bluewave

Plenty of onshore flow coming up with high pressure to our north and east. So no 90° potential for the foreseeable future. The last time Newark didn’t reach 90° in September was 2011 and 2012 for LGA.

A recent study was able to determine just how extreme the Bering wintertime sea ice low in 2018 was.

It would be really odd if LGA didn’t have another 90° day this year. LGA never reached 30 days before without any 90° days in the spring or fall. LGA is currently in 4th place with 34 days reaching 90°. LGA finished JJA with the 2nd highest number of 90° days behind 2010. 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 2010 1 2 12 18 11 4 0 48 2018 0 4 4 10 16 4 0 38 2002 2 0 5 14 13 1 0 35 2020 0 0 5 19 10 0 M 34 1991 0 4 9 10 9 2 0 34 2016 0 3 1 15 10 3 0 32 1983 0 0 5 11 8 7 0 31 2005 0 0 7 10 10 3 0 30 1953 0 1 7 10 9 3 0 30 Monthly Number of Days Max Temperature >= 90 for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Year Jun Jul Aug Season 2010 12 18 11 41 2020 5 19 10 34

According to Brian B, the US record for earliest measurable snowfall after a 100° was 5 days at Rapid City, SD in September 2000. So Denver could potentially see their latest 100° and then one of their earliest measurable snowfalls. 2000-09-17 101 53 77.0 16.8 0 12 T 0.0 0 2000-09-18 93 64 78.5 18.8 0 14 T 0.0 0 2000-09-19 65 48 56.5 -2.7 8 0 0.04 0.0 0 2000-09-20 61 43 52.0 -6.7 13 0 0.00 0.0 0 2000-09-21 66 41 53.5 -4.8 11 0 0.00 0.0 0 2000-09-22 46 34 40.0 -17.8 25 0 0.27 0.5 0 First/Last Summary for Denver Area, CO (ThreadEx) 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 2019 07-19 (2019) 101 09-02 (2019) 100 44 2002 08-16 (2002) 100 08-16 (2002) 100 0 1962 08-10 (1962) 100 08-14 (1962) 100 3 1876 07-06 (1876) 101 08-12 (1876) 100 36 1969 08-08 (1969) 100 08-08 (1969) 100 0 First/Last Summary for Denver Area, CO (ThreadEx) Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Year Last Value First Value Difference 1961 05-13 (1961) 6.4 09-03 (1961) 4.2 112 1962 04-30 (1962) 0.1 09-08 (1962) 0.7 130 1974 04-29 (1974) 0.2 09-12 (1974) 1.8 135 1989 04-30 (1989) 3.7 09-12 (1989) 2.3 134 1993 04-24 (1993) 1.0 09-13 (1993) 5.4 141 1971 04-22 (1971) 4.5 09-16 (1971) 2.7 146

Looks like we will experience near record 500 mb heights for September. But the high will be to our NE with onshore flow.

Yeah, the number of new weather extremes since around 2010 has almost become too numerous to keep track of. Don, thanks for those stats. I guess our version of that near sea level would be February 8th- 9th, 2017. ISP 2017-02-08 62 39 50.5 18.8 14 0 T 0.0 0 2017-02-09 42 18 30.0 -1.8 35 0 1.30 14.3 1

I wonder if this will be the first time that a part of the US experiences snow so soon after highs near 100°? RECORD HEAT THIS WEEKEND TO POSSIBLE SNOW TUESDAY... Upper level ridge centered over the Great Basin will retrograde westward Sunday over California and Nevada. By Monday, what`s left of the ridge is just off the California coast. This ridge will keep it hot and dry Saturday and Sunday. Highs across northeast Colorado are expected to reach the mid 90s to lower 100s. A low pressure trough across eastern Colorado and a short wave trough passing to the north of Colorado will cause west to northwest winds to increase Sunday. This downslope flow will produce very dry conditions. It will likely offset any minor cooling associated with the short wave trough. A weak cold front drops south across the area Sunday night. Gusty east winds behind it are expected for Monday. This will usher in cooler air into northeast Colorado. For Monday, models still showing a strong open trough over the Northern Rockies. This trough then dives south and strengthens into a closed low over somewhere near the Four Corner Tuesday. A strong cold front associated with this system pushes south through the state late Monday afternoon through Monday night. Precipitation develops Monday evening and becomes widespread overnight Monday night and Tuesday. The 00Z GFS, GEM, and ECMWF are quite impressive with the amount of cold that accompanies this storm system. If the current solutions are right or close, it will be cold enough for snow to fall along the Front Range Urban Corridor and nearby plains. Accumulating snow on trees may cause considerable tree damage and related impacts will be possible. This system is four days away and models will likely change some. Confidence is becoming high that snow will occur in the mountains and foothills Monday night through Tuesday evening. A slight change in storm track or a slightly weaker closed low may keep the lower elevations warm enough for rain. Main message is cold and heavy snow is possible Monday night through Tuesday night. Monitor the latest forecasts and consider changing outdoor or travel plans if cold and snow still look on track.

