bluewave

It will be interesting to see if Philly can record their first 3 consecutive years under 40.00” since the early 1990s . Long range precipitation forecasting is very uncertain. The hope is that the STJ can come far enough north with the developing super El Niño to increase the rainfall enough in coming months to get over 40.00” by the end of December. Many spots have been running drier than average starting with the big dip in rainfall in September into October 2024. Monthly Total Precipitation for Philadelphia Area, PA (ThreadEx) Click column heading to sort ascending, click again to sort descending. 2026 2.84 2.24 1.90 2.11 0.37 M M M M M M M 9.46 2025 0.93 2.05 5.36 2.83 6.22 2.20 4.61 1.73 1.79 2.02 2.30 3.35 35.39 2024 5.91 1.49 7.19 4.16 1.72 4.68 2.44 5.07 0.77 T 2.52 3.45 39.40 2023 3.36 1.32 1.99 5.17 0.24 4.24 5.24 3.25 5.99 0.72 2.75 7.92 42.19 2022 3.35 2.87 2.09 4.51 4.16 5.03 2.20 2.70 2.06 5.80 2.89 4.85 42.51 2021 1.55 4.64 4.21 2.69 3.24 3.06 6.72 6.18 4.61 4.81 0.46 1.64 43.81 2020 2.64 2.46 3.94 3.75 2.20 3.21 5.54 8.53 4.23 4.09 4.79 4.38 49.76 2019 3.92 3.27 3.85 3.02 5.22 7.94 6.03 2.78 1.16 3.87 1.16 5.21 47.43 2018 2.85 6.02 4.74 3.94 5.21 3.34 3.06 4.11 9.76 3.08 9.03 6.38 61.52 2017 2.91 1.30 4.26 3.15 6.33 1.86 5.35 6.05 3.86 3.66 1.30 1.31 41.34 2016 2.63 4.36 2.01 1.75 6.65 1.87 3.88 1.70 3.52 2.06 2.17 2.72 35.32 2015 4.52 2.36 5.52 3.58 1.19 8.88 3.16 0.98 6.27 3.76 1.89 5.14 47.25 2014 3.55 5.12 4.23 6.69 2.91 5.46 4.30 3.55 1.69 2.53 4.07 3.27 47.37 2013 3.34 2.12 2.42 2.32 2.33 10.56 13.24 5.91 3.26 2.45 2.73 5.20 55.88 2012 2.59 1.84 0.79 2.55 3.35 2.94 1.48 5.37 5.48 4.08 1.05 4.42 35.94 2011 3.39 2.65 4.29 5.29 1.91 2.56 2.71 19.31 10.27 3.71 3.87 4.37 64.33 2010 2.19 5.75 7.33 2.65 2.53 2.05 6.28 2.19 3.48 5.01 1.76 3.24 44.46 2009 2.70 0.84 1.62 3.99 4.84 4.79 3.35 10.29 3.65 5.51 2.06 8.86 52.50 2008 1.74 3.93 3.67 2.19 4.55 2.87 3.45 2.44 4.31 1.59 4.02 5.57 40.33 2007 3.35 1.73 3.82 9.05 2.68 4.02 3.44 2.94 0.58 4.66 1.45 4.41 42.13 2006 4.34 1.51 0.91 3.71 2.16 7.95 4.27 3.93 5.97 6.42 4.88 2.15 48.20 2005 4.45 2.61 3.66 5.32 1.27 3.31 4.31 2.57 0.21 8.68 2.86 2.97 42.22 2004 1.70 2.50 3.54 6.02 3.62 4.57 7.91 4.17 5.19 2.24 4.55 3.17 49.18 2003 1.93 5.04 4.09 2.20 4.17 8.08 2.01 3.26 4.66 4.45 2.63 5.46 47.98 2002 2.43 0.55 4.03 2.17 3.57 3.73 2.12 2.47 3.67 5.90 4.65 4.05 39.34 2001 2.77 3.04 5.44 1.49 3.99 5.93 1.30 0.97 2.58 0.83 0.56 2.11 31.01 2000 3.22 2.02 6.32 3.05 3.03 3.82 5.54 2.90 8.28 1.51 2.21 2.82 44.72 1999 4.89 2.95 4.02 3.31 3.70 1.16 1.22 5.32 13.07 3.55 