Spring/Summer 2021 Weather Threats Discussion

[Rtd208 3,773]

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. 

[Rtd208 3,773]

Interesting discussion from Mt. Holly for both Friday and Sunday.

Model soundings suggest winds will be increasing in this regime, 
  readily gusting to 35+ mph by afternoon. As winds begin to veer, 
  diurnal mixing peaks, and a reinforcing cold front approaches 
  the area, speeds will likely exceed advisory criteria in much of 
  the area. Winds at 850 mb will be approaching 50 kt, and mixing 
  has the potential to reach or even exceed this level. Seems 
  likely we will need a wind advisory for Friday afternoon and 
  evening, and if mixing ends up being more efficient than 
  currently advertised, a rogue severe-caliber gust may occur. 
  Held off on issuing wind headlines early this morning given 
  ongoing/near-term weather, but expect wind products to be  
  issued for the afternoon package. 
   
  Winds should decrease fairly rapidly Friday night as the 
  migratory surface low takes the strong pressure gradient with it 
  to our northeast. Strong cold advection will be occurring in the 
  post-frontal regime, but winds will not entirely decouple. Thus, 
  kept Friday night lows fairly warm, generally in the 40s to 
  around 50. 

.LONG TERM /SUNDAY THROUGH WEDNESDAY/... 
  A fairly strong system will affect the region on Sunday, though 
  the surface cyclone should lift well north of the region. 
  Nevertheless, upper dynamics look fairly impressive as an  
  initially positively-tilted trough begins to pivot to a more  
  neutral tilt as it approaches the East Coast during the day. A  
  100+ kt speed max at 500 mb will nose into the Mid-Atlantic  
  during the afternoon, collocated with a surging cold front to  
  the south of the aforementioned surface low. As warm advection  
  races north in the developing warm sector, convection should  
  readily develop along the attendant warm/cold fronts. Widespread 
  precipitation should occur in New England and the Mid-Atlantic  
  in this setup, with areal QPF likely exceeding a half inch  
  across the CWA (locally much higher amounts possible). Will need 
  to watch this system closely, as both severe and hydro issues  
  may be present depending on the usual timing/track issues. 

[Qtown Snow 7,804]

april fools

[Snowman11 18,528]

22 minutes ago, Qtown Snow said:

april fools

 

[Snowman11 18,528]

NAO and AO taking a nosedive next week

 

Lets see how long the NAO will stay negative 

[CCB! 36,055]

Just some red meat for you animals.

 

 

CMC:

 

 

Because why not:

 

[donsutherland1 7,174]

Temperatures soared to record highs in much of the region today as clouds yielded to sunshine and strong winds. At New York City's Central Park, the temperature reached 80° in March for the first time since March 31, 1998 when the temperature topped out at a sizzling 86°. Today was also just the 16th day on record when the temperature reached or exceeded 80° in Central Park. Records go back to 1869. Today was also the first 80° reading at JFK Airport since March 29, 1998 when the mercury rose to 82°.

 

High temperatures included:

 

Albany: 75° (old record: 74°, 1986)
Allentown: 77° (old record: 74°, 1963)
Annapolis: 83°
Atlantic City: 83° (old record: 71°, 1986 and 2003)
Baltimore: 83°
Bridgeport: 79° (old record: 70°, 1954)
Georgetown, DE: 86° (old record: 78°, 1988 and 2004)
Harrisburg: 77°
Hartford: 77° (old record: 74°, 1922)
Islip: 78° (old record: 65°, 1976)
Jacksonville: 90° (old record: 88°, 1965)
New Haven: 77° (old record: 67°, 1954)
New York City-JFK: 81° (old record: 67°, 1954)
New York City-LGA: 82° (old record: 72°, 1943)
New York City-NYC: 82° (old record: 76°, 1922)
Newark: 84° (old record: 73°, 1986)
Philadelphia: 83° (old record: 80°, 1921)
Poughkeepsie: 79° (old record: 75°, 1949 and 1963)
Richmond: 86° (old record: 85°, 1939)
Savannah: 90° (old record: 88°, 1929)
Salisbury: 82°
Sterling, VA: 81° (old record: 78°, 2004)
Trenton: 81° (old record: 79°, 1910 and 1921)
Washington, DC: 84°
Westhampton: 72° (old record: 67°, 1954)
White Plains: 80° (old record: 76°, 1963)
Wilmington, DE: 84° (old record: 77°, 1921)

 

Tomorrow will be cooler but still warm for the season. The ongoing sustained period warmer than normal readings will continue through the end of March.

