KATC StormTeam 3 Weather BLOG

Winter Temperature Forecast (December through February)

While I’m not a big fan of making long-term seasonal outlooks (reasons to be explained below), based on the data from the Climate Prediction Center (CPC) and the National Oceanic and Atmospheric Administration (NOAA) it does appear that Acadiana will see a drier than normal winter with temperatures expected to be at or above normal.

While there is high confidence in the precipitation forecast, there is below normal confidence by this author on the temperature forecast.

Cooler than normal equatorial Pacific water temperatures have been developing over the last several months indicating that a “La Nina” pattern has re-developed. 

This pattern is similar to the last two winters for Louisiana/Acadiana which was characterized by below normal rains and well below normal temperatures.

The winter of 2009/2010 (December through February) averaged more than 4 degrees below normal with 17 days of freezing temperatures in Lafayette while the winter of 2010/2011 averaged 2.5 degrees below normal with 27 days of freezing of temperatures.

Last winter would have been considered just as cold as the winter before if it were not for a dramatic swing in the second half of February where temperatures soared consistently into the 70s and 80s.

Interestingly enough there is enormous variability in the number of freezes Acadiana will see in any given winter with some years experiencing just a handful of freezes and other winters more than two dozen.  Last year may have been close to a record for the number of freezes, but these statistics are not readily available. 

Winter Precipitation Forecast (December through February)

In addition, when forecasting winter temperatures we must understand that even in an above normal winter, Acadiana can experience an arctic outbreak that could bring temperatures into the teens or lower.  So perception versus reality also becomes an issue with these type of forecasts.

The real wildcard for winter forecasting, especially for temperatures, is the Arctic Oscillation, which per the last two winters trumped our La Nina influenced weather pattern ushering strong cold fronts to the area.

Per NOAA, “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.”

With all of the above being said, it is with much consternation that we make the long-term outlooks. 

Based on the current information supplied by NOAA and the CPC and given La Nina has kicked back in across the Pacific, Acadiana will likely see drought conditions perpetuating and/or worsening through the spring.

We will buy into above normal temperatures for now, but I would expected several very strong cold fronts nonetheless thanks to a more unpredictable Arctic Oscillation.  

Another key to nailing the temperature forecast is where will the upper level trough axis be most prevalent this winter. 

If the upper “troughing” is similar to the last two years, we will adjust our temperature forecast downward, but just a subtle shift of average trough a few hundred miles to the east will translate to much above normal temperatures.

So there here it is: a low confidence forecast for above normal temperatures and a high confidence forecast of below normal precipitation this winter for Acadiana. 

Based on our late October pattern it would also be a fair prediction that November through early January could actually be below normal in Acadiana with the latter part of January into February possibly more dramatically warmer than normal skewing the numbers for the entire winter. 

And based on the last two winters I would also expect a dozen or more freezes and the possibility of one or two events that may bring temperatures down into the mid-20s or slightly lower.

As for predicting any snow or ice events, your guess will be as good as mine.  If the aforementioned forecast pans out, I wouldn’t be too excited for a winter storm…but if the pattern plays out closer to the last two winters we may indeed get one or two shots at the frozen stuff.

And per usual chances for a White Christmas in Acadiana will remain an abysmal 1 in 1000 year chance…here’s to “wish-casting”!

Rob Perillo

Your thinking is right!  The winter of 2009-10 had a number of events.  From the earliest measurable snowfall on record in December, to the deep freeze in early January, and the 6th coldest February on record with another measurable snow.  The El Nino pattern was in full swing this winter as system after system rolled up the Texas coast with plenty of rain, clouds, and too many dreary gray days to count.  Even though it is now March, we still can’t seem to shake the cold, or the rain.  I, like many others are anxious for Spring to get here!

