WKU Meteorology

Days at a Glance:

Thursday: High – 84  Low – 65  Precipitation – 100% late in the period starting from 10 pm -11 pm where totals could reach .5 of an inch in total   Winds – S at 20-23 mph  Skies – Partly cloudy becoming cloudy after sunset

Friday: High – 52  Low – 33  Precipitation – 90% residual rain showers very early in the period just after 1 am where totals could reach .5 of an inch before ending shortly after  Winds – W at 14-17 mph  Skies – partly cloudy clearing out into the evening

Saturday: High – 59  Low – 30  Precipitation – 0%  Winds – NW at 6 mph  Skies – Sunny

Sunday: High – 66  Low – 39  Precipitation – 0%  Winds – E shifting into the afternoon and evening SE at 6-7 mph  Skies – Sunny

Discussion:

Throughout tomorrow, persistent southerly winds will prime our area with moisture and warm temperatures. The high temperature will once again be in the mid 80’s on a day very similar to today. The main story for this forecast period is the cold frontal passage to impact our area late Thursday night into very early Friday morning. Models are in good agreement that it will pass around 1 am Friday morning with precipitation ahead of the front beginning around 10-11 pm. Expect moderate to heavy rain in a relatively brief amount of time with totals likely to reach one half of an inch. Rainfall should quickly cease after 1 am depending on the exact timing of the frontal passage. The likelihood of severe weather will be on the decline since nighttime cooling will increase the overall stability of the atmosphere. Small to moderate hail will be the main threat, with strong winds likely as well depending on the configuration of the line as it enters our area. Regardless, it is very important that you have weather radios to awaken you in the event of severe weather.

NAM 06Z (1 am) Friday morning surface temperatures, winds, and mean sea level pressure. Notice the distinct N-S boundary traversing our area. This is the cold front.

For Friday, clouds will stick around but will clear out into the evening. Temperatures will be much cooler only reaching the lower 50’s. Cover your plants and gardens since temperatures will dip very close if not at freezing Saturday morning depending on how quickly the skies clear out and if the winds slacken enough. Saturday and Sunday are looking to be beautiful and the start of another warming trend with highs in the upper 50’s and mid 60’s respectively. A light jacket on Sunday morning will be advised since lows will dip into the upper 30’s.

Days at a Glance:

Monday: High – 77  Low – 54  Precipitation – 10% light showers around midnight  Winds – S at 11-12 mph   Skies – partly to mostly cloudy with peaks of sunshine

Tuesday: High – 80 Low – 61  Precipitation – 40% light showers mid-morning into the afternoon associated with a stalling front paralleling the Ohio River to our north  Winds – S at 12-17 mph  Skies – mostly cloudy to overcast

Wednesday: High – 84  Low – 63  Precipitation – 10% light showers mid-morning  Winds – SSE at 12-17 mph  Skies – mostly cloudy early clearing to partly cloudy into the afternoon

Discussion:

After a warm and beautiful weekend, temperatures will remain on the warming trend, but clouds will be more of a presence. A frontal boundary will lose steam and stall out to our north along the Ohio River late Monday night into Tuesday morning. Occasional and spotty showers will be a possibility during this time into the afternoon Tuesday with accumulations under a tenth of an inch. It will remain stationary for most of Tuesday and then progress north as a warm front for Wednesday into Thursday.

NAM 00Z Thursday (7 PM Wednesday night) wind, temperature, and mean sea level pressure. Notice the developing disturbance over the central plains with distinct boundaries taking form to our north and across the upper Great Plains. A snapshot of what’s to come into the latter half of our work week.

South winds will be priming our area with warm, moisture-laden gulf air for the next couple of days. Aloft, a deep disturbance is beginning to take shape, and will provide large-scale ascent for us during the latter half of the work week. With this said, transition is clearly in the air for Thursday and Friday. Further monitoring will continue as the system unfolds.

The AMS/NWA Local Chapter (Meteorology Club) is proud to announce that it will be hosting its first Weather Camp this Summer on July 15 – 19, 2013.  Applications are now being accepted and will be accepted until June 15, 2013.  The cost for the camp is $60 which will go toward Food costs, T-Shirts, and other items that will be needed to run the camp successfully.  This camp will be a day camp only and it will start each day at 9:00 A.M. and will end everyday at 4:00 P.M.  The age group that this camp will be geared toward is Middle School Kids ages 11-14 at the time of the camp.  Our Weather Camp is one of several other camps across the U.S. that are a part of the National Weather Camps program which is geared toward teaching kids the importance of Science and fueling their interest in the Atmospheric Sciences.  What makes our Camp different from others is that it is entirely student led.  For more information about our Camp and to download the Application, go to our website by clicking here.  Also, you can contact Tyler Binkley the Camp Director at tyler.binkley567@topper.wku.edu

Discussion:

The first half of the week has been dominated by warm temperatures with a good mix of sun and clouds throughout. The high today (Wednesday) climbed to 86 degrees at the Bowling Green Airport easily making this the warmest day of the year thus far. In fact we our high was 18 degrees above the average for this time of year. The warmth will come to a screeching halt tomorrow as a very strong cold front will make its way through the area. This front could pack a punch in more ways than one… not only will much colder temperatures move in behind the front but severe storms could also move in along the leading edge of the frontal system.

