Unseasonably Cool Temperatures... Rain Chances

After thunderstorms and rain rolled through south-central Kentucky on Wednesday evening, Thursday was a much calmer day with only an isolated thunderstorm here or there. Bowling Green and Warren County dodged the worst of the storms Wednesday evening and to my knowledge no thunderstorm damage was reported in Warren County despite being under a Severe Thunderstorm Warning for some time. The worst of the storms went just to our north and east where straight line winds knocked down trees and power lines; an EF-2 tornado was even confirmed in NE Larue County. Little, if any, rain fell in the southern half of the county, while some places in the northern to northeast parts picked up 0.25" to nearly 1.0". As mentioned the system moved out creating a mostly sunny and warm day for Thursday. An unusual pattern for June/July is now setting up that will bring back some rain chances in the coming days and also some unseasonably cool air.

The upper-level wind pattern, or the jet stream, is currently becoming an very amplified pattern with a large ridge in the western US and a large trough in the east. Generally speaking, warm temperatures are associated with a ridge while cool temperatures are associated with a trough. This generalization will certainly say alot for the nation's weather this weekend. Beneath the ridge in the west very hot temperatures will occur; areas near/in Death Valley, CA will be in the upper 120s for the next several days! Meanwhile we are forecast to be 5-10 degrees BELOW average for this time of year starting Saturday and continuing into most next week! Highs will be in the low 80s with lows in the low 60s. The reverse of this was occurring this time last year as a ridge was bringing a string of record breaking heat during a time of drought. Records at the Bowling Green Airport included 106 on June 28th and 110 on June 29th.

The mid-level pattern (black arrows) brings systems up over the Rockies and down into the Ohio/Mississippi Valleys. This will create hot and sunny weather over the west and cool temperatures with chances for scattered showers and storms across our area.

A trough in the upper-levels also can bring in a number of disturbances creating the chance for rain. This will indeed be the case starting with today. Currently a few sprinkles and clouds are moving through while the main complex of thunderstorms passes well to our southwest near Memphis. In general most of the thunderstorm activity will remain to our south with the chance of a few showers this morning. An isolated thunderstorm cannot be ruled out this afternoon with chances at about 20% as the front slides south through Kentucky. Things will clear up temporarily overnight and for much of the day on Saturday until clouds increase late in the day. Scattered showers and thunderstorms are possible after 4 pm. Small hail cannot be ruled out with some of the stronger storms due to the cold air aloft... overall this should not be a major concern however. Scattered showers and storms will again be possible Sunday afternoon as well. Rainfall on either day should range between less than 0.1" and 0.25"; these storms will not be the heavy rain producers that storms were earlier this week as some slightly drier air will work in today behind the front. Some locations directly beneath the strongest storms could pick up more however these locations will not be the norm. Scattered rain chances and cool temperatures will continue into the early part of next week. Enjoy the cool temperatures for this time of year.

Daily Forecasts:

Today: 30% chance of a few showers this morning with skies becoming partly to mostly sunny by early afternoon. High near 88. An isolated thunderstorm/shower cannot be ruled out this afternoon. West-Northwest wind at 6-12 mph.

Tonight: Clear to mostly clear skies with a low near 64. Light west to west-northwest winds at 3-8 mph.

Saturday: Mostly sunny skies with a high near 83. 30% chance of thunderstorms by the afternoon. West to west-northwest winds at 6-12 mph.

Saturday Night: 40% chance of a few thunderstorms before midnight, otherwise partly to mostly cloudy skies with a low around 62.

Sunday: Partly cloudy to mostly cloudy skies with a 40% chance of a few showers/thunderstorms. Unseasonably cool with a high near 80. West-northwest winds at 3-8 mph.

Sunday Night: Partly to mostly cloudy skies with 40% chance of a few showers/thunderstorms before midnight. Low in the low 60s.

Monday: Partly to mostly cloudy with a 40% chance of a few showers/thunderstorms with a high near 80.

