The Aftermath...

What an exciting day on Monday if you were a fan of severe weather. After the SPC issued a tornado watch early in the morning yesterday, severe weather moved out of Arkansas and Missouri into west Kentucky. At first, it looked like the storms were going to weaken and save their energy for the early afternoon. Instead, the 'let's get'er done' mode kicked in, and I mean in a big way. As of this post, 2 tornadoes have been confirmed in Ballard county. Other surveys will be conducted today and most likely another 1 or 2 tornado confirmations will be announced on the NWS home page in Paducah.
In addition, the Louisville NWS will be conducting storm surveys at 5 different areas over the next couple of days.
The SPC did an excellent job of posting a tornado watch box for the area. I seriously questioned the extent of the watch box as I felt many locations should not have been included; rather a severe thunderstorm product would have sufficed. Goes to show 'don't underestimate the numbers'. In addition, although there will only be a handful of possible tornado reports, it looks like most of them occurred in Kentucky and within the designated watch box by the SPC.
And kudos to the NWS offices in Paducah and Louisville for their vigilant reporting and timely issuance of tornado warnings. And many thanks to the local media for their reports and others who gave storm reports and submitted pics/videos of their ordeals.
Now, let's look forward to a bit of quieter weather. After today, temps will start 'springing' higher for the rest of the week. Good thing, I gotta get some yard work done and the grill ready and the garage cleaned out, and...
MS

Countdown to the Severe Round

The countdown is on. But how bad will it really get here, not just locally in Louisville, but regionwide? I hope to provide some input. Don't take my word for it. The numbers that I will be providing come from 'professional' sources. Perhaps my take on the weather outlook may be different than the professionals. But, I'll be looking at the same numbers the pros do. So, here we go.

UPDATE 2:30pm edt
There have been numerous tornado warnings primarily south of the Metro area. Although people may not like me saying this, most if not all of these warnings have been unconfirmed. Nevertheless, all tornado warnings that had been issued were for a good reason: lots of spin in the atmosphere. Any spin could reach the surface at any time. Honestly, I did not think mid to late morning was the best time. I expected the activity to ramp up after 1pm. However, I did expect more tornadic cells closer to the TN border, and Hopkinsville and Paducah are pretty close to that area. I also expected severe weather to be located mostly south and east of Louisville.
Currently, there are power outages in the local area and some trees/downed lines across the area as well. I will update the official NWS wind gust report soon.
Severe storm threat has really shifted more south and east of Louisville now.

UPDATE 12:20pm edt
No tornado warnings in effect as of now.
Still wondering if any of that spin reached the surface near Paducah?
These should still remain isolated at best.
Expect a WATCH to be issued for Louisville and points east soon.
UPDATE 12:15pm edt
61-63 mph winds reported near Paducah
UPDATE 12:00pm edt
No confirmation but possible building collapse near Paducah

UPDATE 11:25am edt
tornado warning for McCracken and Ballard counties in west KY. Radar-indicated. So far, no confirmed tornadoes or much severe storm reports. There is a lot of spin in the upper levels, thanks to the shear environment. But will these storms put down a tornado? Perhaps later, but should be farther south. Watch out for severe robbing cells moving out of AR into MS and TN. Could lessen our chances later. We'll see.
UPDATE 11:10am edt
As of 11:05, only 1 tornado warning out (Union AR). Hopefully, current activity will die down, but expect potential redevelopment later this afternoon

UPDATE 10:35am edt
tornado warning for Sikeston, MO radar-indicated

UPDATE 10:20am edt
Right on cue, as soon as I downplay severe threat, the SPC issues a tornado watch for west KY and points south and southwest. I'm kinda surprised. I expect a few severe storms but not overly optimistic about tornado threat yet...maybe after 1 or 2pm.
Currently, t'storm warning products are in effect for areas to our west.
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Yesterday, my assessment of the severe weather outbreak was pretty accurate. The SPC did a fine job of anticipating the extent and type of severe weather yesterday. Lots of hail reports, few tornadoes. The 'numbers' that I saw supported this type of setup.

Now, what are the numbers telling me??? First, let's keep in mind the storms currently rolling through parts of central Indiana and Missouri will continue to weaken throughout the early morning. Therefore, it will be tough to look at the 'current numbers' and gage how strong the storms will be this afternoon. We will need the instability or be in a process of destabilization for any stronger storms to redevelop. We can use the short term models, since they did a pretty good job of forecasting the severe storms across the midwest yesterday.

The SREF model from the SPC shows instability greatest from Tennessee southward. Percentage that LI's of -4 will occur are greatest from Nashville south. Only a 10% chance for LI's of at least -4 here in Louisville.

