAO fell to -1.000 or below during April 1-10, 1950-2019, as was the case this April, wound up with a warmer than normal May. However, uncertainty about the May outcome has increased. The MJO was recently in Phase 1 at an amplitude in excess of 1.500 for two days. During the 1981-2019 period, the MJO was in Phase 1 at an amplitude of 1.500 or above for two or more years in six cases: 1988, 1990, 1995, 1997, 2005, and 2010. During May, three (50%) were cooler than normal; two (33%) were near normal; and, one (17%) was warmer than normal. Ultimately, two-thirds of those cases went on to have a warmer to much warmer than normal summer.

The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.7°C for the week centered around April 8. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.55°C and the ENSO Region 3.4 anomaly has averaged +0.62°C. Neutral and occasionally warm ENSO conditions will likely prevail through mid-May. ENSO Region anomalies could begin a steady cooling during late April or May.

The SOI was +0.07 today.

Today, the preliminary Arctic Oscillation (AO) figure was +0.514.

On April 23, the MJO was in Phase 2 at an amplitude of 2.051 (RMM). The April 22-adjusted amplitude was 1.790.

February 2020 saw the ENSO Region 1+2 anomaly increase by more than 0.50°C. Such a development has typically occurred before a warmer than normal summer. In all such cases, a warmer than normal spring was followed by a warmer than normal summer. Based on recent MJO data, the probability of a warmer than normal summer has increased. Such a summer is now likely in much or all of the East.

Based on sensitivity analysis applied to the latest guidance, there is an implied 96% probability that New York City will have a cooler than normal April. April will likely finish with a mean temperature near 51.0°.

 

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The last 6 days of April are averaging 51.5degs., or about 6degs. BN.

Month to date is  -1.9[50.2].         April should end at  -2.6[50.4].       This is about -1.4sd BN.

47* here at 6am.         54* by 10am.         59* by 4pm.         50* by 11am.

 

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This is the coolest April average and maximum temperature in NYC following a 40+ Dec-Mar. The only other April with close to a similar monthly max was 1998. That was also the coolest summer out of the group. Be interesting to see if we avoid the big heat of most other summers that followed such warm DJFM periods.

Time Series Summary for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Mean Avg Temperature Dec 1 to Mar 31
April  Avg and Max 
1 2012-03-31 43.1 54.8   88
2 2016-03-31 43.0 53.3   82
3 2002-03-31 42.2 56.1  96
4 2020-03-31 41.4 50.1   68
5 1998-03-31 41.1 54.0  73
6 1991-03-31 40.5 55.7   90

Newark number of 90 degree days

2016...40.....5th highest

2012...33.....11th highest

2002...41.....4th highest

1998...21

1991...41.....4th highest

 

 

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52 minutes ago, uncle W said:

don't be surprised if the summer wasn't a scorcher... I'm thinking a normal to below normal summer with average to above average precipitation as of now...1919, 1946 and 1998 are the analogs so far...

@Wxoutlooksblogseems agree and thinks it won’t be a hot summer with this persistent NW flow pattern. Good for severe weather this year around here though. 

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1 hour ago, uncle W said:

don't be surprised if the summer wasn't a scorcher... I'm thinking a normal to below normal summer with average to above average precipitation as of now...1919, 1946 and 1998 are the analogs so far...

Everyone calling for above normal but many thought April would be above normal too

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2 hours ago, MJO812 said:

Beautiful outside

Walking near the water in Manhattan Beach

I had to go to Bay Ridge today and was amazed at the number of folks walking the shore between the Verrazano Bridge ant the old ferry pier. It was gratifying to see that everyone was Wearing protective masks and keeping a safe space and pace. It was also nice to see couples holding hands. The restrictions will be more difficult to maintain once true late spring/earl6 summer .weather really get going.  As always ....

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7 hours ago, uncle W said:

don't be surprised if the summer wasn't a scorcher... I'm thinking a normal to below normal summer with average to above average precipitation as of now...1919, 1946 and 1998 are the analogs so far...

A "cool" summer is still plenty hot. I really don't understand why people want 98° and humid. Just like I don't understand the need of people for it to be -5° and clear. 25° and snow is ideal in winter and 75° and sunny would be a dream in summer.

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Under partly to mostly sunny skies, temperatures rose into the springlike 60s across much of the region. However, the dry respite will quickly come to an end. Another storm will bring a general 0.50"-1.50" rain to much of the region later tomorrow into Monday.

Temperatures will likely average generally below normal across the Middle Atlantic and southern New England regions through the remainder of the month. Warmer conditions will likely return during the first week of May.
 
Past cases that saw the NAO average -0.750 or below during April 1-5 with warmth in the East, as occurred this month, saw the development of a trough in the East after April 10. That trough typically persisted in the means for 1-2 weeks.

Looking ahead to May, 73% of cases that saw one or more days where the NAO fell to -1.000 or below during April 1-10, 1950-2019, as was the case this April, wound up with a warmer than normal May. However, uncertainty about the May outcome has increased. The MJO was recently in Phase 1 at an amplitude in excess of 1.500 for two days. During the 1981-2019 period, the MJO was in Phase 1 at an amplitude of 1.500 or above for two or more years in six cases: 1988, 1990, 1995, 1997, 2005, and 2010. During May, three (50%) were cooler than normal; two (33%) were near normal; and, one (17%) was warmer than normal. Ultimately, two-thirds of those cases went on to have a warmer to much warmer than normal summer.

The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.7°C for the week centered around April 8. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.55°C and the ENSO Region 3.4 anomaly has averaged +0.62°C. Neutral and occasionally warm ENSO conditions will likely prevail through mid-May. ENSO Region anomalies could begin a steady cooling during late April or May.

