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Spring/Summer 2021 Weather Threats Discussion


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Could be pretty active later today   

It seems to me we may be nearing a crossroads. The models had earlier shown a greater likelihood of the change to much warmer conditions at the end of this month. Now they seem more concentrated on th

Just some red meat for you animals.     CMC:     Because why not:  

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Don't see a total repeat of yesterday, there's just less lift available despite the solid instability & high dewpoints. But conditions are still ripe for an afternoon/early evening filled with some strong, albeit somewhat more scattered/isolated cells.

 

 

 

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2 hours ago, CCB! said:

Looks like a decent setup for @Jake302 though either way today, send up those shelf cloud pics later!

 

NAM'd

nam3km_ir_neus_7.png

 

12:30 PM update: I am already seeing a couple turkey tower clouds out there today. I didn't see those yesterday until 5 PM or so

12:40 PM: rising clouds all around me, starting to see signs including a darkening base and thicker clouds

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first storms 

f2d927176c1f56289c6f1f37d910c990.pnghttps://www.lightningmaps.org/#m=oss;t=4;s=0;o=0;b=0.00;ts=0;z=9;y=39.3155;x=-75.3558;d=2;dl=2;dc=0;

7d236cba7f691327ad1363afbaf041a6.png

 

1:17 PM edit: Looking at NWS sterling radar, I can see a precip signature just to my south, and pretty menacing clouds as well. Just not yet on the dover radar.

 

1:19 PM: I just heard distant thunder.

 

9b9c710fc62c8ce1e4c42d17ea5fff6c.pngthat escalated quickly

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EAR SPLITTING THUNDER

 

 

2:33 PM: That was the heaviest and windiest rain EVER

 

2:52 PM: This storm has decided to stall right over Dover.

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Just a few thoughts on why I think setups like the past few days have tended to deliver vs. fizzle. Not everyone is guaranteed to see flooding rains or severe wx, but you usually see something by days end, ironically due to the lack of steering flow.

 

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1 minute ago, Jake302 said:

 

OCMD is about to get obliterated by a mini squall line

The file is too big, but my friend in southern Delware sent me a video with some nasty hail. The stones have dislodged several of his roof shingles, so he's looking forward to submitting his insurance claim with the video as evidence, lol.

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Under abundant sunshine, the temperature again rose to 90° or above in many parts of the region. For the first time this year, all three New York City stations (JFK, LGA, and NYC) reached 90° or above. The last time that occurred was August 27, 2020 when JFK reached 92°, LGA reached 94°, and NYC reached 90°. Last year, there were 10 days on which the temperature reached 90° at all three stations.

 

Today's high temperatures included:

 

Boston: 90°
Hartford: 90°
New York City-JFK: 91°
New York City-LGA: 90°
New York City-NYC: 90°
Newark: 96°

 

90° Days for Select Cities (through June 9):

 

Albany: 1 (2020: 13 days; 5-Year Average: 13.6 days)
Allentown: 5 (2020: 24 days; 5-Year Average: 27.6 days)
Baltimore: 7 (2020: 46 days; 5-Year Average: 44.6 days)
Boston: 7 (2020: 14 days; 5-Year Average: 17.2 days)
Bridgeport: 2 (2020: 11 days; 5-Year Average: 13.4 days)
Burlington: 4 (2020: 20 days; 5-Year Average: 13.0 days)
Harrisburg: 5 (2020: 35 days; 5-Year Average: 30.6 days)
Hartford: 7 (2020: 39 days; 5-Year Average: 29.0 days)
Islip: 2 (2020: 8 days; 5-Year Average: 9.4 days)
New York City-JFK: 3 (2020: 12 days; 5-Year Average: 10.2 days)
New York City-LGA: 5 (2020: 34 days; 5-Year Average: 29.4 days)
New York City-NYC: 4 (2020: 20 days; 5-Year Average: 18.2 days)
Newark: 9 (2020: 31 days; 5-Year Average: 31.2 days)
Philadelphia: 6 (2020: 36 days; 5-Year Average: 34.6 days)
Scranton: 5 (2020: 25 days; 5-Year Average: 16.4 days)
Washington, DC: 7 (2020: 46 days; 5-Year Average: 50.8 days)

 

New York City-Newark Average: 5 (2020: 22 days)
...Expected: 6 (based on regression equation tied to JFK-LGA-EWR data)

 

Following the frontal passage this evening, it will become noticeably cooler. Cooler than normal conditions will likely prevail into the upcoming weekend.

 

Out West, Phoenix will likely see the development of a period of extreme heat this weekend into at least early next week. The temperature could reach 115° on one or more days during the Monday-Wednesday period. The last time that happened in June was June 25, 2017 when the thermometer reached 116°. There were five such days in June 2017. The historic average is 0.4 days per year in June. The 1991-20 average is 0.6 days.

 

Typically, there is a reduced likelihood of additional 115° or warmer days in the July-September period following years where June registered one or more such days (69% of cases had no such days in June-September vs. 56% of cases where June saw no such heat/averages: 0.4 per year in July-August following a June with 115° heat vs. 0.6 per year in July-August following a June without such heat). However, climate change has increased the frequency, magnitude, and duration of extreme heat events in the United States and worldwide. All of the July-August cases with 115° heat following such cases in June occurred 1970 or later and 38% have occurred 2010 or later. One also finds additional evidence in statistical analysis. The coefficient of determination between June and July-August 115° heat is 0.001 (meaning that there is virtually no correlation). However, when time is introduced, the coefficient of determination increases to 0.148. This reflects the impact of a warming climate on the frequency of extreme heat. Considering the combination of ongoing warming and the ongoing drought, it is likely that Phoenix will see additional 115° heat during the summer even if the temperature reaches 115° or above in June.

