WKU Meteorology

Sunday’s rainfall has moved out of south-central Kentucky after the area received anywhere from 0.25 – 0.50 inches of rain.  This rainfall was due to an approaching storm system with a cold front which will not actually make it’s way through the Commonwealth until overnight tonight.  Until the passage of the front the chance lingers for a few showers and sprinkles; any lingering precipitation will be light.  By Monday the rainfall and clouds of Sunday will just be a memory as a surface high pressure will begin to work it’s way in.  The strong low pressure centered over the upper-Great Lakes however will be close enough to make it another windy day (though not as windy as Sunday) with winds from the west from 10-20 mph with gust 20 mph +. Other than the wind it will be a mostly sunny day with highs in the upper 50s to near 60.  Tuesday should be another nice day though slightly cooler thanks to more north-northwesterly winds from the lower levels of the atmosphere to the surface.  Clouds will also be moving in during the afternoon ahead of the next storm system.

An upper-level disturbance will eject from the four-corners region Tuesday and move toward our area.  Furthermore a surface low pressure system will try to develop in Texas and then move to the east and north.  This in turn brings a good chance of showers from Tuesday night through Wednesday.  The sub-tropical jet will bring ample Pacific moisture to the area but the track of the low should be to our south and thus the heaviest precipitation should also pass to our south.  Nonetheless it appears that rain is likely with anywhere from a 0.1 to 0.30 inches of rain mainly during the day on Wednesday.  There is a chance given the strength of the upper-low and the cold pocket of air aloft that will move over our area associated with the system that some wet snow flakes could mix in at times with the rainfall especially Wednesday afternoon. Notice on the image below that the blue 0 degree line at 850 mb is south of most of Kentucky which would normally indicate snow.  However such warm air at the surface will likely keep most of the precipitation as rain.  Nontheless a full transition to wet snow Wednesday afternoon cannot be ruled out however nothing of any significance and no

GFS precipitation and 850 temperatures for noon Wednesday.

accumulation is expected at this time.  Behind this system the weather will turn dry for a while with colder air moving in.  Indications show that from Friday and especially into the weekend much colder air will return to Kentucky.

Climate Prediction Center’s 6-10 day temperature outlook indicates a good chance of below average temperatures.

Daily Forecast:

Tonight: Cloudy skies with a chance for a few sprinkles or even an isolated shower.  Low near 44. 8-14 mph winds from the south switching to the west around midnight.

Monday: Mostly sunny with a high near 58. West winds from 10-20 mph with gusts 20 mph +.

Monday Night: Clear skies with a low near 30. Light WNW winds.

Tuesday: Mostly sunny to start but cloudy by the afternoon; high near 51. Light north to northwest winds.

Tuesday Night: 50% chance of showers with a low near 34.  North to northeasterly winds from 3-8 mph.

Wednesday: 60% chance of showers possibly mixed with wet snow during the afternoon. No accumulation expected. High near 42. Rainfall totals between 0.1-0.3 inches.

Thursday: Morning low near 33; Mostly sunny skies with a high near 58.

After a busy weather weekend, conditions have begin to calm down just a bit with clear and milder temperatures across the state.  High pressure will continue to shift over our region towards the east near Pennsylvania/New York by this evening.  Highs for your Wednesday are expected to reach the upper 40’s, low 50’s with mostly sunny skies.  Winds will be light and variable through much of the day before shifting to  a more southerly wind by Thursday. These southerly winds will be ahead of an advancing trough from the Central Plains as our region looks to be between two systems associated with this trough.  The models continue to show our best chance at some light precipitation with the northern system as we head into Thursday evening and early Friday morning.  Models continue to indicate weak isentropic lift in between the two systems by Thursday evening, leaving the area a chance to see some isolated – scattered showers move through.

GFS 500mb Heights & Vorticity valid for Friday 12Z.

GFS MSLP, PCPN (In.) and 1000-500mb Thickness valid for Friday 12Z.

The latest GFS run for 500mb Heights and Vorticity map shows the northern disturbance over the Great Lakes with a progression towards the northeast.  As far as concerns for precipitation, a light rain event will primarily dominate this event as the GFS precipitation and thickness map hints towards this possibility with 0.01 – 0.10 inches of rain accumulation.  Conditions for your Thursday look to stay dry through the morning hours under partly sunny skies.  Temperatures look to warm up nicely by the afternoon hours with a high around 58º.  Heading into the evening and overnight hours, we’ll see the best chance for showers with a low around 42º under mostly cloudy skies.  Expect the heaviest rains to occur through the evening and overnight hours as we’ll see another high pressure build back into the region by Friday.   Clearing skies accompanied by cooler conditions will be the main talk of the day.  Low to mid 40’s will be expected state wide with light winds from the northwest.