The SOI was -3.53 today.

Today, the preliminary Arctic Oscillation (AO) figure was +0.610.

On April 24, the MJO was in Phase 2 at an amplitude of 2.155 (RMM). The April 23-adjusted amplitude was 2.049.

February 2020 saw the ENSO Region 1+2 anomaly increase by more than 0.50°C. Such a development has typically occurred before a warmer than normal summer. In all such cases, a warmer than normal spring was followed by a warmer than normal summer. Based on recent MJO data, the probability of a warmer than normal summer has increased. Such a summer is now likely in much or all of the East.

Based on sensitivity analysis applied to the latest guidance, there is an implied 99% probability that New York City will have a cooler than normal April. April will likely finish with a mean temperature near 50.5°.

 

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3 hours ago, donsutherland1 said:

Under partly to mostly sunny skies, the temperature rose into the middle 60s this afternoon. As a result, people came out to the parks, some wearing masks, others none.

Larchmont04252020-5.jpg

Larchmont04252020-10.jpg

Larchmont04252020-9.jpg

Larchmont04252020-11.jpg

Larchmont04252020-6.jpg

Looks like Greenwich, CT.  The park on the sound is just delightful.

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The last 5 days of April are averaging 52degs., or about 6degs. BN.

Month to date is  -1.9[50.3].        April should end at  -2.4[50.6].

Big differences between GFS OP/ENS.       Both are wet, +50%, but ENS. has much lower T's.

51* here at 6am, overcast.        53* from 10am-Noon, rain.        49* at 3pm.         46* by 9pm.        45* by 11pm.

I only got to 59.3* yesterday---near the water I guess.      JFK was 61*, but a lot of 65*'s elsewhere.

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Some of the lowest April maximum temperatures on record across the region this month.

Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 2020 69 5
2 1940 70 0
3 1931 71 0
Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 1874 64 0
- 1873 64 0
2 1940 67 0
- 1875 67 0
3 2020 68 5
- 1883 68 0
Time Series Summary for LAGUARDIA AIRPORT, NY - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 1940 67 0
2 2020 69 5
- 1988 69 0
- 1980 69 0
Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 2020 66 5
2 1998 67 0
3 2014 69 0

 

Time Series Summary for WESTCHESTER CO AP, NY - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature
Missing Count
1 2020 64 5
2 1971 67 0
3 1975 68 0

 

Time Series Summary for IGOR I SIKORSKY MEMORIAL AIRPORT, CT - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 2020 66 5
- 1998 66 0
- 1980 66 0
- 1950 66 0

 

Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 2020 64 5
2 1988 68 0
- 1975 68 0

 

Time Series Summary for New Brunswick Area, NJ (ThreadEx) - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 2020 70 6
- 1916 70 0
3 1966 71 0

 

Time Series Summary for PHILADELPHIA INTL AP, PA - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature 
Missing Count
1 1975 73 0
2 1988 74 0
3 2020 75 5
- 1997 75 0
- 1984 75 0

 

Time Series Summary for POUGHKEEPSIE AIRPORT, NY - Month of Apr
Click column heading to sort ascending, click again to sort descending.
Rank
Year
Highest Max Temperature
Missing Count
1 2020 68 5
2 1975 69 0
3 1988 71 0
- 1966 71 0
- 1961 71 0
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A week away but its currently looking that with enough sunshine next Sun (5/3) and/or Mon (5/4) could see the warmest temps of the season before a return to cooler weather into the 5th.

Not betting on it but models hinting brief warm up as transient ridging moves through ahead of the next trough.

Overall it does look like a slower transition away from the sustained troughing/cooler weather we've had since around Easter.  Somewhat reminiscent of 2008 (so far).

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36 minutes ago, Brian5671 said:

where's all the rain today?   Looks like bulk of the day could be dry....

Radar looks light for the NYC metro area currently. Below is Upton’s thoughts.

Area Forecast Discussion
National Weather Service New York NY
1048 AM EDT Sun Apr 26 2020

.SYNOPSIS...
Low pressure impacts the region today through Monday. High
pressure then briefly builds in for Tuesday. A frontal system
approaches Wednesday night and will affect the region through
Thursday night, and possibly the first half of Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Dry air in the low levels as noted on the 12Z KOKX sounding
keeping precipitation light and scattered thus far. Surface
dewpoint depressions are on the rise, but bulk of the
precipitation remains southeast of the area. Short term CAMs
are suggesting some potential for thunder later in the
afternoon than originally forecast, and so updates have been
made reflecting this.

Surface low pressure over the Ohio Valley will track eastward
today while a secondary low develops near the Mid-Atlantic
coast. This low will become the primary low and track just south
us tonight into Monday. Expect periods of rain today. Rain
starts off mostly on the lighter side. More intense rainfall,
mostly moderate, starts in the second half of this morning and
lasts through the first half of the afternoon as models have
trended drier in the mid levels during the late afternoon and
evening hours. This moderate rainfall will coincide with the
strongest thermal and llj forcing, synoptic lift from upper jet
streak dynamics, and deepest moisture available as an H8 theta-e
ridge shifts through. The mid-level drying casts more doubt on
the chances of an afternoon thunderstorm as mid-level lapse
rates steepen and elevated instability shifts through, but the
strongest overall lift is exiting. Will still leave in a slight
chance of thunder and the potential for at least moderate
rainfall for the entire afternoon as confidence is not high
enough to remove the mention completely. It`ll be breezy,
particularly for coastal sections with an E-NE flow. High
temperatures will be well below normal.
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