Just an unbelievable temperature and weather swing in the forecast for the Rockies.

This was the warmest melt season on record. A new paper is out on the continuing Atlantification of the Arctic Ocean. This year the sea ice edge made it to 85°N on the Atlantic side. https://nsidc.org/arcticseaicenews/ Atlantification continues As discussed in a recent paper in the Journal of Climate led by colleague Igor Polyakov of the University of Alaska, the process of “Atlantification” of the Arctic Ocean, first noted in the Barents Sea, is continuing, with significant effects on the sea ice cover during the winter season in the Eastern Eurasian Basin. The relatively fresh surface layer of the Arctic Ocean is underlain by warm, salty water that is imported from the northern Atlantic Ocean. The cold fresh surface layer, because of its lower density, largely prevents the warm, salty Atlantic waters from mixing upwards. However, the underlying Atlantic water appears to have moved closer to the surface in recent years, reducing the density contrast with the water above it. Recent observations show this warm water “blob,” usually found at about 150 meters (492 feet) below the surface, has shifted within 80 meters (263 feet) of the surface. This has resulted in an increase in the upward winter ocean heat flow to the underside of the ice from typical values of 3 to 4 watts per square meter in 2007 to 2008 to greater than 10 watts per square meter from 2016 to 2018. Polyakov estimates that this is equivalent to a two-fold reduction in winter ice growth.

Yeah, the record amplitude may allow allow a piece of energy to cutoff near the Rockies. So some rapidly changing conditions even by Rockies standards are possible. I guess we’ll have to see how this trough evolution influences the Western Atlantic pattern regarding any tropical systems. Courtesy of wx.us and Ryan Maue on twitter.

The first half of the month was cold enough to compensate for the milder second half. But even the second half of the month only made to 56° in NYC with the historic flood cutter. January 1996 finished 30.5° and -2.1. That was like a grand finale in a fireworks show. I never expected in 1996 that we would see such a snow drought from 96-97 to 01-02. It was my biggest weather surprise since the winter of 89-90 historic reversal from the record cold December.

95-96 was the last time for NYC that every month from November to March was below normal. Came close in 02-03 but March finished above normal. 13-14 and 14-15 got interrupted by the warmth in December.

Looks like any major heat will be limited by clouds and onshore flow. But the warmer than normal minimums may take the lead with the higher dew points and winds off the still warm ocean.

Less warm is the new cool.

Extremely amplified pattern coming up. Record 500mb heights forecast along the West Coast by the weekend. Then we see how strong the ridge off the East Coast can get in 7-10 days.

Yeah, those warming WPAC SSTs lead to the record MJO 4-6 activity during recent winters. This served to enhance the La Niña background state over the last 4 winters. It resulted in mild to record warm winters with the SE Ridge dominating and setting a new record in February 2018. But the location of the NPAC ridge made the difference between snowy and nearly snowless winter outcomes. 2017 to 2018 featured the ridge near the Aluetians and more NATL blocking with a snowy pattern. During the 2019 to 2020 period ,the ridge was much flatter near Hawaii. So we got the two recent nearly snowless DJF periods along with a strong NATL PV. While it looks like we could experience a 5th La Niña background state winter, we’ll have to see how the NPAC ridge and NATL pattern influence the snowfall potential.

Updated for August 2020. 8....2020...EWR...10..LGA...5...BDR...3...ISP....6

I wonder what the 500MB height record is for Newfoundland in September? All the models are going near 600 DM In about 10 days.

It looks like we will have a trough in the Great Lakes and Midwest at least into early September. There should also be plenty of high pressure to our north and east with onshore flow here. But we will just have to wait and see how many of the AEWs coming off Africa can actually develop into named systems.

It took until last October for the IO standing wave to emerge with the record +IOD. It continued until mid-December before the record SSTs north of Australia emerged. Then it was off to the races for the record MJO 4-6 which dominated from late December on. There was some research that the IO standing wave being so strong during OND was related to the intense PV which dominated last winter. So it will be interesting so see how the Indian Ocean and Pacific interact this coming fall and winter.

