Wednesday, November 12, 2014

Looking for that first snow day in central KY

Update: Friday 14-November-2014

The storm coming up for Monday morning still looks very similar in the model data to the last several days of runs.  Today's GFS run continues to hammer central Kentucky with several hours of snowfall early Monday.  Take a look:


The change in the forecast is that the northern stream system that looked to maybe bring some snow Saturday is now being forecast to stay mostly north of Kentucky.  So, aside from some flurries I don't expect any accumulation on Saturday at this point.  The southern branch system is still on track for a Monday arrival and the models are still hinting at a deformation band of snow to set up just south of the Ohio River.  The Lexington area could see a few inches of accumulation from this if the surface temperatures are near the freezing mark Monday morning.  The higher elevations of eastern Kentucky could also see a nice snowfall.

I expect that headlines will be coming this weekend and we might see the first Advisory or Watch of the season issued by the fine folks at the National Weather Service as early as tomorrow.  A day out of school is a real possibility for many on Monday.

This will be my final blog update.  You can catch me on Facebook or Twitter @WXinKY for daily updates.  Have a great weekend.

-Shawn

Previous discussion:

Good Wednesday morning.  Hope you all enjoyed Veterans Day.  The weather this week has been delightful in the Bluegrass but that is changing today as temperatures have fallen significantly behind a frontal passage late last night. We are now going into a period of more winter-like weather that will carry us through the weekend.

The big question on the minds of kids and teachers alike right now is:  when will there be a snow day?!

Well, it is impossible to say.  But...Monday November 17th is trying to emerge as a possible winner for that "first snow day" award.

I've been tracking this storm for a few days and haven't really said a whole lot about it because, to be honest, the models have struggled lately.  But we are in that 3-4 day window now where it's time to start looking at this more in depth.  The GFS and ECMWF models are starting to agree just a tad on how this is going to play out.  I hope that with the 12:00UTC runs today they will agree even more on a solution.

The idea here is that on Saturday we could have a system streaking in from the northwest.  This will bring snow to the air but probably will not accumulate much in our neck of the woods.  As that's happening, a separate system will organize to our south and lift northward.  This system will strike on Sunday night.  Southern stream systems are really hard to forecast and the computer models do not have a lot of success with them.  But, IF this system organizes as it's show right now and IF there is enough cold air at the surface we will get a snow day for many counties on Monday.  Keep in mind that there are a lot of ifs in that equation.

The ECMWF model shows the freezing line hanging out directly over us...which is usually the case for Kentucky and that's why it's so hard to predict snow around here.   Geographically, we're just always on the fence.  I will keep watching of course.  And I'll leave you with the current ECMWF run valid Monday early morning:

Temps:

Precip:


There is a chance!


-Shawn

Thursday, October 23, 2014

Halloween Forecast for Central Kentucky

UPDATE 30-October-2014:

We've been tracking a storm system for over a week now that threatens to bring the first blast of winter to central Kentucky this weekend.  It appears that things are coming together just as predicted.  A major blast of cold air is coming and temperatures will fall to the 20s by Sunday morning.  Ahead of this, rain will change to snow by Saturday morning and could possibly dust a few cars and trees and Halloween decorations before it's done, especially along and east of I-75.  This will be my final update on this storm.  Get ready because it's about to get COLD!!  I'll leave you with the latest forecast discussion from the fine folks at NWS Louisville:

Latest GFS, NAM, and ECMWF are in pretty good agreement showing an
deep upper low diving SSE across the eastern OH Valley Friday night.
The GFE 18z ensembles showed the trough aloft being 3 to 4 standard
deviations below normal which is significant. With this system will
come cold air advection and dynamic cooling aloft. The model-
indicated pattern suggests possible development of a winter-like
deformation band within a tight isotach (lines of constant wind
speed) gradient in the left exit region of a 300 mb jet streak
diving south over the lower OH Valley. In these types of patterns, a
definitive mesoscale band of wintry precipitation normally occurs
assuming temperatures within the moist layer and at the surface are
sufficiently cold. In this system, the models suggest all this to
occur, which would suggest a band of snow over the eastern half of
the forecast area, especially east central KY late Friday night.
Model soundings show moisture extending up to between 500 and 600
mb, and cold enough in the moist layer for ice crystal formation
which would stay as mostly snow as it fell to the ground.

If this verifies, then scattered rain showers during the day Friday
likely would diminish or end in the evening, with a band of some
snow developing late at night which would move quickly southeast and
end by Saturday morning with up to an inch or so of snow possible
mainly across the Bluegrass, and especially on grassy areas.



UPDATE 27-October-2014:

The Euro model has sort of taken on the look of the GFS that I posted last week (below).  Imagine that.  Low pressure near the Great Lakes may drive a sort of "back door" cold front through here Friday night and into Saturday morning with much colder air arriving.  Both models take us below freezing Halloween night and into the first morning of November.  The question is, will any precipitation accompany this front?  It's still a little early to tell, but there remains a small chance that we could see a few snowflakes early this coming weekend, especially in eastern Kentucky.  

