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October 2019 General Discussions & Observations Thread


Rtd208
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Temperatures were generally above normal in the Middle Atlantic region today, especially from New York City southward. A generally cloudy, cool, and wet period lies ahead, especially around the Wednesday-Friday timeframe. Amounts of rain will depend on the track of an offshore storm. Parts of eastern Long Island and eastern New England could receive high winds and heavy rain for a time. A moderate to possibly significant rainfall could occur in the larger New York City area, though there remains considerable uncertainty.

However, by the middle of this week, another unseasonably cold air mass will likely move into the northern Rockies. The potential for some record low temperatures exists in the Wednesday-Friday timeframe there with the highest probability being locations in Idaho, Wyoming, and Montana. This air mass will likely result in only a transient shot of cold in the East afterward.

However, after mid-month, the pattern could go zonal and much of the CONUS could become warmer than normal. Afterward, a ridge could redevelop in the East leading to a mild closing week of October.

The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.5°C for the week centered around October 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.78°C and the ENSO Region 3.4 anomaly has averaged +0.02°C. The strong cooling that took place in Region 1+2 during September indicates that the prospects for a neutral-cool ENSO during the winter have increased.

Since 1991 when weekly ENSO region data was available, five years have seen September record two or more weeks with -1.0°C or cooler weekly anomalies in Region 1+2: 1996, 1999, 2007, 2010, and 2017. 4/5 (80%) of those cases went on to feature warm December-February temperature anomalies in the Middle Atlantic and southern New England regions. Those cases include La Niña winters. However, the larger pool of neutral-cool ENSO winters, many of which predate the weekly ENSO regional data, have often featured frequent Atlantic blocking. For now, there is a mixed winter signal.

The SOI was -6.77 today.

Today, the preliminary Arctic Oscillation (AO) figure was +1.015.

Since 1950, there have been five prior cases when the AO averaged -0.500 or below in both July and August: 1950, 1958, 1960, 1968, and 2015. The average temperature for September through November in New York City was 58.9° (59.6° adjusted). All cases featured a warmer than normal fall. The potential for autumn 2019 to rank among the 30 warmest cases on record has increased in recent weeks. For New York City, that would translate into a September-November mean temperature of at least 58.8°.

The latest EPS weeklies show a return to warm anomalies in the East after mid-October, as does the extended range of the EPS. While the timing is far out, the EPS weeklies also suggest that the warmth could roll into the start of November.

On October 6, the MJO was in Phase 1 at an amplitude of 1.291 (RMM). The October 5-adjusted amplitude was 1.301.

The MJO has now been in Phase 1 for 16 consecutive days. That is the longest such streak since June 29-July 14, 2008 when the MJO was in Phase 1 for 16 consecutive days. In both cases when the MJO was moved into Phase 1 in late September or early September and remained in Phase 1 for 12 or more consecutive days, the average decline in the 14-day average temperature for the 2-3 weeks that followed the MJO's moving out of Phase 1 was gradual. The long-duration Phase 1 episode suggests that the second half of October could be warmer than normal. For New York City, an October mean temperature of 58.5°-59.5° (1.6° to 2.6° above normal) would be implied by those long-duration Phase 1 cases.

Based on sensitivity analysis applied to the latest guidance, the implied probability of New York City having a warmer than normal October is approximately 61%.

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Finally some solid rain. If we get the coastal storm far enough Nw we end the flash drought as fast as it started. 

I think there are going to be some pretty serious coastal impacts with this storm. It’s been many years since we had a storm that produced large battering waves over many high tide cycles. Historically some similar events caused damage on par with hurricanes. The key with this setup is the fetch area. With the pressure gradient between the blocking high and coastal storm creating an anomalously long fetch aimed at the MA/NE. 

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45 minutes ago, LongBeachSurfFreak said:

Finally some solid rain. If we get the coastal storm far enough Nw we end the flash drought as fast as it started. 

I think there are going to be some pretty serious coastal impacts with this storm. It’s been many years since we had a storm that produced large battering waves over many high tide cycles. Historically some similar events caused damage on par with hurricanes. The key with this setup is the fetch area. With the pressure gradient between the blocking high and coastal storm creating an anomalously long fetch aimed at the MA/NE. 

Part of beach at Robert Moses State Park is already badly eroded.

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On 10/4/2019 at 10:10 AM, donsutherland1 said:

There is actually some work underway to provide a better measure of heat events based on a combination of duration, intensity, and frequency.

https://www.nature.com/articles/s41598-019-50643-w

Having said that, I agree with the idea of a population-weighted standardized measure for heat events. Constructing such a scale should be readily feasible using the software utilized to calculate NESIS.

I had looked at the current heat in Atlanta relative to the historic early September 1925 heat wave.  The peak of that heat wave occurred on 9/7-9 with an average high temperature of 101.3°. That was 2.96 sigma above the 1891-1920 mean temperature for 9/7-9. The 10/1-3 average for Atlanta is 95.7° (the 10/2-4 figure could be somewhat higher based on today's forecast). That is 3.04 sigma above the 1981-2010 mean temperature for 10/1-3. So, at least at its peak, the current heat wave is somewhat more impressive.