Surface based CAPE vals >500 percentage is greatest south of the western KY parkway. Limited somwhat here in Louisville.

0-1km Helicity values do exceed 150, indicative of moisture transport on the heels of strong low level jet.

The question now is: Will the lack of instability here be overcome by the Helicity values that will be in place?
My current thinking is that some strong winds will mix down to the surface with any thunderstorms. Some may approach severe limits (>58 mph). Best chance for this to occur will be south and east of Louisville. I would give Louisville about 10% chance for severe weather (a warning could be issued but actual severe weather not likely). Hail prospects not too high. Tornado threat quite low.

The farther south and east of Louisville, the greater the chances for severe weather. Generally, east of I-65 and south of the western KY parkway stand the best chance for severe weather. Damaging wind will be the main threat.

More updates later this morning...
MS

Severe Weather Watch Sunday report

I'll be adding to this post throughout the day...Here's the latest about our severe weather chances...
UPDATE 10:50pm edt
Roof damage in Topeka from very high winds >70mph est.
http://wibw.mycapture.com/mycapture/photos/FImage.aspx?ImageID=1107140&EventID=731566&CategoryID=48719&CollectionID=0&Sort=

http://wibw.mycapture.com/mycapture/photos/FImage.aspx?ImageID=1107122&EventID=731566&CategoryID=48719&CollectionID=0

Topeka had a high of 92 today. Wow! Temp at 10pm edt is 56.

Dubuque IA - 3-3.5" hail or teacup size
UPDATE 9:30pm edt
Mostly a hail event thus far in IA, KS, and MO; some 2" in diameter
Topeka has had 70-80 mph winds, estimated

UPDATE 9:15pm edt
Storms have been cranking in Iowa. At least golf-ball size hail is expected with some storms. Possible gustnado reported in Lecompton KS
Winds are calming down some in the local area

UPDATE 6:15pm edt

The winds today have been quite gusty. At my house, I've lost a few small branches, but that's about it.
I noticed on the LGE power outage map that over 4,000 customers are currently without power in a large chunk of the east end of Jefferson county. Don't know if it's due to the wind, though. You can check out the current outages here:
http://stormcenter.lge-ku.com/default.html
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NWS UPDATE 5:00pm edt
AROUND NOON...COLD FRONT WILL APPROACH DESTABILIZING AIRMASS
OVER THE CWA WITH H85 JET AROUND 60 KNOTS TO HELP TRANSPORT MOISTURE
INTO THE REGION. IN THE UPPER LEVELS...RIGHT ENTRANCE REGION OF
100-120 KNOT JET WILL FAVOR MORE FORCING FOR ASCENT AND UPPER LEVEL
DIVERGENCE. 70-80 KNOT WINDS ASSOCIATED WITH FULL LATITUDE POSITIVE
TILT TROUGH WILL ALSO NOSE IN AT THE MID LEVELS. ALL OF THIS WILL
SET THE STAGE FOR STRENGTHENING/ORGANIZING QLCS AHEAD OF THE FRONT
THROUGH EARLY AFTERNOON ALONG OR JUST WEST OF THE I 65 CORRIDOR. AS
THE LINE MOVES EAST...EXPECT STRENGHTENING WITH THE POTENTIAL FOR
BOWING SEGMENTS AND A FEW EMBEDDED SUPERCELLS. THE MAIN QUESTION
WILL REMAIN TO BE HOW UNSTABLE WE GET AHEAD OF THIS LINE AND HOW
WELL LOW LEVEL WINDS WILL BE ABLE TO BE TRANSPORTED TO THE SURFACE.
THE MAIN THREAT WILL BE FOR DAMAGING WINDS...ALONG WITH A LESSER
THREAT OF AN ISOLATED TORNADO WITH BOWING SEGMENTS. THE BEST TIMING
FOR STRONG TO SEVERE STORMS APPEARS TO GET GOING AROUND 2 TO 4 PM
NEAR THE I 65 CORRIDOR... MOVING EAST TO THE I 75 CORRIDOR BY AROUND
6 TO 8 PM EDT.------------------------------------
**Pressure reading and wind update**2:45pm edt
Non t'storm wind gusts:
Champaign IL 53mph
Marion IL  52 mph
Lawrenceville IL 51 mph

Lowest Pressure readings:
Clarion IA  29.24" (990 mB)
Perry IA  29.24"
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**Early Afternoon Update**
Looking at the 'numbers', I'm impressed with the potential for severe storms out west today. Areas just south of Kansas City MO under a moderate risk for severe weather. Large hail looks to be the main threat. In fact hail up to 3" in diameter may occur with the stronger storms. CAPE vals above 3000, LI's -8 to -9, but SR helicity 0-1km not too impressive (therefore, not too concerned about tornadoes near Kansas City). However, am impressed with 'dry line' setting up across Kansas. During the last hour, Garden City reported a temp of 85 with dewpoint of 25. Travel eastward to Topeka, temp is 83 with dewpoint at 60. As the dry line progresses eastward, look for interaction with modestly unstable airmass. Depending on the cap in place, severe storms will fire up in a few hours.
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According to the SPC, the general thinking is for the greatest instability to reside just south of the Louisville area. However, there is still a chance for severe weather with damaging wind the primary threat within the 15 percent range. Overall, this does not look like a widespread severe event for our region at this time.

