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Category: Forecast

The 2022 – 2023 Winter Outlook Factors

Posted on November 5, 2022November 5, 2022 By admin No Comments on The 2022 – 2023 Winter Outlook Factors

I will post the conclusion here:

  • Normal to slightly above normal Temperatures
  • Normal Snow
  • The Wild card is the influence of the Tunga volcano

The BIGGEST concern I have for below-normal snow this year is the presence of La Niña

What is La Niña?

La Niña is a cold pool of water in the equatorial Pacific region. When the equatorial Pacific is Warm (El Niño) this region can supply a strong sub-tropical jet stream and usually a better chance of big snowstorms due to the amount of moisture. Although El Niño winters are not particularly cold, if the timing is right, we can get some whoppers! YES, 2016 was an El Niño year, and we got the last HUGE storm then.

La Niña, on the other hand, tends to make the Jet to the north push milder air into our region. We are often in the Battle Zone between colder to the north and warmer to the south when storms come along. The storms tend to turn to a mix or rain if they have any wintry weather in them at all. In general, we end up being slightly above normal with temperatures. The Pacific Northwest tends to get blasted with rain and Mountain snows. That does not do us many favors for keeping it cold in the east, as we get a ridge of High Pressure (Southeastern US warmer high pressures) pumping warmer air here.

Typical La Niña Pattern:

Typical La Niña Weather Patterns
Typical La Niña Weather Patterns

So this is Factor One for the 2022 – 2023 Winter weather outlook!

You can see in the National Weather Service’s Winter Outlook that they are weighing heavily on the La Niña pattern. If you have been watching the weather the last week or so, you can see that this is what the pattern has looked like!

NWS Winter Temperature Outlook

And, I have to say, we have had a horrible set of winters when there is a La Niña! I saw a meteorologist show that 60% produced below normal snow for the area.

My Thinking On La Nina:

There are a few reasons why we may see some early sneak peeks of winter in November and December, but they are unlikely to be long-lived.

Polar Vortex

The Polar Vortex is not something new and makes visits into the Lower 48 states every winter. The news media LOVES to over hype when it comes into play for the United States. Additional names to this Arctic region airmass could be the Polar Express (the streams of air that bring in the Vortex, or at least portions of it), or the circumpolar vortex.

What is it exactly?

The polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles. (that comes straight from the NWS) In the winter it strengthens.

When it is very circular, it is considered stable and the jet stream is usually very strong. Storms likely will rip across the United States and the coldest air stays “locked” in Canada.

Polar vortex Information from Climate.gov
Polar vortex Information from Climate.gov

Disruptions

If you want there to be colder air masses in the United States, you will want the Polar Vortex to be weaker than normal so that storm systems can disrupt and dislodge the colder air into the United States. Another thing that can help to split and disrupt the Polar Vortex is something known as Sudden Stratospheric Warming. This is warming above the vortex that can “split” the vortex in some situations. When it splits, this also will bring colder air into the lower latitudes. This does not always mean the United States! The Warming and Splitting can take some time and air masses and weather patterns can take some time to respond.

SO WHAT!! What about our winter?

We have already seen some impacts of the disruption in October. And now, all models are showing that an elongation/disruption mid-month. The disruption could cause a link to the cold in Siberia and provide some real cold for the US. It appears that cold will settle in for a lot of the Nation by mid and late month. Will it link with some moisture? There are some hints that it *MAY* – but I would not bet on snow.. but I am going to say that the risk is not zero!

Arctic Oscillation, North Atlantic Oscillation, and the Pacific North American Index, Eastern Pacific Oscillation

These features would take a very long time to explain, but they can work together.

Arctic Oscillation

“The AO is a climate pattern characterized by winds circulating counterclockwise around the Arctic at around 55°N latitude. When the AO is in its positive phase, a ring of strong winds circulating around the North Pole acts to confine colder air across polar regions. This belt of winds becomes weaker and more distorted in the negative phase of the AO, which allows an easier southward penetration of colder, arctic airmasses and increased storminess into the mid-latitudes.” – noaa.gov

My Thoughts:

It seems like the Arctic Oscillation appears that it will have some negative periods this winter due to the weaker Polar Vortex. That could mean some colder intrusions.

North Atlantic Oscillation

“The North Atlantic Oscillation (NAO) index is based on the surface sea-level pressure difference between the Subtropical (Azores) High and the Subpolar Low. The positive phase of the NAO reflects below-normal heights and pressure across the high latitudes of the North Atlantic and above-normal heights and pressure over the central North Atlantic, the eastern United States and western Europe. The negative phase reflects an opposite pattern of height and pressure anomalies over these regions. Both phases of the NAO are associated with basin-wide changes in the intensity and location of the North Atlantic jet stream and storm track” – NCDC

We want a negative NAO (if you want snow) mainly because it will block the retreat of cold air in the area and cause storms to ride up the east coast. That tends to be our snow making helper! When the NAO starts to turn positive, we end up usually doing the best.