Forecaster: Ryan Difani

Severe Thunderstorms This Afternoon/Evening... High Wind Threat

As mentioned in this week's earlier forecast, there is the risk for severe thunderstorms this afternoon and into the evening hours. The Storm Prediction Center has continued to outline south-central Kentucky under a "Slight Risk" for severe thunderstorms this afternoon/evening. In fact the SPC increased the probability of severe storms in our area from 15% to 30% for most of the state of Kentucky. The area was also extended further south so as to include the entire region in the "Slight Risk" area. Specifically the SPC has outlined Bowling Green and Warren County with a 30% chance of severe wind, a 15% chance of large hail, and a 2% chance of a tornado (note: the tornado threat is outlined as a 5% chance just to our NW over much of western Kentucky.

Discussion: An upper-level ridge which has been in control of Kentucky's weather, bringing us scattered storms from time to time, is breaking down. What this means is that the storm track which has been over the lower Great Lakes region will be allowed to dip further south into the Ohio Valley. A mid-level shortwave or disturbance will be set to ride along this storm track right into the Ohio Valley by this afternoon. This mid-level disturbance moving through the area will be the focal point for thunderstorms today. Storms popping up in recent days, including with the disturbance on Monday, have lacked upper-level support in order for the storms to become severe. This afternoon's storms however will be in an environment with adequate upper-level winds to organize the thunderstorms and thus allowing for the storms to become strong to severe. Meanwhile instability or the potential energy available for these storms to grow will be more than sufficient, exceeding threshold values by 2000-3000 units. This will all correspond with high moisture levels today. Dewpoints will be in the low 70s making it feel very uncomfortable outside ahead of the storms. There will also be some low-level directional wind shear, but certainty not high amounts. This creates a tornado potential but keeps the potential low.

With today's thunderstorm setup (with reference from convective forecast models) we start out looking at the  ongoing convection from overnight that is in progress in the making its way across north-central Kentucky. This could provide an outflow boundary that will create the potential for some scattered thunderstorms across south-central Kentucky as early as mid-morning. Furthermore another area of storms is located near St. Louis that is also moving toward western Kentucky; this complex could also move in and spark additional thunderstorms in the mid-morning to mid-afternoon time frame. A few storms could develop in parts of western Kentucky by around the 2-5 pm time frame that may be supercellular. If these storms do develop, they will pose the highest severe threat with high winds, large hail and even tornadoes. These storms will likely begin to merge together into a line as they move toward south-central Kentucky lowering the tornado threat but increasing the high wind threat. I think the threat of supercells today remains a low risk compared to the threat of high winds associated with a squall line/bow echo later in the evening.

The data suggests that another round of storms will fire in the Illinois/Indiana region in response to the mid-level disturbance and quickly move southeast into Kentucky. The storms will likely merge into a line and thus could pose a high wind threat. At this time this seems likely with high damaging winds associated with such a line of thunderstorms. The most likely timing for this line is between 5 pm and 9 pm in Warren County. With high amounts of instability, large hail is also a possibility but morning convection may limit some instability keeping this threat lesser so as compared to the high wind threat. The tornado threat, while not zero, should remain minimal as a line or bowing segment with high winds is a more likely storm mode than tornadic supercells that are possible mainly further west earlier in the day. The risk of an squall line tornado also cannot be ruled out given low-level wind shear today. Finally with the high amounts of moisture present both at the surface and throughout the atmosphere areas will likely experience heavy downpours and some flash flooding could be a possibility. This will be especially true if thunderstorms move over some of the same areas for an extended period of time. In general there most areas can expect 0.5" - 1.0" of rainfall through the day today though with the convective nature some areas will likely receive less while other areas may pick up 1.0" +.

Final Summary:

• A "Slight Risk" of severe thunderstorms has been outlined for our area by the Storm Prediction Center.
• Scattered thunderstorms could impact our area even during the morning to midday hours... these should pose less of a severe threat.
• One or more squall line(s)/bowing segments of thunderstorms are expected to move across south-central Kentucky between 5 and 9 pm.
• The line(s) of thunderstorms will likely contain strong damaging wind gusts; some large hail is also a possibility.
• The tornado threat is low for this afternoon but an isolated tornado cannot be ruled out especially with any supercells that manage to develop before storms merge into a squall line. The supercell potential is highest just west of our area in western Kentucky and exists earlier in the day,,, 2-5 pm.
• Heavy rains will accompany these storms and flash flooding could occur in some locations... especially in locations where storms may move over the same areas.

