Weather Blog

Pattern Changing...again

Highlights:

1) Halloween Outlook
2) Next Cutoff Low
3) Pattern Change for next week...maybe two
4) Will it last?

 

HALLOWEEN
Happy Halloween Everyone!

If you have plans tonight:

In the past, we have had some weather extremes on this date.  The NWS in Louisville put together a nice chart showing our past Halloween weather conditions.  Note the snow in 1993.  We had a track on Halloween, but alittle over 2" the day before on the 30th.  I think most of us remember that one :)

CUT OFF LOW:
Once again, we could be facing a cutoff low setup. I don't think it will linger as long as the earlier ones this Fall have been, but still a slow mover.  (Note: it will be interesting to see if this keeps taking place this upcoming winter too).

The low moves in to the Plains Wednesday.  For us, a nice south flow ahead of it.  Could reach 7o with that south flow as well.

Then the low arrives into Thurs AM...and deepens to our west.  Any storm threat looks elevated as the worst of any severe storm threat will be south of that red line..that is south of us. 

The low weakens some as it moves over us...and gets cutoff from the main jetstream flow. 

Some of the models try to to a top/down cooling, but I don't see any concern with frozen precip at all.  Looks chilly with the low, but nothing extreme.    Highs in the 50s.

The low then moves to the southeast and fads.  How quickly will determine how Friday will turn out.  So we will have to make some gradual adjustments there.

PATTERN CHANGE NEXT WEEK
Looks like will start to see a trend in which the low pressures will form in the Plains then cut toward the Great Lakes.  This means a warmer and at times, stormier pattern.

The first low moves in early next week (sun/mon). Could see a band of shower/storms, but the storm will be "occluding" or wrapping up in Canada...so the "push" that front will have ...will be fading.  We'll watch it though.

Once that front passes..it looks to becoming horizontal and return northward as a warm from as a new low develops in TX.  This will produce some rain around Tue or so..as the warm push from the south begins.

By next Thursday, this low deepens pretty good (this is long range of course...so just purely going verbatium by the model) and moves it to our west and north.  Such a storm track would put us at risk for a thunderstorm event.  Again..around the 1oth. 

There could be a similar storm just after that by the weekend of the 12th.

BEYOND THAT

It looks like that while the storm track has been mostly from TX to the Great Lakes, the cold air has been allowed to build.  Signs are still there that the cold air being lodged to our north will drop south/east as we head toward the last week or so of November.  

Similar to last year in fact. Hmm.

I know I just threat out a lot of what iff's with the models since I went pretty far out, so just know I am just giving you an early preview to the pattern.  The details are still way vague. 

So why show at all? I think it supports the idea that we are going to enter a warmer/stormier pattern that will then drastically change to colder for the end of November. 

We shall see!!

Have a safe and fun Halloween!!

 

Trick or Treat Forecast

The rain is over now, and the clouds are starting to clear a bit.  Temperatures over the past few days have been below normal for this time of year, but not by much.  Today will be no exception with temperatures struggling to reach the 60 degree mark in many locations; however, the sunshine will make it feel and look better.  By the way, we get to keep the sunny skies for tomorrow and Wednesday as well. 

 

Here are some trick or treat times for some local communities:

Bullitt: no set hours

Shepherdsville: Monday 5-9

Clark Co.: Monday 6-9

Floyd Co.: Monday 5-8

Hardin Co.: Monday 5-8 (unincorporated areas)

Elizabethtown: Monday 5-7

Harrison Co., IN: Monday 6-8

HenryCo.: Monday 6-8

Meade Co.: Monday 5-8:30

Nelson Co.: Monday, no set hours

Oldham Co.: Monday, no set hours

Shelby Co.: Monday 5-7

Spencer Co.: Monday 5-8

Washington Co., KY: Monday 6-8

Louisville: no set hours

 

Temperatures will be in the upper 50s when trick or treat begins, then it will cool off to around 50 degrees once it's over (upper 40s in the country).  You may want to add an extra layer under the costumes tonight.

 

Our next chance of rain will be on Thursday as a front moves through Kentuckiana.

 

 

HAPPY HALLOWEEN!

From: Christie & Tori

A COMPLETE LOOK AT YOUR EXTENDED FORECAST

Another frosty start to the morning. Mainly clear skies, calm winds, and hello widespread frost for the second morning in a row. Looking ahead...