Let’s start with temperatures.  Overall the winter was colder than average.  When you take the 90 days of climatological winter (December, January, February), the average temperature is about 53.8 degrees.  This number comes from averaging all of the normal highs and lows for those months.  This winter we finished at 49.0 degrees.  Almost 4 degrees below normal, which is pretty significant for a three month average.  In south Louisiana we don’t have any average highs that are below 60 degrees, but this year we failed to reach a 60 degree high  52 times!  In fact only 26 of the 90 days did we have an above average temperature day!  We dropped below the freezing mark 17 times this winter, compared to only 7 times last winter.  We had almost as many days below freezing this winter as we’ve had for the past three!  There weren’t any breaks this year either.  We’ll go warm, then cold, then warm again in a normal winter.  When I’m talking about breaks, I mean a day where it hits 70 or higher.  Over the past 10 years, we’ve hit 70 degrees about 33 times on average.  This year, only 17.  80 degrees?  Forget about it…last winter we hit 80 once, this year..0!  By the way, February 2010 was tied for the 6th coldest February on record.  Only 2 days were at or above average.  The average temperature was 47.4 degrees, normal is 54.3.  We had 6 days in January where we dropped into the 20s.  The lowest temp of the winter…20 degrees on January 10th, sandwiched in between a pair of 21s on the 9th and the 11th.  And you wonder why everything is brown outside!

Snow…Twice this winter.  December 4th and February 12th.  We’ve had two snows in one winter before, but never three.  I was really hoping to break that record last week, but the snow never came.  December 4th we picked up 0.5″ of snow, and on February 12th we picked up 0.4″.

Rain…Above normal for the winter.  A total of 18.62″, or a little over 3″ above.  We had over 10″ of rain in December, almost 6″ in February.  We caught a break in January with only 2.02″.  Probably because the first 10 days of January were so cold that the air couldn’t hold any moisture!

March is coming in like a lion with the rain, and eventually this afternoon the wind.  It should be cloudy tomorrow, with sunshine returning Wednesday and holding for the rest of the week.  Temperatures aren’t expected to climb to normal until late this weekend when we might hit 70 on Sunday.

StormTeam3 Meteorologist Dave Baker

Good Morning Acadiana-Weekdays 5-7am

weather@katctv.com

After back to back years with observed snowfall in Acadiana we have gone one better with two snowfalls in one winter.  Based on the official records kept in Lafayette this has not occurred since records have been kept going back to 1893.  Guess this is what happens when the Saints win the Super Bowl!  As expected, the rain briefly turned over to all snow (snow showers) for a few hours this morning leaving a light dusting for most and more to the north.  Snowfall totals ranged from a dusting to a half inch along the I-10 parishes to up to 1 inch along the northern Acadiana parishes.  Roughly 2-3″ fell across Central Louisiana.  So much for “global warming/warning”…or as I prefer to say “climate change”…but that’s the subject of another, more extensive blog entry!  For the Mardi Gras weekend expect windy and cold conditions tonight, sunny and a little milder tomorrow with highs in the lower 50s…which is still better than 10 degrees below normal.  Fair and chilly conditions are anticipated for Saturday night with mostly sunny and milder conditions expected for Valentine’s Sunday.  Highs Sunday will be near 60 but a strong cold front will bang through Sunday night leaving us with a very cold Lundi and Mard Gras.  Milder weather is expected finally for later next week. Have a great and safe weekend!

Updating Dave’s most excellent and honest blog entry…we are still on course for cold, sloppy rains Thursday into Thursday night.  Once again, we are faced with marginal conditions that could generate a rain/snow mix Thursday night with a possible change-over to all snow in the northern most portions of Acadiana before the precipitation ends during the pre-dawn hours of Friday.  For this reason the NWS has issued Winter Weather Advisories for Beuaregard, Allen, Evangeline and St Landry Parishes for Thursday night for the possibility of a light slushy accumulation.  Temperatures however should stay above the freezing mark at the surface through tomorrow night…but aloft conditions should be cold eneough for snow and/or sleet to mix in with the rain.  With that being said cold air to our north and aloft could get entrained into this system, especially if our surface winds stay consistent out of the NE or NNE.  Farther to the north a significant accumulating snow may be possible from Alexandria to Baton Rouge while the best target for a good snow will be in SW Mississippi where 2-4″ of snow will be likely with up to 6″ possible there.  Winter Storm Watches are posted from Northeast Texas eastward through CenLa into Mississippi including the Baton Rouge Parishes.  For most of us the precipitation will start off lightly and sporadic Thursday morning with some sleet quite possible to mix in, then all rain for the balance of the day and then possibly a slow changeover to a wintry mix Thursday night.  I am not expect any roadway hazards in Acadiana with this system with the exception of the northern portions of the northern parishes of Acadiana ground temperatures may be too warm.  But grassy areas, trees and roof tops may whiten by Friday morning.  Most of us along and south of the I-10 corridor should stay almost all rain.  But like the last two December snow events (2008 and 2009) we may wake up Friday morning with some folks to the north making snowballs while others just getting to see it on video!  Stay tuned for the latest computer model runs and radar trends!