2.31 2.99 48.49 1998 4.24 3.25 3.93 2.70 3.87 4.91 1.79 1.26 1.86 1.84 1.18 0.82 31.65 1997 2.80 2.48 3.91 2.58 2.32 1.49 2.38 4.56 1.59 1.83 3.49 3.09 32.52 1996 4.39 2.12 4.27 4.48 3.25 4.73 8.17 4.29 4.95 4.30 3.03 8.47 56.45 1995 3.10 2.41 1.67 1.96 2.67 0.62 2.92 1.15 3.55 5.99 3.34 2.15 31.53 1994 4.27 3.27 6.44 2.86 3.66 1.74 10.42 4.54 1.64 0.94 3.03 2.11 44.92 1993 1.97 3.03 6.61 4.20 2.42 1.52 1.98 5.18 6.66 2.69 2.23 3.69 42.18 1992 0.88 1.31 3.19 1.26 2.74 1.84 5.05 2.00 3.04 1.23 3.26 4.61 30.41 1991 4.10 0.75 4.13 2.81 1.82 3.36 4.79 3.86 3.58 1.61 1.55 3.86 36.22 1990 4.09 1.44 2.59 3.16 6.08 3.39 2.62 4.07 1.71 1.68 1.17 3.79 35.79 1989 2.41 3.25 4.41 2.27 6.76 4.73 9.44 3.92 5.03 3.44 1.79 1.21 48.66 1988 2.72 4.11 2.24 2.92 3.67 0.57 8.07 3.16 2.62 2.16 5.17 1.00 38.41 1987 4.58 1.17 1.16 3.63 3.15 2.01 4.82 3.72 2.78 2.62 2.08 1.68 33.40 1986 4.13 3.38 1.25 4.46 0.70 1.99 4.10 3.70 2.33 2.22 6.27 5.89 40.42 1985 1.55 2.44 1.95 0.52 4.99 1.88 4.66 2.82 5.78 1.54 6.09 0.98 35.20 1984 2.22 2.81 6.14 4.25 6.87 2.85 6.99 3.28 1.96 2.56 1.56 2.17 43.66 1983 2.81 3.53 6.95 8.12 7.03 2.75 0.68 2.57 3.45 3.69 5.71 7.37 54.66 1982 4.45 3.16 2.66 6.06 4.47 5.76 1.94 2.20 2.32 1.94 3.67 1.80 40.43 1981 0.50 2.94 1.61 3.60 4.53 4.40 4.54 5.11 2.83 2.68 0.95 4.14 37.83 1980 2.27 0.96 7.01 4.79 3.22 1.73 6.58 0.80 2.79 5.03 2.85 0.77 38.80 1979 8.74 6.44 2.43 4.08 3.98 4.34 3.95 5.95 4.89 3.84 2.48 1.67 52.79 1978 8.86 1.35 4.31 1.76 6.01 1.75 5.27 6.04 1.59 1.20 2.20 5.61 45.95 1977 2.61 1.33 4.19 5.59 0.70 5.33 1.47 8.70 3.44 3.11 7.76 5.19 49.42 1976 4.50 1.66 2.38 2.06 4.35 3.42 4.04 2.17 2.44 4.30 0.32 1.63 33.27 1975 4.00 2.91 4.68 2.97 4.99 7.57 6.32 2.21 7.21 3.24 3.14 2.89 52.13 1974 2.95 2.14 4.91 2.77 3.21 4.43 2.08 3.83 4.68 1.93 0.81 4.04 37.78 1973 3.93 2.96 3.52 6.68 4.14 7.88 2.39 2.03 3.39 2.16 0.64 6.34 46.06 1972 2.34 5.09 2.69 4.08 4.11 5.79 2.62 3.76 1.12 3.77 9.06 5.20 49.63 1971 2.13 5.43 2.58 1.84 4.10 1.01 4.84 9.61 5.83 3.84 5.37 1.21 47.79 1970 0.74 2.08 3.83 6.12 2.57 4.60 2.75 3.99 0.82 3.66 4.71 3.27 39.14 1969 1.57 1.88 1.92 1.68 3.30 7.31 8.33 2.66 4.38 1.13 1.97 7.23 43.36 1968 2.90 1.40 4.98 1.57 5.17 5.89 2.00 1.24 0.44 3.15 4.17 2.54 35.45 1967 1.67 1.82 4.53 2.17 3.49 4.12 7.11 7.08 2.96 2.00 1.99 5.88 44.82 1966 2.82 4.30 0.68 4.35 2.95 0.41 2.35 1.63 8.70 5.12 2.36 4.33 40.00 1965 2.35 2.18 3.19 2.33 1.23 2.85 3.22 4.05 3.02 2.02 1.05 1.85 29.34 1964 3.92 2.83 1.94 5.27 0.47 0.21 3.83 0.49 2.42 1.73 1.64 5.13 29.88 1963 2.31 2.19 3.94 1.13 1.06 2.88 3.13 3.35 6.44 0.09 6.67 1.76 34.95

