Sandy to Treat us with Sunny Skies but Trick us with High Winds!

After an exceptionally warm week last week, colder air made a return to the Commonwealth Friday and the colder temperatures and clouds stuck around for much of the weekend.  The cold front that ushered in the colder weather weakened as it moved to our east thanks to a very strong low pressure system moving up the east coast named Hurricane Sandy.  Speaking of Hurricane Sandy, this tropical system will quickly become extra-tropical as it gets absorbed into a negatively tilted trough that currently extends from southwest Ontario down into Kentucky.  The system is expected to make landfall somewhere along the New Jersey shoreline Monday evening and wreak havoc on much of the northeast and mid-Atlantic states.  Any impacts for us here in south-central Kentucky??  Despite what you may initially think, our weather for much of this week will actually be controlled by post-tropical cyclone Sandy, but will she bring us a trick or a treat?  The biggest impact on Warren Co will be blustery winds.  Winds will likely be sustained between 20-25 mph on Monday and between 25-30 mph on Tuesday; winds could gust between 35-40 mph.

NAM sea-level pressure and surface wind (in kts) forecast for mid-day Tuesday.
Winds will be as high as 25-30 mph with gusts up to 40 mph on Tuesday!

Sandy will also force the trough to stay put and thus we here in Kentucky will remain fairly cool.  Overall, low temperatures will fall into the 30s while highs will only be reaching into the low to mid 50s.  Skies should stay predominately clear however, as south-central Kentucky will be located in an area of dry air throughout most of the week. Occasionally some high clouds may move in from the east off of Sandy, though the clouds should stay mainly to the east of I-65. Glancing into the later part of the week for us here in central KY, no rainfall is expected and a gradual warm-up should occur as the trough begins to break down.

Daily Forecast:

Monday: Low: 32  High: 54  Sunny skies and windy.  Winds will be from the northwest increasing from around 8 mph early to between 20-25 mph in the afternoon.

Tuesday: Low: 38  High: 57  Mostly Sunny with occasional high clouds.  Windy!  Winds will be from the northwest between 25-30 mph and winds could gust between 35-40 mph.

Wednesday (Halloween): Low: 31  High: 56  A beautiful sunny day and not as windy.  West winds between 12-16 mph.

Thursday: Low: 35  High: 58  A few clouds are possible early before becoming mostly sunny.  West-northwest winds between 8-12 mph.

Forecaster: Ryan Difani

Cold Blast This Weekend

The past couple of days have been pretty boring, but a great chance to enjoy the beautiful leaves and sunshine. The upper level ridge allowing this persistent pattern will begin to break down tomorrow into Friday. A deepening trough from the west is approaching our area bringing strong winds aloft beginning early Friday into the weekend. The pesky ridge is looking to block the main flow of wind to just north of the area. This will reduce the amount of lift over our area. With the surface ridge over our area this past week, the moisture values are less than spectacular. Moisture inflow is shown to be relevant Thursday night into Friday as the surface high finally scoots east. This isn't too promising since the front is depicted by the NAM and GFS to roll through the area early Friday. There is some discrepancy with the frontal passage though. The mention of upper air blocking earlier makes me think the frontal movement will slow down as time progresses, which is supported by the SREF model. This is coupled with the surface low moving to the far north into Canada's Hudson Bay. Considering these facts and how it will occur in the morning, indicating a lower temperature gradient, the front should still have enough steam to pass our area. The timing is the issue.

Everything in consideration, I'm predicting an early afternoon frontal passage. Therefore, high temperatures will not reach as high as today or tomorrow. The amount of precipitation is in question. The models are not showing a high probability of precipitation thanks to the diminishing lift and lack of moisture in our area. The front will bring cooler temperatures, but its intensity will be weakening.

The GFS 10/24 18Z run valid Friday 10/26 at 15Z. It supports both the precipitation and timing predicted for our area.

After the frontal passage, cold air will filter into the region. Lows Friday are looking to drop to the lower 40's to upper 30's. Highs on Saturday and Sunday will hover in the 50's, while the lows hang in the 30's. Clouds will clear out after the frontal passage Friday as a high pressure settles into our area for the weekend.

