bluewave

They are actually running a few degrees above 2010 for the warmest April so far. Time Series Summary for BRADFORD REGIONAL AIRPORT, PA Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Apr 1 to Apr 17 Missing Count 1 2023-04-17 52.2 0 2 2010-04-17 50.3 0 3 2017-04-17 47.8 0 4 1967-04-17 47.2 0 5 2021-04-17 46.9 0 6 1991-04-17 46.0 0 7 1988-04-17 45.3 0 - 1969-04-17 45.3 0 8 2002-04-17 44.9 0 - 1999-04-17 44.9 0 9 1968-04-17 44.8 0 10 2015-04-17 44.7 0

May be a struggle to get a really strong and sustained WWB while the daily PDO dropped again in the last few weeks.

Models just don’t have enough skill to forecast the El Niño details until after the spring predictability barrier. https://www.climate.gov/news-features/blogs/enso/spring-predictability-barrier-we’d-rather-be-spring-break Now let’s shift our attention to making an ENSO prediction for the coming winter season (for the November-January seasonal average). How useful are the models? Well, if you’re running a model using October data as input, then you’re in pretty good shape as you can expect close to 90% of the winter ENSO fluctuations to be predicted. In terms of lead time, that’s the same horizon as a forecast made in April for May-June-July (MJJ), and yet there is a huge difference in forecasting ability (5). The skill (or forecasting ability) of model runs based on February-October observations to predict the November-January (NDJ) average value in the Niño-3.4 SST region (ENSO). Results shown here are an average correlation coefficient from each of the 20 models between 2002-2011 (data used from Barnston et al, 2012). Percent Explained Variance (%) is calculated by squaring the correlation coefficient and multiplying by 100 (see footnote #1). Models that explain all ENSO variability would equal 100%, while explaining none of the ENSO variance would equal 0%. Graphic by Fiona Martin based on data from NOAA CPC and IRI. However, hope slowly grows as we emerge from the spring. In particular, models run based on May data are getting close to explaining half of the coming winter variability, which isn’t shabby. But, still, predictions are still far from assured. Using July and August data, about three-quarters of the winter ENSO fluctuations are predicted by the models. So while forecast “surprises” are becoming less frequent, they still lurk around. Overcoming the Spring Barrier? So, why is the accuracy of the models so bleak during the spring? Is there reason to believe that more model development will improve upon the low skill we see during the spring? While there are many ideas on why the spring barrier exists, there are no definitive culprits (Webster and Yang, 1992, Webster, 1995, Torrence and Webster, 1998, McPhaden, 2003, Duan and Wei, 2013). One of the reasons that the spring barrier is said to exist is because spring is a transitional time of year for ENSO (in our parlance, signals are low and noise is high). The spring is when ENSO is shifting around— often El Niño/La Niña events are decaying after their winter peak, sometimes passing through Neutral, before sometimes leading to El Niño/La Niña later on in the year. It is harder to predict the start or end of an event than to predict an event that is already occurring. There is also weaker coupling between the ocean-atmosphere in the spring due to a reduction in the average, or climatological, SST gradients in the tropical Pacific Ocean. However, for various reasons, these factors don’t fully explain why we see lower skill (6).

Looks like they made it to 96° on the update. RECORD EVENT REPORT NATIONAL WEATHER SERVICE BOSTON/NORTON MA 0519 PM EDT FRI APR 14 2023 ...RECORD HIGH TEMPERATURE SET AT HARTFORD CT... A RECORD HIGH TEMPERATURE OF 96 WAS SET AT HARTFORD CT TODAY. THIS BREAKS THE OLD RECORD OF 82 SET IN 1941.

Yeah, their earliest mid 90s by a few days. https://threadex.rcc-acis.org 4/7 93 in 2010 90 in 1991 90 in 1929 4/8 89 in 1991 87 in 1929 84 in 2010 4/9 85 in 1991 77 in 1945 75 in 2001+ 4/10 84 in 1922 79 in 2017 78 in 1955+ 4/11 88 in 2017 79 in 1955 78 in 2023+ 4/12 88 in 1977 81 in 2023 79 in 2008+ 4/13 92 in 2023 86 in 1977 85 in 1968 4/14 82 in 1941 81 in 1968 78 in 2022+ 4/15 88 in 1941 82 in 1994 82 in 1938 4/16 92 in 2012 90 in 2002 88 in 2017 4/17 95 in 2002 92 in 1976 78 in 2012+ 4/18 95 in 1976 92 in 2002 85 in 1964 4/19 96 in 1976 87 in 1972 86 in 2004