At least we are doing better than areas just to our south. Through May 14th Philly is having their 4th driest March 1st through May 13th. The drought should help boost the high temperatures in the usual warm spots next week. Pretty impressive to see the GFS, Euro, and CMC all showing 95+ potential for the usual warm spots. Time Series Summary for Philadelphia Area, PA (ThreadEx) Driest March 1 to May 13 Click column heading to sort ascending, click again to sort descending. 1 1926-05-13 3.79 0 2 1938-05-13 4.20 0 3 1930-05-13 4.32 0 4 2026-05-13 4.38 0 5 2012-05-13 4.42 0 6 1995-05-13 4.64 0 7 1985-05-13 4.71 0 8 1969-05-13 4.77 0 9 1887-05-13 4.91 0 10 1883-05-13 4.98 0

Yeah, we had the split forcing in the 2023-2024 El Niño with the record warm pool near the Dateline and another center off of Mexico like we are currently seeing. The 1997-1998 El Niño had very east based forcing since Nino 4 was so much cooler. 2023-2024 was more of a full basin event rather than an east based one like 1997-1998.

While the NAM often had unrealistic precipitation amounts especially since it wasn’t upgraded in almost 10 years, it did do much better than other models with the warm nose at 700mb to 800mb and snow to mix precipitation timing. So we may just have to compensate for this by manually speeding up the snow to mix precipitation timing in situations which the other models are too weak with the 700-800 MB WAA. The other story is that the SPC HREF was one of the best models showing snow banding and extreme heavy precipitation amounts. It did very well with the late February KU and several flash flooding events over the years.

I like focusing on where the +30C warm pools are. Since the actual forcing driving our sensible weather follows those areas. The current forecast is for split forcing centers near the Dateline and off of Mexico in late May.That Dateline forcing is closer to near record Nino 4 and MJO 7 and the forcing further east is with the record +PMM.

Not much outside of the Great Lakes this spring. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=24&which=cd&csector=conus&var=precip&w=rank&p=day&year=2026&month=4&sdate=2026%2F03%2F01&edate=2026%2F05%2F13&cmap=RdYlBu&cmap_r=on&_r=t&dpi=100&_fmt=png

JMA has the current velocity potential and an archive with 5 day to 3 month means. https://www.data.jma.go.jp/tcc/tcc/products/clisys/figures/db_hist_mon_tcc.html

Yeah, the last Nam upgrade was in March of 2017. It nailed the January 2016 event. Sad to see the SPC HREF go as its ensemble max snowfall was actually pretty good with the split bands west and east of NYC and 20”+ amounts for the February 2026 event. https://www.noaa.gov/media-release/review-of-jan-2016-blizzard-preliminary-snow-totals-validates-dc-measurement The preliminary Central Park measurement will be adjusted upward to 27.5 inches, which will become an all-time snowfall record for New York City when certified by NOAA’s National Centers for Environmental Information. A communication error between the weather forecast office in Upton, New York, and the Central Park Conservancy, which volunteers to take official snow measurements in Central Park, led to an inaccurate preliminary total of 26.8 inches. The snow team found the mistake when reviewing the Conservancy’s logbook.

