Three Winters

By the title, one might ask what in the world...there are 3?  Sort of; astronomical, meteorological, and solar.  I'm sure others can think of many other types of winters (Jonathan, nuclear, frosty...) but I will stick with these 3 for today.  And I'd like to very much focus on the "solar" winter but will address the other two.  The reason I'm doing this today is since the date is December 1, we are commencing on "meteorological" winter which corresponds to the coldest 3 months of the year when divided into quarters.  Most people are familiar with the "astronomical" winter which begins this year on December 21 at 5:02 am EST.  Let's start with the last...

The diagram above indicates the sun-earth relationship on or about December 21 most years (exact time and date above for 2020).  At that specific point in time, the sun will stop (solstice) moving south from our northern hemisphere perspective and begin its 6 month journey moving north until the next "sun-stop" or solstice which is the 1st day of astronomical summer.  On the December solstice, our noon sun angle is at its lowest (~26.5° altitude above the southern horizon) and our daylight is the shortest.  The coldest days are seldom the shortest days in December since our planet is water laden and with water's ability to hold onto its heat much longer than the dry land, there is a good 3 week lag time for the coldest weather to occur in the NH.  Hence the saying, "as the days lengthen, winter's chill strengthens"!  With all of this said, astronomical winter 2020 will begin December 21 and end officially at 5:37 am March 20 when the sun's 90° vertical angle strikes the earth's equator still moving north until its next solstice.  As a side note...for those of you not fond of winter, it is shorter than summer since the earth is moving faster in its orbit during our NH winter months as we are nearer the sun and therefore have a greater orbital speed than 6 months later in July!  But all of that is slowly changing as well...just like everything does...including earth's climate!  Isn't that kinda cool?  

As for meteorological winter, today (Dec 1) is day 1 of 90 days of meteorological winter; the 3 coldest months climatologically of the year.  Here in Pennsyltucky as my one friend affectionately refers to our stomping grounds, that marks cloudier, damper, cooler/colder, rainier, snowier, sloppier and darker weather conditions than the other 9 months.  Here in the northern fringes of the sub-tropics, we often experience relatively milder winters than the folks living just 100-200 miles north of here.  Due to our proximity to the ocean, our winter precip events are often a slop fest as the warmth of the unfrozen ocean often wins out over the polar and arctic air masses trying to move south and east off of the interior of the continent of North America.  KMDT averages just around 30" of snow annually...but as you are quite aware, one good nor'easter is capable of delivering the majority of that total in one fell swoop!  Below is a graphic of our average annual snow totals for PA.  The lee of the Lakes and the Laurel Highlands certainly have enhanced snows as you can see...just like today!

Solar winter?  It's linked to SAD (seasonal affective disorder).  Today marks our earliest sunset at 4:41 pm EST.  However, our sunrise continues get later until 7:30 am at the end of December.  Yet, the absolute shortest day is Dec 21 where we will experience 09h 18m 03s of daylight.  And if we have clouds, those days near the solstice are quite dark...even in the middle of the day!  With the increasingly lower sun angle in November, days do tend to be dark but not like the 2-3 weeks either side of the solstice.  Currently we are losing about 1 minute per day, but that rate slows as we approach the solstice.  Again, the rate of change is rather confusing due to the curved surface of the earth, the tilt of the earth, and the elliptically shaped orbit of the earth.  For those of you so inclined, The Equation of Time will better describe the whys of this occurrence.  With that said, today is only ~12 minutes longer than the shortest day and our noon sun angle is only 1.5° higher...so we are certainly in the middle of "solar winter".  Suffice to say, December is a month where the decorative lights can certainly shine brightly...even in the middle of many of the days!  The graphic below shows the rise-noon-set time and position of the sun for here in Harrisburg this upcoming winter solstice...

Welcome to winter!  Take your pick.  On the "bright" side, we've completed one month of solar winter...but...we haven't even begun astronomical winter; kinda funny.  I've been told my song sometimes works and sometimes not?  I don't know what's going on!  Darn Russians...ha!  If this works, enjoy it, I know I did.  And thanks for reading...

Smitty

AA:  3 types of winter; Astronomical which is from the winter solstice until the vernal equinox which most people acknowledge as the official winter season.  Meteorological winter which tends to be the 3 coldest months of Dec, Jan, and Feb.  And then there's solar winter when the daylight is least and the sun's angle is lowest.  That runs from Nov-Jan.  Enjoy the winter memories with the youngins!  

