bluewave

Nice write-up on the rapidly intensifying flash drought. https://droughtmonitor.unl.edu/ Rapidly intensifying “flash drought” — attributed in part to extreme late-summer heat — continued to afflict many areas from the lower Midwest and Mid-Atlantic States to the Gulf Coast. Likewise, an abysmal Southwestern monsoon (to-date) led to increasing drought intensity and coverage in Arizona, while short-term drought persisted across the Hawaiian Islands. Conversely, moderate to heavy rain eased or alleviated dryness and drought from the Great Lakes into the Northwest as well as in southwestern Alaska and southern Puerto Rico.

The near normal monthly temperature departures through the 19th will climb to above normal with the coming warm up. Looks like another long gap between temperatures in the 40’s at Newark. There was an extended one in 2017 between 9-2-17 and 10-01-17.

This time the blob is mostly at the surface and not as deep as it was back in 2014. So it could shift very quickly if the weather pattern driving the anomaly changes this fall into winter. It will probably come down to how the tropical forcing with the ENSO, SOI, IOD, and MJO evolves. https://alaskapacificblob.wordpress.com/2019/09/17/has-the-blob-returned/ Based on this analysis, it seems that the current northeastern Pacific warm anomaly is really only evident in the surface layer, and therefore despite a robust surface presentation, we might say that the Blob is a mere shadow of its former self. If correct, this suggests that it wouldn’t take much to wipe out the warm anomaly if the weather patterns shift over the northeastern Pacific in the coming months; but on the other hand, if relatively high pressure and light winds prevail this winter (as they did in winter 2013-2014), then the warm anomaly could deepen significantly and become more firmly established next year. Time will tell if this second round of the Blob anomaly will prove to be as significant as the first.

Islip holding in 1st place for driest September with very little rain in the forecast. Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Sep Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 2019 0.33 12 2 1985 0.81 0 3 1986 0.82 0 4 1965 1.01 0 5 1982 1.12 0 6 1980 1.28 0 7 2007 1.31 0 - 2005 1.31 0 8 1997 1.42 0 9 1976 1.49 0 10 1967 1.57 0

A big ridge north of Hawaii in October usually occurs with more of a La Niña-like pattern. The late September pattern is probably related to the MJO becoming active again. Very confused Pacific state currently. -35 daily SOI and +1 IOD are more El Niño-like. The cold Niña 1+2 is typical for a La Niña. Plus we have the near record SST blob again in the NE PAC. Kind of difficult to predict how all these competing influences will evolve and interact for the winter pattern at this early point.

NSIDC 5 day trailing average extent dipped to 4.153 million sq km on 9-18. http://nsidc.org/arcticseaicenews/faq/#average-vs-daily Values within 40,000 square kilometers (15,000 square miles) are considered tied. Why do you use the 5-trailing average to announce the minimum/maximum and not the daily extent? We use a 5-day trailing average to smooth out the day-to-day variability from the influence of weather (such as storms causing false retrievals) and coastal or surface effects on the data. Five days is a typical synoptic timescale that helps create a continuous curve that is easier to follow and interpret. ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx Lowest 5 day average 3.387....2012-9-17 4.153....2019...9-18 4.155....2007-9-18 4.165....2016-9-10 4.344....2011-9-11 4.433....2015-9-9  4.586....2008-9-19 4.615....2010-9-21 4.656....2018-9-23  4.665....2017-9-13

Looks like the more active MJO is shifting us back to a warmer pattern for the rest of September. Much more Niña-like pattern with the big ridge building north of Hawaii. So we are shifting away from the big Canadian high pattern that has dominated since August. Going forward we have to monitor the ridging north of Hawaii. That was one of the factors that spoiled last winter. If this ridge becomes more established north of Hawaii, then that record warm SST blob could shift west with it. Probably too early to know for winter. But just something to monitor going forward.

Values within 40,000 square kilometers (15,000 square miles) are considered tied. Very large daily drop for so late in the season. ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx Lowest 5 day average 3.387....2012-9-17 4.155....2007-9-18 4.165....2016-9-10 4.170....2019...as of 9-17 4.344....2011-9-11 4.433....2015-9-9 4.586....2008-9-19 4.615....2010-9-21 4.656....2018-9-23 4.665....2017-9-13

Any guesses for this October?

1988 actually beat it for duration it with 20 consecutive days reaching 90. But 1953 still stands as our greatest late season heatwave. This decade has been so wet, that those 2 records remained out of reach. Really need extreme drought over the Central or Eastern US to get such a long heatwave. Number of Consecutive Days Max Temperature >= 90 for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Run Length Ending Date Period of record: 1931-01-01 to 2019-09-17 1 20 1988-08-17 2 14 2010-07-29 3 12 1995-08-04 - 12 1972-07-25 4 11 2012-07-08 - 11 1973-09-05 - 11 1953-09-03 5 10 2006-08-05 - 10 2002-08-19 - 10 1993-07-16

Today is a perfectly clear day with no clouds anywhere near NYC. A rarity over the last 19 months when there always seemed to be clouds popping up.

