While we're all familiar with lake effect snow (if not, click here), lake effect rain is a far less common occurrence. The same phenomenon applies, cold air blows over the relatively warmer waters of Lake Ontario, picking up moisture and depositing it upon us. This time, the air is not quite cold enough to support snowfall, so precipitation falls as rain. Just like lake effect snow, the rain falls in finger-like bands. The example below is from this morning. As we can see, a narrow but intense band of rain is situated just south of Watertown.
The rapidly changing wind direction today will lead to periods of rain and low clouds, followed by breaks of sun. As the wind changes to a southerly direction tomorrow, we will see a return to pleasant and sunny conditions. However, as another cold front swings through on Monday, switching the wind to a northwesterly flow, the lake effect rain will return, and we will see the frequently changing conditions throughout the day.
Why don't we see this more often?
As discussed in the lake effect page, lake effect snow and/or rain is fueled by a difference in temperature between the lake water and the air mass above it. With today's high being in the mid 40s, and the lake temperature being about 58ºF, the temperature difference is just enough to allow for lake effect. If the air temperature were 5ºF warmer, there would not be enough of a difference to allow for lake effect. If the water were 10ºF colder, the precipitation would be falling as snow, not rain. Given the relative stability of lake temperatures, air temperatures that can support lake effect rain are generally only range from about 35ºF to 45 ºF. On the other hand, a temperature anywhere from 34ºF to -20ºF, a 54ºF range, can support lake effect snow. To summarize, there is a lot smaller margin of error for lake effect rain conditions than there is for lake effect snow conditions.
Out of Nowhere
It seemingly sprang up out of nowhere. Fueled by favorable wind conditions and above-average water temperatures, Hurricane Michael blew up from a tropical depression to a Category 4 Hurricane in the matter of three days. While it appears at this point that Michael will make landfall as a Category 4 Hurricane, that did not seem to be the case three days ago. Weather models, especially the GFS-the favored model of the National Hurricane Center-predicted a substantially greater wind shear than what ended up happening. Wind shear refers to wind blowing in different speeds and directions at different altitudes within the atmosphere. Having strong wind shear essentially rips a hurricane apart by pushing and pulling at it from all different directions. Without the strong wind shear yesterday and today, Michael was able to rapidly develop. The illustration below shows what hurricanes will do when there is and when there is not strong wind shear. Unfortunately for the folks of Florida, Michael is taking the scenario demonstrated by the right side of the picture.
Although landfall is inevitable at this point, there are still slight differences in the track that will have a major impact in terms of the devastation. This is because of questions whether or not the bullseye of the Hurricane will track through Panama City, a significant population center on the Florida Panhandle, or just to the east, impacting a far less populated area of the state. As of now, the model trend seems to be pushing Michael just to the east of Panama City. We shall see if this comes to fruition.
Will Central New York be Impacted?
No. Thankfully, a cold front that will move through the area later today will help to steer the eventual remains from Hurricane Michael well east of our area, with the storm forecasted to move out to sea after it exits the continental U.S. along the Carolina Coast.
Summer has made a brief return to the area, and will be with us through Wednesday. Highs are forecasted to crack the 80 degree mark on both Tuesday and Wednesday. The humidity will also be a factor, making the temperature feel 3 to 5 degrees warmer than they actually are. Accompanying this warmup will be a period of generally sunny skies, as high pressure moves over the area.
Enjoy it while it lasts.
The aforementioned high pressure system scoots out of the area Wednesday night, giving way to a strong cold front that will drop daytime highs by over 30ºF. As this cold front continues to move east, it will stall out as it winds from Hurricane Michael will push against the cold front's forward momentum. The obvious good news is the presence of this stalled front will keep the remains of the hurricane far away from Central New York. The bad news is the stalled front will keep clouds and gloomy weather over the area for an extended period of time. It's not likely that we'll catch a glimpse of sun until late Sunday, no pun intended.