 

In contrast, April could start out on the cold side. Historic experience following a warm to very warm March suggests a probability that is skewed toward a warmer than normal April.
 
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 +9.57 today.

 

The preliminary Arctic Oscillation (AO) figure was +3.347 today.

 

On March 24 the MJO was in Phase 2 at an amplitude of 1.394 (RMM). The March 23-adjusted amplitude was 1.483 (RMM).

 

Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal March. March will likely finish with a mean temperature near 45.2° (2.7° above normal).

 

[MR FREEZE 357]

1 hour ago, donsutherland1 said:

Temperatures soared to record highs in much of the region today as clouds yielded to sunshine and strong winds. At New York City's Central Park, the temperature reached 80° in March for the first time since March 31, 1998 when the temperature topped out at a sizzling 86°. Today was also just the 16th day on record when the temperature reached or exceeded 80° in Central Park. Records go back to 1869. Today was also the first 80° reading at JFK Airport since March 29, 1998 when the mercury rose to 82°.

 

High temperatures included:

 

Albany: 75° (old record: 74°, 1986)
Allentown: 77° (old record: 74°, 1963)
Annapolis: 83°
Atlantic City: 83° (old record: 71°, 1986 and 2003)
Baltimore: 83°
Bridgeport: 79° (old record: 70°, 1954)
Georgetown, DE: 86° (old record: 78°, 1988 and 2004)
Harrisburg: 77°
Hartford: 77° (old record: 74°, 1922)
Islip: 78° (old record: 65°, 1976)
Jacksonville: 90° (old record: 88°, 1965)
New Haven: 77° (old record: 67°, 1954)
New York City-JFK: 81° (old record: 67°, 1954)
New York City-LGA: 82° (old record: 72°, 1943)
New York City-NYC: 82° (old record: 76°, 1922)
Newark: 84° (old record: 73°, 1986)
Philadelphia: 83° (old record: 80°, 1921)
Poughkeepsie: 79° (old record: 75°, 1949 and 1963)
Richmond: 86° (old record: 85°, 1939)
Savannah: 90° (old record: 88°, 1929)
Salisbury: 82°
Sterling, VA: 81° (old record: 78°, 2004)
Trenton: 81° (old record: 79°, 1910 and 1921)
Washington, DC: 84°
Westhampton: 72° (old record: 67°, 1954)
White Plains: 80° (old record: 76°, 1963)
Wilmington, DE: 84° (old record: 77°, 1921)

 

Tomorrow will be cooler but still warm for the season. The ongoing sustained period warmer than normal readings will continue through the end of March.

 

In contrast, April could start out on the cold side. Historic experience following a warm to very warm March suggests a probability that is skewed toward a warmer than normal April.
 
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 +9.57 today.

 

The preliminary Arctic Oscillation (AO) figure was +3.347 today.

 

On March 24 the MJO was in Phase 2 at an amplitude of 1.394 (RMM). The March 23-adjusted amplitude was 1.483 (RMM).

 

Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal March. March will likely finish with a mean temperature near 45.2° (2.7° above normal).

 

Are you sure March 2012 didn't hit 80 on any days?

[MR FREEZE 357]

1 hour ago, MR FREEZE said:

Are you sure March 2012 didn't hit 80 on any days?

Just looked into it and it appears 76 was the best it got to in the park.  Still, this was one of the warmest March's on record in many places in the eastern third of the country.  Numbers were skewed warmer at both Kennedy and LaGuardia airports.

