Long Range: Models hinting at “cutoff low” next week

On the heels of a developing unsettled weather pattern for late this week, which we detailed in a post on Wednesday Night, forecast models are hinting that the medium and long range pattern could remain unsettled. The main feature in the medium and long range guidance now appears to be a large upper level “cutoff” low, which will cut off from the northern stream (northern jet stream) in Canada and drop into the Great Lakes and Northeast States next week. Such an occurrence isn’t exceptionally rare, especially in the Autumn and Spring. The resulting weather won’t be too extreme, either, but the cutoff lows usually provide a continuing chance of unsettled weather including showers during the day and cooler/cloudier weather in general. So, in essence, the development of the cutoff low as medium and long range guidance suggests would provide a continuing pattern of unsettled weather through early next week. Not all is lost under a cutoff low, however, as the weather can still be pleasant and sunny at times — but the threat for showers will always linger. The other wild card with cutoff lows is the duration of their stay — they can sometimes meander in the area for several days. Luckily, the current pattern isn’t overly slow, so the cutoff low should be pushed out eventually by another trough.

GFS Ensembles showing mid-atmospheric height anomalies. Note the cutoff low over the Great Lakes indicated by below normal anomalies.

Beyond the cutoff low, long range forecast models are indicative of a near-average pattern..but there are some hints of below normal anomalies in the mid-levels of the atmosphere working into the Central and Eastern United States by Day 10, with a large ridge on the West Coast of the United States. This is especially prevalent on the GFS Ensembles this morning. The Euro hints at a similar pattern — which adds some credibility to the potential for a developing below normal height pattern. Such a pattern would provide continued chances for precipitation and below normal temperatures as we head into the first few weeks of October. We’ll keep a close eye on it, especially now that we’re heading into October, where the pattern begins to take its first steps towards a hint at what to expect for winter. Yes,  the magic word. More updates in a few weeks (we love a good cliffhanger).

Stay tuned over the next several days for more updates on the potential cutoff upper level low and its impacts on the weather in the NYC Area next week. And, of course, keep a close eye on our Facebook and Twitter accounts for constant updates on the near and short term weather late this week and weekend.

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