Yeah, NYC used to warmer than LGA during the summer in the 70s and earlier before the excess tree growth. https://www.nytimes.com/1977/07/22/archives/vandals-in-central-park-forcing-weather-service-to-seek-new-site.html Harold Gibson, the meteorologist in charge of the New York bureau, When the devices at the castle are not functioning, the Weather Service substitutes readings from La Guardia Airport. But Mr. Gibson said those readings do not really reflect conditions in the city, because they may be several degrees cooler in summer or warmer in winter than those in Central Park. NYC is the only station with the same number of 90° days in the recent era as the 70s due to tree growth too close to sensor. It used to have more 90° days than LGA and 3 less than EWR. Now it’s 7 fewer days than LGA and 14 lower than Newark. Monthly Number of Days Max Temperature >= 90 for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season Mean 0 1 2 7 6 2 0 18 1970 0 2 1 4 8 7 0 22 1971 0 0 5 6 5 2 0 18 1972 0 0 0 11 3 1 0 15 1973 0 0 4 4 6 4 0 18 1974 0 1 1 10 5 0 0 17 1975 0 1 1 2 4 0 0 8 1976 3 0 6 2 4 0 0 15 1977 1 2 0 11 7 2 0 23 1978 0 1 2 3 5 0 0 11 1979 0 2 0 7 8 1 0 18 1980 0 2 1 11 15 3 0 32 Monthly Number of Days Max Temperature >= 90 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season Mean 0 1 2 5 4 1 0 13 1970 0 2 1 5 9 5 0 22 1971 0 0 3 3 2 1 0 9 1972 0 0 0 3 0 1 0 4 1973 0 0 3 3 7 4 0 17 1974 0 1 1 9 2 0 0 13 1975 0 1 1 2 3 0 0 7 1976 1 0 5 1 3 0 0 10 1977 0 1 0 9 3 1 0 14 1978 0 0 0 3 1 0 0 4 1979 0 2 0 7 7 0 0 16 1980 0 0 3 8 9 2 0 22 Monthly Number of Days Max Temperature >= 90 for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season Mean 0 1 3 8 7 2 0 21 1970 0 2 2 5 8 5 0 22 1971 0 0 6 7 7 2 0 22 1972 0 0 0 16 4 1 0 21 1973 0 0 5 9 12 5 0 31 1974 1 2 2 10 3 0 0 18 1975 0 1 3 3 5 0 0 12 1976 2 0 7 2 4 0 0 15 1977 1 3 1 14 6 1 0 26 1978 0 1 3 8 4 0 0 16 1979 0 2 1 8 9 0 0 20 1980 0 1 3 8 12 3 0 27 Monthly Number of Days Max Temperature >= 90 for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season Mean 0 1 3 8 5 2 0 18 2012 0 0 5 10 3 1 0 19 2013 0 2 3 10 1 1 0 17 2014 0 0 0 3 3 2 0 8 2015 0 0 1 5 8 6 0 20 2016 0 2 0 10 7 3 0 22 2017 0 3 3 5 1 1 0 13 2018 0 2 3 6 7 3 0 21 2019 0 0 1 10 3 0 1 15 2020 0 0 2 14 4 0 0 20 2021 0 0 8 4 5 0 0 17 2022 0 2 1 10 11 1 0 25 Monthly Number of Days Max Temperature >= 90 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season Mean 0 2 4 11 7 2 0 25 2012 0 2 6 14 6 0 0 28 2013 0 2 2 15 1 1 0 21 2014 0 0 0 3 1 2 0 6 2015 0 0 3 6 8 3 0 20 2016 0 3 1 15 10 3 0 32 2017 0 3 3 8 2 1 0 17 2018 0 4 4 10 16 4 0 38 2019 0 0 4 14 5 2 1 26 2020 0 0 5 19 10 0 0 34 2021 0 0 9 8 8 0 0 25 2022 0 3 3 11 13 0 0 30 Monthly Number of Days Max Temperature >= 90 for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Oct Season Mean 0 2 5 13 9 3 0 32 2012 0 2 6 16 7 2 0 33 2013 0 2 4 15 3 1 0 25 2014 0 0 2 8 2 3 0 15 2015 0 2 4 11 13 5 0 35 2016 0 3 3 16 13 5 0 40 2017 0 3 5 9 2 3 0 22 2018 0 4 5 9 14 4 0 36 2019 0 1 4 14 4 3 1 27 2020 0 0 5 17 9 0 0 31 2021 0 4 12 11 13 1 0 41 2022 0 4 6 20 18 1 0 49