Currently a 1004 mb low pressure system is located near the St. Louis, MO region with a warm front extending to the east into southern Ohio and the strong aforementioned cold front extending south through Arkansas and into Louisiana. Both of these fronts have been the focal points for severe storms today. Tornadoes have been reported in both Arkansas and Missouri along with numerous other severe weather reports that continue to come in at this hour. Severe weather watches extend along these areas of thunderstorms including a tornado watch for parts of western Kentucky. This is all headed toward the south-central Kentucky area but the question is how will it effect us?

Current thinking is that a line of thunderstorms will continue to move in our direction along and ahead of the front some of which could be severe. In fact the Storm Prediction Center has outlined all of south-central Kentucky in a slight risk for severe storms. Areas along and east of I-65 have been included n the 30% probability area.

A slight risk of severe storms has been outlined by the SPC for all of south-central KY for Thursday. This includes an area of 30% probability east of I-65.

Several things are coming together to create this possibility:

• A diffluent flow is present in the upper-levels which should help create synoptic scale lifting
• A strong closed area of low pressure with an associated area of vorticity is located over at 500 mb will be moving over the Midwest
• Around a 50 kt low-level jet will be advecting warm moist air from the Gulf of Mexico as well as helping to increase low-level shear
• Warm and moist air at the surface will allow for at least weak to moderate instability of around 250 – 500 j/kg
• A strong cold front will create lift
• Finally an area of 35-45 knot surface to 500 mb bulk shear

NAM forecast reflectivity (left), CAPE (center), and MSLP/winds/temp (right) for around 1 pm Thursday.

These conditions are all setting the stage for possible severe storms with threats of hail and damaging winds. It appears that directional shear and even speed wind shear will be minimal and thus the threat for tornadoes is also small. This however does not rule out the possibility of a spin up tornado along the squall line much like what we had in late January near Smith’s Grove in Warren Co. If any storms are able to initialize ahead of the squall line, these storms would also pose an increased risk of severe weather as well but these storms are not expected to be widespread, if at all, in our area. Overall though, expect a line of storms to move in between 9 am and 1 pm that could very well contain bowing segments which could lead to strong to severe winds. Some hail is also possible with these storms. Lastly and not to be outdone is the flash flooding potential as 1 to 2 inches of rain is likely and it could fall very quickly within thunderstorms.

SPC day 1 Total Precipitation indicates 1 -2 inches of rainfall possible in south-central Kentucky.

After the storms pass through rain will continue into the evening before ending. Colder air will make its way into the area as well as temperatures will drop into the low 40s by Friday morning. Our high Friday will be much cooler as well only reaching the upper 50s to near 60. Saturday morning temperatures will likely drop into the upper 30s and some frost is possible. We’ll make a nice rebound this weekend however as conditions clear and temperatures warm back into the 60s for Saturday and the 70s by Sunday. Data is currently suggesting a return to the 80s by early next week.

In summary expect:

•  A line of strong to possibly severe storms to pass through the area tomorrow.
• The timing of these storms should be between 9 am and 1 pm for south-central KY
• The main threat will be damaging winds with bowing segments in the line of thunderstorms, hail and isolated tornadoes are also possible.
• Heavy rain will accompany thunderstorms and 1 -2 inches rain is possible by tomorrow afternoon. Flash flooding is possible is association with the thunderstorms.

Daily Forecasts:

Thursday: Thunderstorms and rain are likely; some storms could be severe and rainfall between 1 and 2 inches is possible. Cooler with a high near 74 early before dropping into the 60s throughout the afternoon. Winds will be breezy from 10 – 20 mph.

Thursday Night: Rain will have ended but skies will remain overcast. Cool with a low near 41. West winds from 5 – 10 mph.

Friday: Cooler with a high of only 59 under mostly to partly cloudy skies. Winds from the west a 8 – 18 mph.

Friday Night: Frost possible with a low near 35 under partly cloudy skies. Winds will be light to 8 mph.

Saturday: Mostly sunny skies a warming up with a high around 64.

Sunday: Mostly sunny with a morning low in the low 40s and a high in the mid 70s.

Daily Forecasts:

Sunday Night: Partly to mostly cloudy with a low near 54. South to southwest winds 3-8 mph.