THIS AFTERNOON

A cold front to our West will continue its Eastward track and eventually affect parts Kentuckiana. Throughout the rest of the day we'll see increasing cloud cover stream in from the West due to the approaching cold front. Much of the morning and early afternoon will be filled with sunshine...hopefully enough to warm us into the low to mid 60s. Here's the deal...should we see clouds sooner our temps may not warm as much, however we're ahead of a front which typically brings warmer temps...so it will be a battle to see what scenario plays out. Either way, expect a chilly Fall afternoon.

TONIGHT

As the front gets closer showers are likely to develop in Western KY late tonight into early tomorrow...with rain expected in and around the metro around anytime between 4-8am. This front doesn't have much punch with it...but I think it has enough to squeeze out some rain. It won't be widespread flooding rains or anything like that...but just be aware some rain is possible into tomorrow morning. Which brings us to Halloween!

HALLOWEEN

As the front passes through the area tomorrow cooler temperatures will follow. Highs tomorrow will remain in the 50s under mostly cloudy skies early and a chance for a few showers. As the front pushed Eastward I think there will be a definitive cut off line from clouds to no clouds...so I expect some sun to return by tomorrow afternoon. Trick or treating forecast: Temps settle into the upper 40s and low 50s under dry conditions.

LOOKING AHEAD...

A stronger cold front looks to approach Kentuckiana mid to late next week. This one looks to have more giddy up with it. Still several days away, but some data hinting at winter precip on the backside of the system. Speaking of winter precip...hello Northeast snow storm! Can you believe that? What a whopper of a Nor'easter...check out this link...( http://www.erh.noaa.gov/hydromet/erEventDisplay.php )  for updated snow totals. A few spots picked up more than 2 FEET of snow. Mind blowing...just goes to show Mother Nature is in control. :) Have a wonderful and safe Halloween...I'll see you back here Saturday morning at 6am!

FROSTY START TO THE WEEKEND - RAIN ON HALLOWEEN?

Have you been outside this morning? If not...brrr! Bundle up! Upper 20s were common this morning and widespread patchy frost developed. We've posted this on facebook and twitter before...but incase you missed it...click on the link (  http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lmk&storyid=74445&source=0 ) for why our area isn't included in Frost/Freeze advisories this morning and why we won't be going forth this year. Nonetheless...it's cold!

THIS AFTERNOON

Despite all of the expected sunshine temperatures will remain below average once again this afternoon. We'll slowly warm to a high of 57 degrees here in Louisville. Kickoff temp for the U of L game this afternoon: right around 50 degrees with light winds. Again, we won't see any shortage of sunshine...just a shortage of warm temps. :)

TONIGHT

Heading out tonight? If you'll be at the UK game this evening expect temps in the mid to upper 40s for kickoff and right around 40 to wrap up the game. Another frosty night expected overnight as temps will once again settle into the upper 20s/low 30s.

SUNDAY

Another day filled with plenty of sunshine tomorrow, and again...it won't help us much in the temperature department. I think we'll be a few degrees warmer as winds shift to the South ahead of an approaching cold front. Typically ahead of frontal boundaries temps warm...so we have two things working in our favor tomorrow. Unfortunately, I think we'll remain below average once again (average high: 67) We'll shoot for temps right around 60 tomorrow with increasing clouds as we progress through the day. Rain looks to be in the area come Halloween-day...so make sure to join a welcomed face tonight John Belski for your Halloween forecast. He'll be filling in for Andy this weekend. :) See you back here tomorrow morning from 6-8am!

 

THE STRETCH OF CHILLY AIR ROLLS ON...RAIN TOO?

We'll end the work week with a bang...chilly air for much of the region especially North of the River. Patchy frost was reported this morning in addition to temps in the mid to upper 30's in Southern IN. Unfortunately, if you're a fan of warmer weather today won't be your day as temps aren't expected to warm much. Here's the set up for today and looking ahead...

TODAY

A cold front pushed through the region yesterday, it brought us rain then and colder temperatures now. With the cold front still in the region, combined with an approaching area of low pressure, cold cover should remain thick most of the morning and afternoon. How will that influence temps? Well, the same as it does when you need clear skies to see temps drop...you need cloud cover to act as a "blanket" to keep temps warm. That will be the case today. I think we'll see some sun...especially the later we head into the afternoon, but for most of us expect mainly cloudy skies....and rain?!? Well, we're not done with the rain just yet, at least for some of us. An area of low pressure positioned to our South and West will ride along a cold front to our Southeast...this is important because it will take the heaviest, constant, rain with it. However, it will come awfully close to influencing parts of Kentuckiana. I think especially Southern and Eastern KY stand a chance at some rain today. But for most dry conditions prevail and cool, too. Highs expected to top out in the mid 50s.