My thoughts:

The NAO looks like it will have some negative phases as well. We had a good negative run in October, but that changed at the end and as we have gone into the first 2 weeks of November.

Pacific North American

“The Pacific-North America (PNA) pattern is one of the most prominent modes of low-frequency variability in the Northern Hemisphere extra tropics, appearing in all months except June and July. The spatial scale of the PNA pattern is most expansive in winter.” – NCDC

We basically want a positive phase which means a Ridge on the West Coast and a trough bringing colder conditions and the winter storm track would be good for the area. (if you like snow!) It could also connect to the cold over the Arctic and from Siberia.

My Thoughts

I think this will depend on the way that the Ocean temperatures impact the region out west.

Ocean Temps

La Nina is the big one. The cold area of water in the Equatorial Pacific is very prevalent. The other interesting areas are the Pacific Northwest warmer air temperatures. The other area is the warmer Ocean temperatures off the East Coast. The different areas seem to offset each other.

Huge Volcano Tonga moisture Input

This is a huge unknown this year. When Tonga exploded it put a ton of moisture into the atmosphere. This is something I think already impacted the Hurricane season and the southern Hemisphere winter. I do not know how it will impact, but it could help it be colder.

CONCULSION

I think we will see an early start to colder temps in late November and I would not be surprised to see some snow late November and early December. I think we still end above normal in temperatures. Additionally, the La Nina impacts will be the biggest one. So we end up with 16 to 25 inches of snow which is just normal amounts.

Forecast

What will Impact Winter 2021 -2022 – #5 Ocean and Great Lakes Temps

Posted on October 28, 2021November 10, 2021 By admin No Comments on What will Impact Winter 2021 -2022 – #5 Ocean and Great Lakes Temps

The Mid-Atlantic has a lot of factors because of the proximity to the Atlantic Ocean, Mountains, and even the Great Lakes. I want to outline the impacts of these AND the Pacific which will all impact this winter, especially early in the year!

Atlantic Temps are WAY WARM!

The Atlantic Ocean is currently much warmer than normal. I think this will impact us in several ways:

  1. Storm systems will have a lot more moisture to work with! The heat should evaporate more moisture and juice up any storm system. This is part of why I think each time the forecast models say it will be a dry period, they back off pretty quickly
  2. The Western Atlantic Ridge (which at times is known as the Bermuda High) will be strengthened by the warmer air. This could slow the infiltration of colder air and stall fronts away from the coast and make them just inland. This could have a significant effect on the rain/snow line!
  3. Warmer temps from the ocean will also make marginal (close to frozen events) more likely to be a mix or even rain. That heat will make it inland! This becomes less of a factor for the western zones, but does impact the upper levels which could make sleet and freezing rain a problem. This is not new, but could be a more common set up

The Greenland Temperature Gap

There is often a cold pool off the Northeastern United States that is linked, many times, to a better negative NAO (See previous posts for information on the NAO)

Great Lakes

You would not think the Great Lakes would have too much impact on our weather, but it really does! The Great Lakes can provide additional moisture to some storm systems, and, if it is warm, it can help moderate temps that are being impacted by winds that go across them. I am not saying this is a huge factor, but it does have an impact.

The Pacific Looks Poor

Probably one of the worst looks I have seen in a long while. The colder weather will encourage cold storms and the Jet Stream to be in a poor setup for us. I will discuss the Pacific Decadal Oscillation, the Pacific North American weather patterns, and the Eastern Pacific Oscillation in a post soon. All I can say is the pattern will favor milder terms for us and drier than normal conditions. I just do not like it.

Of course, we also have La Nina which will not bode well for big storms.

Summary

Most of the ocean looks terrible for us for winter. It is also the biggest signal that the winter may be warmer than normal and have less snow.

Forecast

What will impact Winter 2021 – 2022 #3 Snow Advance Index (SAI) & #4 North Atlantic Oscillation(NAO) and Atlantic Oscillation (AO)

Posted on October 27, 2021November 10, 2021 By admin No Comments on What will impact Winter 2021 – 2022 #3 Snow Advance Index (SAI) & #4 North Atlantic Oscillation(NAO) and Atlantic Oscillation (AO)

Snow Advance Index

The Snow Advance Index is a feature that is not always the best indicator for how our winter will be. The basic principle is that the advancement of snow cover in October is closely linked to the phase of the North Atlantic Oscillation.

North Atlantic Oscillation

The North Atlantic Oscillation (NAO) measurement is a KEY FEATURE needed to help get snowstorms on the East Coast of the United States. For example, the NAO is currently negative, which helps to slow down and aid in the development of big Nor’easters like the one we are having this week (October 26 – 27, 2021)

Really, though, the negative NAO (NAO-) is not the key to these storms, it is as the NAO flips back and forth between the negative and positive (NAO+) that usually signals a storm

Anyways, when the Snow Advance Index shows a great increase, the NAO *COULD* end up being more negative for the winter.

So what is the Snow Advanced Index Looking Like?