Monday: Partly to at times mostly cloudy and warm with a high near 77. Breezy with south to southwest winds at 10-20 mph.

Monday Night: Partly to mostly cloudy skies with a low around 59. South to southwest winds at 3-8 mph.

Tuesday: Mostly to partly sunny skies with a high around 80. South to southwest winds 10-15 mph.

Tuesday Night: Partly to mostly cloudy with a low near 60. South winds from 5-10 mph.

Wednesday: Partly to mostly cloudy a warm with a high near 80.

Thursday: Increasing clouds Wednesday night with a 70% chance of thunderstorms after midnight and into the morning hours. Some storms could be severe. Temperatures will drop from the 60s early into the 50s.

Discussion:

After a chilly and much below average March and even a cool start to April, spring has finally made it’s two and half week late arrival this weekend… better late than never! Temperatures soared into the 70s both Saturday and Sunday, in fact, the high of 76 at the Bowling Green Airport makes today the warmest day so far in 2013 and the warmest since October of 2012! It’s unlikely that will be the last time we can make that statement this week as temperatures will remain in the mid to upper 70s through the first half of the week. It’s even possible that some locations in south-central Kentucky crack the 80 degree mark on Tuesday and Wednesday.

Temperatures have finally warmed thanks to a zonal flow in the upper levels (as opposed to a trough which would bring in cold air) combined with a high pressure system located over the southeast. This surface high in the southeast along with a low pressure to our west have brought warm and moist southerly winds into Bowling Green. This pattern will hold through Thursday and thus until then warm temperatures will continue. A few disturbances will pass just to our north through the first half of the week and thus the occasional stray shower or storm is possible.  This will also create a mix of clouds and sun through the first half of the week.

The southerly flow (red arrows) created by the low pressure to our west and the high pressure to our east will keep the warm weather in place through Wednesday.

Wednesday night into Thursday morning is when the storm system to our west will finally move east and into our area. Anytime you have very warm air ahead of a strong system there is the risk of severe weather and this is in fact the case Thursday morning. At this time confidence is increasing that a squall line will push through Kentucky late Wednesday night/early Thursday morning. Of course the exact timing is too difficult to pinpoint at this time. Severe weather in the form of high winds and spin up tornadoes appear possible but this is very contingent on all the right conditions coming together. This system is still days away and thus the specifics and details are yet to be determined but at least be aware that severe storms are possible in the aforementioned time frame. Further updates will be given here on the WKU meteorology blog addressing the severe weather potential. Until then, stay tuned and enjoy the warm spring temperatures.

Day 4 severe weather outlook as of Sunday places the severe weather threat just to our west on Wednesday.

Conditions across the area have been very nice although a cool start kicked off our Saturday morning.  Overnight lows dipped into the  upper 30’s to around 40 degrees in many locations across south-central KY.  Mostly clear skies and calm winds through the overnight hours helped temperatures drop a couple degrees cooler than advertised.  Clear and cool conditions have prevailed for the morning hours, but things are beginning to warm up nicely.  With the retreat of the jet stream to the north, much milder air will continue to works it way into the Ohio Valley Region.  A surface ridge aligned from Michigan through Tennessee will continue to keep conditions rather calm with warming temperatures throughout the day.  Projected highs will be warmer today, with temperatures reaching the upper 60’s for folks to our north with low 70’s across south-central KY.

Surface Temperature Map Valid for 21Z Saturday. (Twister Data)

Looking ahead for this evening, conditions should remain calm, quiet, and nice.  Mild overnight lows are expected as temperatures drop to around 50 degrees.  Mostly clear skies will remain through the overnight and into our Sunday with light and variable winds.

Wednesday started out as a breezy but cool day across the area.  Plenty of sunshine with southwesterly winds around 5-10 mph gave a brisk chill to the air, but quickly warmed up into the low 50’s across south-central Kentucky.  Through much of the morning and early afternoon hours, sunshine filtered in over the region, but increasing clouds from the southwest has since moved in as overcast conditions have began to take over.   High pressure is currently situated over the Great Lakes region and will continue its progression towards the east.  Tightening pressure gradients between the stout high to the north and deepening low pressure system to the south has been increasing easterly winds across southern Kentucky.  Into the evening hours, winds are expected to settle down a bit as relative humidity values will rise.  Clouds will continue to thicken and lower, especially over central and south-central Kentucky.  Overnight lows are expected to be cold with temperatures dropping into the low 30’s.  Areas to our north could see slightly colder overnight lows as clouds will be slower to move in, allowing temperatures to drop a few degrees below the freezing mark.

NOAA/HPC precipitation forecast (Day 1-2) valid for Thursday 00Z – Saturday 00Z.