Highlights:    High     Low      Precipitation
Thursday:     81         62               0.0
Friday:         72         41                0.1
Saturday:     54         31                0.0
Sunday:       59          37               0.0

Forecaster: Austin Boys

Stubborn High Pressure

Current conditions have Bowling Green under the dominance of a surface high pressure system. As Chris stated in the previous forecast, it will linger around through the middle of the week. There is an upper level ridge situated over the central US preventing the influence of any disturbances into our area. This looks to change into Thursday as the ridge begins to break down. The surface high pressure is then depicted by both the NAM and GFS to progress eastward.

The SPC Mesoscale Analysis 850 mb temperatures, dewpoints above 50 degrees F, and heights valid 11pm 10/21. The moisture axis across the central US is clearly visible, as well as the high pressure shielding our area.

Our start to the week is not a complete snooze. The picture above shows the strong moisture axis stretching from the Texas Gulf coast into eastern Oklahoma northeastward into Missouri, Iowa, and Illinois. This inflow of warming temperatures and higher moisture values looks to continue across that area into the middle of the week. This is significant because there is a low pressure system shown to develop along a stalled cold front boundary in the Great Plains. Models depict the associated warm front to extend across the lower Great Lakes eastward starting tomorrow into Wednesday. The low pressure system is not shown to progress eastward but to the north since our area will be shielded by the persistent dome of high pressure, leaving us with little chance of rain.

With this said, expect a dry and beautiful start to the week. Temperatures will stay consistent with today with a slight warming trend. Highs in the upper 70's and lower 80's and lows in the lower 50's. Get outdoors and enjoy the weather, or lack thereof.

Forecaster: Austin Boys

Weekend update...

The last shortwave along the back side of the upper level cut-off low over the upper Midwest was over central Illinois and Indiana earlier this morning and has continued to dive southward towards Cincinnati.  In return, cloud cover has continued into the afternoon hours and will hang tough into the early evening.  As the low continues its slow progression northeastward, conditions across the Commonwealth will begin to clear from west to east.

Visible Satellite produced and provided by simuawips valid for Saturday 18Z.

By tonight, skies will be mostly clear as the surface high pressure moves into our area.  In return cool overnight lows will be anticipated as temperatures drop into the upper 30's to around 40 degrees.  As we look to wrap up the weekend, Sunday appears to be a start of a very nice stretch of fall time weather for the Bluegrass.  The stubborn ridge will hang tough over the region bringing sunny and warmer conditions over the next few days.  In general, highs should remain in the low to mid 70's with overnight lows in the 50's with sunny conditions.

Forecaster: Chris Johnson

Showers and storms set to impact the area tonight....

Warmer conditions have flooded much of the region for the past couple of days as highs have gradually warmed into the low to mid 70's across the area.  Mostly sunny conditions have ruled the skies for Wednesday as those fall time colors have begin to really show across the area.  We wrapped up the weekend on a wet and windy note as a system worked its way though the region bringing showers and very windy conditions.  The front eventually tracked its way through the state and pushed eastward as a ridge of high pressure begin to build over Central Plains and into the Ohio Valley by Monday.  In return, pleasant and cooler conditions returned to the Bluegrass to kick off the week. 

We now turn our attention towards a similar set up that we had this past Sunday.  The 250 mb heights and winds map shows an upper level cut-off trough slowly tracking eastward over the Dakota's.  Jet streaks have been very strong with upper level winds reaching 100-120 knots over parts of the Central Plains as the trough continues to dig.    

250 mb Heights and Winds map valid for 06Z Thursday.

The trough will continue its progression eastward and in return drape a cold front from parts of Minnesota down into Missouri and Oklahoma.  Similar to the last set up we had on Sunday, the lack of instability seems to be the main problem with the development of widespread severe storms.  Surface-500 mb bulk shear map shows strong mid-level winds over the Central Plains ranging from 50-80 knots.  At 700mb the atmosphere continues to show a saturated upper level which is important for the development of these showers and storms.  Surface dewpoints lack a bit but range from 50-60 degrees as precipitable water values range from 1.1-1.5 inches over parts of western and south-central KY.  The SPC's latest outlook outlines the possibility for severe weather over parts of the Central Plains as those areas are under a SLIGHT risk for severe storms this evening.  The risk also includes far Western Ky counties as well as the line of showers and storms could potentially affect those areas as the front continues to slide eastward.  

SPC's latest outlook map showing a SLIGHT risk for severe weather.

