Saturday, November 14, 2015

Nice Sunday Before Rain Returns Next Week - Colder Changes Towards Thanksgiving?

SATURDAY NOVEMBER 14, 2015.....Hello everyone.  Here is hoping this post finds you doing well.  We started out today with the coldest readings of the season thus far.  Indianapolis dipped down to 26 this morning!  The temperature reading for Indianapolis is usually a bit warmer than surrounding areas due to the urban heat island effect - and even the "warmer" location dropped into the middle 20s last night.  Many outlying spots were in the low 20s this morning.  Very cold!!  Despite the very cold start, what a fantastic mid-November day this was.  Absolutely sunny skies, finally a day with very little wind, and temperatures that topped out in the middle to upper 50s.

Temperatures tonight will not be as cold despite clear skies.  We have a warmer air mass advecting into the area on a light south/southwest flow.  Expect lows Sunday morning to be a good 10-13 degrees warmer than what we had to deal with this morning.  Sunday looks spectacular!  Expect plenty of sunshine with highs reaching the low to mid 60s.  NOTE:  Last year during this same time we were dealing with early season snow...southern Indiana saw 3-5" of snow during the 16-17 of November 2014.

We have some mild and wet weather on the way for this upcoming week.  There will be a storm system across the Plains that will lift north and bring the potential for a good deal of rain around here.  Check out the strong southerly flow setting across our area during this time....

It appears scattered showers will begin to break out across the area on Monday, with chances increasing as we head deeper through the day.  Rain looks likely for Tuesday, with a break possible late in the day and evening hours before the rain really picks up late Tuesday night into Wednesday.    It appears that the rains will begin to pull east of here late in the day Wednesday with drying conditions Wednesday night.

How much rain could fall during this time-frame?  Anywhere from 1-3", with the higher totals the farther west you go.  Even heavier totals of 3-5" possible west and south of Indiana.

Once we get beyond this system, I do believe we will see a pattern that gradually takes on a more wintry look.  Thanksgiving week has had my attention for the past couple weeks as blocking develops over the eastern Pacific.  I think we slip into a colder than normal period that may feature our first flakes of the season at least, but can we get something more than that?  Cannot rule that out. Initially behind our system this week we will have seasonable cool air.  It appears we will have another system coming in around next weekend, and behind that is when make our way towards a potentially colder than normal period of weather.  Here is a look at the GFS ensembles 5-day average temperature anomalies from the 24 to the 29th.....

That shows much of the country dealing with colder than average temperatures for Thanksgiving week.  Now here is what the Canadian model ensembles are showing during this same time-frame...

We will see how this all plays out.  Nothing set in stone by any means, but it appears rather likely that we are going to slip into a period of colder than average temperatures during the Thanksgiving holiday time-frame.  This has been my thinking for quite some time.

Thanks for reading.  Have a fantastic rest of the weekend!

Saturday, February 14, 2015

Snow Chances On the Rise for Monday - Heavy Snow in southern Indiana??

A rare late night update tonight to make you aware that I am closely monitoring snow chances for central and especially southern Indiana late tomorrow night through the Monday evening time-frame.  Considering the noted changes in the data, I do not want anyone to feel caught off guard.  On Friday, it really looked like the bulk of any snow would stay well to the south of Indiana..with perhaps a little snow grazing southwest Indiana.  Things have certainly changed in the past 24 hours.  The model trends today and tonight are taking the snow much farther north.  To show you how much things have shifted, I put together snapshots of the last three runs of the GFS.  Shifting northward with each run....

 The model runs coming in tonight are all in very good agreement on our system for Monday bringing snowfall much farther north than earlier thought.  Since we are within about 24 hours of the event getting underway, I will go ahead and show you what some of the model data is suggesting as far as snow accumulations.  As always, I give the disclaimer that this is just forecast guidance!  

NAM model snowfall accumulations:

Graphic courtesy of Earl Barker's model page - WxCaster

This model suggests significant snow accumulations for far southern Indiana with light snow making it to about a Terre Haute to Martinsville to Franklin line.