Already 90° in SE CT. Chester FAIR 90 43 19 N6

I don’t think so.The closest NYC came was within 5 days during April 1976. Walpack did it within 2 days this week. Have to go out West for 90° days that start below freezing. https://www.wunderground.com/cat6/extreme-short-duration-temperature-changes-us Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 1976-04-12 43 25 1976-04-13 62 36 1976-04-14 72 48 1976-04-15 76 53 1976-04-16 82 56 1976-04-17 91 66 1976-04-18 96 70 1976-04-19 92 68 ▼ Walpack NJ 2023-04-13 SafetyNet 91 41 29.93 29.81 0.00 16 ▼ Walpack NJ 2023-04-12 SafetyNet 83 48 29.94 29.81 0.00 20 ▼ Walpack NJ 2023-04-11 SafetyNet 76 27 30.29 29.94 0.00 20 ▼ Walpack NJ 2023-04-10 SafetyNet 70 23 30.49 30.29 0.00 11 ▼ Walpack NJ 2023-04-09 SafetyNet 60 20 30.51

I guess part of the problem is that people were doubting the strength based on the previous winter forecast being so far off. Also never had a 2nd year El Niño super event since 1950. We technically got some Modoki-like west based forcing with the biggest snowstorm on record in NYC during January. Then the first below 0° since 1994.

https://threadex.rcc-acis.org NYC recorded only 2 daily record daily high temperatures since 2015 in JJA with all the extra tree growth over the sensor. Poughkeepsie is at 10 record daily highs since 2015. Newark has 10 also since 2015 during the summer. With bare trees during the winter, NYC has had 15 record highs DJF. There were 21 record highs at Poughkeepsie. With 16 winter record highs at Newark. So NYC has had 4 daily record highs this year so far. That is 4 times more than when the trees were fully leafed out in the summer since 2015.

Yeah, the lower dewpoints this month allowed the minimum departures to remain much lower than the maximum departures.

That’s pretty impressive. While this data only goes back to 1998, it’s probably safe to say it’s a new record high in your area. https://xmacis.rcc-acis.org Almanac for MONTGOMERY ORANGE COUNTY AP, NY April 13, 2023 Daily Data Observed Normal Record Highest Record Lowest Max Temperature M 59 81 in 2018 45 in 2007 Min Temperature M 35 53 in 2002 24 in 2000 TEMPERATURE (F) TODAY MAXIMUM 90R 2:57 PM 88 1945 60 30 77 MINIMUM 48 5:43 AM 19 1986 37 11 38 AVERAGE 69 48 21 58

Made it before the trees had a chance to leaf out and block the sensor.

50° range today at Walpack. https://www.njweather.org/data/daily/79 Walpack NJ 2023-04-13 SafetyNet 91 41

We would expect the -PDO to weaken from these -2 values should the El Niño actually become strong. But even a neutral to -1 PDO with a moderate to strong El Niño could displace the Nino +PNA ridge over to the Northeast. These seasonal model forecasts don’t have that much long range skill. So the El Niño and PDO values will have to wait. Plus the models have really struggled with El Niño forecasts since 2012. 2012-2013 El Niño never developed due to strong -PDO and trades 2014-2015 El Niño much weaker than forecast 2015-2016 forecast was pretty good 2017-2018 El Niño was but forecast never developed 2018-2019 El Niño never coupled

Central Park tied the record of 88° before the trees fully leafed out.

Coastal sections of Northern California had their 2nd coldest March on record. I have been using NOAA. The coastal bouy off San Diego recorded its lowest SST on record. So the trades have been slow to relax back to the Central Pacific with this pattern. Notice how the WWBs are further west near Indonesia instead of closer to 180. So the subsurface near Dateline is much less impressive than years like 2015 and 1997 as GaWx posted yesterday. https://www.ncei.noaa.gov/access/monitoring/pdo/

ISP tied the record high of 82° at 10am. 4/13 82 in 1977 72 in 2018 72 in 1968

Don’t have that one. But NOAA came in at -2.35 for March. Lowest March reading since 1956. https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

25 inches of rain for Fort Lauderdale.