DC picks up another 2 days of 90 degrees or higher. So they pull ahead of Newark by 32 days which is the highest for the 2010’s. Just goes to show how many times the front has stalled just to the south of our area since the late spring. 90 degree days at DCA and EWR ..........DCA....EWR....difference 2019....57..25....+32 2018....45...36.....+9 2017....43...22....+21  2016....58...40....+18 2015....52....35....+17 2014...24....15.....+9 2013...35.....25.....+10 2012...53.....33......+20 2011....50.....31.....+19 2010....67.....54......+13

Lower dewpoints coming this week after we failed to convert on the recent more humid pattern.

A stalled out front will also do it like with the record flash flooding last September. https://www.weather.gov/okx/FlashFlooding_092518#picture

10k daily NSIDC extent decline moves 2019 into 3rd place place on 9-15. Only 6k behind the 2nd place 2007. Currently in 3rd place for NSIDC extent.  3.387....2012-9-17 4.155....2007-9-18 4.161....2019 4.165....2016-9-10 4.344....2011-9-11 4.433....2015-9-9 4.586....2008-9-19 4.615....2010-9-21 4.656....2018-9-23 4.665....2017-9-13

The convection has been mostly a miss for many this month. Islip is only at .33 for September so far. That ties for driest first half September this decade. Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Precipitation Sep 1 to Sep 15 Missing Count 1 2019-09-15 0.33 0 - 2010-09-15 0.33 0 3 2014-09-15 0.63 0 4 2016-09-15 1.18 0 5 2013-09-15 1.23 0 6 2018-09-15 1.64 0 7 2011-09-15 2.51 0 8 2012-09-15 2.54 0 9 2017-09-15 2.58 0 10 2015-09-15 2.80 0

Pattern has really dried out with all the Canadian high pressure dominating. NYC could end the record 19 month streak of 3.00 or more inches of precipitation. Many of our stations including NYC have less than 1.00 if rain through the first half of the month. Monthly Total Precipitation for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 2018 2.18 5.83 5.17 5.78 3.53 3.11 7.45 8.59 6.19 3.59 7.62 6.51 65.55 2019 3.58 3.14 3.87 4.55 6.82 5.46 5.77 3.70 0.82 M M M 37.71

The late season acceleration of sea ice losses is in response to the return of the strong Arctic dipole anomaly. This was the dominant pattern from May through August 20th. A new Arctic high pressure record was set for this period. Now high pressure has returned to near record levels for this time of year.

Arctic sea ice pulling closer to 2007 and 2016. Now at 4.171 million sq km for 9-14 with a 38k NSIDC daily decline. ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx Currently in 4th place for NSIDC extent.  3.387....2012-9-17 4.155....2007-9-18 4.165....2016-9-10 4.171....2019 4.344....2011-9-11 4.433....2015-9-9 4.586....2008-9-19 4.615....2010-9-21 4.656....2018-9-23 4.665....2017-9-13

Very consistent pattern. Next big Canadian high with extended easterly flow arriving in a few days. Then maybe 90 degree potential for the warm spots in about a week as the Bermuda high flexes. More easterly flow Next 90 in warm spots?

Very sharp temperature gradient across the region this September so far. Cool in New England with record heat over the Mid-Atlantic.

Large 71k NSIDC daily extent decline for so late in the season. The 9-13 extent drops below the previous minimum recorded back on 9-4. This puts 2019 in 4th place not far behind 2007 and 2016. ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx Currently in 4th place for NSIDC extent.  3.387....2012-9-17 4.155....2007-9-18 4.165....2016-9-10 4.209....2019 4.344....2011-9-11 4.433....2015-9-9 4.586....2008-9-19 4.615....2010-9-21 4.656....2018-9-23 4.665....2017-9-13

2nd coolest first few weeks of September for our area this decade. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Sep 1 to Sep 13 Missing Count 1 2017-09-13 66.7 0 2 2019-09-13 71.2 0 3 2013-09-13 73.2 0 4 2011-09-13 73.7 0 5 2010-09-13 73.8 0 6 2012-09-13 73.9 0 7 2018-09-13 74.3 0 8 2014-09-13 75.1 0 9 2016-09-13 75.5 0 10 2015-09-13 77.7 0

Don’t try this at home. https://www.theguardian.com/world/2019/sep/12/south-east-spain-battered-by-heaviest-rainfall-on-record

The big high driving the easterly flow is close to record levels for September. The barometer reading in NYC is at 30.49. The record highest for September is around 30.58.