May Flowers or May Showers?

The outlook for April worked out great.  Highs in the 50s and 60s were common most days, and it turned out to be a wet month.  Let me give a few thoughts about May.  They say April showers bring May flowers but for 2013 we’re probably just looking at more showers.

 

The weather for Derby weekend is looking iffy.  On one hand you’ve got the GFS model which tries to hold a cut-off low out in Missouri and that would mean showers and storms staying just west of I-65 through Saturday.  On the other hand you’ve got the ECMWF model bringing the low closer to Kentucky and the resulting rain moves into our area for Saturday.  Both models are pretty similar, but in this case 100 miles is going to make the difference.  It’s going to be a very tough forecast.  Will the Kentucky Derby run in the rain or on a dry track?  That is anyone’s guess.  These pesky cut-off low pressure systems spin over an area for days on end and really wreak havoc with everything.  One thing that’s pretty sure is that the weather will be unsettled this weekend with chances for rain through at least Monday.

 

As we head into mid-May, signs are pointing to more upper level blocking occurring in Canada.  Unfortunately this means a continuation of northerly flow and cooler air.  It looks to me like the weather we’ve seen in April will carry us into most of May as well.  We normally start seeing a big warm-up in May with days in the 80s being common.  I don’t think that’s going to be the norm this year.  I think a generally cool and wet pattern is going to rule the month.  Those who enjoy outdoor activities won’t be very excited about that forecast, but agricultural interests should be happy for frequent rainfall and mild temperatures.  This may turn out to be a pretty good growing season.  The bottom line is that we’re going to have to hang onto the jackets a little longer than usual this year.

 

 

 

 

Shawn

 

Kentucky Derby Forecast

Well, we are now a week away from KY Oaks and KY Derby action in Louisville, Kentucky.  Let’s take a look at what the weather may have in store…because the weather is everything for this event.

 

For the past couple of days, the GFS model has been consistent in showing an upper air pattern developing by Thursday that would create a lot of blocking across North America.   This, in turn, would cause a storm system moving through the Ohio Valley sometime around Thursday to put the brakes on and stall out.  We could potentially see a lot of rainfall and possible flooding issues with this system as it moves through on Thursday. 

 

The parent low is then forecast to get caught up in the blocking and become cut-off from the main flow.  Cut-off lows are horrible things…they spin over the area for days on end and bring clouds, showers, and generally nasty weather.  It is unfortunately starting to appear that this is exactly what’s going to happen next weekend.

 

Check out the brand new GFS run hot off the press.  It shows the cold backlash of air coming in on Friday behind the cold front, the day of KY Oaks action, with high temperatures topping out in the 40s!  Yuck!

 

 

 

As the low becomes cut-off from the main flow, it will spin over the area throughout the Derby weekend.  Here is the GFS forecast for Saturday evening.  Notice that we’re in the 40s for a high on Saturday as well, with WET conditions area-wide.

 

 

 

For the thousands of fans planning to attend this year, the weather forecast is a nightmare.  For the jockeys and horses entering the races, it’s not much better.  We haven’t seen frozen precipitation on Derby Day since 1989.  This year there is a much better than average chance that we could put some frozen precip. on the board for Derby Day.

 

I will continue to watch this forecast evolve over the next few days, but for now you can plan on the Kentucky Derby weather being down right AWFUL this year.

 

 

-Shawn

 

Tornadoes Possible in Kentucky

Good afternoon.  A severe weather outbreak is occurring now and will continue to get worse as we head into the evening hours.  A powerful cold front is running into a warm and moist airmass in the Ohio Valley and wind parameters are favorable for bowing structures and tornado spin-ups inside the squall line.  It appears that this squall line will move across the area this evening and tonight and we will probably see damage along its path.  The current model data is pretty impressive looking with this line later today.

 

Here is the current outlook from the Storm Prediction Center.   Notice that areas west of I-65 are in the Moderate Risk zone.

 

 

 

Based upon the latest computer model data here is what I think will happen..

 

Areas out to our west around Paducah, KY will see the greatest chance of severe weather.  Western Kentucky will begin to be affected by the squall line as early as 18:00 tonight.  As the line moves eastward, it should reach the Elizabethtown area by around 22:00 tonight.  I think that it will maintain its severe nature as it moves eastward, and based upon forecast soundings I would say that a few tornadoes will occur with this activity.  Wind damage will be fairly widespread out in western KY, southern IN, and western TN.  By midnight (0:00EDT Friday) the line will advance into the Bluegrass of Kentucky and by this time it will be in a weakening phase.  All of the major computer models drastically decrease the severity of the squall line by the time it reaches the Lexington, KY area just after midnight.

 

There will still be isolated wind damage reports in central and eastern KY…but by far the worst of this storm will occur in western KY.  The rain shield will move across central KY Friday and should clear the area by noon on Friday.  It may be that flooding issues will be the worst part of this storm for the Bluegrass and also eastern KY.  Remember…flash flooding is the #1 killer of severe weather!