TONIGHT

Clouds are expected to break up just a bit and will give way to some clearing. That will allow temps to drop into the mid to upper 30s for many. Patchy frost is likely especially in outlying locations.

THIS WEEKEND

Our friend Ms sunshine will make a return thanks in part to high pressure. Stable, dry air will work in this weekend, but unfortunately it won't help us warm much. Highs will struggle to hit 60 degrees both tomorrow and Sunday. Should we see a warmer day of the two, it will probably be Sunday. Yes, I'm expected increasing clouds (a factor to keep us cool) but we're also ahead of a cold front (a factor that would warm us) So we'll have to see which one wins the battle...nonetheless expect temps near 60 both days.

HALLOWEEN

A cold front is expected to sweep through the Ohio Valley late Sunday into early Monday morning...it may squeeze out some rain on our area but it will quickly clear out by Halloween-day. Brian Goode will have the latest on your Halloween forecast and beyond today starting at noon on WAVE 3 news. Hope you have a wonderful afternoon! See you back here tomorrow morning from 6-8am! -Lauren

UPs and DOWNs. Getting used to this...

Highlights:

1) Spotty Showers early
2) Dry weekend
3) Spooky Shower for Halloween
4) Another cold snap
5) More 70s??

SPOTTY SHOWERS
They are moving through our southern counties right now.  Light and quick moving.  Any more activity should be confined to south KY and TN tonight/tomorrow.

DRY WEEKEND
Looks like we will be in between systems over the weekend.  Decent wet snow event for the NE.  As the system passes by SE KY..there could be some wet snow that mixes in...but no where in our viewing area...I am referring to far SE KY.  But look what is sneaking up on us from the NW

SPOOKY SHOWER
That sneaky lil system to our NW will move into the Ohio Valley early Monday morning.  It will be moisture starved so only a brief shower/sprinkles expected...and most of that looks to be around sunrise.  Dry for the afternoon and for the trick-or-treaters at night.  Temps in the evening still look to average around 50 or so. 

ANOTHER COLD SNAP
Another potent front looks to approach late Wednesday in Thursday.  GFS and EURO in pretty good agreement on this. Here is the GFS

And EURO temps showing the same front pushing in.

This looks like a glancing blow of cold air...and the the pattern is pretty progressive. No blocking.  So this cold snap should only last 1-2 days and pushing NE.  Highs during the snap may hold in the 40s on Thurs or Fri, still time to fine tune that.   Moisture looks to be all along the front...so don't see precip type issues right now as dry air takes over.

MORE 70s???
The pattern gets more dynamic as we approach mid month.  Signs are there for a big low pressure in the Plains.  Remember a few weeks ago, I stated it would be a PLains severe weather outbreak that will change our pattern to cold.  And I think the first signs of such an event are trying to showing up.

In advance of this low, it looks really warm. I put in some 70s in the 14 day based on this big storm idea.  Timing still has to be worked out however so don't focus on the exact dates just yet.

Obviously, after this storm...the mother load of cold air in Canada is wanting to head south.  This could make Thanksgiving very interesting...again this year.

One last thing, mom came to visit me today at the station.  She brought some goodies for everyone. Now everyone calls her mom :)

 

Kevin took her away 5 mins later...

Time will tell.

COLD FRONT = RAIN AND COLDER TEMPS!

What a start to the day! Damp, dreary, and chilly. My favorite. ;) The culprit? A cold front....not just any cold front, one that extends from nearly coast to coast. This thing means business. Not only will it bring rain to much of the US but also cool temps behind it.

REST OF THIS AFTERNOON...

