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October 2020 General Discussions & Observations Thread


uofmiami
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Rain associated with the remnants of Hurricane Delta will likely impact the tomorrow night through Tuesday. The potential exists for a widespread 1"-3" rainfall with locally higher amounts.

Generally above normal temperatures will prevail through mid-month. By mid-month, New York City will likely have an October 1-15 mean temperature above 60° and the region will likely see temperatures running an overall 1°-3° above normal. Afterward, a period of cooler than normal to near normal temperatures could develop.

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -1.1°C for the week centered around September 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.82°C and the ENSO Region 3.4 anomaly has averaged -0.92°C. La Niña conditions will likely prevail into at least the start of winter.

The SOI was +14.31.

Today, the preliminary Arctic Oscillation (AO) figure was -0.931.

On October 9 the MJO was in Phase 5 at an amplitude of 1.713 (RMM). The October 8-adjusted amplitude was 1.513.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO.

In addition, from the larger pool of La Niña winters following El Niño winters, there were four cases where October saw the MJO in Phases 4-6 for 20 days or more: 1983-84, 1988-89, 1998-99, and 2016-17. All four cases featured an EPO+/AO+ winter. Three cases saw the MJO in Phases 4-6 for less than 20 days: 1995-96: 12 days, 2007-08: 6 days, and 2010-11: 6 days. Both 1995-96 and 2010-11 featured a predominantly negative AO. The latest ensemble guidance favors October 2020 falling into the former pool. Among that pool, October 1983 and 2016 featured above normal and near normal rainfall respectively. October 1988 and 1998 saw below normal and much below normal rainfall respectively.

Based on sensitivity analysis applied to the latest guidance, there is an implied 64% probability that New York City will have a warmer than normal October. October will likely finish with a mean temperature near 58.3°.   

 

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The next 8 days are averaging 60degs.    Making it 55degs. , or about -2.0.

64*(91%RH) here at 6am.     66*(76%RH) by 9am.       67*(64%RH)  by Noon.        69*(60%RH) by 3pm.       65*(61%RH) by 6pm.      62*(72%RH) by 9pm.

Delta's leftovers[34.3N 87.6W]:     NAM 3",  GEM 2.8",  GFS 1.8",  EURO 1.7",   SREF 2.0"---heaviest about 11am tomorrow.    Could start by 5pm today.

More tropical activity in the Carribean by Oct. 21st.?       Similiar to Sandy by Oct. 27th??      Deep trough in Midwest like Sandy setup---I think.    It was the 500mb connection, in the upper atmosphere,(and blocking)  that pulled Sandy back to the EC, they said.    Let's see first if we even get a tropical system there by the 21st. to ponder over.

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Stronger Western Atlantic Ridge during the first 10 days of October than the models forecast. So the forecast for a cooler than normal start verified as +1 to +3 across the region. We have seen this model forecast bias frequently in recent years with the record SST warmth to our east.
 

EWR...+1.1

NYC...+1.4

LGA....+2.2

JFK....+1.6

BDR...+2.9

ISP.....+2.0

 


10AAFDFE-9B73-4176-83B6-E7A31F4FF227.thumb.png.c3beeb31957a71bf6d8cc7cb4c3e821b.png

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11 hours ago, jfklganyc said:

The smoke (or high clouds) never allowed it to get as warm as predicted. Happened about 2 PM.

That said, quite mild at 8pm

I was right at the smoke line for a while yesterday, it was so cool seeing a straight line across the sky with vivid blue on one side and dingy beige on the other. It was 6* warmer on the sunny side.

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Morning thoughts...

Partly sunny skies will yield to increasing clouds. Rain from the remnants of Hurricane Delta will begin to overspread the region late in the day or during the evening. Before then, temperatures will likely reach the middle and even upper 60s in much of the region. Likely high temperatures around the region include:

New York City (Central Park): 65°
Newark: 68°
Philadelphia: 69°

Yesterday, Atlanta picked up a daily record 4.55" rainfall (old record: 3.42", 2018) from the remnants of Delta. A general 1"-3" rainfall remains likely across the region with some locally higher amounts.

 

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Clouds ahead of the remnants of Delta overspreading the area.  Rain arrived this evening and heaviest rains look overnight into the early afternoon tomorrow.  Widespread 2 inches (+).  Slow to clear front out Tuesday  before some more dry and sunny weather Wed - Friday (near normal).  ECM continues to show a chilly but brief weekend (10/17-18) before the back and forth col warm follows the week of 10/19.  Looks overall warm between a warmth and cool shots bias cool northwest of the region with stronger perhaps longer east coast ridging towards the last week of the month.

 

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As of 8 pm EDT, rain associated with the remnants of Hurricane Delta has now reached Philadelphia. Rainfall from Delta will likely impact the region tonight through Tuesday. A widespread 1"-3" rainfall with locally higher amounts is likely. Tomorrow will see temperatures remain largely in the upper 50s to near 60° in much of the region.  

