Wintery Weather To Close Out the Week?

Currently, we're feeling the shock of Old Man Winter once again as 18 mph NW winds cut to the bone bringing in the much dreaded colder air. Temperatures will continue to drop tonight into the upper 20's, but will feel colder with the persistent winds in the morning. We will see temperatures into the mid 40's tomorrow under mostly cloudy skies. Tomorrow night represents one of the two bugaboos for this forecast. A weak front will move through the area in the early evening hours, providing some surface lift. With the dry, cold air already in place, there will be hardly any moisture to work with. The issue is that the temperature will be hovering around freezing at the time of and after passage. Models are indicating close to a trace of light to moderate precipitation, but closer inspection will have to be made into tomorrow as far as how much and precipitation type.

GFS 03Z (9 pm) 2/1/13 6 hr accumulated precipitation (in.) Notice our area is projected for a trace (.01 in) of precipitation over a six hour span. Very light precipitation expected.

After the frontal passage, winds will be slackening, skies will be clearing, and temperatures will be plummeting into the mid to upper teens for Friday morning. The high temperature for Friday will struggle to get over 30 as skies remain clear and winds will be low. Friday night lows will dip into the mid 20's, but will hold steady and slightly warmer after midnight. Warming will continue into Saturday afternoon with highs in the low to mid 40's. Right now, models are depicting a frontal disturbance crossing the area in the afternoon, but have not come together for a definite time. Simulated radar returns are suggesting early morning precipitation, but most of the moisture inflow, although small, will be occurring into the afternoon. As of now, I am trending towards an afternoon passage, hence, afternoon precipitation. Most of the heavier precipitation is projected to stay just to our south and southwest. We will have to closely examine this feature closer to Saturday in hopes to nail down the magnitude of moisture inflow, timing, and strength of this front. Precipitation is a real possibility, and considering these factors will help to distinguish type and amounts. Saturday night will have temperatures dipping into the mid 20's while Sunday is looking nice with high's nearing 40 degrees.

Days at a glance:

Thursday: High: 40  Low: 27  Winds: 14-18 mph W switching to 11-14 mph NW around 9 pm  Precip: 70% chance with type to be determined

Friday: High: 28  Low 16  Winds: 8-12 mph NW switching to W near noon  Precip: 0%

Saturday: High: 41  Low: 25  Winds: 13-17 mph SW switching to 8-11 mph WNW into evening  Precip: 80% chance with type to determined

Sunday: High: 41  Low: 26  Winds: 11-14 mph WNW  Precip: 0%

Forecaster: Austin Boys

Strong Cold Front Wednesday Morning

As the title insinuates, this week is looking like a tale of two halves regarding temperature. The first half of the week will help to shake off the shivers that were gained from last week's cold spell as temperatures climb into the mid to upper 50's on Monday and mid to upper 60's for Tuesday and early Wednesday. Get out and enjoy the warm, but a mostly cloudy few days. Light rain showers may affect us Monday night into Tuesday morning due to a warm front to our north across central Illinois and Indiana. All in all, this substantial warming is preceding a rude awakening for Wednesday morning.

NAM 15Z (9 AM) 1/30/13 showing winds (kt), temperature (deg F), and mean sea level pressure (mb). Notice the wind change and stark temperature boundary over south-central Kentucky marking the cold frontal boundary.

A line of storms associated with a strong cold front will quickly push its way through our area around 9 am. Precipitation should be relatively brief, but intense with amounts for Bowling Green likely to be .75 to 1 inch in total. Along with heavy precipitation, damaging winds will be a key hazard associated with the strong temperature gradient as the front passes our area. After the frontal passage, expect the rain to stop after lunch with a quick cool down Wednesday night as temperatures drop back below freezing for Thursday morning. The rest of the week will stay on the cool side with a mid-week update to cover the details.

Days at a glance:

Monday: High: 58  Low: 43  Precip: 10% rain showers late night  Winds: S 12-17 mph

Tuesday: High: 68  Low: 53  Precip: 10% rain showers early morning  Winds: S 17-23 mph

Wednesday: High: 60  Low: 33 Precip: 100% chance of heavy rain around 9 am  Winds: S 23-29 mph then switching to WNW decreasing to 5-6 mph throughout the day

Forecaster: Austin Boys

Ice This Morning!