The heaviest of the rain has come to an end as the front pushes Northwest to Southeast. This morning much of the metro area saw constant rain...that has since come and gone. Now we're left with the possibility of lingering light rain and drizzle. 24 hour rain totals continue to pour in with areas seeing as low as half an inch as isolated locations picking up more than 2 inches. Here in Louisville we're looking at around 1.50". Much of the afternoon will remain dry, seeing as the front is still in the vicinity we can't rule out some moisture going forth. Stubborn clouds remain this afternoon and won't do us any favors in the temperature department. Highs are expected to top out in the low to mid 50s for most of us. Any sunshine that develops (highly unlikely) could warm us a degree or two. Bottom line...average high this time of year is 67 and we will be well below it with highs in the low to mid 50s under a breezy North wind.

TONIGHT

Mainly cloudy skies continue for most of us this evening and I expect any rain that sticks around through the evening hours to dissipate overnight. Again, the front will remain in and around the area so light drizzle is possible under thick clouds but any substantial rain won't be in the cards for us tonight. Temps dip into the upper 30s for many.

LOOKING AHEAD...

We'll be under the mercy of high pressure for the next few days meaning sunshine returns. It looks like clouds could stick around for part of the day tomorrow but some sun can be expected with temps again well below average with highs only in the mid 50s. As we head into the weekend we can expect a break from cloud cover as the liquid gold makes a return. Although we'll see sun, we won't see temps warm much. Highs in the upper 50s and low 60s can be expected this weekend. We're watching a small disturbance that may influence parts of Southern IN come Sunday night into early Monday morning. A small rain chance is possible, and it looks so minimal at this time we may have to take it out of the forecast going forth. Halloween forecast? Well...I can't give it away now, that would be too easy! :) Brian Goode will have the latest on that today at noon. Have a great day!

(10/26) WAVE 3 Weather Team - Fun Winter Forecast

I asked each of our staff to submit (just for fun) some winter weather guesses! 

*  The date of the first snow flakes of the season.
*  What the coldest temperature of the season would be.
*  What the total snowfall for the season would add up to.

Below is what we say (just don't hold us to it - we're just having fun)... feel free to comment on the blog.

(10/26) Kevin Harned's Winter Weather Forecast

BOTTOM LINE (at the top) – With a similar weather pattern to last year I think the snow lovers will be pleased.  I’m not convinced there will be as many ‘snow events’, but the seasonal average of 14.7” shouldn’t be hard to reach.  Based on the data (current & forecast) it appears the winter will get off to a cold & stormy start – keep in mind winter is considered (December, January & February).  While a cold start doesn’t mean a cold finish with a weaker La Nina, I’d expect temperatures to warm a bit through mid January & February.  Overall temperatures will be above average – in part due to warmer nighttime lows.  I’d expect snowfall amounts will be above average in December & near normal in January & February.  I wouldn’t rule out a big late season snowfall and with wild temperatures swings the battle ground will be set across the Midwest & Ohio Valley for possible ice events.    To say this winter will be worse than last would be a matter of interpretation – I think snow totals will be comparable, but I feel the way we get that amount will be different.  In other words, instead of frequent ‘little’ snow events my thinking is more in line with heavier snowfalls.  Regardless of what actually happens this winter season... just know that we’ll be here to watch and forecast our daily weather – something I feel I’m far better at than seasonal forecasting – it’s still fun to look over and take a stab at!  I like to say... Weather is my hobby.  People are my passion!  -Kevin Harned

There are several factors that go into making an educated prediction as to what the seasonal forecast will hold... then there’s a little guessing & also some luck. 

While forecasting for a season ahead has come a long way in the past few decades. There are hundreds of dedicated, brilliant researchers who have spent careers developing and refining techniques which have improved statistical accuracy in seasonal forecast well beyond the proverbial "coin toss."

There are several factors that go into making an educated prediction as to what the seasonal forecast will hold... then there’s a little guessing & also some luck. 

While forecasting for a season ahead has come a long way in the past few decades. There are hundreds of dedicated, brilliant researchers who have spent careers developing and refining techniques which have improved statistical accuracy in seasonal forecast well beyond the proverbial "coin toss."

Still, seasonal forecasting can be dicey to say the least. There are certain atmospheric and oceanic "signals" (like ENSO phases) that can be reliable indicators of jet stream and weather patterns months in advance. Yet, those signals may be reliable only part of the time, for certain seasons and for certain parts of the globe.

The ENSO outlook calls for a weak to moderate La Nina in the tropical Pacific, but not as strong as last winter's La Nina.

ENSO cycles: El Nino La Nina phases can tell us a lot about an upcoming winter. Strong El Nino or La Nina years can have as high as a 70% correlation with mild (El Nino) or cold & snow (La Nina) in the Upper Midwest. They can also provide useful "forecast skill" on rainfall patterns in the south.