The record breaking IO standing wave is making headlines again. Now it looks like it’s producing an early September pattern resembling MJO phase 1. So this translates into the big ridge along the West Coast and trough over the MW/GL. It will limit our early September 90° potential.

It really depends on how long the ridge says locked in along the West Coast. This hasn’t been our typical September pattern during the last decade. There has usually been a trough out there with a ridge over New England.

I agree that the MYI loss is the big story. https://climate.nasa.gov/news/2817/with-thick-ice-gone-arctic-sea-ice-changes-more-slowly/ With thick ice gone, Arctic sea ice changes more slowly The Arctic Ocean's blanket of sea ice has changed since 1958 from predominantly older, thicker ice to mostly younger, thinner ice, according to new research published by NASA scientist Ron Kwok of the Jet Propulsion Laboratory, Pasadena, California. With so little thick, old ice left, the rate of decrease in ice thickness has slowed. New ice grows faster but is more vulnerable to weather and wind, so ice thickness is now more variable, rather than dominated by the effect of global warming. Working from a combination of satellite records and declassified submarine sonar data, NASA scientists have constructed a 60-year record of Arctic sea ice thickness. Right now, Arctic sea ice is the youngest and thinnest its been since we started keeping records. More than 70 percent of Arctic sea ice is now seasonal, which means it grows in the winter and melts in the summer, but doesn't last from year to year. This seasonal ice melts faster and breaks up easier, making it much more susceptible to wind and atmospheric conditions. Working from a combination of satellite records and declassified submarine sonar data, NASA scientists have constructed a 60-year record of Arctic sea ice thickness. Right now, Arctic sea ice is the youngest and thinnest its been since we started keeping records. More than 70 percent of Arctic sea ice is now seasonal, which means it grows in the winter and melts in the summer, but doesn't last from year to year. This seasonal ice melts faster and breaks up easier, making it much more susceptible to wind and atmospheric conditions. Kwok's research, published today in the journal Environmental Research Letters, combined decades of declassified U.S. Navy submarine measurements with more recent data from four satellites to create the 60-year record of changes in Arctic sea ice thickness. He found that since 1958, Arctic ice cover has lost about two-thirds of its thickness, as averaged across the Arctic at the end of summer. Older ice has shrunk in area by almost 800,000 square miles (more than 2 million square kilometers). Today, 70 percent of the ice cover consists of ice that forms and melts within a single year, which scientists call seasonal ice. Sea ice of any age is frozen ocean water. However, as sea ice survives through several melt seasons, its characteristics change. Multiyear ice is thicker, stronger and rougher than seasonal ice. It is much less salty than seasonal ice; Arctic explorers used it as drinking water. Satellite sensors observe enough of these differences that scientists can use spaceborne data to distinguish between the two types of ice. Thinner, weaker seasonal ice is innately more vulnerable to weather than thick, multiyear ice. It can be pushed around more easily by wind, as happened in the summer of 2013. During that time, prevailing winds piled up the ice cover against coastlines, which made the ice cover thicker for months. The ice's vulnerability may also be demonstrated by the increased variation in Arctic sea ice thickness and extent from year to year over the last decade. In the past, sea ice rarely melted in the Arctic Ocean. Each year, some multiyear ice flowed out of the ocean into the East Greenland Sea and melted there, and some ice grew thick enough to survive the melt season and become multiyear ice. As air temperatures in the polar regions have warmed in recent decades, however, large amounts of multiyear ice now melt within the Arctic Ocean itself. Far less seasonal ice now thickens enough over the winter to survive the summer. As a result, not only is there less ice overall, but the proportions of multiyear ice to seasonal ice have also changed in favor of the young ice. Seasonal ice now grows to a depth of about six feet (two meters) in winter, and most of it melts in summer. That basic pattern is likely to continue, Kwok said. "The thickness and coverage in the Arctic are now dominated by the growth, melting and deformation of seasonal ice." The increase in seasonal ice also means record-breaking changes in ice cover such as those of the 1990s and 2000s are likely to be less common, Kwok noted. In fact, there has not been a new record sea ice minimum since 2012, despite years of warm weather in the Arctic. "We've lost so much of the thick ice that changes in thickness are going to be slower due to the different behavior of this ice type," Kwok said. Kwok used data from U.S. Navy submarine sonars from 1958 to 2000; satellite altimeters on NASA's ICESat and the European CryoSat-2, which span from 2003 to 2018; and scatterometer measurements from NASA's QuikSCAT and the European ASCAT from 1999 to 2017.