Last week’s wild weather continued into the weekend as continuous Alberta Clipper systems swept through the Ohio Valley Region. Parts of Central and Eastern Kentucky received the first dose of measurable snowfall with a couple clipper systems dropping 2-4 inches of snow for those areas. South-central and western parts of the state missed out on most of the action by picking up a dusting of snow, with far western counties receiving no accumulations. Another clipper system developed over the mid-west and quickly moved through parts of Missouri late last night. Quick burst of snow was recorded over parts of St. Louis as accumulations ranged from 2-3 inches of snowfall. The HRRR last night showed positive signs for snow lovers across south-central KY as 1 hour accumulated snowfall rates of 1-2 inches/hr were possible along the I-65 corridor and westward.

Snowfall was forecast to impact the Bowling Green area this morning and did so by dropping an official inch of snow.  This intense and quick hitting system affected areas just to our north and west as the hardest hit areas along a narrow axis extending from Ohio County through Edmonson, Barren and southern Hart counties picked up 2-3 inches of snow.  As far as Bowling Green is concerned, some photos were taken this morning as the heaviest snow began to fall around 3am.

Photo captured early this morning on campus. Heavy snow covered many roads and side streets along the area making for cautious travel around town. (Credit Photo to STN)

Another photo capturing the heart of Campus with a light blanket of snow covering the ground. (Credit Photo to STN)

Snow abruptly came to an end shortly after its impact over Bowling Green as the system continued to work its way through eastern Kentucky and Tennessee by late morning.  Cloudy skies are expected to stick around through the afternoon hours before some partial clearing to our west occurs.  Temperatures in the forecast look to warm up as highs make a run towards 40 degrees in Bowling Green.  Clouds should continue to push to our east as Mostly Sunny conditions should prevail by mid-afternoon with wind from the west around 10-15 mph.  Expect partly cloudy conditions tonight, with a cold low around 24 degrees.

Looking ahead for your Monday, another system is expected to impact the area by Monday evening and could bring a rain/snow mix to the area.  The latest model run (NAM) shows another system with a bit warmer air mass and more moisture to sweep through as precipitation is likely to start out as rain before switching to snow late Monday night/early Tuesday morning.  Light snow accumulations are expected at best with better chances of snow to our north.

NAM valid for Tuesday 3Z… MSLP, Thickness (1000-500mb), and Precipitation.

Latest NAM model run shows the 5400 line cutting the state nearly in half as this gives a good idea where the rain/snow line could exist.  As mentioned before, areas to our north will see a better chance at a light accumulation with more of a rain/snow mix towards the south and west.  Monday’s temperature will continue the warming trend with highs around 47 degrees with a slight chance of rain through the late afternoon hours.  Lows for your Monday night will hover right around the freezing mark as the chance for rain/snow mix will exist.

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Tuesday: Partly sunny conditions. High: 45º. Southwest wind around 5-10 mph.

Tuesday night: Mostly Clear skies. Low:29º. Light and variable winds.

Wednesday: Mostly Sunny. High:48º

We saw about every season this week.  From tornadoes to snow.  It has been a crazy, intense week here in South Central Kentucky.  We first saw fall like temperatures earlier on in the week and then we transferred right to summer like temperatures with 70 degree temperatures Wednesday Morning.  Yes, that’s right, Wednesday morning at 1 am.

Here’s what happened:

Tuesday night into Wednesday there were two EF-2 tornadoes that touched down near Bowling Green.  One was in Smiths Grove and destroyed someones barn and silo.

Then there was another one near Penrod, Ky.  This one tore apart a barn and left debris in the trees.

Picture taken by Landon Hampton and posted on Facebook. This is damage from the EF-2 tornado near Penrod, KY.

There were numerous storm reports on Wednesday morning and the NWS went out and surveyed the damage, deciding what was caused by winds or a tornado.

Lets move on to the other drastic change.  We are back to the cold temperatures of January.  Another cold front is moving in tonight and is bringing with it snow.

We could see up to 1 inch of snow when all is said and done.  We will see sunny skies on Friday after the snow and clouds move out, but then there is more.  ANOTHER COLD FRONT will move into the area on Saturday bringing with it another shot at some accumulating snow.