 

More immediately, the unseasonable heat that will develop this weekend will likely extend northward into southern Canada including Alberta and Saskatchewan. It remains uncertain whether this extreme air mass will impact the region at some point later in the month.

 

Overall, the first half of June will likely wind up much warmer than normal. The MJO's passage through Phase 4 at an amplitude of 1.500 or above during the May 15-25 period coupled with ENSO Region 1+2 temperature anomalies above -1.0°C and below +1.0°C, as has been the case this year, has typically seen warmth in the East during the first 10 days of June. Cooler conditions typically prevailed when the ENSO Region 1+2 anomalies were outside that range. Based on the accumulated data and latest guidance, the June 1-10 anomaly will likely average 5.5° to 6.5° above normal.

 

The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.2°C for the week centered around June 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.30°C. Neutral ENSO conditions will likely prevail into at least mid-summer.

 

The SOI was -0.42 today.

 

The preliminary Arctic Oscillation (AO) figure was +1.259 today.

 

On June 7 the MJO was in Phase 7 at an amplitude of 0.870 (RMM). The June 6-adjusted amplitude was 0.954 (RMM).

 

In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer.

 

Based on sensitivity analysis applied to the latest guidance, there is an implied 70% probability that New York City will have a warmer than normal June (1991-2020 normal). June will likely finish with a mean temperature near 74.0° (2.0° above normal).

 

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Somewhat cooler than normal conditions will likely prevail tomorrow into the upcoming weekend. However, some warming is likely on Sunday and Monday.

 

Out West, Phoenix will very likely see the development of a period of extreme heat this weekend into at least early next week. The temperature could reach 115° on one or more days during the Monday-Thursday period. This unseasonable heat will likely extend northward into southern Canada including Alberta and Saskatchewan. It remains uncertain whether this extreme air mass will impact the region at some point later in the month.

 

Overall, the first half of June will likely wind up much warmer than normal. The MJO's passage through Phase 4 at an amplitude of 1.500 or above during the May 15-25 period coupled with ENSO Region 1+2 temperature anomalies above -1.0°C and below +1.0°C, as has been the case this year, has typically seen warmth in the East during the first 10 days of June. Cooler conditions typically prevailed when the ENSO Region 1+2 anomalies were outside that range. Based on the accumulated data and latest guidance, the June 1-10 anomaly will likely average 5.5° to 6.5° above normal. Through 7 pm, the preliminary June 1-10 anomaly in New York City is 6.5° above normal.

 

The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.2°C for the week centered around June 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.30°C. Neutral ENSO conditions will likely prevail into at least mid-summer.

 

The SOI was +1.05 today.

 

The preliminary Arctic Oscillation (AO) figure was +1.434 today.

 

On June 8 the MJO was in Phase 7 at an amplitude of 0.746 (RMM). The June 7-adjusted amplitude was 0.871 (RMM).

 

In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer.

 

With Phoenix likely to reach 115° or above next week, that development could provide another hint of a warmer than normal summer. Since 1896, 76% of years that saw Phoenix reach 115° or above in June had a warmer than July-August. The ratio of top 30 July-August temperatures relative to bottom 30 temperatures was 6:1 in favor of the warmth. Overall, the ingredients continue to fall into place for a warmer than normal to potentially hot summer.

 

Based on sensitivity analysis applied to the latest guidance, there is an implied 74% probability that New York City will have a warmer than normal June (1991-2020 normal). June will likely finish with a mean temperature near 74.2° (2.2° above normal).

 

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The weekend will be partly to mostly cloudy and somewhat cooler than normal. However, some warming is likely on Monday. Overall, despite a cooler weekend, the first half of June will likely wind up much warmer than normal.

 

Out West, Phoenix will very likely see the development of a period of extreme heat this weekend into at least early next week. The temperature could reach 115° on one or more days, especially during the Monday-Thursday period. For reference, Phoenix's daily records for the June 13-18 period are posted below.

 

Record high maximum temperatures:


June 13: 114°, 1896 and 1936
June 14: 115°, 1987
June 15: 115°, 1974
June 16: 115°, 1974
June 17: 114°, 2014
June 18: 115°, 1989 and 2015

 

Record high minimum temperatures:


June 13: 87°, 2018
June 14: 90°, 2018 (earliest 90° low on record)
June 15: 88°, 1936
June 16: 86°, 1988
June 17: 88°, 1986 and 2008
June 18: 88°, 2008

 

It should also be noted that the earliest temperature above 115° occurred on June 19, 2016 when the temperature reached 118°. A year later, the temperature again reached 118°. This record will likely be broken.

 

This unseasonable heat will likely extend northward into southern Canada including Alberta and Saskatchewan. It remains uncertain whether this extreme air mass will impact the region at some point later in the month.

 

The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.2°C for the week centered around June 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.30°C. Neutral ENSO conditions will likely prevail into at least mid-summer.

 

The SOI was -3.16 today.

 

The preliminary Arctic Oscillation (AO) figure was +1.460 today.

 

On June 9 the MJO was in Phase 8 at an amplitude of 0.512 (RMM). The June 8-adjusted amplitude was 0.746 (RMM).

 

In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer.

 

With Phoenix very likely to reach 115° or above next week, that development could provide another hint of a warmer than normal summer. Since 1896, 76% of years that saw Phoenix reach 115° or above in June had a warmer than July-August. The ratio of top 30 July-August temperatures relative to bottom 30 temperatures was 6:1 in favor of the warmth. Overall, the ingredients continue to fall into place for a warmer than normal to potentially hot summer.

 

Based on sensitivity analysis applied to the latest guidance, there is an implied 73% probability that New York City will have a warmer than normal June (1991-2020 normal). June will likely finish with a mean temperature near 74.2° (2.2° above normal).

 

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