Last year's strong La Nina episode delivered on promises of extreme winter weather and this year La Nina is back for an encore in the tropical Pacific. But all La Nina's are not created equal. This winter's event is not predicted to be as strong as last year's. 

The Climate Prediction Center explains it like this:  "Currently, La Niña is not as strong as it was in September 2010. Roughly one- half of the models predict La Niña to strengthen during the Northern Hemisphere fall and winter. Of these models, the majority predict a weak La Niña (3-month average in the Nino-3.4 region less than -0.9°C). In addition, a weaker second La Niña winter has occurred in three of the five multi-year La Niñas in the historical SST record since 1950. However, the NCEP Climate Forecast System (CFS.v1) predicts a moderate-strength La Niña this winter (between -1.0°C to -1.4°C) and CFS.v2 predicts a strong La Niña (less than -1.5°C), which rivals last year's peak strength. For CFS forecasts made at this time of year, the average error for December-February is roughly ±0.5°C, so there is uncertainty as to whether this amplitude will be achieved. Thus, at this time, a weak or moderate strength La Niña is most likely during the Northern Hemisphere winter."

NAO, AO, PNA, PDO, etc: There are many other indicators that can point to winter weather trends. While each one may suggest a trend...the real problem lies in connecting the dots with reliable accuracy. Which one do we rely on?

The North Atlantic oscillation (NAO) is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic low and the Azores high. Through east-west oscillation motions of the Icelandic low and the Azores high, it controls the strength and direction of westerly winds and storm tracks across the North Atlantic. It is part of the Arctic oscillation, and varies over time with no particular periodicity.

Positive NAO INDEX

• The Positive NAO index phase shows a stronger than usual subtropical high pressure center and a deeper than normal Icelandic low.
• The increased pressure difference results in more and stronger winter storms crossing the Atlantic Ocean on a more northerly track.
• This results in warm and wet winters in Europe and in cold and dry winters in northern Canada and Greenland
• The eastern US experiences mild and wet winter conditions

Negative NAO INDEX

• The negative NAO index phase shows a weak subtropical high and a weak Icelandic low.
• The reduced pressure gradient results in fewer and weaker winter storms crossing on a more west-east pathway.
• They bring moist air into the Mediterranean and cold air to northern Europe
• The US east coast experiences more cold air outbreaks and hence snowy weather conditions.
• Greenland, however, will have milder winter temperatures

The Arctic oscillation (AO) is an index (which varies over time with no particular periodicity) of the dominant pattern of non-seasonal sea-level pressure variations north of 20N latitude.

NOAA says... "For the second winter in a row, La Niña will influence weather patterns across the country, but as usual, it's not the only climate factor at play. The 'wild card' is the lesser-known and less predictable Arctic Oscillation that could produce dramatic short-term swings in temperatures this winter. 

"The evolving La Niña will shape this winter," said Mike Halpert, deputy director of NOAA's Climate Prediction Center. "There is a wild card, though. The erratic Arctic Oscillation can generate strong shifts in the climate patterns that could overwhelm or amplify La Niña's typical impacts."

The Arctic Oscillation is always present and fluctuates between positive and negative phases. The negative phase of the Arctic Oscillation pushes cold air into the U.S. from Canada. The Arctic Oscillation went strongly negative at times the last two winters, causing outbreaks of cold and snowy conditions in the U.S. such as the "Snowmaggedon" storm of 2009. Strong Arctic Oscillation episodes typically last a few weeks and are difficult to predict more than one to two weeks in advance."

The Pacific-North American (PNA) teleconnection pattern is a climatological term for a large-scale weather pattern with two modes, denoted positive and negative, and which relates the atmospheric circulation pattern over the North Pacific Ocean with the one over the North American continent.

The "Pacific Decadal Oscillation" (PDO) is a long-lived El Niño-like pattern of Pacific climate variability. While the two climate oscillations have similar spatial climate fingerprints, they have very different behavior in time.  This oscillation tracks shifts in temperature patterns in the North Pacific Ocean. PDO has a warm and cool phase which can affect USA weather. The PDO is much longer term, with phases that can last 20 to 30 years.

