Fall is fast approaching which opens the door for winter forecasts in the US based on various atmospheric and oceanic phenomena. One such parameter is ENSO, (weak El Nino this year?), another major contributor is the atmospheric pattern around Greenland.
This article is not a winter forecast at all, rather a look at the current to near future weather in Greenland. A low-pressure system is currently in far northeaster Canada moving northeast and will be intensifying throughout Wednesday. Moisture is being advected originally from the Gulf of Mexico through portions of eastern Canada up into this low pressure system fueling a heavy precipitation event in southern Greenland. With temperatures cold enough to support snow, or mostly snow across the region (possibly excluding the far southern immediate coast), a pretty impressive snow storm will develop dropping anywhere from half an inch of liquid precipitation further inland to close to 2 inches near the coast, especially on the southeastern side of the country (refer to the image above from Tropical Tidbits). As this low-pressure system drops close to the 970 mb range, strong winds will impact the coastal regions as well.
Above, the storm system deepening to the east of the southern tip of Greenland. Notice the Precipitable Water being drawn north from portions of the US, which originated in the Gulf of Mexico, as well as the Atlantic to create anomalously high moisture streaming into Greenland leading to this hefty snowfall (Image from Pivotal Weather).
GFS interpretation of the snowfall across Greenland, notice heavier amounts closer to the coastal regions, especially on the eastern side where the low pressure is expected to intensify near and track just to the east and northeast (Image from Tropical Tidbits).
The upper level pattern near Greenland is associated with the North Atlantic Oscillation. At this time, a positive NAO has developed, leading to anomalous low-pressure systems in the upper atmosphere around the region, in a direct cause and effect relation to this surface system development as discussed before. Shown above (Image from CPC), the NAO has been neutral to positive throughout the entire summer, but recent ensemble guidance shows a possible dip to neutral to possibly slightly negative values near mid-September. By the fall and early winter, East Coast snow lovers want the NAO to trend, or continue to trend in the negative which blocks up the atmosphere and allows for colder air to spill in from the far north. If the southern jet stream can provide moisture (as it is looking like an El Nino winter, this tends to happen along the southern US), while this negative NAO develops injecting bouts of colder air, a potential big snowstorm can develop.
Above, upper level low pressure near and around Greenland symbolic to the positive NAO being forecast around this time.
Whether all or some of these factors pan out to produce an eventful winter will not be known for several months, however, Greenland may become an important factor within the coming weeks/months and may hint at some possible patterns for the upcoming winter season. Until then, GWCC will continue to monitor these ever-changing conditions with future articles. Stay tuned to the latest winter weather right here!
©2018 Meteorologist Joe DeLizio