 

If I lived west of I-65 I would take the time now to prepare for possible tornadoes and wind damage.  Have a plan ready for your family in case you take a direct hit.  Remember to keep a NOAA weather radio on alert mode to keep you updated on the latest warnings.

 

Here is a graphic from the NWS office in Louisville, KY showing their forecast timing on when this line of storms should move into your area.

 

 

 

I will update via Twitter for the remainder of the afternoon and evening.  @WxinKY

 

 

-Shawn

More Storms Coming

Looks like another round of storms this afternoon.  The HI-Res NAM wants to blow the area up again, the visible sat. channel is showing good sunshine along I-65, and SPC is monitoring for a possible watch and upgrade back to Slight Risk for us.  I’d say in a couple more hours we’ll see round 2 pop off in this soupy airmass with dewpoints in the 60s.  All kinds of outflow boundaries are left behind also.  Pretty textbook environment for more activity here today.

 

Question will be how far north and east of I-65 will it occur.  We’re still socked into left over cloudiness from this morning’s convection here in Frankfort.  Might be a close call for Frankfort and Lawrenceburg.  Right now I think that areas along and west of I-65 will see the best coverage of storms.  The Bluegrass counties in and around Lexington may possibly see storms drift into the area from the southwest this afternoon, or if we see enough clearing we could possibly get new convection to form here.  Any storms that do form will be capable of large hail once again, because the air aloft is very cold at a low altitude. 

 

Keep your eyes peeled this afternoon and evening. 

 

The thinking for Friday at this point is that the squall line will be severe in western Kentucky Thursday night, but will be in a weakening phase on Friday morning when it rolls into the Lexington area.  Strong storms likely…but severe weather and damage isn’t looking like a sure bet here in central KY at this point.

 

Here’s an image courtesy of my friend Brian Goode at WAVE-TV from last night’s hailstorm near Louisville.  I can assure you that the people under the storm were not smiling.  J

 

 

Shawn

 

Severe Weather Possible in Kentucky Thursday

Update 2 (10-April-2013 8:04EDT):  SPC has now upgraded most of Kentucky to the 30% risk zone for severe storms tonight and into Thursday.  Today, most of the damaging activity will be along and just west of the MS river.  Tonight and Thursday, this activity will spread eastward into Kentucky and Tennessee.  Here is the current outlook for Thursday:

Also, I wanted to show you the current upper air sounding from southern Ohio (this is the closest sounding to the Bluegrass region).  A few things to note here.  The freezing level is at only 11,000 ft. or so.  Wet bulb zero heights are only around 9,000 ft.  This means that large, damaging hail will be likely with these storms.  Keep that in mind if you plan to be out in an automobile.  Also, notice how the wind direction at the low levels is out of the southwest?  But you go 15,000 ft. up in altitude and now the winds are strong out of the west.  This is a classic, although not perfect, wind shear profile.  This means that TORNADOES will be a good possibility with the strongest storms.

In addition to all this, winds will be very strong today ahead of the front and this may blow around trash cans and lawn furniture.  Then after dark tonight all eyes will be on this system as it marches across Kentucky.

I urge everyone to keep the NOAA weather radios on and ready to alert you.  Have a plan of action ready to go for your family.  Spring is here and business is about to pick up.




Update:  The Day 2 convective outlook makes it pretty clear that SPC is expecting damaging weather to approach the MS river valley and into western Kentucky tomorrow evening.  This squall line will then transition into central Kentucky during the day Thursday, per the latest model data, and will be weakening as it does so.

I think that at this point, strong thundershowers with isolated damage reports will be found in the Bluegrass area of Kentucky on Thursday, but this does not appear to be a massive and widespread event for us.  To our west is where the heavy duty action will be this go-around.  Don't let your guard down, however.  Keep those NOAA radios on and ready to alert you.

More info. coming with the 12Z model runs later today.

Previous discussion:

Well, we finally came out of that brutal March filled with nothing but winter weather and we are now into Spring for certain.  As I mentioned in my April outlook, however, this warm-up is going to come at a price.  Severe weather will start forming more frequently now and the first real episode looks to occur Wednesday and Thursday of this week.

I will have more details later, but for now it appears that the middle MS river valley and possibly back into the Plains will see a pretty healthy outbreak of storms tomorrow and on Wednesday.  Many of these will become severe and cause damage.  As the system moves east it will likely bring a squall line through Kentucky on Thursday.  There is a possibility that some of the activity that affects our area could be on the strong to severe side as well, but differences in the model data are preventing me from saying for certain what we can expect at this time.  The upper jet support is there, moisture is there, and the front looks to take on a neutral tilt…but instability is going to be the question.  Time of day will make all the difference.

For now, bear in mind that Thursday could be a dangerous day in this part of the world and plan accordingly if you are going to be outdoors.  I’ll update with more specific information once we get one or two more model runs of data to look at.

Shawn