[Analog96 10,883]

30 minutes ago, MR FREEZE said:

Just looked into it and it appears 76 was the best it got to in the park.  Still, this was one of the warmest March's on record in many places in the eastern third of the country.  Numbers were skewed warmer at both Kennedy and LaGuardia airports.

More consistent warmth. There were no cold spells in between the warm days.

[uncle w 4,332]

10 hours ago, MR FREEZE said:

Just looked into it and it appears 76 was the best it got to in the park.  Still, this was one of the warmest March's on record in many places in the eastern third of the country.  Numbers were skewed warmer at both Kennedy and LaGuardia airports.

warmest March temps in NYC...

86 3/29/1945.........
86 3/31/1998......... 
85 3/13/1990.........
84 3/21/1921......... 
84 3/28/1945......... 
83 3/20/1945......... 

83 3/27/1998
82 3/16/1990.........

82 3/26/2021
82 3/28/1921......... 
82 3/30/1998.........
82 3/29/1985......... 

81 3/29/1977

81 3/29/1998

80 3/28/1998

[MJOP8 4,271]

3 hours ago, uncle w said:

warmest March temps in NYC...

86 3/29/1945.........
86 3/31/1998......... 
85 3/13/1990.........
84 3/21/1921......... 
84 3/28/1945......... 
83 3/20/1945......... 

83 3/27/1998
82 3/16/1990.........

82 3/26/2021
82 3/28/1921......... 
82 3/30/1998.........
82 3/29/1985......... 

81 3/29/1977

81 3/29/1998

80 3/28/1998

Wow, March 98.

[Rtd208 3,773]

https://www.spc.noaa.gov/products/outlook/day2otlk.html

 

[MR FREEZE 357]

3 hours ago, MJOP8 said:

Wow, March 98.

4 straight days over 80 in the park has to be the record for consecutive 80+ days in March.

[MR FREEZE 357]

7 hours ago, uncle w said:

warmest March temps in NYC...

86 3/29/1945.........
86 3/31/1998......... 
85 3/13/1990.........
84 3/21/1921......... 
84 3/28/1945......... 
83 3/20/1945......... 

83 3/27/1998
82 3/16/1990.........

82 3/26/2021
82 3/28/1921......... 
82 3/30/1998.........
82 3/29/1985......... 

81 3/29/1977

81 3/29/1998

80 3/28/1998

I would be interested to know if April cooled back down a bit or if the park reached 32 again.  I can't recall off the top of my head but I do remember that the summer of 1999 was more brutal than the one that occurred in 1998.  

 

Also, I also think I recall the park hitting the single digits in March 1990 shortly before that hot day on the 13th?  It was like the mini bookend to Dec 1989 which was awesome for its endless cold but yielded to an awful Jan and Feb.

[Analog96 10,883]

2 hours ago, MR FREEZE said:

I would be interested to know if April cooled back down a bit or if the park reached 32 again.  I can't recall off the top of my head but I do remember that the summer of 1999 was more brutal than the one that occurred in 1998.  

 

Also, I also think I recall the park hitting the single digits in March 1990 shortly before that hot day on the 13th?  It was like the mini bookend to Dec 1989 which was awesome for its endless cold but yielded to an awful Jan and Feb.

The summer of 1998 was very cool.  The summer of 1999 was very hot.  March 1990 was probably the most topsy turvy month ever.

We had bitter cold to start, then record warmth, and there was slushy snow at the end of March.

[donsutherland1 7,174]

Tomorrow mostly cloudy with some showers and possibly thundershowers. It will remain mild for the season. The remainder of March will continue to see generally warmer than normal readings.

 

As March concludes and April commences, the Arctic Oscillation (AO) is forecast to plunge more than 3 sigma from its current value. As recently as 2018, the AO fell from +1.743 to -2.188 during the March 26-April 3 period. There was a strong cold shot and even a snowstorm. A cold shot is more likely than a snowstorm this time around.

 

Overall, April could start out on the cold side. Historic experience following a warm to very warm March suggests a probability that is skewed toward a warmer than normal April.
 
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 +9.62 today.