If you look at the 540 line (red dashed) in the top right and bottom right pictures,  that is showing the line of where snow would form to the north of.  So we are going to see some light snow on Saturday.

The Weekend:

Friday: Sunny skies with highs in the mid 20s.  The wind chill could be in the single digits.  Bundle up!

Saturday: We will see a chance of snow showers in the morning before noon, then that will mix with some rain.  Could see some slick spots on the road.  Less than a half of inch is possible.

Sunday: Mostly sunny, highs in the low 40s.

Everyone enjoy the warmth this afternoon, because it is all about to change.  The front will pass through overnight tonight and with that it is going to bring the chance of severe weather and colder temperatures after the front.  The CAPE is slightly higher than previous models have shown, which hints to us more instability in the atmosphere.

With the amount of CAPE, it is possible to see some small hail and isolated tornadoes.  Along with these threats, we may see strong winds move through Bowling Green tonight ahead of the storm and with the storm.  The moisture axis is right through Bowling Green and surrounding areas.  This adds to the instability of the atmosphere.

The strongest winds are also near South Central Kentucky.  We could see wind damage as we wake up tomorrow morning.  Downed trees and power lines will most likely be the main threat.

We are going to see periods of heavy showers and rumbles of thunder tonight.  Here is the radar for overnight tonight.  The cold front will bring heavy rain and thunderstorms between 2am and 4am. This makes it more of a hazardous situation because it is coming overnight.  1-2 inches of rain is expected through the storm.

The model below is showing a high vorticity value in the top left box and the front just to the west of Bowling Green in the top right box.  This is indicator of strong storms tonight. This is showing the change in wind speed with height and is showing upper-level divergence in the atmosphere, which is why there is a possibility of isolated tornadoes and a supercell thunderstorm.

As the front passes and we go through the day on Wednesday, temperatures are going to decrease.  We should see our highest temperature in the morning on Wednesday, and we will cool off as the day goes on.  The colder temperatures will come behind the cold front.  Then we are back to seasonal temperatures for the remainder of the week.

Today: We will remain cloudy for the day and temperatures will near 70.  Our record is 74 degrees and was made in 1975.

Tonight: Make sure you stick to your television or radio for the up to date weather information.  The strong line of storms has the possibility of bringing small hail, strong winds, and isolated tornadoes across South Central Kentucky.

Tomorrow: We will see cooling temperatures as we go through the day tomorrow.  Clouds will move out leaving us with partly cloudy skies in the afternoon.  We will see more seasonable temperatures before tomorrow is over.

I am sure everyone is in the need of a break from the winter weather that we have seen the past couple of days.  Well the break is on the way.  Temperatures will make their way into the upper 50s and into the 60s this week.  This is about 20 degrees above average.  But with these milder temperatures comes the chance of severe weather in the middle of this week.

This is showing the severe weather potential for Tuesday night into Wednesday.  Bowling Green is on the edge of a slight severe potential for the week.  This would come in the form of a squall line, which has the possibility of damaging winds.  In the picture below, it shows a squall line moving through the area overnight on Wednesday.

 If you take a look at the top right image, this is showing that there will be a cold front that comes through Tuesday night into Wednesday.  If you take a look at the bottom right image, we may see about one inch of rain as the system moves through.  Also, Bowling Green is near the heaviest amount of rain.  The winds will be strong during this time frame.   After the cold front comes through, temperatures will be back to reality, with temperatures back in the 30s.

Week Forecast:

Today- We have a slight chance for rain as we go through the day today.  Temperatures in the upper 40s.

Monday– Another slight chance for showers and highs near 60 degrees.

Tuesday-Showers, temperatures in the mid and upper 60s.  Later in the evening, we will hear rumbles of thunder as a squall line moves through.  There is a possibility of damaging winds.

Wednesday-Showers linger throughout the day and temperatures will drop.  Our high will be in the morning, so we will be back to seasonal temperatures by the afternoon.

Thursday-Mostly sunny, with highs in the upper 30s.

Friday-Mostly sunny, highs in the upper 20s.