GFS (American) model snowfall accumulations:

Graphic courtesy of Earl Barker's model page - WxCaster

GFS also suggesting significant snow amounts for far southern Indiana with light snow making it as far north as about I-70.  The entire state of Kentucky gets HAMMERED!

GEM (Canadian model) snowfall accumulations:

The Canadian model also shows heavy snow accumulations in far southern Indiana with light snow making it to the I-70 corridor.

Graphic courtesy of TropicalTidbits

ECMWF (European model) snowfall accumulations:

And the last model for the 00z data suite is in...very similar to all the other models.  Heavy snow in extreme southern Indiana.. with the potential for light snow to make it as far north as the I-70 corridor.  

Forecast uncertainties I have is how far north the snow will go....and the amount of dry air that will eat into the northern extent of the snow.  I will say this.  A lot of the models posted assume snow totals at a 10:1 snow ratio.  With very cold air in place, this will be a high snow ratio event.  With higher snow ratios you get more snow with less moisture.  Essentially "more bang for your buck."  While the cold air helps for higher snow ratios, the cold/dry air mass can also make it tough for the precipitation to overcome the dry low levels.  This will mainly be a potential issue for the northern extent of the precipitation shield.   

Bottom line: I want to be clear that I feel more and more confident that this will be a significant snowfall for portions of far southern Indiana.  The farther south you are, the more snow you will see.  ALL areas south of I-70 are now in play for the potential for some accumulating snow, with the highest confidence across far southern Indiana where this could really end up being a decent snowstorm!

Timing: It appears the snow will push into southwest Indiana at some point after midnight Sunday night, and begin to expand across southern Indiana by daybreak Monday.  The system will be at its peak throughout the day Monday with snow falling across the southern half of the state...with heavy snow possible in far southern Indiana.  There will be a sharp cut-off on the northern edge and where that sets up is to be determined.  The snow would not exit southern Indiana until at some point Monday evening into Monday night.  

Are the models done trending north?  Hmm.  Will be interesting to see if there are any additional shifts in the data tomorrow. 

Thursday, February 12, 2015

Good Thursday evening everyone! Very cold night ahead as lows drop into the singles and teens.  Friday will be slightly milder than today, with highs recovering into the upper 20s and lower 30s. Another arctic front plows through Saturday bringing snow showers and an even bigger drop in temperatures. The timing has trended slower with this it appears that southern portions of Indiana may briefly rise in the low-mid 30s around midday Saturday before things crash later in the day.  It is going to be just brutal out there Saturday evening with howling winds and dangerous wind chills. Also be aware that snow showers will likely make for some slick travel during the day Saturday as well. The good news is that the snow showers should exit by the late afternoon/evening time-frame. Sunday morning will be frigid. It appears everyone will be in the single digits, with some below zero readings possible in the northern portions of the state. The wind chill [feels-like temps factoring in the wind] no doubt will be well below zero. Most of the state won't even be able to get out of the teens for highs Sunday afternoon.

As we head into next week...a southern storm system has been on the charts for a while during this time-frame.  Trends right now keep this system way south of us... with just cold/dry conditions locally next week. The system really won't get sampled until this weekend. That is when we should get some good data for this system. So bottom line....the trend is for any wintry precip to stay well south of us, but things can and will change since we are several days out.

Friday, January 30, 2015

Latest on the Weekend Winter Storm

Yesterday I said that there will likely be some shifts in the model guidance today as our weekend storm gets fully sampled.  That has indeed been the case.  The data coming in continues to trend farther north and warmer for our weekend storm.  

Precipitation will push in Saturday evening around or just after sunset.  This will likely fall as mostly snow, with some rain possibly mixed in across southern Indiana.  Here is the 12-km NAM for 10pm Saturday, showing that push of snow moving in ahead of the main system.

Nam 12-km courtesy of

That shield of precipitation will work northward through the night, with a lull likely across the I-70 area southward later in the night.  As we head into Sunday morning, the main system is approaching with widespread precipitation moving in.  The area of low pressure will work through southern Indiana throughout the day Sunday, bringing heavy precipitation across the state.  Likely falling as snow along/north of I-70, rain across southern Indiana.  