Update (12:57 am): Precipitation has come completely to an end across the area and temperatures are rising above freezing. As of 11:55 it was sitting right at the 32 at the Bowling Green-Warren County airport, meanwhile mesonet sites across the area range from 31-32. We are also seeing a good amount of sunlight penetrate the clouds.  All of these factors are suggesting that the melting process is taking place.  This of course was not before a good amount of ice this morning with 0.10-0.20 of ice accrection. This caused numerous wrecks across southern Kentucky, some of the worst of which have been on I-65 between Bowling Green and E-town; as of this time the interstate was still reportedly blocked.  Temperatures will not get too warm today however as we'll likely only reach a high around 35-36 by this afternoon.  Temperatures will fall back below freezing sometime after 6 pm and thus any residual moisture may freeze again this evening and overnight and thus caution should still be used through tomorrow morning.  Lows tonight will fall to around 23 and we'll rebound to a high tomorrow near 38 under partly to mostly sunny skies.  Below are a couple of my favorite pictures that I took while walking around the Western Kentucky campus.

Ice can be seen on Normal Drive in Bowling Green.

A glaze of ice can be seen on this car parked at WKU.

A glaze of ice can be seen in the trees on campus. You can see that we picked up  between 0.1-0.2 inches of ice.

Update (8:27 am): Freezing rain is coming to an end across the county and across much of south-central Kentucky. Generally around a tenth to 2 tenths of an inch of ice has accumulated.  Roads are slick! As already stated there have been numerous accidents this morning so staying off the roads until midday when the temperatures are warmer is advised.  Just because this precipitation is ending does not mean that the roads aren't still slick.  Until temperatures rise above freezing, which is expected between 10-12 am, icy patches will be found on roads, sidewalks, etc...  The temperature is expected to rise to around 36 degrees today.

Update: An Ice Storm Warning has been issued for Warren Co and the surrounding counties until 1 pm CST. Details: http://forecast.weather.gov/showsigwx.php?warnzone=KYZ071&warncounty=KYC227&firewxzone=KYZ071&local_place1=&product1=Ice+Storm+Warning

I just wanted to do a quick update this morning.  As most know freezing rain is occurring across most of south-central KY including here in Warren Co just as we expected.  Temperatures have been holding steady in the upper 20s.  Numerous accidents have been reported including on I-65 and the Western Kentucky Parkway... roads are slick! This freezing rain is still expected to continue through around 9 am before precipitation will tapper off from west to east. Several bursts of freezing rain will move through between now and then however.  Most of the county will see 0.10-0.20 inches of ice by then.  Temperatures are still expected to warm above by noon so any lingering precipitation will not freeze and any accumulated ice can melt. If you must travel, use extreme caution.

Forecaster: Ryan Difani

Winter Storm Update

Currently an upper level trough is located over Manitoba with a jet max stretching from Minnesota down to northern Indiana and southwestern Michigan.  An upper level ridge axis stretches from Mexico up into Canada.  A vorticity maximum associated with the upper level trough.  Through time, the vorticity increases prolonging the life of the trough.  Moisture values associated with the trough are high with a narrow band of moisture influence coming from the Pacific ocean and wrapping around the ridge, then getting pulled into the trough.  This will help to set the stage for winter weather Thursday night into Friday morning.                                           

700mb Relative Humidity Map

The current temperature in Bowling Green is 38 with winds out of the west at 6 mph with partly cloudy skies. The temperature this evening will get down to 35, therefore be prepared if you have to go outside.  Surface low pressure is located over Canada at the North Dakota border, with the surface high pressure located over the Florida panhandle.  The low will move to the southeast tomorrow bringing cold air and the effects will be felt in the morning.  Tomorrow morning we will start out with a temperature of 31, and the temperature will drop throughout the day.  Winds will be out of the north causing the temperature to feel colder. 

The winter weather set up as it stands at this hour appears to be a freezing rain event, so keep the snow shovels packed away.  The precipitation could start out as sleet/snow then changing over to freezing rain.  The key to this set up is timing and the amount of moisture.  The timing of this event is varying with the models, however, late Thursday night into Friday morning during morning commute is highly likely.  The temperature Friday morning will be 31, which gives way to possible travel problems Friday morning.  We will continue to monitor this situation and will have the latest updates on this Winter Weather situation.