I suspect that if the NAO had been closer to neutral, one would have seen far more frequent readings in the 90s into southern and perhaps central New England.

Prior to 10/2/2019, JFK's latest 95° or above reading occurred on 9/11/1983 when the temperature hit 96°.

The heat index topped out at 98° on 10/2.  That was the latest 98° or above heat wave on record. The previous latest, which was a 100° heat index figure, at JFK occurred on 9/22/1970.

Thanks Don, it's great that we're coming up with such a scale- perhaps we can compile a "Top 10" of heatwaves- I wonder how many of the ones we've experienced here in the NE would do on that list!

Some big ones come to mind:

Summer 1980,  1983, 1988, 1991, 1993, 1995, 1999, 2002, 2010, 2011.

Those are just some that I've experienced- going back further we have the Dust Bowl era (especially 1936), 1944, 1948, 1953, 1954, 1955, 1966

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7 hours ago, LongBeachSurfFreak said:

Finally some solid rain. If we get the coastal storm far enough Nw we end the flash drought as fast as it started. 

I think there are going to be some pretty serious coastal impacts with this storm. It’s been many years since we had a storm that produced large battering waves over many high tide cycles. Historically some similar events caused damage on par with hurricanes. The key with this setup is the fetch area. With the pressure gradient between the blocking high and coastal storm creating an anomalously long fetch aimed at the MA/NE. 

reminds me of Dec 1992!

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On 10/5/2019 at 11:24 AM, uncle W said:

I laugh when I here the word drought now...anyone who lived through the mid 1960's drought will agree with me...1962 was a pretty dry year...1963 almost set the record for the least amount of annual precipitation if not for a late December snowstorm...1964 was drier and broke the record for the driest year...then in 1965 the record was destroyed by a lot...the first eight months of 1966 were dry climaxing with the driest summer on record...There was a drought busting deluge in September 1966 and not for a few set backs it has not come close to that drought...

1966-67 would have been my favorite period of time on record had I been alive then, going from hot and dry to snowy and cold lol..... the closest comparison I can come up with is 2010-11 which featured similar extremes.

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On 10/5/2019 at 12:30 PM, eco94 said:

My concerns about the flash drought- and I'm near JFK- were in regards to vegetation.  for everyone dismissing that, it's really important, too. Luckily most young trees seemed to make it through this one, and more rain this week is extremely  welcome too. Just because it didn't affect the water supply doesn't mean it was/is something to shake off- I'm still pretty concerned about the tree canopy.

Another year with a hot and dry summer followed by extreme rains was 1999, the drought buster that year was Floyd in mid September.  2002 also had hot and dry conditions, I remember yellow lawns that year that looked like hay.

 

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The next 8 days are averaging 58degs., or just Normal.

Month to date is  +3.6[64.5].        Should be about  +1.6[61.0] near mid-month.

59.9* here at 6am.

EURO is 2" thru Sun., and the GFS is 1".     GFS does have 3" falling on the 22nd. alone though.   Lol.

JB warning of hurricane gusts and 5" on central LI on Thurs/Fri.     We are a little safer with 50mph gusts and less rain.

LI Buoy Swells:     Pyramid Building in the 21st. Century.    Lol.

wna.44025.bull.2.png

 

 

 

 

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50 minutes ago, Brian5671 said:

0z Euro backed off-couple inches of rain mainly NYC east

EPS looked quite strong and N though, wouldn't be surprised to see models shift further NW today. 

Regardless it looks like a cool, dreary and breezy period especially Wed-Fri.

Should see, at minimum, some moderate coastal impacts due to prolonged onshore flow.

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46 minutes ago, bluewave said:

Very confused look to the Pacific right now. This may be our first time in October with Niño 4 this warm and Niño 1+2 so cool. 
 

The latest weekly SST departures are:
Niño 4 Niño 3.4
Niño 3 Niño 1+2
1.0oC 0.5oC 0.3oC
-0.6oC

Is that an ideal look for the east coast?

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2 minutes ago, bluewave said:

Right now the convection is suppressed near the dateline. Root for that to change if you want to see more of an El Niño atmospheric response. 

It seems to me that if the current pattern continues, we'll see a lot of big storms hitting the great plains region to the upper midwest.

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22 minutes ago, LibertyBell said:

It seems to me that if the current pattern continues, we'll see a lot of big storms hitting the great plains region to the upper midwest.

Very extreme pattern right now. Developing powerful East Coast Storm and Upper Plains snowstorm. Followed by the typhoon recurve impacts on the pattern for the next few weeks.

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Just now, bluewave said:

Very extreme pattern right now. Developing powerful East Coast Storm and Upper Plains snowstorm. Followed by the typhoon recurve impacts on the pattern for the next few weeks.

If this is going to be the pattern going forward, I could see it bearing fruit for wintry weather when wavelengths shorten later in the season.  This could be another one of those backloaded winters if that's the case.  December and January would be very stormy but would feature coastal huggers and inland runners.

 

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8 minutes ago, Brian5671 said:

nothing like yesterday's Euro-might have been a burp run there-coastal flooding and erosion appears to be the biggest issues here vs rain/flooding

Yesterday was def a burp run but the 12z Nam  ended up further west than 6z 

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