Winter has been in full force here is south-central Kentucky this week.  We had the coldest air of the season makes its way into the area for Monday night and Tuesday.  We reached a low of 16 at the Bowling Green airport Tuesday morning and only climbed to a high of 28.  Thanks to southwesterly winds today along with sunny skies we managed to reach a high of 46 yesterday but don’t expect that to last.  Another re-enforcing shot of cold air is currently making it’s way into the Ohio Valley from south-central Canada.  So what does that mean regarding our temperatures… more cold!  It looks like for the 2nd time this week we won’t make it above the freezing.  Highs should be from 28-31 across the region today.  It’s this late tonight when the weather gets interesting.  With the cold air that will be in place as well as a mid-level disturbance that will be moving through the area wintry weather will likely be impacting our area.  Models agree that temperatures will be cold enough to support an all winter weather event but it looks like that winter weather will be in the form of sleet and freezing rain.  Why sleet and freezing rain and not snow you may ask?? This is because further up in the atmosphere the temperature will be above freezing thus allowing what was a snowflake to melt.  Then when it re-enters the cold air which we will have here at ground level the  raindrop freezes; it would be sleet if the snowflake doesn’t fully melt in the

The HPC’s model guidance for ice accumulation suggests up to a 60% of >0.01 of ice for both before 6 am Fri (left) and after 6 am (right).  Notice the best chance for accumulating freezing rain is along the KY/TN border.

atmosphere.  The biggest question with this event will the the amount of precipitation that falls.  Overall models agree that this event should be light in that total precipitation should remain below a quarter of an inch… the problem is that even just a tenth of an inch of ice could cause considerable impacts especially during the morning rush after a very cold week. In the end I think this will be more like a winter weather nuisance more so than anything else but once again due to the timing as well as the fact that surfaces including roads/bridges are cold due to this weeks cold temperatures the system could cause impacts.  On the bright side of things it appears as though we could see a nice warm up next week.

Hi-resolution NAM shows precipitation in the form of freezing rain and sleet Friday morning.

Winter Nuisance Outline:

-Freezing drizzle should begin sometime after midnight tonight.
-Freezing rain and sleet should be heaviest between 5 am – 9 am.
-Temperatures will range from 29-32 during this time frame.
-Precipitation totals should generally be between 0.05-0.10; this could be primarily ice (freezing rain) but sleet could often mix in which would bring ice totals down.  Precipitation totals will increase as you go south (ie. the closer you are the TN border, more precipitation should fall).
-The amount of precipitation is still not certain! Some data suggests only about a tenth of an inch while some data suggest at least a quarter… that’s a big difference when talking ice! Thus stay tuned to an evolving situation.
-Even the lightest precipitation WILL STICK due to the very cold temperatures we have had this week including over 24 hours at or below freezing preceding this winter weather event.
-Roads, especially bridges/overpasses will likely become slick during rush hour Friday morning.
-Temperatures will warm above freezing between 10 and 12 am which should allow any wintry accumulation to melt.

Daily Forecasts:

Today: COLD!! Mostly sunny with a high near 31. Northeast winds from 5-10 mph.

Thursday Night: Cloudy with a 70% chance of freezing drizzle/rain and sleet after midnight (primarily after 3 am). 3-8 mph winds switching from the east to the southeast.

Friday: 80% chance of freezing rain & sleet before noon; some drizzle may linger through midday.  Total ice accumulation between 0.05-0.15 in.  High near 36.  6-12 mph winds switching from the southeast to the west.

Friday Night: Mostly clear and cold with a low near 22. WNW winds from 3-8 mph.

Saturday: Partly cloudy, increasing clouds especially late in the day.  High near 33.

Sunday: Mostly cloudy with a high near 42.

The nearly 60 degree weather we had on Saturday is all just a distant memory now as much colder air has spilled its way south into the Ohio Valley.  Yesterday highs still managed to reach the upper-40s and thus temperatures were still slightly above average.  Today however temperatures will struggle to reach the mid-30s and as for tomorrow, highs will only be in the mid to upper 20s!  Meanwhile overnight lows will drop to the low to mid teens for both Tuesday and Wednesday morning.

So why all the cold? In the upper-levels a strong ridge has developed over the western US coast while a strong trough has developed over the central US.  This has allowed cold air to drop south over the central US from Canada. Furthermore at the surface a high pressures system is centered over the northern US Rocky Mountains and the clockwise flow around the high is bringing in the cold air even at the surface.  As long as this high pressure is too our west or over top us the cold air will be locked in place.

Current mean sea-level pressure and 1000-500 thickness. The X marks the polar vortex over southern Canada. The high pressure over the N. Rockies will bring in the cold air from Canada (blue arrows) making for a very cold first half of the week!

By Wednesday this high pressure will indeed begin to move off to our south and east which will then allow some warming.  Until then it will be down right cold!