Storms that do develop over parts of Missouri, Arkansas, and Louisiana will develop and track eastward ahead of the front. With the lack of instability over our area, the storms are expected to weaken considerably as they approach lesser amounts of instability.  Nonetheless, given the strong wind fields aloft, some of the convection overnight could pose a wind threat as these storms may be able to transfer some of that higher momentum air down to the surface.  These storms will have a decent amount of moisture to work with as QPF amounts range from 0.5-1.0 inches for the area.  In addition to the showers and storms, the pressure gradient will tighten up over the region bringing south to southwest winds across the area around 15-25 mph with gust up to 35-40 mph. The latest HPC forecast gives a good idea of precipitation amounts expected. 

Latest HPC map showing widespread rainfall amounts across the area.

As the system tracks through the Ohio Valley region later tonight, expect mainly windy conditions with light to moderate rain over the area.  Expect lows to drop down in the low 50's under cloudy skies as the chance for showers will loom later tonight and into your Thursday morning.  Look for partly cloudy skies across the area with highs struggling to hit the mid 60's.  Clouds look to hang tough heading into Thursday evening as lows drop into the low to mid 40's with light winds from the south.  By Friday, look for dry conditions to prevail as partly sunny skies are expected.  Highs will be a tad cooler as temperatures struggle to reach the mid 60's with winds from the southwest around 10-20 mph.

Forecaster: Chris Johnson

Sunday Severe Weather Threat Update and Weekend Forecast

Moving into the weekend, we will see a strong shortwave trough continue to advance east over our area. This disturbance will have weakened somewhat upon arrival but will still allow for the development of severe weather across Western Kentucky.

The lacking factor in this set up will be instability. CAPE parameters are lacking looking through the day Sunday with values less than 750 j/kg^-1.  This is likely due to forecast overcast skies Sunday that will inhibit any daytime heating and air mass destabilization. With this in mind, we are looking at a linear squall line even for Western Kentucky with the biggest threats being damaging winds and hail though an isolated squall line tornado is not out of the question. The Storm Prediction Center has placed Bowling Green in the slight risk for Sunday. Taking a look at the probabilistic  outlook, we see Bowling Green in a 15% chance for severe storms Sunday. 

A strengthening pressure gradient out ahead of the system will contribute to a strong low level jet and gusty Sunday. A high wind advisory may need to be issued into the day Sunday. Temperatures will take a dip after the passage of the cold front Sunday night with surface ridging building in behind. 

Sunday Forecast Overview:

High, 75. Low, 56. Gusty winds throughout the day with thunderstorm development in the late afternoon. Main threats high wind and hail. Storm to continue into the night with rain ending in the early hours Monday morning.

Forecaster: Emily Yates

Next Update: 10/14/12

End of the Week Forecast and Look Into Possible Severe Weather this Weekend

We have experienced a cool week here in Warren County with frost advisory most mornings and cools starts to the day. Tonight a Freeze Advisory has been issued by the NWS in Louisville valid until 8 am CDT tomorrow. Tonight, we will have clear skies over the area allowing the temperature to drop lower than previous forecast lows. Overnight, an area of high pressure with slide over the area and move out to the east into Thursday. This will keep our skies mostly clear and morning lows low.

Our next chance for showers and thunderstorms will come Thursday night as another trough axis swings through the upper levels. A merging/splitting pattern of the polar jet and subtropical jet will provide enhanced difluent flow aloft which will provide some upper level support for thunderstorm development. Moisture will again be somewhat limited with northerly winds advecting dry air from a cold air mass over the great lakes and Dakotas over our area. A warm front will move north from the south west and cause and increase in clouds by Thursday night. This will allow us to warm temperatures a few degrees as the warm front passes Friday-Saturday and winds shift from the north west to the south east gradually into Thursday night. 

Looking into the weekend, we see a powerful system develop off the west in the form of a cut off low that develops off the west coast and slowly wobbles our way with fast moving winds circulating through it at the 500 mb and 250 mb levels. This system will drag over the Rockies and develop an associated surface low as it passes over the mountains and into the lower plains. As this system progresses, the low will be reabsorbed into the polar jet flow Saturday night into Sunday as it progresses towards our area. The next forecast update will detail the expectations for this system further.

Forecast Overview: 

Thursday: High, 65. Low, 50. Clouds increasing into the night as another weather system moves in. 30% chance of showers and thunderstorms Thursday night.

Friday: High, 70. Low, 50. Left over precipitation will move out with temps warming back up.