Stay tuned to our Facebook and Twitter pages for more frequent updates during severe weather.

Forecaster: Ryan Difani

Average Temperatures with Thunderstorm Chances... Severe Storms Wednesday Night?

Daily Forecast:

Today: Scattered thunderstorms are likely (60%) with localized areas receiving heavy rainfall. Today's high will be near 88. South to southwest winds at 6-12 mph. Rainfall will generally be between 0.1" and 0.5" but some locations could receive 1" +.

Tonight: Skies will becoming clear to mostly clear as temperatures drop to a low near 69. Light (calm - 5 mph) south to south-southwest winds.

Tuesday: Sunny to mostly sunny skies with a high near 90. South to southwest winds at 6-14 mph. A stray thunderstorm is possible but unlikely.

Tuesday Night: Clear to mostly clear skies with a low around 71. South to southwest winds at 4-8 mph.

Wednesday: Sunny to mostly sunny skies throughout the day with a high near 92. Southwest winds at 6-14 mph. 20% chances of a thunderstorm in the afternoon, increasing into the evening hours to 30% by 6 pm.

Wednesday Night: 50% chance of thunderstorms some of which could be severe with severe winds being the primary threat. Some rainfall could be heavy at times with some areas receiving as much as a 0.5" or more. Southwest winds at 8-15 mph.

Thursday: 40% chance of scattered rain and thunderstorms otherwise partly cloudy with a high in the upper 80s.

Discussion: It was generally an average start to summer temperature wise over this past weekend as sunny skies dominated. Our average high for this time of year is 88 degrees and our highs over the past weekend have been either 88 or 89... can't get much more average than that. Our weather has been controlled by an area of high pressure across the southeastern US which is currently located off the Carolina coast.

Currently however there is an upper-level wave of energy that is moving across the Ohio Valley which has helped to kick off an area of rain and thunderstorms located in the Evansville to Owensboro to Lake Barkley region. Given the upper-level support and the high amounts of moisture in the air (current BG dewpoint is 70) the area of rain and thunderstorms is likely to persist at least to some degree. Current forecast data also suggests that at the very least a few scattered thunderstorms and showers are likely after 10 am today. Given high amounts of moisture heavy downpours are possible. Severe weather associated with today's rain/storms is unlikely given the lack of wind shear needed to organize storms but a few isolated reports of high winds can't be completely ruled out. Some locations could receive 0.5" to 1.0" + of rain if located under the areas of heavy localized rainfall but most locations will only receive 0.1" to 0.5" of rain if any at all. Rainfall will be scattered in nature. Given this area of rain and storms set to move through the region today clouds will likely move in during the mid-morning hours and persist until breaking up and becoming scattered this afternoon and into the evening.

An upper-level wave of energy (green shade) is moving across KY setting of an area of scattered thunderstorms (see radar underlay) over western Kentucky today.

Beyond today rain chances lessen at least initially. The upper-level wave of energy will move east and the main flow in the upper-levels will push north toward the southern-Great Lakes region. An isolated thunderstorm cannot be ruled completely out on Tuesday but chances are less than 20%. It will generally be a sunny to mostly sunny day with temperatures warming back to the upper 80s to near 90. Wednesday will generally be a repeat of Tuesday through most of the day however things may change by that afternoon. The area of high pressure in the upper-levels will completely break down by Wednesday afternoon allowing another wave of upper-level energy to move through. This wave looks to be stronger and be better supported by upper-level winds giving way to increased wind shear. Thus some severe storms appear possible after 6 pm on Wednesday and especially into the evening and overnight hours on Wednesday. The main risk at this time looks to be damaging winds. The Storm Prediction Center has already placed Warren County and Bowling Green on the edge of a "Slight Risk" of severe storms for Wednesday evening/night. Heavy rain will also likely accompany storms Wednesday night with 0.5" to 1.0" seemingly possible in some areas.

The Storm Prediction Center has outlined our area under a "Slight Risk" for severe thunderstorms Wednesday evening.