 

Watching Siberian snow cover:
A new correlation that seems to have some skill in predicating the severity of winter and snowfall patterns in the USA happens to be watching Siberian snow cover in September and October.

The theory goes like this. More snow in Siberia deepens atmospheric waves that cause the Polar Vortex to warm and the jet stream to plunge down over the eastern USA... bringing cold and snow.

Anomalies in Siberian snow cover in September and October can provide evidence that above average snowfall in Siberia in autumn causes shifts in the polar vortex. This can mean warmer than average conditions in the Arctic, and more frequent cold air outbreaks in the northern USA as the cold is displaced southward during winter.

So far in 2011, snow cover has been running near or below average over much of Siberia, especially in western Siberia. The past week has brought significant snow to Siberia, so Siberian snow pack has increased in recent days.

 

I can’t help but to have noticed similarities in recent times to those of the 1930’s & 1950’s.  Each of those decades came in with some impressive winter weather events.  One in particular I found interesting was a top 25 weather event for Louisville... it was the 1951 Ice Storm & Cold Blast in late January & early February.

1951 Ice Storm and Cold Blast
January 29 - February 3, 1951 

An extremely strong high-pressure system started making its way into the region, pulling harsh, cold, polar air in with it.   In the meantime, a strong low pressure system was moving through areas farther south along a cold front, stretching from the Gulf of Mexico and up into the Northeast.  The cold front caused temperatures to drop, so that on the evening of January 30th, temperatures for Nashville, Tennessee, were only at 18 degrees Fahrenheit (-8 degrees Celsius).  However, temperatures just above the surface at 5,000 feet were actually above freezing, registering at 48 degrees Fahrenheit (9 degrees Celsius).  This was the perfect set up for the development and occurrence of freezing rain and sleet. 

In Bowling Green, almost 3 inches of snow and sleet had covered the city by morning of the 31st, causing roads to become almost impassable.  By noon, the snow had turned to rain due to the above freezing warmer air aloft, however on the surface temperatures had only risen to 28 degrees Fahrenheit.  This caused the rain to freeze upon impact, worsening the traffic situation.  Bulldozers were called out to help the effort and scrape the ice, with little effect. 

Then a turn for the worse occurred yet again.  By the next morning, on February 1, temperatures started dropping dramatically.  Before the day was over a low of -1 degrees Fahrenheit had been recorded, and another 7 inches of snow had fallen.  Travel by this point was virtually impossible, causing major delays for airlines, busses, and trains throughout the state.  Damage was reported throughout the region as tree limbs cracked and fell onto power lines due to the dense ice packed onto them.

The cold only continued.  At 4:45 a.m. February 2, Bowling Green recorded a temperature of -20 degrees Fahrenheit, the coldest official temperature ever recorded up to that time.  The precipitation continued as well, leaving behind 9 inches of snow and sleet on the ground in Southern Kentucky.  Crews were working around the clock to restore both power and phone lines.  Water pipes burst under the extreme cold, transportation remained halted, temperatures remained unbearable, and ten days later the area had yet to recover from the ice and the snow. 

The Great Ice Storm of 1951, as it came to be known, covered the south in a linear path of ice from Louisiana to Ohio.  Heaviest accumulations fell in a line from Memphis to Nashville, Tennessee and northeastward into Lexington, KY.  It was the costliest winter on record for the time, causing an estimated $100 million in damage.  The impact on forest, livestock, crops and fruit trees was responsible for $64 million of that total.  It is estimated that 25 people lost their lives across the areas affected by the storm, and another 500 were injured.

Brian Goode's Winter Forecast

Finally that time of the year!! 

As you know, 2011 has been a very volatile year weather-wise for the United States.  FEMA has declared more disaster areas than ever before.

So the upcoming winter has everyone wondering---what will happen next?

 Before I get into the meat and potatoes of the forecast, we to first look at the factors that impact our weather pattern/jet stream and well, earth in general.

 LA NINA

We will start off with the infamous La Nina.  Lots of talk about with this one.

 

What is La Nina?  Cooling of the central/eastern Pacific waters.  What does the weather pattern look like with La Nina?

 

 Basically is the opposite of El Nino, which is the warming of the ocean waters.  Here is the weather pattern with El Nino.

 

 Right now, NOAA says we are in a La Nina pattern, and have been.  The debate seems to be how strong of a La Nina will be in this winter, and when will it trend back to "normal" levels?     Here is their discussion...click here

Keep in mind, we had a La Nina last year, but as you can tell from the map above, the weather pattern didn't match up. 