Forecaster: Emily Yates

Next Update: 10/12/12

Weekend Wrap Up and Forecast 10/8-10/10

Temperatures are beginning to become more fall like after a strong cold front and canadian air mass moved through Kentucky over the weekend. Surface high pressure has built in behind with winds remaining out of the north allowing the colder temperatures to continue to be advected into Kentucky.  

Another area of low pressure has begun to develop over the Canadian border. A trough continues to deepen to the west over the Canadian border and propagate to the east into the week bringing more cold temperatures and chance of showers by Tuesday night as another cold front develops and moves east over Kentucky. As with the last Canadian air mass, this one will also be dry which will inhibit precipitation chances. Both NAM and GFS models paint a line of precipitation moving through Wednesday ahead of the front. With a tight band of moisture out ahead of the front, this looks bleak. A few stray showers/sprinkles cannot be ruled out Tuesday night into Wednesday. Frost advisories are likely to remain into the week as cold overnight lows and dew points in the 30's combine. 

Forecast Overview:
Monday 10/8: High, 62. Low, 39 . 10% chance of precipitation, morning frost likely. Winds chilly out of the north.

Tuesday 10/9: High, 68. Low, 43. 20% chance of precipitation, morning frost likely. Front approaching overnight Tuesday with colder temperatures filtering in behind. Winds will remain northerly. 

Wednesday 10/10: High, 63. Low, 39 . Front passes through with colder temperatures in behind. Morning frost likely. Temperatures drop further with passage of front. Winds chilly and out of the north. 

FORECASTER: Emily YatesNEXT UPDATE: 8/10/12

Strong Cold Front Moving Through: Rain & Cold Temperatures!

A strong cold front has provided cold enough temperatures to bring the first snow of the season to areas from North Dakota to Minnesota this morning (Thursday). While snow will not be making an early arrival to Kentucky, that very strong cold front will come through the state Friday evening that will lead to much cooler temperatures by Saturday.  After rain early in the week, yesterday was a nice fall day as will be today but it is tomorrow when the affects of the front will begin to impact the area.  Though tomorrow should start out a nice day with temperatures rising to near 80 clouds will be moving in during the afternoon and especially into the evening as the front approaches.  Models agree that the front should come through south-central Kentucky between 6 and 10 pm bringing with it 8-10 mph winds out of the north which will bring in much cooler temperatures.  Below is a video of the NAM model forecast temperatures/winds/pressure from 1 pm Friday though 6 am Saturday.  Notice the much colder temperatures moving in behind the front.

Some light rain will also likely make it's way in behind the front late Friday night into Saturday morning. Rainfall should remain fairly light but some the area could pick up about a quarter of an inch.  Don't expect things to clear out Saturday however as an upper-level disturbance will make its way across the central US which will provide enough lift to create showers from Saturday evening into Sunday morning.  Also with the cold air mass firmly in place along with cloudy skies, highs likely won't climb out of the 50s Saturday. Rainfall  Saturday night should once again only total between a 0.05 to a 0.20.

The Hydrometeorological Prediction Center's rainfall forecast through Sunday morning indicates between 0.25 and 0.5 inches of rainfall totaled from both rounds of rain in south-central Kentucky.

High pressure will work its way in on Sunday pushing out any rain and most of the clouds making for a much nicer day despite cool temperatures.  Temperatures Sunday will start out in the low 40s and will only warm to highs in the mid 50s, talk about a fall like day.  Looking toward Monday morning, south central Kentucky will likely see the coldest start to the day in months as temperatures could dip into the low to mid 30s.

Daily Forecasts:

Today: Mostly sunny skies with a high near 80 with southwest winds from 5-10 mph.

Friday: Low near 55 in the morning and a high around 82.  Skies will be mostly sunny early but clouds will increase throughout the day.  West-southwest winds from 6-12 mph.  The cold front should push through sometime after 5 p.m. bringing cool north winds from 8-10 mph.  70% chance of showers after 6 pm into the overnight.

Saturday: Cloudy skies with a 40% chance of showers lingering in the morning.  Low near 47 with a high only in the upper 50s near 58.  60% chance of showers after 6 pm and into the overnight.  Northerly winds from 5-10 mph.

Sunday: Mostly cloudy skies early with a low around 42 will give way to a partly sunny day with a high only around 55.

Forecaster: Ryan Difani