 

The preliminary Arctic Oscillation (AO) figure was +2.927 today.

 

On March 25 the MJO was in Phase 2 at an amplitude of 1.068 (RMM). The March 24-adjusted amplitude was 1.391 (RMM).

 

Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal March. March will likely finish with a mean temperature near 45.4° (2.9° above normal).

 

[uncle w 4,332]

I hit 90 on March 31st 1998 on Staten Island...five straight days 80 or higher from the 27th-31st...that was a week after the snowfall on March 22nd...March 1990 had 3-5" of snow on the 6th with near record cold afterwards...there was record cold at the end of February 1990...Nov-Dec 1989 was very cold...January to the end of February was very warm...a cold last week in Feb and 1st week in March gave way to 80's on the 15th...April 7th 1990 had almost an inch of snow...it hit 90 by months end..

[uncle w 4,332]

some April stats for NYC...

Warmest Coldest temperatures...

96 17th 2002........12 1st 1923

96 18th 1976........20 5th 1874

92 16th 2002........21 4th 1874

92 7th 2010......................

92 19th 1976........21 5th 1881

92 26th 2009........21 6th 1982

92 27th 1915........21 7th 1982

91 25th 1915........21 19th 1875

91 30th 1942........22 12th 1874

91 17th 1976........22 1st 1919

91 18th 2002........22 2nd 1919

91 27th 1990........23 7th 1881

91 27th 1962........23 6th 1881

90 8th 1991..........23 5th 1995

90 12th 1977........23 4th 1954

90 18th 1896........23 1st 1874

90 20th 1927

90 28th 1990

90 28th 2009

Coldest daily max...

30 5th 1881

30 7th 1982

31 6th 1881

32 4th 1879

32 5th 1879

33 6th 1938

34 6th 1943

34 5th 1944

34 3rd 1896

34 1st 1874

 

Biggest snowstorms...

10.2" 3-4th 1915

10.0" 13th 1875

9.6" 6th 1982

8.5" 1st 1924

6.5" 8-9th 1917

6.5" 5th 1944

6.4" 6-7th 1938

5.5" 2nd 2018

5.0" 9th 1907

4.2" 8th 1956

4.0" 7th 2003

3.3" 8-9th 1916

3.3" 5-6th 1896

3.0" 18th 1887

3.0" 25th 1875

2.6" 11-13th 1918

2.5" 4th 1957

2.5" 4th 1870

2.5" 5th 1898

2.2" 9-10th 1942

2.0" 2nd 1871

1.9" 14th 1950

1.7" 12-13th 1940

1.2" 9th 2000

1.2" 2nd 1965

1.0" 12th 1894

1.0" 15th 1892

1.0" 4th 1886

[OHweather 2,368]

Ignoring the snow potential later this week for now...I'm highly skeptical of anything more than mood flakes (it does get cold, but I don't trust an anafront in January let alone April this far out)...strong forcing, strong low-level shear, and great hi-res model on a low topped squall that could bring gusty / damaging winds, maybe a spin-up or two even into much of E PA, NJ and the Hudson Valley on Sunday!

 

 

The HRRR soundings are easily unstable enough for a severe threat...this is an average from the lower HV through much of NJ and far SE PA:

 

 

The NAM is a little bit more stable, and would perhaps limit the severe threat:

 

 

My hunch is it's closer to the HRRR and we have a severe threat, but we'll see if the earlier rain can keep temperatures on the cooler side of guidance, which would be the most obvious way to limit the northward extent of the severe threat. 

 

For now, the 0z hi-res models are in remarkable agreement:

 

 

HREF mean (consisting of many of the above models) also bares out a high shear situation with adequate CAPE rather far north, along with most models explicitly showing a gusty line of storms:

 

/

 

 

Don't get me wrong, I find out of season snow to be strangely fun, but these forced low topped lines seem to be exciting more often than not, so let's see what Sunday brings! I'd almost say slight risk for all of E PA and most of NJ, maybe clipping like Orange and Rockland Co's in the Hudson Valley, something like 15% wind, 2% tornado on the SPC categories.