It's finally here! After weeks of looking over global computer models, and climate records from previous years with similar conditions going into the winter season, I am ready to release my outlook for this upcoming winter.
For starters, let's establish a ground rule. Given that this outlook covers such a broad timespan, This forecast is largely based on global weather patterns, and microscale events that shape our day-to-day weather simply cannot be taken into consideration this far away. Therefore, this outlook does not forecast specific snow storms, cold snaps, etc., but rather, what we can expect this winter to be like as a whole. With that being said, let's get started!
December & January: 3°F to 5°F above average
February & March: 2°F below average to 1°F above average
The first thing to consider when making a winter temperature outlook is the El Nino-Southern Oscillation (ENSO) cycle. This is essentially just a fancy way of referring to the ocean temperature of the Pacific Ocean between the West Coast of South America and Australia. The ENSO cycle has two phases: El Nino and La Nina. During an El Nino phase, water temperatures are above average, while they are below average during a La Nina cycle.
Now, why exactly are we concerned with ocean temperatures in the eastern Pacific Ocean? Because it is these temperatures that determine the overall trajectory of the jet stream, which functions as the highway that major storms travel along, as well as the dividing line between cold air (to the north of the jet stream) and mild air (to the south of the jet stream). This season, we are looking at a moderate El Nino pattern.
As we can see from the graph above (courtesy of NOAA), an El Nino pattern keeps the frigid temperatures associated with the Polar Jet Stream to the north of Central New York. That's not to say we won't have any cold snaps, we will, but in general, expect a warmer winter than average, especially during the first half of the season. As winter progresses, however, we can expect the temperatures to become slightly colder. This prediction is attributed to long-range models suggesting the North Atlantic Oscillation (NAO) transitioning from a positive phase to a negative phase as the season goes on. The NAO is separate from El Nino and La Nina, as the NAO takes place in the Atlantic (hence the name), and has to do with atmospheric pressure, rather than ocean temperatures. Similar to El Nino and La Nina, NAO effects the direction of the jet stream. A negative phase causes the jet stream to wrap around the East Coast of the US, allowing Arctic air to infiltrate Central New York. On the other hand, a positive NAO keeps the cold air to our north.
With all of that being said, I'll conclude the temperature section by stating that specific spans of mild and cold periods throughout the winter are determined by the interaction of the ENSO and NAO cycles. These factors are too complex and specific for weather models to pick up on this far away, but by looking at the general cycle patterns of each, we can have a broad idea as to what the temperatures will be like during this winter.
December & January: 33" (average: 40")
February & March: 52" (average: 57")
Forecasting snowfall for Central New York is notoriously tougher than temperature predictions. This is because while cold air masses and air masses effect entire regions of the country, snowfall is a much more localized phenomenon, especially here in Central New York. This is primarily due to lake effect snow, which can dump huge amounts of snow over a very small area. For more information on lake effect snow, click here. With that being said, lake effect snow is the primary component of the snowfall forecast. As of October 3rd, NOAA reports that the surface temperature of Lake Ontario (the source of our lake effect) is running over 6°F above average. That is significantly above average, and will continue to remain above average for at least the next several months.
Although a warmer lake temperature allows for more powerful lake effect snow events, I still predict that we won't see above average snowfall because of the prevailing wind direction, brought by El Nino and a positive NAO (at least during the beginning of winter-the most active time for lake effect), will keep the bulk of most lake effect snow events just north of the Holland Patent school district. Areas such as the Tug Hill Plateau and western Adirondacks will face the brunt of this lake effect, and therefore they will likely see average to above average snowfall during December and January.