NAM 12-km courtesy of

As we head into Sunday evening, the system pushes off to our east with precipitation diminishing.  However, check out that deformation band across northern Indiana.  Northern portions of the state are in the prime spot for heavy snowfall.  It is not out of the question that locations up there could see as much as 10-12" of snow.  This is where snow will be falling for the longest duration.  

NAM 12-km courtesy of
I think this model may have the track of the low pressure just a little too far north.  However, the other models have trended closer to this more northern solution.  The BIG question is how far north will the rain/snow line get????  Some of the models now try to take it as far north as Indy on Sunday.  I want to have a good look at the 0z data that comes in tonight before making any changes to my forecast.  Just know that the TREND for this storm is farther north which brings warmer air farther north into the state.  Could it still shift a little farther south with new data tonight?  It is still possible.  Here is MY current thinking on snow totals.... 

I have a feeling there will be a sharper range in totals south of Indy than I have, but I want to see some new data tonight before making any changes.  Here are the NOAA Weather Prediction Center probability maps for at least 4" (image on the left) and the probability for at least 8" (image on the right).  

I will post updates on my Twitter and Facebook pages once some new data comes in tonight to see if there are any big changes.  

Wednesday, January 28, 2015

Watching the Weekend Closely

Good Wednesday morning.  After a cold and frosty start, today is going to be a great day with sunshine around and seasonable temperatures.  Highs will generally be in the 30s with 40s possible across southwest Indiana.  

A weak clipper will bring some light showers tonight through Thursday, mixing with snow showers tomorrow afternoon and evening.  This should not be any big deal.  At most, a very minor accumulation possible over northeast portions of the state.  Highs tomorrow will be warmer with much of central and southern Indiana reaching the 40s.

Dry and cooler weather will be the rule Friday and Saturday.  For the second half of the weekend, the main focus continues to be on a potential storm that will impact the state.  Actually, confidence is very high that there will be a storm system moving through the region on Sunday.  This has the potential to be a decent winter storm for portions of our region.  How strong will the storm become?  Where will it track?  Those are the big questions right now.  The models should gradually come into a better consensus over the next few days.  If you have plans for Sunday, you need to keep a close watch to the forecast.  

Have a great Wednesday!  

Tuesday, January 27, 2015

Warmer Mid-Week - Wintry Weather this Weekend?

Roads are slick this morning after light snow and freezing drizzle overnight.  This has caused several accidents.  Another reminder that it only takes a tiny bit to cause major problems on the roadways.  Be careful as you venture out this morning.  Conditions will improve through the day, with any lingering precipitation ending by mid-morning.  We may even see some sun later today.  

The middle of the week will feature a warming trend.  Tomorrow looks mostly sunny, with highs ranging from the upper 20s over snow-packed northeast Indiana, to around 40 in southwest Indiana.

Our next system arrives Thursday.  Precipitation may start out as some light freezing rain early Thursday mainly across the northern half of the state.  Temperatures will quickly warm into the lower 40s during the day, so any travel issues would be short-lived.   Colder air will push in on the backside of the system, meaning a transition to light snow showers Thursday evening.  

After this, all eyes will be on a potential storm system this weekend.  All three major global models now show a storm impacting the state, but solutions vary with each model.  That is to be expected when we are still five days out.  Timing of this potential system would be Saturday night through Sunday night.  

The GFS (American model) is the warmest of the models for this storm.  It tracks the low pressure up near the Ohio River.  Taken at verbatim, this would be mainly snow north of I-70, with a mainly rain event for southern Indiana.

Image courtesy of

The ECMWF (European model) is a colder solution.  It tracks the low from central Tennessee up through central Kentucky.  This would be a very favorable track for accumulating snow for much of Indiana. 
Image courtesy of Penn State's weather models site.

The GEM (Canadian model) is the coldest/most suppressed solution tracking the system farther south.  Taken literally, this would put the heaviest snow swath across southern Indiana and Kentucky.  

Image courtesy of

Remember this is just guidance.  The models will continue to waffle around over the next few days.  Right now it is feasible to say the potential is increasing for wintry weather this weekend, but many, many details to be ironed out in the days ahead.  

Have a great Tuesday!!