Forecaster:  Tyler Binkley

            

Gonna be a Cold One!

Currently there is a jet max over Canada stretching down to South Dakota which will propagate through the jet stream causing the trough, which is located over Manitoba, to dig.  A surface high pressure is located over the northeastern corner of Montana and northwestern North Dakota which will bring with it colder temperatures Tuesday and Tuesday night.  Relative humidity is 30% which indicates the dry air over the area indicating few clouds for tonight and tomorrow.  Winds are currently out of the northwest at 17 mph making the current temperature of 27 degrees Fahrenheit feel like 19.  For tomorrow, surface high pressure will be dominating the area, winds out of the northwest at 11 mph with a morning low of 15 with a wind chill at 8.  The high for tomorrow will be 26 with the wind chill making it feel like 10.  Be sure to grab your coat and mittens, but keep the snow shoes packed up for now.  The high pressure will move out of the area and by Thursday a low pressure system will move into the area bringing a wintry mix precipitation by Thursday night.  More on this later in the week. 

Wednesday:  High 43  Low 14

Thursday:  High 37  Low 23

Morning temperatures for Tuesday, January 22, 2013.

Forecaster:  Tyler Binkley

Winter Weather Recap and End of the Week Forecast

Recap of Last Night:
The forecast for last nights winter weather event was somewhat a challenge at times. A change in degree here or there really can mean the difference between an ice storm and rain. Last night, Bowling Green temperatures reached freezing later into the event. We saw some icing on elevated surfaces such as signs, hand rails, and car tops but nothing substantial. Areas as close as one county over in Butler County received more significant icing. The location of the freezing line (line of change over from rain to mixed wintry precipitation) was the saving grace for Warren County last night. This line stayed mostly off to our west which meant that most of our precipitation changed over to rain with only a short period of some freezing rain and sleet for parts of far western and northwestern Warren county.

Image taken from Tempestchasing.com. A great depiction of the location of last nights freezing line at 6 pm CST.


The most icing reported from downtown BG was only a thin coating on hand rails, car tops, and street signs. The trees and bushes in my area remained rain coated with no visible icing. While not as favorable for pictures sake, a huge near miss in the way of headache and danger.

Forecast Discussion for 1/17-1/20:

A strong upper level low located over Texas, Arkansas, Louisiana looks to advance northeast over Mississippi and Tennessee Valleys throughout the day Thursday. A surface low is forecast to begin development Thursday morning and become more organized over the border of Georgia and South Carolina by 18z (12 pm CST). This surface low will then advance northeast along the Carolinas. Far eastern Kentucky will remain on the cold side of this low (where colder air is the dominate advection). This will provide a chance for a light wintry mix event to occur in far southeastern Kentucky. 

09z ( 3 am CST) 1000-500 thickness MSLP and precipitation showing surface low development over GA/SC border.

Moisture looks to be sufficient for showers to develop as the low pressure system brings southeasterly winds and gulf moisture up along the cold frontal boundary extending from Florida to the Carolinas into the Atlantic.  HRRR High Resolution Rapid Refresh model shows a broad swath of precipitation from Mississippi to Northern Kentucky throughout the day Thursday. As the surface low develops, the heavier precipitation is shifted northeast as the low advances northeast.

24 hr forecast snow fall totals ending at 6 pm Thursday (CST). Shows far eastern KY in the 80% range for > 1 in with majority of eastern KY in the 30-75% chance of > 1 in.

Warren County could see a few light rain showers from this but no mixed precipitation is forecast though a few occasional flurries cannot be totally ruled out. Most wintry mix should stay to the east of Warren County. Any showers would be in the early morning clearing out later on in the day. Clouds should recede as well as the low pressure system passes to the east allowing some sunny skies to poke through after lunch time and into the afternoon as surface high pressure moves in behind. Partly sunny skies will be the trend into the weekend as we wait on our next significant weather system into early next week as another upper level trough becomes dug out from a jet max out of Canada. This system will bring the clouds and precipitation back into the Ohio Valley. Once under the influence of surface high pressure, temperatures will be slightly warmer into Friday and the weekend with highs in the mid to upper 40's even reaching the 50's by Saturday as our surface winds become more southwesterly.