 

 The reason? Other factors always at play when it comes to weather, and one in particular overpowered any La Nina effect---- the NAO (see below).

 So even with a La Nina forecast this winter, it may not mean too much if we see another dominating factor come in a steal the show.

By the way, in my research for this forecast---I did come across an interesting article that suggests there perhaps is a NEW El Nino.  By reading the article, it sounds like a hybrid of La Nina and El Nino.  (notice it has been awhile since we have heard about El Nino...so maybe they are on to something).

CLICK HERE to read the article.

 

 OSCILILATIONS

There are several of these that impact the global weather pattern; I plan to focus on 3.    PNA, NAO and AO.  

_________________________________________________________________

NAO (North Atlantic Oscillation)
Click here to read the scientific explanation.

 

 The NAO (as mentioned above) was the determining factor that overpowered the La Nina last year.  NAO basically is a good "blocking" indicator.  When you block the weather pattern, you get extreme weather events (drought/snow/cold/flooding).  The blocking last year led to a cold/snowy pattern.  Granted, most of the big storms missed us, there were some big storms to be had. 

Some of you have seen this chart below quite a bit from me.

 It is daily measure of the NAO.  The solid black line is 0 or neutral.   The black wavy line is the history of the NAO to date.  The red squiggly lines are the forecast models of how they thing it will trend.

The thing to keep in mind:

POSTIVE trend= warmer for KY
NEGATIVE trend= colder for KY

 The NAO is will be key factor for this winter again as I think "blocking" will becoming an issue.  I will get into that further down.

 _____________________________________________________________

PNA (Pacific North American "oscillation")

Click here to read the scientific explanation

 

 PNA usually is the good indicator of how the jet stream will line up across the USA.  Same chart type is used:

 

 POSTIVE trend= colder for KY
NEGATIVE trend= warmer for KY

_____________________________________________________________

 AO (Arctic Oscillation)
Click here for the scientific explanation

 

 

 Once again, same chart is used:

 

POSTIVE trend= warmer for KY
NEGATIVE trend= cold for KY

 So in summary, if we see a negative NAO, positive PNA and negative AO...we then have pretty high confidence that KY will enter a cold pattern.  Same is true for the opposite trends of course.  But these charts are very helpful for us in picking out Arctic Outbreaks and major snowstorms.  You will see me post these from time to time.

 BLOCKING

This is mostly in reference to the NAO, but what is blocking exactly?

 

 The Greenland high pressure "block" is what usually will send the NAO negative every time.  And we seem to be seeing it more often.  That very blocking is helping lead to the drought situation in TX as well. 

Is blocking on the increase in recent years?  Global Warming advocates say yes...and the blocking will increase in frequency in 2011/2012.  Other scientists say it will lessen.  So ya, ho hum.  But personally, it seems like the blocking has increased.  I am not sure if more droughts around the world are the cause of that (leading to more high/dry air locking up the jet stream).  You see, La Nina/El Nino...and blocking leads to areas of droughts/floods.  But then those very weather phenomena’s keep feeling future blocking patterns. It is like a revolving door. 

There are other types of blocks that are out there that have nicknames...some you may have heard of before:

 OMEGA BLOCK

 

 REX BLOCK

 

 

 RING OF FIRE (SUMMER)

 

 CUT OFF LOW  (can be anywhere...not just in the SW as the graphic shows)

 

 

 It seems like we have had many cutoff lows this fall.  That is from a blocking pattern.

So be on the lookout for when we say "blocking pattern" that means a change in our weather...that will last several days. 

 TEXAS DROUGHT

This is a factor I could not find a lot of data on when it comes to impacts on the jet stream.  The jet stream IMPACTS a drought, but not much data on the other way around.  Having said that. I do think it will have an impact in 2 ways:

1) Creating a high pressure zone that will feel cold fronts on the east side of it (Great Lakes/Ohio Valley)

2) Dry air that could impact lows from the Plains (snow stealers)

 

The drought in TEXAS is unreal...look how much of that area is in the highest drought level you can go (EXCEPTIONAL).

 

 I am concern that unless we get a strong flow off the Gulf of Mexico or the SE coast this season, the dry air from the Plains may eat at our snow events.  Not that that ever happens around here :)   But we will have to watch that west or southwest wind this season.  It may rob us from a good moisture source.  There isn't lots of data regarding this, but I am just throwing it out there.  Maybe we can get data from this season to see if there were any impacts at all for future winter forecasts.

