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March 2021


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1 hour ago, donsutherland1 said:

The City radiates poorly. I had thick frost the past two days (not today), as well. 

Good morning Don. Tradition/political considerations aside where ( if any place ) would it be best to take official readings/measurements for NYC?  As always ...

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3 minutes ago, rclab said:

Good morning Don. Tradition/political considerations aside where ( if any place ) would it be best to take official readings/measurements for NYC?  As always ...

Much of the City is now tainted by the urban heat island effect. Parts of the northern Bronx and also Staten Island are less severely impacted. Central Park could be improved with some commitment to greater accuracy there. That would entail managing the tree growth around the station, measuring snowfall when the snow stops falling, etc. The issue of trees has a larger impact on temperatures. 

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17 minutes ago, donsutherland1 said:

Much of the City is now tainted by the urban heat island effect. Parts of the northern Bronx and also Staten Island are less severely impacted. Central Park could be improved with some commitment to greater accuracy there. That would entail managing the tree growth around the station, measuring snowfall when the snow stops falling, etc. The issue of trees has a larger impact on temperatures. 

Yeah, the issue of trees blocking direct sunlight has had a much bigger impact on temperature accuracy. You can see the cooler maximum temperatures now when the trees are fully leafed out. UHI has been remarkably steady since 1900 in Central Park.

466B33B4-E2B0-431C-8ED1-43719FAFC18D.thumb.jpeg.89dd97a62292a50bf2244d34ae9d595b.jpeg

 

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there is something different about radiation shields and weather shelters or box's for thermometers...I've found radiation shields are not as good as the old weather shelters or box's in direct sunlight...I think Central Parks instrument location effects nightime lows too...

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15 minutes ago, uncle W said:

there is something different about radiation shields and weather shelters or box's for thermometers...I've found radiation shields are not as good as the old weather shelters or box's in direct sunlight...I think Central Parks instrument location effects nightime lows too...

The low temperatures in NYC seem to be doing better that the highs during the summer. Notice how there has been a slight decline in average high temperatures since 1981. This reflects the overgrowth of trees and vegetation. White Plains and NYC have a similar rise in minimum temperatures. But you can see the highs increasing there since the sensor at the airport isn’t under a dense canopy. So while people rightly take issue with Central Park snowfall measurements, the error is far less than the temperature sensor getting overgrown by vegetation. 

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3 minutes ago, bluewave said:

The low temperatures in NYC seem to be doing better that the highs during the summer. Notice how there has been a slight decline in average high temperatures since 1981. This reflects the overgrowth of trees and vegetation. White Plains and NYC have a similar rise in minimum temperatures. But you can see the highs increasing there since the sensor at the airport isn’t under a dense canopy. So while people rightly take issue with Central Park snowfall measurements, the error is far less than the temperature sensor getting overgrown by vegetation. 

6FEC0B54-C045-4E0F-82C5-9B868858E1D8.thumb.jpeg.d3c916a2572dfd35e2e7cba4ccdcf633.jpeg

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its hard to radiate when you have a roof of branches above the probe and being shaded it helps keep daytime highs down...so we have cooler highs and warmer lows...you can say that's because of the extra water vapor in the air...probably a little of both...

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2 hours ago, uncle W said:

its hard to radiate when you have a roof of branches above the probe and being shaded it helps keep daytime highs down...so we have cooler highs and warmer lows...you can say that's because of the extra water vapor in the air...probably a little of both...

COOP sites are maintained much better than Central Park.

Most recent photo in 2013...must be even more overgrown by now...

64A951ED-8B71-4D6B-9A45-C021705ADDEE.jpeg.d6c9d33c81053e8ca1c206ac0b8272e7.jpeg
 

Old photo before vegetation was overgrown

 

A9B5A8D0-FF44-4029-8216-C3B759E638E4.jpeg.a7484811c8efa7fa024bf66efa19ae50.jpeg

 

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2 hours ago, jm1220 said:

Long Beach 51 degrees right now, my neighborhood 63. So glad I don’t have to endure “spring” there again. 