NAM forecast surface temperatures for 18z (12 am) Saturday.

Forecast Overview:

Thursday 1/17: High, 43. Low, 24 . Northwesterly winds peaking between 5-10 knots. Slight chance of light morning showers. Clearing for some peak through sunshine into the afternoon with temperatures warming up. Mostly clear and cool night.

Friday 1/18: High, 43. Low, 26. Winds shifting to the southwest during the day. Mostly clear with few clouds. Winds peaking at 3-5 knots. 

Saturday 1/19: High, 50. Low, 32. Mostly clear and sunny and and overall beautiful day!

Sunday 1/20: High, 37. Low, 25. Clouds increasing into afternoon. Winds shifting more southerly. 

Cool Down to Continue Returning to More Seasonable Temperatures

Forecast Update: A Hazardous Weather Outlook for Warren County concerning possible mixed wintery precipitation event later into the evening. Visit NWS Hazardous Outlook for more information. Only small accumulations are expected but roads could become slick and motorists should be cautious of changing road conditions tonight!

 A Flood Warning remains in effect for Drakes Creek near Alvaton. Currently, the creek is at 16.6 feet with it's flood stage being 22 feet. The river is forecast to make it above this stage by Monday morning. The warning includes Butler and Warren Counties. For more information, visit NWS.

NAM current surface temperatures with cold front clearly depicted by strong temperature gradient extending from Maine back through Tennessee and Mississippi Valleys. 

Temperatures across Western Kentucky have taken a dive after the passage of a strong cold frontal boundary this evening. This boundary has also taken all the moisture with it leaving behind very dry cool air pooling in behind. Temperatures in Warren County have dropped around 25 degrees over the past 24 hours. Cold frontal boundary is expected to become stationary again over the Carolinas. Several wave impulses will rotate through at the 700 mb level and help kick off some post frontal showers over western Kentucky Sunday night into Monday drying out into Tuesday night. With temperatures very cold and freezing line nearby, we can expect some light flurries and mixed precipitation at times.

NAM and GFS models are in good agreement with placement of current trough axis over the western United States. The polar and subtropical jets are currently super-imposed upon each other helping to funnel the moisture for our weekend rain event into the Mississippi and Ohio Valleys. Models both show this trough staying semi-stationary and becoming more elongated and digging slightly to form a more organized upper level low. As this low develops it becomes slightly cut off and then becomes reabsorbed into the main flow during the day Wednesday. As the low develops, the subtropical jet again becomes independent of the polar jet as the low becomes absorbed into the polar jet. A zonal flow extends across the continental U.S. Thursday into Friday. This system looks to stay off to our west until the weekend when another cold frontal boundary will develop and push through the region. The rest of the week from Wednesday into Friday look to remain dry with more seasonal type temperatures.

Forecast Overview: 

Monday: High, 35 . Low, 24. Slight chance of morning showers clearing out with showers returning in the evening.

Tuesday: High, 40 . Low, 25. Slight chance of afternoon and evening showers with some mixed precipitation possible.

Wednesday: High, 45. Low, 30. Drying out with clearer conditions.

Forecaster: Emily Yates
Next Update: 1/16/13

Rain Rain, Go Away!

The warm up is here and in progress as we are seeing temperatures throughout the night rise. We could possibly see some records broken this weekend as well! The cutoff low is just to our west in the upper levels. It'll dig out a little first before being reabsorbed into the jet. Winds coming from the south are saturating the air in the 700mb levels of our atmosphere and a warm front on the border of northern Kentucky is bringing in those warm temperatures. The rain tonight will begin to push out late tomorrow morning and become scattered.

Another system is on tap for Saturday. A deepening trough will be working its way to the east and will be dominating our pattern for the remainder of our weekend and into next week. Take a look at the saturated air moving in:

700mb Relative Humidity valid for Saturday afternoon. Notice the saturated air dominating the state of Kentucky.