Synoptic snow refers to snow that comes from literally any other type of snow storm besides lake effect. It goes without saying that synoptic snow is the other component of my snowfall forecast. Given the direction of the jet stream, as determined by the ENSO and NAO cycles, I predict that some synoptic storms that impact our area will track to our west, Whenever winter storms track to the west of Central New York, they bring milder air, and we get a cold rain event instead of snow. To learn more about how the track of a storm determines if we get rain or snow, click here. It is because of this that I predict we will see slightly below average snowfall during the second half of winter, even with colder temperatures predicted.
I hope you have enjoyed reading the 2018-19 Winter Outlook. If you have any thoughts or questions, comment below!
Looking around Holland Patent at the end of September, one would normally expect to see an abundance of yellow, orange, and red in the trees. That is not the case this season. As of September 23rd, virtually all the deciduous trees were green, with only some Oak trees exhibiting the faintest patches of yellow. Typically, the Holland Patent area would be barreling toward the peak of the foliage, which normally takes place during the last week of September into first week of October. This year, I'm not forecasting colors to peak until between the 2nd and 3rd week of October.
So, why the delay?
We first have to note that September 2018 is on course to go down as the 4th warmest on record, with an average temperature around 6 degrees above average. While chlorophyll production in the leaves is controlled by the daylight hours, it is the temperature that controls the decomposition of the chlorophyll. Even though the deciduous trees have all but stopped producing chlorophyll, as the days have shortened just like any other season, the chlorophyll already produced is not breaking down as fast as normal. It is only after the chlorophyll breaks down that one can observe the red, orange, and yellow in the leaves. Unfortunately, even though the chlorophyll is breaking down at a slower rate, the leaves themselves are still dying like they would any other year. That means some leaves just turn from green to brown, as the leaf is dead by the time the chlorophyll finishes breaking down. With that being said, it's not that we won't see any color at all, as most leaves will not be fully dead when all of the chlorophyll breaks down. The colors this year will just be slightly less robust than they were in previous seasons.
As we enter the final week of September, with seasonable temperatures finally returning for the moment, I'm awestruck with just how warm it's been up to this point. 14 out of 22 days thus far in September have been above average, with just three falling below average.
Why has it been so warm?
We can attribute the bulk of this extended and persistent heat to a strong area of blocking high pressure situated several hundred miles off of the Virginia Coast. This weather setup gets its name simply because it prevents, or blocks, any other type of weather system from moving into the area that it is occupying. High pressure systems of this magnitude are usually only displaced by major shifts in the jet stream, which can overpower and push the high pressure away from the area that it had been occupying. The rotation of the high pressure system essentially acts like a fan. Because the high pressure is situated to the southeast of Central New York, and high pressure systems spin in a clockwise direction, we're right in the path of warm humid air from the Gulf of Mexico to be whisked up our way. This diagram from last week showcases the setup we found ourselves in for most of September.
While this type of high pressure setup in it of itself is not rare, especially during the summer months, the duration of the high pressure is. It's longevity can be attributed to the absence of any jet stream shifts. Up until now, the jet stream has been parked well north of our area, exiting North America as far north as Newfoundland. Going into the end of September, the jet stream will finally creep south, and displace the blocking high. This will usher in an extended period of seasonable temperatures.
If you don't like the heat, were there still any positives to this setup?
Due to the moist nature of the airmass, the Holland Patent area experienced frequent but scattered rain showers throughout the past few weeks. This helped the Holland Patent area recover from the minor drought (2.5" below average rainfall over the summer) that it found itself in at the beginning of the month.
What can we expect going forward?
As we close out September, and head into the first week of October, cool and unsettled weather will be the rule. As the Northern Hemisphere as a whole begins to cool down as it receives less and less solar exposure, the jet stream will continue to slide south. This movement is not uniform. In other words, the jet stream will bounce back and forth as it inches southward. Because storm systems travel along the jet stream, we can expect an increase in cloudy and unsettled days as the jet stream will be spending a lot of time in the vicinity of Central New York. There's still no signs of a prolonged period of below average temperatures over the next few weeks, however it's fair to say that this time of above-average temperatures has come to a close.