I feel the same way having lived in Far Rockaway. 68 here, at least 15 degrees colder there.

Summer occasionally sucked too with that Ambrose jet.

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Tomorrow will be mostly cloudy with some showers, along with cooler temperatures. Following passage of the warm front, Thursday and Friday will be much warmer. Highs in the region will reach the upper 60s and lower 70s Thursday and lower to middle 70s with some upper 70s on Friday. Some showers and even thundershowers are possible, especially on Friday.

A sustained period of above to much above normal temperatures is now underway. In general, above normal temperatures will persist through the end of March. Any cool shots will likely be modest and brief. Some of the guidance suggests that a cold shot and at least some snow could affect northern New England near the end of March.

The ENSO Region 1+2 anomaly was +0.5°C and the Region 3.4 anomaly was -0.5°C for the week centered around March 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.08°C and the ENSO Region 3.4 anomaly has averaged -0.77°C. La Niña conditions will likely give way to neutral-cool ENSO conditions as the spring progresses.

The SOI was +5.41 today.

The preliminary Arctic Oscillation (AO) figure was +3.596 today.

The 31° temperature recorded at Central Park on March 19 was likely New York City's last freeze of 2020-21 based on a combination of the latest ensemble guidance and the diminishing frequency of April freezes.

April freezes have become less frequent in recent years. During the 1991-2020 base period, there were 12 cases where the last freeze occurred in April. The last time the temperature fell to freezing in April occurred in 2018.

Select April Statistics:

1951-80: Years with freezes: 17; Mean days with lows of 32° or below: 1.1
1961-90: Years with freezes: 17; Mean days with lows of 32° or below: 1.3
1971-00: Years with freezes: 16; Mean days with lows of 32° or below: 1.2
1981-10: Years with freezes: 12; Mean days with lows of 32° or below: 1.0
1991-20: Years with freezes: 12; Mean days with lows of 32° or below: 1.0

Least years with freezes: 10, 1984-2013

Most years with freezes: 26, 1874-1903, 1880-1909, 1895-1924, 1896-1925, and 1897-1926

Lowest number of average days with temperatures of 32° or below: 0.8, 1983-2012, 1984-2013, 1985-2014, and 1986-2015

Highest number of average days with temperatures of 32° or below: 3.7, 1871-1900 and 1872-1901

Least days in April with temperatures of 32°: 0, Most Recent: 2020

Most days in April with temperatures of 32°: 11, Most Recent: 1874   

Based on sensitivity analysis applied to the latest guidance, there is an implied 95% probability that New York City will have a warmer than normal March. March will likely finish with a mean temperature near 44.6° (2.1° above normal).

 

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8 hours ago, bluewave said:

Friday could be the warmest day of the year so far. Euro has mid to upper 70s. Then 50 mph + wind gust potential with the cold front.

 

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For west of the city sure. East of the city it's about when the front passes and winds turn westerly. If it's early to mid afternoon most of us could get over 70. 

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16 hours ago, donsutherland1 said:

Much of the City is now tainted by the urban heat island effect. Parts of the northern Bronx and also Staten Island are less severely impacted. Central Park could be improved with some commitment to greater accuracy there. That would entail managing the tree growth around the station, measuring snowfall when the snow stops falling, etc. The issue of trees has a larger impact on temperatures. 

Don, what about the area near Bayside, Queens?  I've always thought that part of the city had more natural conditions.  The other area is near JFK or possibly parts of Staten Island.

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15 hours ago, bluewave said:

COOP sites are maintained much better than Central Park.

Most recent photo in 2013...must be even more overgrown by now...

64A951ED-8B71-4D6B-9A45-C021705ADDEE.jpeg.d6c9d33c81053e8ca1c206ac0b8272e7.jpeg
 

Old photo before vegetation was overgrown

 

A9B5A8D0-FF44-4029-8216-C3B759E638E4.jpeg.a7484811c8efa7fa024bf66efa19ae50.jpeg

 

whats their excuse for not cutting the vegetation- can't they be fined for not doing it?