Nevertheless, generally above normal temperatures will prevail through mid-month. By mid-month, New York City will likely have an October 1-15 mean temperature above 60° and the region will likely see temperatures running an overall 1°-3° above normal. Afterward, a period of cooler than normal to near normal temperatures could develop. The potential exists for a fairly sharp shot of cold just after mid-month.

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -1.1°C for the week centered around September 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.82°C and the ENSO Region 3.4 anomaly has averaged -0.92°C. La Niña conditions will likely prevail into at least the start of winter.

The SOI was +11.99.

Today, the preliminary Arctic Oscillation (AO) figure was -0.329.

On October 10 the MJO was in Phase 5 at an amplitude of 1.681 (RMM). The October 9-adjusted amplitude was 1.719.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO.

In addition, from the larger pool of La Niña winters following El Niño winters, there were four cases where October saw the MJO in Phases 4-6 for 20 days or more: 1983-84, 1988-89, 1998-99, and 2016-17. All four cases featured an EPO+/AO+ winter. Three cases saw the MJO in Phases 4-6 for less than 20 days: 1995-96: 12 days, 2007-08: 6 days, and 2010-11: 6 days. Both 1995-96 and 2010-11 featured a predominantly negative AO. The latest ensemble guidance favors October 2020 falling into the former pool.

Based on sensitivity analysis applied to the latest guidance, there is an implied 63% probability that New York City will have a warmer than normal October. October will likely finish with a mean temperature near 58.3°.   

 

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Morning thoughts...

Delta’s remnants will produce a rainy day with a chilly east-northeast to northeast wind. Temperatures will likely be confined to the 50s across much of the region. Likely high temperatures around the region include:

New York City (Central Park): 56°

Newark: 58°

Philadelphia: 60°

Rain from the remnants of Hurricane Delta will depart tomorrow and the sun will return, along with a rebound in temperatures. 

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1 hour ago, Brian5671 said:

That will likely be a problem into early winter at least-the warm SST tends to make it hard for cold to hit and hold in the east

The WAR has been regularly verifying stronger than forecast with the record SSTs since late 2015.

 

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After a few warm dry days Wed (10/14) and Thu (10/15) front comes through Friday and ECM still has a brief 48 hour  frost / freeze chilly weather this coming  Sat (10/17) and Sun (10/18). back and forth with more warmth 10-/19 - 10/22 with more chill pushing east briefly by 10/23.  We'll see looks bias warm on the coast with the core of the cool west into GL/MW/OV.

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For the most part, rainfall from Hurricane Delta's remnants was below what had previously been modeled. Through 8 pm, storm total rainfall amounts included:

Atlantic City: 2.11"
Baltimore: 1.32"
Bridgeport:0.18"
Islip: 0.94"
New York City: 0.80"
Newark: 0.71"
Philadelphia: 0.80"
Poughkeepsie: 0.25"
Washington, DC: 1.50"

Additional light rain and showers will depart tomorrow. In response to a return of sunshine, temperatures will rebound well into the 60s.

Generally above normal temperatures will prevail through mid-month. By mid-month, New York City will likely have an October 1-15 mean temperature above 60° and the region will likely see temperatures running an overall 1°-3° above normal. Afterward, a period of cooler than normal to near normal temperatures could develop. The potential exists for a fairly sharp shot of cold just after mid-month.

The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -1.2°C for the week centered around October 7. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.92°C and the ENSO Region 3.4 anomaly has averaged -1.00°C. La Niña conditions will likely prevail into at least the start of winter.

The SOI was +11.28.

Today, the preliminary Arctic Oscillation (AO) figure was -0.107.

On October 11 the MJO was in Phase 5 at an amplitude of 1.781 (RMM). The October 10-adjusted amplitude was 1.685.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO.

In addition, from the larger pool of La Niña winters following El Niño winters, there were four cases where October saw the MJO in Phases 4-6 for 20 days or more: 1983-84, 1988-89, 1998-99, and 2016-17. All four cases featured an EPO+/AO+ winter. Three cases saw the MJO in Phases 4-6 for less than 20 days: 1995-96: 12 days, 2007-08: 6 days, and 2010-11: 6 days. Both 1995-96 and 2010-11 featured a predominantly negative AO. The latest ensemble guidance favors October 2020 falling into the former pool.

Based on sensitivity analysis applied to the latest guidance, there is an implied 66% probability that New York City will have a warmer than normal October. October will likely finish with a mean temperature near 58.3°.  

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The next 8 days are averaging 62degs.       Making it 57degs., or just Normal.   

Seems the BN period will not start now till the 22nd---instead of the 17th.       A waiting for the bus on a discontinued route scenario may be in the works.   lol.

57*(99%RH) here at 6am.       60*(97%RH) by Noon.

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