Sunday Gusty Sunday

 If you opened my "Winter Outlook" using 1988, 1995, and 2010 as my go to analog years, or were the recipient of duplicate emails, you noticed I had a few glitches my first time back on Blogger in a year.  So this post is just as much practice as it is to show Sunday's weather event and the whys behind the upcoming gusty day.  Before I jump in, I do thank you all for reading these blog postings and the several nice compliments I received back from many of you.  Let's now take a plunge (likely not as invigorating as the one shown below!) into the windy Sunday...

For starters, look at the wind gusts modeled for later this Sunday afternoon!  Note the wind speeds over the Great Lakes and the "Hurricane west wind" (thanks Gordon Lightfoot) over Lake Erie!  Also note many of the wind gusts at this time are aided in places of topographic relief.

These surface wind gusts are being created by a strong pressure gradient and a powerful jet stream across our region.  A very deep mid-latitude cyclone is developing north of the Great Lakes while a large high pressure is sinking deep into the southern plains.  Note how the isobars are bending south across the mid-Atlantic states; that clearly indicates the location of a cold front that will be marching towards the east today!  Take a look...

The storm is forming in response to crashing mid atmospheric heights (cold pool moving SE) and a powerful jet stream moving across the CONUS.  First the anomalous 500 mb heights.  As the atmosphere gets colder, the air becomes more dense and "heavier" and therefore the 500 mb level lowers towards the surface of the earth.  The map below shows how far from "normal" these heights are...

That rather large blob of unappealing green has its sights aimed directly at the mid-Atlantic region.  The tight pressure gradient is is creating a strong jet across the Ohio Valley and through the Appalachians.

With a jet like that above our heads here in PA, expect some precipitation and certainly some gusty winds to be sure.  Currently as I type this, there are NWS Wind Advisories issued for western PA.  I believe wind gusts here will be enhanced as the front passes through later this afternoon as a line of showers with possible thundershowers embedded with the front.  That front is ushering in colder air from O Canada.  Remember, I like to study the 850 mb level for air mass changes as the friction of terra firma is greatly reduced 1 mile up.  You can also clearly see the front up the Ohio Valley into PA.

The coldest 850 mb temps reside over PA later Tuesday into Wednesday...

Look for the wind to play a role in some of the NFL games today.  And though it pains me to say this, at least I have the Steelers to view if I want to see quality football this fall...if you catch my drift!

OK practice is over.  Now to post the appropriate song...one that reminds me of my youth!

Enjoy your Sunday funday!

Smitty

AA:  Quite windy today.  A strong cold front will pass through today with fast moving rain showers and gusty winds...maybe even some thunder?  Winds will remain gusty right through Wednesday with windchills in the upper 30s to low 40s through midweek.

 

Upcoming Winter Thoughts

Well it's been nearly a year since I last visited this Blogger site since I've been giving just brief snippets about the weather over on FB.  But these thoughts that I've been pondering needed the format of blogger since there will be more verbiage (at the risk of losing some of my loyal readers...) and just a few more graphics.  My idea on this upcoming cold season was requested by a few...so please indulge this post if you are so inclined.

As many of you know, I believe the earth's oceans are a major driving force of earth's weather patterns and ultimately earth's climate system.  In addition, I do find it rather myopic of both media types and political pundits to simply spew out causes of global climate changes when the reality is that earth's climate system is extraordinary complex.  There are a myriad of factors for which one has to account in order to even theorize about the "whys" of the weather observations and trends.  I find it so intriguing as to how our talented physical scientists and mathematicians are able to model short term weather patterns with relative accuracy knowing all of the parameters that must be part of their programs' ingest data.  Yet, many state quite often that "the weathermen are always wrong".  I know you've heard that...maybe even you have made a similar statement.  But so many take many of the climate predictions as gospel!  That's something that I have difficulty grasping.  Earth's climate system is extremely complex, but I do feel there are 2 primary drivers; the sun (aka 'ol Sol) and the oceans.  That's why I'm using these 2 factors in the maps I'm sharing.  Let's dig in...(my 2nd Pike Place has me rolling!)