The upper-level pattern that will set-up late Wednesday will persist into the late week time frame. This pattern will be somewhat of a northwest flow pattern which is a pattern that often brings down waves of energy which spark off areas of thunderstorms and rain (much like that forecast Wednesday night). Given this pattern scattered rain and thunderstorm chances exist late week with continued seasonal high temperatures in the upper 80s to near 90 and lows around 70. An update on the possible mid-week severe storms will be posted as necessary.

Forecaster: Ryan Difani

Hot conditions expected for the first official weekend of Summer...

It was another hot and sunny day across southern Kentucky as a ridge of high pressure continues to shift from the northeast towards the Atlantic.  High temperatures topped out in the mid-upper 80’s across the area under partly sunny skies.  Diurnal convection this afternoon helped spark some isolated showers/storms across southern Kentucky as a weak inverted trough developed over the Bluegrass Region.  Lingering shower and storm activity is expected to continue into the late afternoon hours but should quickly dissipate this evening with the loss of heating. Generally, another mild night is expected as temperatures fall into the 60’s for most locations under partly cloudy skies.  Patchy fog could develop late tonight/early tomorrow morning especially along areas that received rainfall this afternoon.  The first day of summer will feel very summer-like across southern Kentucky as highs top out in the mid-upper 80's once again under mostly sunny skies. A slight chance for an isolated shower/storm will exist into the afternoon hours. 

NOAA/WPC Short-range Forecast Valid for Friday 12Z.

Over the next few days our region will be sandwiched between the Bermuda high just to our east and a stationary low pressure area east of the Central Rockies. A southerly flow will begin to provide increasingly warm, moist air into the Ohio Valley Region over the next several days allowing temperatures to gradually warm into the upper 80’s to around 90 degrees for the first official weekend of summer.  Much like today, the chance for an isolated shower or storm will exist as day time heating could spark some isolated convection across the area.  However, pop-up chances will remain low, as most areas should remain dry through the weekend. 

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A look ahead...

Friday Night: Partly cloudy. Low 66º. South wind around 5 mph. 

Saturday: Mostly Sunny. Hot. High: 90º.  South winds around 5-7 mph. 

Saturday Night: Partly cloudy. Mild. Low: 68º. 

Sunday: Mostly Sunny. Isolated shower/storm. High: 89º. Chance of Precipitation: 20%. 

Sunday Night: Partly Cloudy. Mild. Low: 71º. 

Forecaster: Chris Johnson

Chance for rain, a few storms arrives for Monday...

As we begin to wrap up another weekend and Father's day, we did see a couple waves of isolated showers/storms move through the state temporarily postponing any of those outdoor festivities for Father's Day. Storms that developed brought heavy downpours, gusty winds, and some lightning as the main threats before quickly pushing eastward this evening. Storms will continue to weaken out tonight as a pause in the action sets in before our next system arrives on the doorstep by tomorrow. A cold front currently located from Lake Erie to St. Louis  is expected to slide southeastward tonight into southern portions of Indiana by early tomorrow morning. Expect increasing clouds through the overnight hours with mild overnight lows in the upper 60's, low 70's.  Fog is expected to develop in wake of the recent rainfall and could be dense in those low lying fog prone locations while reducing visibility.

HPC/NOAA QPF Precipitation Forecast Valid for Monday 00Z - Wednesday 00Z. 

As anticipated, showers and storms will begin to develop across the region as the front slides through the Commonwealth Tuesday morning. Development for stronger storms will lye across southern parts of Kentucky as more moisture and instability will exist. Rain should become more widespread by tomorrow evening while pushing northward as the disturbance tracks through the Ohio Valley. Pop-up showers and a few storms will be likely Tuesday across south-central KY extending towards the Bluegrass region. The HPC/NOAA precipitation forecast continues to hint towards a moderate rainfall event, especially across southern and southeastern portions of the state. Model guidance continues to show highs running in the upper 80's, but increased cloud cover will hinder those high temperatures a bit as mid 80's will be more realistic with tomorrow's conditions.


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A look ahead:

Monday Night: Showers and storms likely. Mostly cloudy, with a low near 68º. Chance of precipitation: 60%. Rainfall amounts between a 0.50 - 0.75'' inches possible.