This is just priming the area for the next system coming through. A cold front will be making its way across the state early Sunday morning. The temperature gradient on this front is decent. I chose this picture (below) because it is easy to see the cold front. Can you see it? Take a look at the wind barbs. Notice the line of the barbs coming from the northwest then just to the east notice the barbs then coming from the south.

Notice the cold front beginning to move through Bowling Green, and the temperature gradients behind it. Almost 30 degree differences within miles.

With this front coming through, rain will follow. Amounts will be high, in the range of 1.5 to 2 inches of water falling in Bowling Green. Expect higher amounts to the west.

HPC rainfall forecast valid for Friday through Sunday. More precipitation the further west one goes.

Severe weather does not seem to be a concern for this system at the moment but we will keep you updated if anything fires up. So what kind of temperatures can we see for this weekend?

Friday:      High 70      Low 57     Record: 68 (1916) - Bowling Green

Saturday:  High 71      Low 56     Record: 73 (1916) -Bowling Green

Sunday:    High 55      Low 33 

So to recap, rain pushing out Friday late morning and becoming scattered. Another round of rain and thunderstorms on Saturday and a slow dragging cold front moving through Sunday morning with heavy rain at times and thunderstorms. Have a great weekend everyone!

Forecaster: Brian Urbancic 

Showers in the Forecast

That's right folks, showers headed our way. In this post I will break down the timing of this system, temperatures we could see this week, and how much rain we can expect in our area. Clear tonight in Bowling Green allowing those temperatures to dip down into the lower 20s this morning, but once that sun comes out look for a rise! We could reach a high of 55 tomorrow.

 But our main weather maker is on Thursday to Friday. By Thursday morning the United States will be under a meridional flow, with a cutoff low beginning to be reabsorbed into the jet to our north. This is the system which will give us this rain (shown below).

300mb NAM Valid for Thursday morning. Notice the active weather pattern across the US. Strong jet on the eastern side of the cutoff denotes a northeasterly movement to be reabsorbed.

So moving down to the 500mb level, we generally look at vorticity values. This indicates energy needed to fuel a storm. Most of the energy with this storm is to our north and moving northeast. This will affect our precipation values. Both models, the GFS and the NAM, are in agreement on the placement on this. The NAM does provide more moisture with this storm though. Both models do show winds from the south, but again the NAM has higher relative humidity values from the Gulf.

700mb NAM model valid for Thursday morning. Notice winds from the south with high relative humidity values in Bowling Green. 

Now the temperatures coming in on Thursday and Friday look interesting. Surging into the mid to possibly upper 60s. Dew points look to be decent for January, as well as decent wind shear. Instability indices look to be low though. So could we see thunder storms? Yes! Will they be severe? Right now it doesn't look so for our area but it could be possible. Expect rain to begin to move into Bowling Green Wednesday night and then scattered Friday morning as the system begins to push out.

Late Wednesday night composite reflectivity. Rain beginning to enter our area. 

So let's discuss amounts! I believe just over an inch is pretty safe to say at this moment. As we get closer, I will fine tune those amounts. Look for another system moving into our area Saturday as a cold front stalls. Expect temperatures to crash Sunday and next week. Could this be the return of old man winter for next week??? Teleconnections look to be on board along with an active pattern. Time will tell.

So to recap, expect sunny skies tomorrow. Rain will move in late Wednesday night and push out Friday morning. Expect a few claps of thunder with this system. Temperatures will surge as the week continues.

Wednesday: High 60     Low 49 

Thursday:    High 65     Low 50

Friday:         High 66     Low 52

Saturday:       High 66     Low 50

Forecaster: Brian Urbancic

Big Changes Coming

Good Sunday afternoon everyone! Hope you all had a restful weekend so now let's dive into some weird wild weather moving into our area in the next few days. Generally quiet in the upper atmosphere with a trough located to our northwest. A weak cold front will be making its way through  this afternoon which will provide us with clouds and slightly cooler temperatures. Out in the western half of the United States a split flow is dominating from the Four Corners region to Arkansas and Missouri. A cutoff low is also taking shape in California and will reabsorb back into the jet later in the week which will be the big weather maker for us this week.

300mb GFS model map valid for 12z for Thursday at 1:00 PM.