First the sunspots cycle; the 11 year tendency for sunspots to appear and disappear from the photosphere of the sun.  Sunspots are areas of anomalous magnetism observed on the sun's surface.  They appear darker since they are slightly cooler than their surroundings.  Over the years, there has been some correlation to sunspots and the earth's weather.  If you are so inclined, you may want to look into the Maunder Minimum or The Year Without a Summer.  Our current sunspot cycle is in its minimum part of the 11 year cycle.  I do think sunspots play a role in weather patterns but how that plays out is way above my pay grade.  However, I will use low sunspot activity as one of my 3 parameters.  Below is a graph of our most recent sunspot cycles and the aforementioned longer view dating back to the Maunder Minimum and then some...

I also am using the largest ocean on earth and its current state as to help see what the upcoming cold season may bring.  The ENSO (El Nino Southern Oscillation) index is often helpful in identifying how the sensible weather might just play out...especially in the 2 extreme seasons of summer and winter.  It also affects the Madden-Julian Oscillation (MJO) which is a tool that often helps in the monthly weather patterns that are likely to develop.  Although the equatorial Pacific has been rather neutral the last several years, we are now and forecast to remain in a weak La Nina pattern.  La Nina is a cooling of the central Pacific while El Nino is a warming of the ocean.  Below is a graphic of our most recent Sea Surface Temperature (SST) anomaly.  NOAA has an 85% likelihood of La Nina remaining into spring 2021.  Note the cooler than normal in the central Pacific.  So I chose this as a factor for our our upcoming winter.  I am also showing a graphic of what a La Nina might indicate for the cold season.

OK...timeout to walk our dogs and throw some kettlebells around!  I'll be back...

Sorry for the digression...The final parameter is one that all of you reading this is one with that you are quite familiar.  And that would be the tropical cyclone activity or as most simply call...hurricanes.  2020 was quite an active year for named storms (the most ever); however, the overall amount of cyclone energy was not as robust as many years in the past.  Today, many storms get named that in the past would have simply been briefly monitored at best and more likely ignored due to their open ocean location and improbable impact to land.  In addition, pre-satellites era, only some wayfaring vessels would have noticed larger than normal waves at best.  But hurricane activity is certainly a result of warm tropical oceans and favorable atmospheric circulations.  And again with 70% of earth's surface being covered with water, I do look to the oceans for some signals for our weather.  This year we did have an abundance of tropical activity and that I believe can be a good indicator of what is to come.?.

So after perusing the data the last couple of days...not nearly enough time to thoroughly analyze all of the nuance that also needs to be included, I noticed 3 years that had similar oceanic and solar characteristics.  The abundance of tropical activity, an oncoming La Nina, and low sunspot activity were my chosen variables.   I only went back to 1980 since that is when the satellite era became prevalent though reanalysis is a skill set that is quite reliable.  The 3 years are 1988, 1995, and 2010.  They are not perfect analogs, but they are good enough for my hobby.  Then I used the Earth Science Research Lab (ESRL) website to see how the period of December, January, February, and March reacted to these factors.  Here are the results below:  1st Temperature...

And now for the precipitation...

The precipitation matches a La Nina nearly perfectly!  Wet Ohio Valley and wet Pacific NW.  Dry desert SW through TX and the SE.  The cold in the northern plains is a solid match as well.  However, the cold east coast does not match a La Nina mild east coast.  Also, with a warmer than normal ocean off of our eastern seaboard and the fact that we've had several months prior with above normal temps, I'd hedge on the side of near normal to slightly below than much below normal temps as the ESRL analog map indicates.  The precip matches pretty well and therefore, although we've had a dry last several months, a wetter pattern appears to be on the horizon.   Time will tell!

Since I'm back to Blogger, I'm gonna leave y'all with a song since I've had many tell me over the years that's really all they go to!  And since this about a winter discussion and forecast, I'll leave you with one of my favorite "folk" songs first performed by Joni Mitchell, but I like O Canada's Sarah McLachlan version a tad more.  Funny stuff!

Enjoy this beautiful Saturday...gotta love nice November weather!  

Smitty

AA:  Upcoming winter thoughts...You won't need to mow very much, landscaping will slow, the plow may need to be greased up for a 6 week period from Christmas to Groundhog Day and then again early March.