Big Euro and AI upgrade. https://www.ecmwf.int/en/about/media-centre/news/2026/ifs-cycle-50r1-aifsv2-live A significant upgrade to ECMWF's Integrated Forecasting System (IFS), Cycle 50r1, has gone live today (12 May 2026) alongside an update to the Artificial Intelligence Forecasting System (AIFS v2). Cycle 50r1 introduces a more consistent and integrated approach to forecasting the atmosphere’s interactions with the ocean through fully coupled data assimilation, and improvements to known issues with accurately forecasting sudden, heavy, localised rain. It also brings more advanced representation of waves and sea ice. The update to the AIFS introduces, among other features, ECMWF’s first data-driven wave and snow cover forecasts. Florian Pappenberger, Director-General of ECMWF, said: “This is an important upgrade for ECMWF and for everyone who relies on our forecasts. IFS Cycle 50r1 strengthens our physics-based forecasting system, including through fully coupled atmosphere–ocean–sea-ice assimilation and new ocean and sea-ice capabilities. "With AIFS v2, we are expanding its performance, bringing a new generation of AI forecasting into operation, building on ECMWF’s technical competence, operational expertise and data infrastructure. Together, these advances reflect ECMWF’s commitment to innovation and close co-development with our Member and Co-operating States in delivering better forecasts, increasing the value to society.” Matthieu Chevallier, ECMWF’s Head of Forecast Evaluation, added: “The updates to these systems, being formally announced today, will together provide numerous benefits to users of our forecasts. Alongside the scientific and technical advances in coupled modelling and data assimilation, and innovation with AI techniques, we have responded to users’ feedback, for example, with new products. We look forward to hearing their reaction to the quality and accuracy of our forecasts, and on how it impacts their applications.” Forecasting improvements One of the most significant changes to the IFS introduced with Cycle 50r1 is a better representation of convective precipitation, which causes heavy rainfall and violent thunderstorms but is hard to predict because it occurs at smaller scales. The revised convection and cloud-microphysics scheme will reduce excessive stationary rainfall and, instead, represent more realistically how it moves from the ocean across the land. IFS users will also see the introduction of the new NEMO4-SI³ ocean and sea-ice model, bringing substantial improvements in forecasts and analysis over the marine areas, as well as over 40 new ocean and sea ice-related variables. Key improvements include a more accurate representation of how sea ice affects the power of waves and the interactions between waves and ocean currents, often at play in rougher seas. Other improvements for IFS include improved tropical upper-air temperature and wind forecasts, and improvements to temperature and humidity forecasts around the tropopause. For the Copernicus Atmosphere Monitoring Service (CAMS), one of two Copernicus services operated by ECMWF on behalf of the European Commission, the IFS update will enhance the atmospheric composition and greenhouse gas forecasts. The improvements range from the assimilated observations to aerosols and reactive gases, as well as enhanced input data on human-driven emissions. For AIFS, both the Single and Ensemble versions of the system are being upgraded to version two, with each introducing a new wave component. Eleven wave-related variables are being made available to users, enabling predictions, for example, of when we will experience rougher seas. In addition, the AIFS Single v2 wave component shows substantial improvement in the medium-range skill of wave forecasts compared to the physical model, IFS Cycle 50r1. ECMWF’s first data-driven snow cover forecasts are also being introduced with this upgrade. Again, the AIFS Single v2 forecasts show improved performance compared to IFS Cycle 50r1 forecasts, with the predicted snow cover fraction closer to observations. Victoria Bennett, ECMWF's Head of User Services Section, said: “These new cycles bring improvements to the models and introduce new products that address requests from users. In addition, with IFS, we have now removed the duplication between the old “HRES” single forecast and the Ensemble control and introduced other minor technical updates to reduce complexity. We have worked closely with users during the testing period, and with their positive feedback, we are excited to be making the switch.” All the upgrades to our systems are live with immediate effect.

This is the first that the +30C warm pool near the Dateline made it down to 100m in April with a developing El Nino. Notice how much warmer in all aspects we are than 2023 during the same time. You have to wonder if this continues leading to a slower cold pool formation than we typically see toward the later stages of the El Nino in the Western Pacific. We probably wouldn’t know until next winter whether it could cause this one to wind down more slowly than usual during the spring.

The westward lean is closer to the +ENSO MJO 7 composite with the ridge from coast to coast. But notice how the troughs are weaker in the coming forecast near the Aleutians and Baja. Similar to the weak La Niña this past winter when the ridge out West was stronger than the trough in the East. While it may be too early to draw conclusions about next winter, this would result in a weaker Aleutian Low and possibly a weaker low in the Southeast like we saw in 2023-2024 and 2015-2016 relative to 1997-1998 and 1982-1983.

No surprise that the El Nino is beginning to couple with a westward lean close to the +30C warm pool.

Other stations have done it further back in time with Caldwell being the most recent in 2021. Monthly Highest Max Temperature for CALDWELL ESSEX COUNTY AP, NJ Click column heading to sort ascending, click again to sort descending. 2021 84 90 91 91

It will be interesting to see what the pattern does in June following the mid to late May warm up. So far it appears we are in a pattern similar the warmer 2015 El Niño mid to late May as opposed to the cooler 2023 one. The 2015 analog is showing up on the day 8-14 analog composite. 2015 was a warmer summer here than 2023 was. New York, Climate Division 4 Average Temperature June-August higher ranks warmer with 2010 ranking #131 warmest June-August 2025 73.2°F 120* June-August 2024 74.0°F 127 June-August 2023 72.2°F 103 June-August 2022 74.1°F 128 June-August 2021 73.4°F 123* June-August 2020 74.3°F 130 June-August 2019 73.2°F 120* June-August 2018 73.4°F 123* June-August 2017 71.9°F 97* June-August 2016 74.2°F 129 June-August 2015 73.1°F 118 June-August 2014 71.6°F 92* June-August 2013 72.9°F 115* June-August 2012 73.4°F 123* June-August 2011 73.9°F 126* June-August 2010 75.2°F 131 June-August 2009 70.7°F 64* June-August 2008 72.5°F 108* June-August 2007 71.6°F 92* June-August 2006 73.0°F 117* June-August 2005 73.9°F 126* June-August 2004 70.6°F 62* June-August 2003 71.7°F 94* June-August 2002 72.9°F 115 * June-August 2001 72.0°F 100* June-August 2000 69.8°F 33

Hopefully, the developing El Niño can ease these historic drought conditions across the CONUS.