Following Dave’s most excellent analysis of the ongoing weather forecast there is not much change to our current thinking.  The National Weather Service is keeping the Winter Storm Watch in effect for all of Acadiana late tomorrow afternoon into tomorrow evening.  This may get changed to a “Winter Weather Advisory” if snow totals stay below 2 inches…which we think it should.  If we were to expect 2″ or more the advisory would then switch to a “Winter Storm Warning”.  One major rule of forecasting: never forecast a record-breaking event!  And if we see a measurable accumulation of snow Friday evening it will be the earliest recorded snowfall on record in Lafayette going back through 1893…and the earliest snowfall was recorded just last year on December 11th!  But due to overwhelming data and dynamics we will break the golden weather rule!  The current thinking is that cold drizzle and patchy rain will be developing tomorrow afternoon with temperatures holding in the 40s accompanied by increasing north winds which will make it feel about 10 degrees colder.  Rain should then switch over to snow around dusk Friday evening with a few hour window of opportunity for all snow.  Surface temperatures should stay above freezing during the precipitation process Friday afternoon/evening but accumulations on grassy areas may approach an inch.  Northern portions of Acadiana could potentially see more than an inch or two.  If temperatures drop ahead of schedule hazardous travel conditions would be more likely if the snow is moderate enough so we’ll be watching for this closely.  All in all this may turn out to be quite similar to last year’s snow, but there are more wild cards with deeper low pressure well out in the Gulf and available moisture staying inland remaining in question.  It is entirely possible that this forecast will be a bust if all the precipitation stays offshore closer to the low!  As I have been saying…snow events are so rare and hard to generate in our area that we really d0 not have much confidence in these events until we see how things evolve on the radar…so if it’s snowing in Houston midday tomorrow…look out for the possibility of a winter wonderland!   Finally, look for the coldest readings of the season Saturday morning with temperatures dropping to or slightly below the freezing mark.  Wind chills Saturday morning will likely be in the low-mid 20s!  As always with winter in Acadiana, temperatures in the 70s will return sooner than later…and that could be on Monday!  Stay tuned to KATC for the latest on this possible winter weather event…always exciting to see if we are going to set a new snow record…”wish-casters” rejoice!

The NWS also has put together an awesome Snow Climatology Chart of our area so check that out too.

We should have a one day reprieve from thick cloud cover and rain for our Thursday but increasing cloudiness and patchy rainshould return Friday afternoon/evening.  Yet another El Nino enhanced low pressure system will likely develop in the Gulf of Mexico Friday.  This time around the track of the low should be much farther to the south so heavy rainfall and thunderstorms should be out of the mix…but a light wintry mix may be in the offing Friday night!  The models continue to advertise plenty of chilly air entrenched across the area Friday afternoon and evening with upper level dynamics cold enough, as Dave mentioned in the last blog entry, for some snow or sleet.  The big questions are how cold will we be Friday night and where will the deepest moisture be when upper level conditions support more wintry precipitation regimes?  Right now the most prudent forecast would call for patchy cold rains to develop Friday afternoon and evening with temperatures cooling further into the mid-upper 30s Friday night.  Upper level dynamics should force enough lift Friday night for more widespread light rains that could mix with snow during the night time hours.  Ground and surface temperatures will preclude any kind of significant accumulations of snow in Acadiana…if we even see snow, but there will be the chance of some light accumulations (less than an inch) across intereor portions of Southeast Texas and Western and Central Louisiana.   As Dave mentioned, we have never seen a significant snow accumulation before December 11 of last year, so forecasting anything more than some snow and/or sleet mixed with the rain and not sticking to anything other than grassy areas is the best forecast at this time.  Generally around our part of the world we never truly know what kind of winter weather event  we are going to get until we are just a few hours away…so stay tuned!  With last year’s snow event, it didn’t look favorable for the snow event until about 6 hours before it came in, so you won’t want to miss our weathercasts Friday!  Temperatures should plunge to near the freezing mark or a little below Saturday morning but the precipitation will be long gone by then.  Don’t get your hopes up too high for Friday night…and remember we have lots of winter ahead!