 Chances for rain will increase around Thursday and here is why. Notice the image above. The cutoff is moving to the northwest, and beginning to be reabsorbed into the jet. Vorticity values look limited at the 500mb level but plenty of moisture will be moving into the area on Wednesday with this storm. Winds coming from the south will help bring in the Gulf air at the 700mb level (shown below).  This will keep us mostly cloudy on Wednesday, and on Thursday which is when this system will move in.

700mb Moisture map valid for 12z for Thursday at 1:00 PM.

Rain will begin Wednesday night and early Thursday morning. Precipitation will increase throughout Thursday, and finally push out Friday morning. Temperatures will be surging next week around this time. Expect highs into the 60s on Thursday, Friday, and Saturday. Strong temperature gradients on Thursday will keep our chance for thunderstorms in the forecast. No severe weather is expected though.

ECMWF 12z, 850mb temperatures and heights on Friday.

The European weather model, shown above, is in agreement that warm air is coming in but does show a lag in the low pressure moving through. This map shows 850mb temps, and heights. So to recap, expect cool temperatures tomorrow and then a steady warm up through next week. Rain moving in late Wednesday night and pushing out Friday morning. Temperatures next weekend could get up to the mid 60s.


Monday:          High 43     Low 21, Sunny skies

Tuesday:          High 52     Low 26, Sunny skies

Wednesday:     High 53  Low 46, Skies becoming cloudy

Look for another update tomorrow with a better idea of precipitation amounts for this storm and a discussion of our winter weather chances!

Forecaster: Brian Urbancic  














  

Slight Chance of Wintery Precipitation

Currently, we are underneath the left entrance region of a downstream progressing jet streak, which implies convergence aloft and divergence at the surface.  Hence, a surface high pressure is nosing into our region producing westerly and then northerly winds to the south, keeping the Gulf moisture to the south of our area. This is partially why the cold front to our NW is weakening and will remain dry, but will provide slightly cooler air for Friday as it passes the area. A stationary front, marking the moisture boundary, is draped across the coastal southeast showing a broad swath of precipitation from coastal Carolina to southeast Louisiana. This is underneath the right entrance region of the jet streak, which implies divergence aloft. The jet streak will help to lift out the positively tilted trough that has been present throughout the past week. In the process, it will form a cutoff low over the mountain west. Over the Rocky Mountains, there is a split flow to the jet stream, which is converging over the lower Ohio River valley. This will create a more zonal flow until mid to late Saturday when the earlier stated cutoff low will become reabsorbed in the flow, creating divergence over the Ohio River valley. This divergence will be enhanced by the coupling of two jet streaks Saturday afternoon into the evening seen below.

21Z (3 PM) Saturday NAM 250 mb Heights and Wind (kt) over 50 knots. Notice the coupled jet streaks over the central Appalachians and the New England Atlantic coast.

At the surface, the high pressure will move east and quickly break down as a surface low sweeps across the lower Great Lakes, with an expected cold frontal passage around 6 AM Sunday. On Saturday, expect a slight warming trend ahead of the front. This is looking to be the main focus for precipitation for the forecast period, supported by the strongest 700 mb vertical velocity returns. Even so, moisture advection will be very slight and brief before the frontal passage. The significant nose of moisture is staying just south of south-central Kentucky shown below.

00Z (6 PM Saturdy) Sunday GFS 850 mb Mixing Ratio and Wind (vector). Notice the broad, but weak advection of moisture with the major nose only extending into northern Alabama.

The freezing line will be bisecting and to the south of the area, so any precipitation that falls could be mixed or in the form of snow. With the lack of moisture, I will keep the forecast dry. After the cold frontal passage, ridging aloft will take over and a surface high pressure will settle into the area giving way to a warming trend into the next week.

Forecast at a Glance:
Today: High: 41  Low: 21  Precip: 0%  Wind: NW to N at 4-7 mph
Friday: High: 39  Low: 22  Precip: 0%  Wind: NW to W at 6-8 mph
Saturday: High: 45 Low: 28 Precip: 20% chance of mixed Wind: SW at 5-10 mph
Sunday: High: 38  Low: 23 Precip: 30% chance of mixed/snow  Wind: SW at 5-10 mph switching to NW at 10-13 mph then to 4-7 mph late.

Forecaster: Austin Boys