Snow Progression


The index is actually below where I would like to see it, but it is higher than last year!

imageywstm.png
Source – https://www.aer.com/science-research/climate-weather/arctic-oscillation/

The NAO Has been running Negative for a long while now. We will see if this can continue into November and Beyond! That would be a good sign for offsetting the La Nina impacts. (The line is below the 0)

NAO Index
NAO Index from Climate Prediction Center

Arctic Oscillation

Another factor for colder conditions is the Arctic Oscillation! As noted yesterday, when the Polar Vortex gets disrupted, it can turn negative! WE NEED THE NEGATIVE (if you like snow)! That is a better indication for more snow in the east! It has been running back and forth between positive and negative phases. We will see how this works out, but it looks like it is heading to negative again so the colder long-range seems to be linked to this as well! (Observed in black and red the various model predictions)

I am not super convinced we get non-stop help from the Arctic Oscillation this year, but I do expect a lot of variabilities which could help us at times be colder and have a chance of winter weather.

In Summary

I do not think we have much to count on from the Snow Advanced Index, North Atlantic Oscillation, or Arctic Oscillation. The negative NAO has been encouraging, but that alone will not set us right for winter weather.

Forecast

Winter Outlook Factor #2 – Polar Vortex Strength

Posted on October 26, 2021November 10, 2021 By admin No Comments on Winter Outlook Factor #2 – Polar Vortex Strength

The Polar Vortex is not something new and makes visits into the Lower 48 states every winter. The news media LOVES to over hype when it comes into play for the United States. Additional names to this Arctic region airmass could be the Polar Express (the streams of air that bring in the Vortex, or at least portions of it), or the circumpolar vortex.

What is it exactly?

The polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles. (that comes straight from the NWS) In the winter it strengthens.

When it is very circular, it is considered stable and the jet stream is usually very strong. Storms likely will rip across the United States and the coldest air stays “locked” in Canada.

Polar vortex Information from Climate.gov
Polar vortex Information from Climate.gov

Disruptions

If you want there to be colder air masses in the United States, you would want the Polar Vortex to be weaker than normal so that storm systems can disrupt and dislodge the colder air into the United States. Another thing that can help to split and disrupt the Polar Vortex is something known as Sudden Stratospheric Warming. This is warming above the vortex that can “split” the vortex in some situations. When it splits, this also will bring colder air into the lower latitudes. This does not always mean the United States! The Warming and Splitting can take some time and air masses and weather patterns can take some time to respond.

SO WHAT!! What about our winter?

Two things I am noticing this fall! The first is that the Polar Vortex appears weaker! Remember, this will allow for the influence of storm systems that could dislodge the colder air and give us cooler weather. I am also ALREADY SEEING THIS HAPPENING!

If you have been following me on the My Facebook “Speculations” I mentioned some “signals” that we could see some cold early. It was SPECIFICALLY related to the disruptions being forecast by models for November. The disruptions started showing on models two weeks ago and are now happening. It looks like this disruption pattern could come in a few waves in November! Some is coming into play next week, and some other long-range speculations show the middle of the month. Just because we get disruptions does not mean we will get cold here. That mid-month intrusion seems pointed towards the middle part of the country, and maybe down into Texas! Remember, when you get past 5 to 7 days in forecasting, the forecasts become much more speculative as the models may be failing to pick up on some things. HOWEVER, these Polar Vortex disruptions do seem likely, again, because the vortex is so weak. And, while in this stage, we could see some below normal spells in November! Snowflakes would not surprise me at some time. However, sustained cold air may be a challenge, as it should be, since it is so early in the colder months.

Forecast

Loudoun County Weather Outlook for Tuesday, October 26, 2021

Posted on October 26, 2021October 26, 2021 By admin No Comments on Loudoun County Weather Outlook for Tuesday, October 26, 2021

Summary

A very windy day ahead with wind advisories in effect from 12pm to midnight. Heavy rains are possible Friday. Halloween looks breezy but mostly sunny.

Loudoun County Weather Outlook for Tuesday, October 26, 2021
Loudoun County Weather Outlook for Tuesday, October 26, 2021

Short-Range Loudoun Weather Outlook

Looks sunny tomorrow. Cloudy Thursday and then rain Thursday Night through Friday with highs around 60. There is a chance of some flooding rains Friday.

Mid-Range Loudoun Weather

The weekend will have a good chance of rain Saturday. It looks dry and breezy for Halloween.

Weather Prediction Center Rain Forecast for the next 7 days
Weather Prediction Center Rain Forecast for the next 7 days

Long-Range Loudoun Weather Outlook
Description

6 to 10 Day Temperature Outlook from the Climate Prediction Center
6 to 10 Day Temperature Outlook from the Climate Prediction Center
6 to 10 Day Precipitation Outlook from the Climate Prediction Center
6 to 10 Day Precipitation Outlook from the Climate Prediction Center
8 to 14 Day Temperature Outlook from the Climate Prediction Center
8 to 14 Day Temperature Outlook from the Climate Prediction Center
8 to 14 Day Precipitation Outlook from the Climate Prediction Center
8 to 14 Day Precipitation Outlook from the Climate Prediction Center
Forecast

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