Here are the temps and precip predicted by the European model.  Notice the freezing line dropping into Kentucky by 8:00PM Halloween and then the precip shield which is depicted as getting really close to the Bluegrass that night.  Interesting...  just something to watch.















As we wait to see how El Nino is going to shape up for winter and what impact it may have on our temperatures and snowfall, we are currently soaking up the final nice days of the year in Kentucky.  Sunshine has returned after a week or two of ICKY weather and by the weekend we’ll see the 70s for highs come back for several days…well into next week.  Ahhh…  enjoy it!!  The leaves are peaking at this time as well, which will make for some absolutely delightful days to finish out October.

Speaking of finishing out October…the last day of the month, Halloween, falls on a Friday this year and that means big plans for trick-or-treat and parties/social events/etc.  What’s the weather going to look like?  Will it look great like a piece of hot pumpkin pie with whipped topping or will it look scary like a headless horseman carrying a bloody sword?

The models are hinting at a cold front that would sweep through mid to late week and that would usher in much colder air for the weekend.  At the same time that is going on, a Nor’easter will move up the east coast.  This *may* throw enough moisture back into parts of KY to interact with the cold air advection sweeping in behind the front and allow a few snowflakes Halloween night.  The weather for that weekend does indeed look active and there will be a LOT of eyes on this forecast in coming days.  We are over a week out and there is lots of uncertainty right now.  I will update later today with the new 12Z data and show you the current thinking on the situation.

Now go outside and enjoy this nice weather!

UPDATE: Here's today's 12Z GFS run.  You can see the low wrapped up in the northeast with strong cold air advection bringing the CHILL into Kentucky Halloween night.  It's conceivable that we *could* possibly see a few flakes.  As always, I'll fine tune this forecast in a few days.





Shawn

Wednesday, September 17, 2014

Winter 2014-2015 in Kentucky

Update 2-December-2014:

Well it's time to wrap this up.  Meteorological winter began yesterday, and astronomical winter begins in just three weeks.  Here's how I see it.

December: Average snowfall for the Lexington area is 2.5 inches.  I predict that the first ten days of the month will work out to near average before cold air takes us below average quickly.  We should finish the month near average in terms of snowfall.

January: Average snowfall is 3.9 inches.  I am thinking that we will see above normal snowfall and below normal temperatures.  It will turn out to be a frigid and wintry month in central Kentucky.  High utility bills, over-worked heat pumps, and rampant illness spreading due to people being "cooped up" all month will become reality.  People flying south for winter will be thankful.

February: Average snowfall is 4.6 inches.  I believe we'll finish near or slightly below average for snowfall, but temperatures will be wild with some warm spells and some very cold spells.  The threat of an ice storm will be greatest during February.  This could potentially be a utility lines killing ice storm.

March:  Average snowfall is 1.4 inches.  I can see this being a month with a BIG snow storm.  There is a good chance of blowing way beyond the monthly snowfall average with a single storm during the first two weeks of the month.  Temperatures will remain cold during March.  People will be longing for spring...but it will be a long way off.  A few warm spells may come immediately ahead of a severe storm outbreak but as a whole March will be colder than average.

April:  Average snowfall is 0.3 inches.  I think we'll finish near average for snowfall.  We'll see some warm spells but the month as a whole will finish below average for temperature.  There will be some late frost that could damage trees and flowers.  The days will be getting longer but the weather will be slow to catch up.

For my local school district (Anderson County Schools) I predict a total of 16 snow days this season.

That's a quick rundown of how I expect winter 2014-2015 to pan out.  For those hoping for a white Christmas, the good news is that our odds are a little higher than average this year.  The weather models are hinting at much colder weather by the third week of December with the jet stream starting to become active.  Fingers crossed!


-Shawn



Update 24-September-2014:

Just for kicks, let's look at the official government projection for the upcoming winter.  Specifically, the 3-month period running December to February which is meteorological winter.  The Climate Prediction Center issues these seasonal forecasts and updates them generally during the third week of each month.  The brand new outlooks are showing something interesting.  

First of all, they expect temperatures in the Ohio Valley to be average.  There is no signal for warm or cold temperatures, compared to average.  They are calling for normal temperatures for this winter period.


What about precipitation?  I.e., snow chances?  Well, they are predicting the Ohio Valley to be drier than average.  So, less rain and less snow than we'd typically get in a winter.  Take a look:




Now, of course, I do not agree with their assessment.  It's worth noting that I've been watching these outlooks for many years and they rarely have ever panned out to be correct.  But, it IS the official government outlook for the upcoming winter after all, and I thought I'd post it for your viewing pleasure.

I am expecting quite the opposite, with cold temperatures and frequent precipitation, especially for Indiana, Ohio, Illinois, and Kentucky.

One of the big keys to the forecast this year will be the ENSO cycle.  The El Nino/Southern Oscillation refers to the temperatures of ocean water out in the pacific and the flows and patterns that govern it.  This is the breeding ground for storm systems that eventually make their way into the United States, and so by watching this area closely we can get a good idea of how our weather here may be affected.