Tuesday: Cloudy, with a high near 83º. Showers and thunderstorms possible before noon. Chance of rain: 40%.  Gradually clearing skies expected by the afternoon hours. Northwest winds 5-10 mph.

Tuesday Night: Partly cloudy skies. Low: 65º. Calm winds.

Wednesday: Mostly Sunny. High: 86º.

Wednesday Night: Partly Cloudy. Low: 66º.


Forecaster: Chris Johnson

Chance of Storms Brings an End to Warm Temperatures

Discussion:

Temperatures in Warren County reached 94 today this afternoon as an upper level ridge made its way over the area from the southwest. Winds from the southwest at 10-15 mph  will continue to usher in warmer temperatures tonight as the low temperature will only dip to around 75 degrees. A threat for storms exist late tonight as a dangerous cluster of storms over northern Illinois and northern Indiana will weaken as they move southeast. The Storm Prediction Center has placed Warren County on the edge of the slight risk for severe weather tonight as this weakening MCS moves into southern Kentucky. The main threats with these storms will be damaging winds and hail. Heavy rain is not too much of a concern as model guidance indicates precipitation totals around a tenth to a quarter of an inch with higher amounts possible in thunderstorms. The chance for severe weather will depend on how far south this complex of storms can hold itself together. Any strong storms associated with this complex would be isolated in nature. Due to low confidence in severe weather late tonight and early Thursday, have decided to hold off on going on alert status and will monitor the situation closely. These showers and storms should move over the area later tonight after 1 A.M. A cold front will move across the area Thursday morning possibly causing a few showers to pop up in the morning as well

Day 1 SPC Outlook showing Warren County on the edge of the slight risk area.

. Behind the front, a northwesterly flow will keep temperatures cooler as the high on Thursday will top out around 85 degrees with clearing skies. Thursday night will be cool with a low in the lower 60s. As high pressure moves in from the northwest a nice weekend will shape up. Friday and Saturday will feature sunny skies and high temperatures in the lower to mid 80s with lows in the 60s. On Sunday the temperature will near 90 again with a slight chance of showers and thunderstorms.

Days at a Glance:

Wednesday Night: Low - 75 Winds - SW 10 to 15 mph.
Precipitation: 30% chance of showers and thunderstorms after midnight. A strong storm containing damaging winds or hail cannot be ruled out. Precipitation totals - 0.1" to 0.25".

Thursday - High - 83 Low - 63 Winds - SW wind around 10 mph becoming north on Thursday night.
Precipitation - 20% chance of a shower or thunderstorm before noon with skies becoming clear during the day and into Thursday night

Friday - High - 82 Low - 61 Winds - Calm wind becoming a north wind around 5 mph Friday night.
Precipitation - 0% Skies - Clear

Saturday - High - 86 Low - 68 Winds - South wind around 5 mph becoming calm overnight.
Precipitation - 0% Skies - Mostly Sunny

Sunday - High - 90 Low - 71 Winds - SW 5-8 mph
Precipitation - 20% of thunderstorms late Sunday Skies - Partly Cloudy

Forecaster: Zack Leasor

Stormy Start to the Week

Discussion: Scattered thunderstorms continue to move over Southern Kentucky this evening, with the strongest convection occurring to our west in an area outlined by a severe thunderstorm watch. This shower and storm activity will weaken as it slides east overnight with scattered showers and thunderstorms continuing into the early morning hours. Weakening instability should keep these storms below severe threshold, but gusty winds and lightning are possible with these storms. As a cold front approaches the area tomorrow, more storms are on tap as the temperature climbs to around 80 degrees. A mid-level jet max over southerm Kentucky will allow storms to become strong to possibly severe on Monday afternoon. The SPC has placed  Warren County in a slight risk for tomorrow with the main threat being damaging winds and hail, but will hold off on upgrading to alert status until the morning as overnight convection and cloud cover Monday morning could stabilize the atmosphere and limit the severe threat. Showers and thunderstorms will come to an end Monday night with lows in the lower to mid 60s. An upper level ridge will move into the area by Tuesday allowing for clear skies and much warmer temperatures to dominate the forecast into Wednesday. Highs on Wednesday will approach 90 degrees. There is a slight chance of thunderstorms again on Wednesday night.