Thursday into Friday our next low pressure system with precipitation associated with it will move in.  I think with the cold air in place there could be some wintry precipitation in the form of snow, sleet and possibly even freezing rain especially on the front end of the system.  The models currently do not have a good handle on this system with some models taking the low up the Ohio River which would quickly change any wintry weather here over to rain, while other models take the low over BG or just to our south which would create a better chance for wintry weather.  As with any winter storm the low track is essential and at this time that track remains unknown.  We’ll have a mid-week update here on the blog that will address this possible winter storm as we should know a lot more by then. Until then be aware that there is a chance of wintry weather Thursday into Friday.  Temperatures look to cool off again behind this system which should make for a chilly weekend.

Daily Forecast:

MLK Jr. Day (Today): Mostly sunny but cool with a high near 35.  WNW winds from 8-14 mph.

Tonight: Partly cloudy to at times mostly cloudy.  Cold with a low near 14.  Northwest winds from 5-10 mph.

Tuesday: COLD!! Partly cloudy with a high near 26. Northwest winds from 4-8 mph.

Tuesday Night: Cold with a low near 15 under partly to mostly cloudy skies.  Winds will be light.

Wednesday: Warmer but still cool.  Partly cloudy with a high near 40.  Southwest winds from 3-10 mph.

Thursday: Morning low near 27.  Increasing clouds with a 30% chance of precipitation especially in the afternoon.  High near 38.

Since Tuesday night’s ice potential the weather has gotten much calmer with the sun finally deciding to join us again.  Luckily during Tuesday night’s system temperatures had a very hard time falling below freezing but rather hover at or just above the freezing mark for most of the event.  1 degree or even just a half degree colder would have made quite a difference in how much ice accumulated.  Just to our southwest in north-central Tennessee, there were reports of over a 1/4 inch of ice.  With that our long streak of cloudy and rainy days came to and end so lets look to a better weekend ahead!

I’ll keep this discussion brief because this weekend will be generally a welcomed calm weekend weather-wise.  I’m sure you noticed that temperatures we’re much warmer on Thursday that earlier this week.  This trend should continue and we should even make it to the mid-upper 50s by Saturday.  This is because a surface high pressure system over the south is moving eastward which will put Kentucky in the southerly-warm return flow.  On Saturday the winds bringing in this warmer air will be quite strong with sustained winds from 15-20 mph and gust 25+ mph.  This will be due to the pressure gradient between the surface high pressure in the southeast and a strong surface low pressure over the Great Lakes.  Speaking of this system over the lakes,

A warmer windy Saturday will be thanks to the return flow (red arrows) around a surface high pressure in the southeast. A cold front will move through Sunday which will bring some very COLD air for early next week.

it will be moving east over the weekend dragging a cold front behind which will sweep through Kentucky Sunday.  This cold front will bring our warming trend to a quick and major halt.  High temperatures on Sunday will return to the 40s and lows by Monday morning will be in the low 20s.  As for temperatures Monday and into Tuesday, that’s when the full force on the cold air mass will be felt; temperatures likely won’t make it out of the 20s for day time highs.  This very well cold be the COLDEST air of the season so far!  Lows will likely drop to the low teens! A gradual warm-up will occur starting Wednesday.  Our next chance for rain will come Thursday into Friday of next week, until then enjoy a much needed week of sunny skies!

Daily Forecast:

Today: Sunny and getting warmer with a high near 52.  Southwest winds from 5-10 mph.

Friday Night: Mostly clear with a low around 30.  Southwest winds from 3-7 mph.

Saturday: Sunny and warmer with a high around 56.  Windy!! Winds from 10-20 mph with gust 25+ mph!

Saturday Night: Partly cloudy with a low near 34.  Winds from 5-10 mph switching from the WSW to the WNW.

Sunday: Mostly sunny but cooler with a high near 44.  Winds NW 3-7 mph.

Martin Luther King, Jr. Day: COLD!!! Sunny with a morning low near 21 and a daytime high near 28.

The recent 8-day streak of measurable rainfall (0.01″ or more) from 1/9 – 1/16, 2013 at Bowling Green tied for the 3rd longest since 1893. The longest rainfall streak of 10 days occurred three times, most recently from 9/17 – 9/26 of 2009. The most recent 8-day streak occurred from 4/22 – 4/29, 2011. The recent 8-day streak produced 3.64″. Nearly all of the precipitation during the streak was rain, although 0.1″ of sleet was recorded on 1/14. Precipitation is not expected through the weekend.