Let's take a look at history:

You can see that last year we were sort of in a neutral phase.  The end of 2012 had a weak El Nino, while the beginning of 2013 went into weak La Nina conditions, and basically the 2013-2014 period was neutral to ever so slightly La Nina.  These neutral conditions meant that the ENSO cycle didn't play much of a part in our weather here, and other variables were allowed to take over.

Here's the current predition for the upcoming months:



On the chart, 0.0 is neutral.  Anything 0.5 or greater is considered El Nino.  Anything -0.5 or less is considered La Nina.  You can see that most computer models are predicting us to see a weak El Nino return this winter, with some models getting toward a moderate El Nino.

If this does occur, it will likely influence our winter weather here in the Ohio Valley and my forecast for a cold, snowy, harsh winter may be a bust.  In my experience, El Nino brings mild winters to Kentucky.  Look at the strong El Nino of the late 1990s on the above chart.  That period of time had 70s around Christmas and nice weather all winter for a couple of winters in a row!

Having said all this, the models have been predicting El Nino to begin all year, and as of late September we are still in neutral conditions.  There are some who believe it'll never pan out...and I'm one of them.  I think we'll stay close to neutral going into winter.  It's something to definitely keep an eye on.

Autumn just began and obviously winter is anyone's guess.  There is very little skill in forecasting months in advance.  For now, I'm relying on history and also current conditions and two week model forecasts and I'm sticking to my guns...  this winter is going to be harsh.

More info coming later...  

Previous discussion below.


-Shawn



Astronomical Autumn begins on Monday, but it’s also time to start thinking about Winter.  After the record setting winter we had last year I started to dig into history and see where it stacked up on the all time list.  And something I noticed was that our ferocious winters typically came in twos or threes in history.  There’s one bit of evidence that points toward another horrendous winter this year. 

Another thing I’ll be doing soon is looking at seasonal models, watching current trends, looking at pattern tendency in the medium range models, and a few other things.  Generally speaking, the eastern half of the nation has been in a trough for a couple of years now.  This has led to two cool summers in a row, and a terrible winter last year as well.  There is no evidence pointing toward this pattern breaking up any time soon.

I’m expecting a cold, snowy, harsh winter again this year.  In the coming weeks I’ll be adding more charts and details as we begin to track the pattern and make a forecast for Winter 2014-2015.  Check back every so often.



-Shawn

Tuesday, July 8, 2014

Possible Wind Damage Today

A cold front to our NW brought a round of thunderstorms for many in central Kentucky last night.  This was the "appetizer" if you will.  Today, the main course will be served as the front pushes into the state.

The sun is now shining in the Bluegrass of Kentucky as of 9:30EDT and instability is on the way up.  Outflow boundaries from last night's storms have left areas to generate new storms upon.  Moisture is there and forcing will be there later today as the front approaches.  This should set the stage for another round of storms that will be more widespread across Kentucky this evening.

The tornado threat will be higher to our NE across parts of PA but it will still be non-zero across KY as well.  The main threat though is wind damage here and SPC has included most of KY in the high-end Slight Risk for wind damage today.

Stay weather aware!




-Shawn

Monday, June 2, 2014

Derecho? Maybe! Severe Weather Outbreak Possible

Good morning everyone, and welcome to Summer!  June 1st was not only the beginning of hurricane season but also the beginning of meteorological Summer!

It's been a while since I made time for a blog post but I think it's time to discuss what's going on in the world of Kentucky weather.  First of all, how about this humidity?!  Crazy isn't it?  Typically we get into the middle part of Summer before it really gets sticky.  This year however we've already gone straight to 70°F dewpoint temps before May even came to an end.  I admit, I did not expect that after the Winter we just came from.  My Spring outlook worked out pretty good in Kentucky overall though with a calm severe weather season that picked up a little as time moved forward.  But now we're staring straight at Summer and the weather is becoming very active.

For this upcoming week what we've got to keep an eye on is a possible outbreak of severe weather that could stretch from South Dakota all the way into the Appalachian mountains by week's end.  The models are indicating this to occur as a large MCS (mesoscale convective system) that would race eastward and leave large amounts of damage in it's wake, possibly even as a Derecho.  However, the exact storm mode is not known just yet.  Here's how the WRF model sees things as of the wee hours of the morning on Wednesday:



Even though I'm not sure of what mode this storm activity will take on, I am pretty confident in saying that there will be an outbreak of storms across the nation's midsection this week and it will likely end up leaving quite a bit of damage behind.  Kentucky may get in on this action Wednesday, as the MCS strikes us from the northwest.  Here is the current convective outlook from the Storm Prediction Center valid on Wednesday the 4th of June:



So keep in mind if you will be outdoors this week that severe weather is a good possibility and plan accordingly.  As of right now, I believe that wind damage will be widespread and will be the main threat, especially in areas to our northwest.  However, tornadoes and some hail will also be possible.  As always, stay alert and keep the NOAA weather radios on.  You can follow me on Twitter @WXinKY



-Shawn