Current SPC Day 2 Outlook for Monday outlining Warren County in a slight risk area.

Days at a Glance:
Monday: High - 80 Low - 62 Winds - SW at 5-10 mph becoming calm overnight.
Precipitation - 70%  Scattered thunderstorms, some possibly strong to severe, especially in afternoon/evening. Storms will end into Monday night Otherwise, expect mostly cloudy skies during the day, with clearing skies overnight.

Tuesday: High - 86 Low - 70 Winds SW at 5-10 mph becoming calm overnight.
Precipitation - 0% Skies- Mostly Sunny

Wednesday: High - 90 Low - 74 Winds SW at 4-8 mph becoming calm overnight.
Precipitation: 20% chance of showers and thunderstorms Wednesday night otherwise expect mostly clear skies, especially during the day.

Forecaster: Zack Leasor

Start with Rain, End with Heat.

Days at a Glance:
Thursday: High - 80  Low - 65  Winds - S switching to WNW near midnight Friday at 6-8 mph  Precipitation - 60% scattered showers diminishing into the afternoon  Skies - overcast becoming partly to mostly cloudy into the evening and overnight hours

Friday: High - 79  Low - 61  Winds - WNW at 6-7 mph  Precipitation - 10% isolated showers before noon  Skies - mostly cloudy with peaks of sunshine emerging more into the afternoon

Saturday:  High - 77  Low - 56  Winds - W switching to SW near midnight Sunday at 6-7 mph  Precipitation - 0%  Skies - mostly sunny

Sunday: High - 84  Low - 63  Winds - SSW at 10-12 mph  Precipitation - 10% pop up showers late afternoon and into the early evening  Skies - partly cloudy with clouds increasing into the evening

Discussion:
Showers today in south-central Kentucky were less intense and much more isolated than advertised. Bowling Green could still receive overnight showers with totals under .10-.20 of an inch expected. This threat will continue into tomorrow morning as a weakening cold front slides through before drastically diminishing into the afternoon hours. Overall rainfall accumulations will likely be under half of an inch with .25 as the base estimate.

Weather Prediction Center's 6 Hour Probabilistic Forecast for Thursday from 7 am - 1 pm for rainfall accumulations greater that .25 of an inch. Notice the general band of greater than 40% probability spanning SW to NE over our area that denotes the cold frontal boundary. 

Showers will again be scattered in coverage and light to moderate intensity. Clouds and the last few sprinkles of rain will clear out by noon on Friday with morning totals only reaching a few hundredths of an inch at best. Friday afternoon and Saturday are looking pleasant and will be a nice relief from the approaching summer-like conditions as the heat and humidity makes a return on Sunday.  

Forecaster: Austin Boys

Quiet Weather to Start the Week

Days at a Glance:
Monday: High - 80  Low - 57  Precipitation - 0%  Winds - N at 6 mph  Skies - mostly cloudy clearing throughout the day

Tuesday: High - 84  Low - 56  Precipitation - 0%  Winds - N switching to ESE at 6 mph  Skies - clear with clouds increasing into the evening and overnight hours

Wednesday: High - 85  Low - 62  Precipitation - 60% scattered showers into the evening  Winds - SSE at 6 mph  Skies - mostly cloudy becoming overcast into the afternoon and evening

Discussion:
As the lingering clouds clear out of the area tonight into tomorrow morning, sunny skies and warming temperatures will prevail before a subtle but tricky disturbance enters the area on Wednesday. Models are not in complete agreement on the timing or amounts but offer potential rainfall accumulations between .25 and .50 of an inch from Wednesday evening into Thursday before midday. This is associated with a weakening cold front that will become stationary over the area Wednesday into Thursday. This will offer nice surface convergence despite insignificant support aloft for increasing surface moisture from the Gulf of Mexico.

NAM 06/06 03Z (10 pm Wednesday night) Composite Reflectivity. Notice the precipitation along the frontal boundary spanning from northern Kentucky SW over our area into northern Louisiana.

As a result, scattered light to moderate showers as seen in the image above will be the main concern since minimal wind shear will prevent significant storm organization. 

Forecaster: Austin Boys