 SUNSPOTS

These were Tom Wills’s favorite...and mine too.  I really do think this has more of an impact on our decadal cycles of climate that is fully being recognized.

CLICK HERE to read more on sunspots.

 What is interesting about sunspot activity...is that it goes through a cycle of "life".  It almost acts as a conveyor belt when it forms.  It is when it collapses we then see the "spot".  The time process for this ranges from as short as 20 years to as much as 40 years.  And if you remember my post from the summer, it seems like our weather patterns have followed that same cycle as well.

Here is a look at the sunspot activity as a whole. 

 
 

 Don't pay attention to the obvious ups/downs...but how many low-topped ups there are.  That is considered low activity.  

 Recently, activity has been increasing.  Here is a good site to show where the current sunspots are:

 

 Scientists say there will be a max in activity in 2012.  There are many doubters of this.

The trend seems to be low activity- colder the climate.  But global temps have been setting records in recent years despite the low activity. So you can see how there is still quite some argument on sunspots vs. climate.    I think there is an obvious pattern setting up. Just need more data over time.

 Look at the number of SPOTLESS days over the last few years; you can see the change….

 Spotless Days
Current Stretch: 0 days
2011 total: 2 days (<1%)
2010 total: 51 days (14%)
2009 total: 260 days (71%)

 TROPICS:

We have to watch this as we head into the end of fall.  There is still activity going on in the tropics (RINA still out there).  Tropical systems have an incredible amount of energy with them...and moisture. 

 

 You factor these systems into a growing colder air mass across the country---you are going to get some blockbuster storms.  So that is why late Nov into early Dec has a chance to be a wild ride for the eastern USA.  We'll have to watch that carefully.

 SOAPBOX TIME

So there are the factors that I decided to pick out when considering this forecast.  There are others, but these seem to be the most significant. 

Keep in mind, while I plan to state what I feel will happen, I think everyone knows that winter forecasting in Kentuckiana is extremely difficult and very short term when it comes to accuracy.  We are in the part of the country where we are impacted by many blocking patterns and moisture sources.  In my opinion, this is the most difficult area to forecast in the country for winter weather.  As a meteorologist, that makes forecasting in advance a huge challenge.  Having said that, I do think we can at least identify weather patterns using the above factors about 10-14 days in advance.  We have been successful in doing so.  Snow wise, that isn't so easy to pick out 10-14 days in advance.  However, if I see a big storm in a colder pattern, of course I am going to mention that it could snow.  I think that is logical and fair.  I will not be "wish casting" snow events.  If it won't snow, or looks more like a flurry...I will say that.  If it looks like an accumulating snow or a big snow...you bet I will tell you that too.  I am not going to hold back on my thoughts with my forecast.  I don't think as meteorologists we should ever "hold back" in order to protect people’s emotions.  That implies that I control the weather and/or I am 100% confident in what will happen.  Well, as my WKU professor always told me, never say "never" and never say "always".   Snow lovers may love me at times...some will hate me.  Same with the snow haters :)   I just ask for patience this season...and more importantly folks, let's just have fun with winter forecasting.  It is interesting to see how models try to predict our weather pattern and add our thoughts too.  This is your rare chance to see what is going on behind the scenes, and you are all welcome to join in on the ride.

 

So are you ready?

Here we go.

 

OUTLOOKS

Overall, the thing to keep in mind when listing departures from average is that the 30 year average temps for the country this year ...are different.  They change every 10 years...and this will be the first winter with the changes.  So the 1970s are no longer considered in the averages with temps and precip (snow). It now ranges from 1980 to 2010. The 70s were a cold decade for many of us with lots of snow. So the averages this winter are warmer...and with less snow.  My point? It wouldn't take much to get us below average temps or above average snow.  As an example, Louisville's avg winter snowfall dropped to 11.3” with around 15” for the year average.  Personally, just a few small snow events can get us above a foot for the year.  So I think above average snow is likely.

 

WINTER TEMPS:

 

 

 

SNOWFALL

 

 

 Total snow for the season: 23"  Coldest: -5  

Thoughts? Be sure to comment.

I am on facebook as well.

BRIAN GOODE

 

Thanks for reading!