HRRR has 3rd earliest 90° for Newark.

Has Newark ever had a record low max which was above 60° in the spring with a dewpoint in the 20s before? The previous record low max of 59° in 2017 had a dewpoint of 51°. The record for 4-13 had a 60° dewpoint. So these record low maxes usually occur on higher dewpoints above 50° early mornings. Newark/Liberty CLOUDY 65 29 4/12 59 in 2017 56 in 1948 56 in 1947 6:51 AM 60 °F 51 °F 72 % 4/13 61 in 2019 6:51 AM 61 °F 60 °F 97 % 4/14 62 in 2014 6:51 AM 62 °F 55 °F 78 %

The last 35 dewpoint at Newark in July was in 2010. Plenty of dry heat that month. The drought feedback boosted the heat that month. https://www.wunderground.com/history/daily/us/nj/newark/KEWR/date/2010-7-1 4:51 PM 79 °F 35 °F 20 % https://www.wunderground.com/history/daily/us/nj/newark/KEWR/date/2010-7-3 2:51 PM 92 °F 41 °F 17 % https://www.wunderground.com/history/daily/us/nj/newark/KEWR/date/2010-7-4 2:51 PM 99 °F 43 °F 15 % https://www.wunderground.com/history/daily/us/nj/newark/KEWR/date/2010-7-5 1:51 PM 100 °F 45 °F 15 % https://www.wunderground.com/history/daily/us/nj/newark/KEWR/date/2010-7-6 12:51 PM 102 °F 56 °F 22 % Data for July 1, 2010 through July 30, 2010 Click column heading to sort ascending, click again to sort descending. State Name Station Type Highest Max Temperature NY MINEOLA COOP 108 NJ CANOE BROOK COOP 107 NY WANTAGH CEDAR CREEK COOP 107 NJ HARRISON COOP 106 NJ RINGWOOD COOP 106 NJ CRANFORD COOP 104 CT DANBURY COOP 104 NJ NEWARK LIBERTY INTL AP WBAN 103 NY LAGUARDIA AIRPORT WBAN 103 NY NY CITY CENTRAL PARK WBAN 103 NJ TETERBORO AIRPORT WBAN 103 NY WEST POINT COOP 103 NY SHIRLEY BROOKHAVEN AIRPORT WBAN 103 Data for July 1, 2010 through July 30, 2010 Click column heading to sort ascending, click again to sort descending. State Name Station Type Highest Max Temperature NJ SOMERDALE 4 SW COOP 106 PA MARCUS HOOK COOP 105 NJ NEW BRUNSWICK 3 SE COOP 105 NJ PENNSAUKEN 1N COOP 104 PA NORTHEAST PHILADELPHIA AIRPORT WBAN 104 NJ TRENTON-MERCER AIRPORT WBAN 104 NJ FREEHOLD-MARLBORO COOP 104 NJ SOUTH JERSEY REGIONAL AIRPORT WBAN 104

Newark ties with 1977 for 7th earliest 85° or warmer day of the season. First/Last Summary for NEWARK LIBERTY INTL AP, NJ Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Year First Value Last Value Difference 1-1990 03-13 (1990) 86 10-09 (1990) 87 209 2-1945 03-20 (1945) 85 09-29 (1945) 89 192 3-1998 03-30 (1998) 86 09-27 (1998) 91 180 4-1991 04-07 (1991) 85 09-17 (1991) 95 162 4-2010 04-07 (2010) 92 09-25 (2010) 90 170 5-2013 04-09 (2013) 85 10-04 (2013) 89 177 6-2011 04-11 (2011) 87 10-10 (2011) 85 181 7-1977 04-12 (1977) 90 09-18 (1977) 85 158

I learned more about weather forecasting using resources on the internet than trying to use textbooks and Alden Difax maps in the 1980s. You don’t even need to understand calculus to be a good forecaster these days. But an advanced math background is required if you want to work in model development or other research areas and academia. Though you can still understand the concepts in papers without advanced math. A big part of forecasting is understanding model strengths, weaknesses, and biases. Learning basic weather statistics can go a long way.