Doug Simonian

Gorgeous week ahead: 80s on Wednesday

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We hope everyone enjoyed the beautiful weather we had today! This trend is expected to continue, but with gradually rising temperatures through Wednesday. A weak backdoor front will cross Wednesday night, cooling temperatures a tad for Thursday and Friday, but highs will still run well above average. An additional weak warm front may develop for Friday night, resulting in a few showers.

Current surface analysis indicates a departing low pressure system offshore, and building high pressure systems to our south.

Current surface analysis indicates a departing low pressure system offshore, and building high pressure systems to our south.

Current surface analysis shows a large area of high pressure to our south, helping to deliver pleasant, warm conditions. This ridge of high pressure has gradually been building northward, but had been a bit halted by the departing low pressure to the east. Remember, that storm well offshore was what some models had being a major nor’easter last week — thank goodness it missed! Tonight will be pleasant and cool; clear skies and low temperatures dropping into the 50s.

As the low pressure continues to escape further from our area, that will give more room for the ridge of high pressure to build northward. This will lead to temperatures warming into the upper 70s to around 80 tomorrow, and potentially mid 80s on Wednesday! The building area of high pressure and the clockwise flow around it will bring warmer mid-level temperatures, and westerly winds — downsloping off of the Appalachian Mountains — which yields maximizing warmth, even for coastal locations. Low temperatures will be in the upper 50s for most locations — with lower 60s in more urban areas.

There may be a few stratus and cumulus clouds tomorrow as a weak shortwave traverses on top of the ridge, giving some on-and-off periods of shade and sun, but partly cloudy skies should mostly prevail. Wednesday will be mostly sunny.

This afternoon's high resolution NAM model shows temperatures warming into the low and mid 80s for Wednesday afternoon.

This afternoon’s high resolution NAM model shows temperatures warming into the low and mid 80s for Wednesday afternoon.

As seen in the image above, the entire area is projected to reach the low to mid 80s for Wednesday afternoon.

Thursday will see temperatures cool down to around 80, and Friday will have temperatures in the upper 70s with a few more clouds around ahead of a weak developing warm front. Any potential showers should hold off until Friday evening and night as the warm front crosses the area, but it will not be a washout.

The weekend will continue to feature above-average temperatures due to the passage of the warm front.

The next chance of more organized rain will be on Sunday night and Monday. But this is far out in the future, and there are still many variables at play — the chance is there that the rain could miss to our west.

For now, enjoy the terrific weather this week!

Doug Simonian

Why next week’s storm will not affect our region

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As Autumn has arrived, the jet stream tends to get a bit stronger and sag to the south, helping make nor’easters more likely. Some computer model guidance had been hinting at a strong coastal storm approaching the area early next week, which would bring strong winds, heavy rain, and coastal flooding. However, the pattern does not support such an occurrence.

Looking at last night’s European model ensembles at the 500mb level, there do appear to be some features that support the potential for a strong nor’easter to head towards our area. Initially, there is a kink in the heights at 500mb just offshore of the Eastern Seaboard, which indicates our storm system. With strong storms like Sandy, we had a blocking ridge near and to the north of the storm, forcing it to stay to offshore of the southeast coast, instead of shooting out to sea. We also had a trough diving into the Central Plains, heading eastward, eventually capturing the storm and bringing it to the west. At the basic level, those two features certainly exist, which raise an eyebrow.

Last night's European model ensembles, valid for 8 a.m. Saturday morning. Image is courtesy of the WSI model lab.

Last night’s European model ensembles, valid for 8 a.m. Saturday morning. Image is courtesy of the WSI model lab.

However, taking a deeper look at things, it is not prudent to say that a storm will trek towards us. For one thing, although there is a strong ridge in the east, extending up through SE Canada and New Foundland, it is merely a function of being downstream of the trough, and is not a block. Blocking typically occurs in higher latitudes — such as Greenland — and the height contours are typically closed. The true blocks are very slow to move and act to buckle the weather pattern, rather than being within the “flow” of the pattern. Since the ridge is merely downstream of the trough — it is within the “flow” of the pattern, and there is nothing to keep this ridge in place. It is thus a transient feature, and will eventually scoot out to sea and weaken. In fact, looking the higher latitudes, the heights are actually very low up there; more evidence that there is no true blocking.

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John Homenuk

October blocking could hint at winter pattern

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Autumn began just a few days ago, but the weather pattern has already adjusted to the fall-like pattern with temperatures falling into the 30’s and 40’s at night. The first cold nights of the year typically come in mid to late September, as the warm and humid days of summer fade. The cooler, more crisp air gives us the first small taste of the cold winter which is only a handful of weeks away. The pattern has begun its seasonal change, and we are beginning to feel the effects of it. Yet, the best hints of what the winter pattern may have in store for us may be hundreds and thousands of miles to our north — over the high latitude/arctic region.

Seasonal forecasting can be a tedious and intricate task for meteorologists. Many times, meteorologists and forecasters alike find themselves drawing upon past events, analogs, and other research for help with predicting the months ahead. This is especially true in the Autumn season, as winter forecasting begins. Meteorologists are about to enter a flurry of forecasting over the next few months (yes, we are somehow enjoying this benign and calm weather right now). So as we look forward to the winter, we can often use the preceding months as indicators of the pattern to come. The pattern itself can often tip its hand, giving us a clue as to what we may be dealing with a few months down the road.

The words “high latitude blocking” likely will instantly bring back memories of some of our stronger storms and more volatile weather patterns in recent memory. The Blizzard of 2010, Hurricane Sandy, the Nor’Easter just a few weeks afterward. They all occurred during episodes of high latitude blocking, with a negative NAO cor North Atlantic Oscillation (for a background and more information on the NAO, click here). Still, high latitude blocking episodes which occur months before these events can often serve as accurate predictors, foreshadowing in a sense, of the upcoming pattern a few months after. A few months ago, we published some research on the blocking pattern during the month of May helping to predict the pattern during the summer months.

For a bit of reference, high latitude blocking refers to blocking ridges which occur in the higher latitudes over Canada and the North Atlantic (background on atmospheric blocking can be found here). These ridges slow down the jet stream/weather pattern. The high latitude blocking over Greenland, the North Atlantic, or Canada during the winter months often leads to the displacement of very cold arctic air over the United States, very often the Northeast US. The more amplified/slower pattern also leads to the potential for large coastal storm systems and has historically featured snowier and colder periods in the Northeast US.

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John Homenuk

Forecast: Another stretch of awesome weather

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There hasn’t been much to complain about lately, at least when it comes to the weather. In the last week, we have been fortunate enough to settle into a very pleasant pattern. Last week itself featured 5 straight pleasant days featuring low humidity and plenty of sun. After a brief return to humidity and a cold front with showers on Saturday into Sunday, the comfortable weather has returned again. In fact, this airmass is a bit more chilly — if you haven’t already noticed this morning. Temperatures fell into the 30’s in the interior this morning, and the upper 40’s even in the urban areas. The low of 47 was the coldest so far this season in New York City.

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