Looking ahead for tomorrow, temperatures will once again start off very cool, but should quickly warm up into the low 50’s for southern Kentucky where cloud cover and approaching showers will keep temperatures slightly cooler than areas to our north.  Both the GFS and NAM models continue to trend the system tracking to our south as the Tennessee Valley Region and points southward will see the best chance for precipitation.  Areas along southern Kentucky should see rain showers filter into the area, but should remain light at best.   The HPC suggest that the broad area for heavier rain will occur to our south and eventually to the southeast and along the eastern coast.  Counties along the KY/TN border will see the best chance for showers.

The aforementioned high pressure will continue to move off towards the east coast as any showers along the southern and eastern parts of the state should come to an end as winds begin to back towards the north by Thursday evening.  Thursday night should feature a rather calm, clearing night with a low around 40 degrees.  Skies should begin to clear throughout the overnight hours and into Friday morning, as the long awaited arrival of spring will finally impact the region.  Highs for your Friday are expected to reach the low to mid 60’s under mostly sunny skies! Winds should remain light and from the north around 5-10 mph!

Well, this week has been interesting, but we are on the up and up temperature wise.  Today was a gorgeous day with temperatures in the 50s.  These should continue to go up to the mid to upper 50s by tomorrow.  This is all because of a high pressure system just to the west of Bowling Green.

Now this weekend we are going to see some rain and possible thunderstorms because of a low pressure system sweeping into our area.  This will cause our temperatures to stay relatively the same and may go down a bit. If you look in the second box, the 540 line is clearly to the north of us, so we will see only rain and now snow.  We will see showers throughout the whole weekend.  There is tons of moisture in the atmosphere.

Weekend forecast:

Friday: Slight chance of showers, high of 53.

Saturday: Showers likely, high of 60.

Sunday: Showers, highs in the low 60s.

First off, we were under a Severe Thunderstorm Warning this afternoon and with it came some hail.

Photo taken my Landon Oliver in Bowling Green, KY.

Now onto the forecast.   Today we are going to continue to see showers and thunderstorms roll through.  Now as we go through the evening, its going to get a little tricky.  Depending on the temperatures we are going to see a mix of rain and snow tonight, we could see up to a half inch of snow. Then, tomorrow another half inch is possible.

In the top right image, there is a low situated to our north.  Also, notice the line in the bottom right, that is the rain/snow line.  We are going to see small accumulations as we go through the night tonight.  Again, it all depends on the temperatures   Northern counties will likely see more snow. There is tons of moisture and because of the temperature the snow is going to be a wet and slushy consistency if we see any.

Forecast:

Monday: Rain showers likely, could mix with snow.  Highs in the mid 30s.  Could see snow anywhere up to one inch.

Tuesday: Highs in the upper 30s, 30% chance of rain.

Wednesday: Clear skies, highs in the mid 40s.

Days at a Glance:

Thursday:  High – 39  Low – 18  Winds – 5-7 mph NW  Precipitation – 0%  Skies – Clear

Friday:  High – 49  Low – 22  Winds – 5-6 mph E  Precipitation – 50% widespread rain showers into the evening and overnight hours  Skies – Clear becoming mostly cloudy and overcast by late afternoon

Saturday: High – 52  Low – 33  Winds – 6-8 mph ENE  Precipitation – 100% widespread rain showers in the early morning hours with more scattered, but heavier rain further into the evening and overnight

Sunday: High – 51  Low – 32  Winds – 6-8 mph E increasing to 20-23 mph SW mid afternoon slackening to 15-17 mph NW late evening Precipitation – 80% residual rain as the front moves through the area with total accumulations for both days under one inch

Discussion:

Currently, the temperature at the WKU Farm Mesonet is at 27 F. By tomorrow morning, temperatures will have bottomed out to the upper teens, so bundle up! Tomorrow will be another nice day with temperatures struggling to escape the 30’s. Thursday night will be another cold one in the lower 20’s. Friday will be another beautiful day with a high near 50, but clouds will be increasing throughout the day into the evening. Widespread, but light rain showers will be an increasing possibility into the overnight hours and Saturday morning before tapering off by mid-morning. Clouds will stick around throughout the day with increasing winds until another round of rain impacts the area into the evening and around midnight. This will be more scattered, but intense in nature because it is associated with a cold front compared to the warm front Saturday morning.

GFS 12Z (7 am) surface winds, temperature, and mean sea level pressure Sunday morning. Notice the low pressure system responsible for the weekend rain passing our area, and the cold, northwest winds behind it.

Models are not agreeing very well with total rainfall accumulations, but I’ll keep the baseline at half of an inch with one inch as the limit for the weekend event. With the rain clearing out by mid Sunday morning, skies will clear out by late afternoon with temperatures falling throughout the day thanks to gusty NW winds.

Forecaster: Austin Boys