Fine them 1000 a day until they do it!

 

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Interesting read for today/tonight from Mt. Holly 

.NEAR TERM /THROUGH TONIGHT/... 
  The lengthy stretch of dry weather comes to an end today.  
  Beautiful satellite imagery over the CONUS this morning as an  
  occluding mid- latitude cyclone slowly approaches the western  
  Great Lakes. Ahead of it lies an expansive frontal zone of cloud 
  cover with a large band of cold cloud tops observed on IR from  
  Canada to the Gulf of Mexico. Precipitation in most of this band 
  is limited and on the light side as of early this morning,  
  however. Meanwhile, a weak but pesky surface low which has sat  
  well to our south for days was observed on radar moving inland  
  over North Carolina overnight. The landfall was reminiscent of a 
  weak tropical cyclone moving ashore. FSU cyclone phase space  
  diagrams suggest it had at best a marginal and shallow warm core 
  at landfall, and a lack of any deep convection rendered it  
  firmly non-tropical. But it has a good envelope of higher  
  moisture air associated with it from the sub-tropics, and as the 
  day goes on it will begin to interact with the approaching  
  frontal zone. This combination will lead to the blossoming of an 
  area of showers which will bring a solid dose of rain to the  
  area.  
   
  Prior to the start of rainfall, we`ve seen low clouds fill in  
  over much of the area overnight as the low levels moisten  
  further in the continued light onshore flow regime. This trend  
  should continue into daybreak, and we should see more in the way 
  of fog develop as well. It is possible we could see some breaks 
  in the clouds during the mid morning hours as mixing begins and 
  before rain arrives, but this is uncertain and probably less  
  likely than not. As the day goes on, what remains of the low to  
  the south will become entrained in the slow moving frontal zone  
  and will move towards our region. Continuing a trend that has  
  been ongoing for at least 36 hours now, most model guidance  
  continues to trend higher on QPF for this event. There has  
  certainly been a trend higher in projected PWATs for today,  
  which appear poised to rise to 1.2 to 1.4 inches across the  
  region. Low level omega shows notable improvement over the area  
  today, especially this afternoon. There is also a somewhat  
  subtle ~95 kt upper jet streak which moves into New York state  
  this afternoon, adding a bit of divergence at the upper levels.  
  With this said, continuing the connections to tropical weather,  
  there are at least some loose parallels to a Predecessor Rain  
  Event (PRE) in play today with the rising PWATs and right  
  entrance jet dynamics, especially considering the actual center  
  of the compact low remains south of the region for most of the  
  day. While there is quite a bit of variation in the models, it  
  now appears many areas will pick up 0.5 to 1.0 inches of rain  
  today, with the potential for some localized higher amounts  
  especially over southeastern portions of the area near the low  
  center, and possibly over eastern PA with some orographic  
  enhancement as well as the better jet dynamics. The trends have  
  been a little slower on timing of rainfall, but showers should  
  overspread the region from southwest to northeast mainly between 
  9AM and 2PM. Lighter showers or drizzle are possible before the 
  arrival of steadier rain. Once the steadier rain arrives, it  
  should continue through at least most of the daylight hours,  
  possibly tapering off late in the day to the southwest. Given  
  the rising PWATs and respectable dynamics, some heavier  
  downpours are possible. So a wet day overall, especially this  
  afternoon. While the air mass remains on the warm side, the rain 
  and clouds will hold highs down in the mid to upper 50s in most 
  of the area. 
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The last 8 days of March are averaging 54degs.(45/63), or +8.0.

Month to date is 42.2[+1.0].          March should end at 45.2[+2.7].

50*(86%RH) here at 6am.       54* by 9am.     57* by 11am.         53* at 5pm (rain started back at 2pm).

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The weak low that almost  had subtropical characteristics will bring some much needed rains  today. The models have elevated convection with locally heavy downpour potential. This tucked in low track looks similar to the tropical systems last summer that affected the area. More of the same on tap for this year? Stay tuned....


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