MS

Did You Know (segment 2)???

Here is another segment of Did You Know?...

• 2011 Atlantic Hurricane season expected to be active; 15 tropical storms with 8 attaining hurricane status and 3 major hurricane status (AccuWeather.com)
• Professor William Gray of Colorado State University is predicting 17 named storms, 9 hurricanes, and 5 major hurricanes

• California drought is over...thanks to an abundance of snowpack, some 159 percent of the water expected on April 1
• La Nina continues to weaken...in fact, the negative anomalies associated with La Nina have recently become positive
• The National Weather Service's 169 Doppler radars may soon be replaced over the next few years if all things go according to plan. Dual-pol radars (Dual Polarization) will play a big role in spotting tornadoes because the new technology can see the unseen.

The Dual-pol image above depicts a tornado near Shawnee Lake OK (center circle, right image) while detecting debris from 2 other tornadoes (top and bottom circles, left image).

I will have more about our severe weather chances tomorrow... In the meantime, enjoy the game. Go Cats!
MS

Severe Weather Watch

***Sat p.m. UPDATE***
Nothing new to really add. Wind advisory out for Sunday. Our local NWS office is still talking about heaviest axis of precip and instability east of I-65. Damaging wind is the primary threat but isolated tornadoes along the LEWP is possible, given the high helicity values. I'll have more info either late tonight after the UK game or first part of Sunday as I'll turn my attention to the 'numbers' from the SPC.
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**Sat a.m. UPDATE**
Brief summary of other NWS offices about severe weather chances...
PAH - Large hail threat; deep stable layer or cap in the lowest 7-10k  right up to frontal passage thus limiting tornadic and/or damaging wind risks. On the other hand, if cap breaks...kaboom!; system appears to be moving quicker than originally forecast

MEM - focuses on faster movement of cold front; by 1pm cdt for them; cap to be in place but slowly eroding; high low level helicity supports greatest tornado threat over NE Mississippi and west TN; heavy rainfall of 1-2", isolated 3" possible

LOU - heavy rainfall threat still there, but not as impressive with a faster moving front; despite marginal instability, low level jet and downdraft CAPE numbers suggest gusty winds transported to surface along storm/frontal passage thus severe weather still a possibility. Best chance for severe in the southern and southeastern parts of the Louisville CWA

INDY - Severe threat still there, but speed of frontal passage may limit severe overall than previously thought
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This weekend, I'll be focusing on the threat for severe weather for our region coming Monday. As of now, the Storm Prediction Center has placed much of the region in a slight risk category. Here is the most recent image:

As I mentioned in my previous post, pay attention to the low level jet. The SPC mentions a 50-60kt south-southwesterly low level jet that will support moisture transport northward across the warm sector. The greatest instability should be confined from the Tennessee valley southward. However, although instability will tend to be marginal with northward extent, the strength of the deep layer and low level shear should overcome that limiting factor and support mainly a damaging wind threat across the Ohio Valley.
I'll have much more during the day and Sunday.
MS

Keeping a Watch for Severe Weather...

As we may have already heard from our weather heroes, an increasing chance for severe storms exists for Monday/night. Personally, I'm awaiting additional data before I start becoming too concerned. However, there is the potential for severe weather, including tornadoes.

There are so many scenarios that could unfold, either to support or not support a severe weather outbreak.
Despite some of the obvious parameters that help us identify the likelihood of strong/severe storms, I'm paying special attention to the low-level jet strength.

What is this low-level jet? Well, there are two types: nocturnal and cyclone-induced. In this case, I'm talking about the cyclone-induced low level jet. It is a fast moving ribbon of air in the low levels of the atmosphere, generally around the 850 mB level, or about 5,000 feet high.

Here are a couple of questions to ponder:
What causes the high wind speeds within a cyclone-induced low-level jet?
A strong pressure gradient force originating from the developing mid-latitude cyclone causes the high wind. The strong pressure gradient force is caused by a large temperature gradient between the cold air behind the cold front and warm air ahead of the cold front.

Why is the low-level jet important to severe storm development?
Transports moisture and WAA (inflow) into a developing thunderstorm's updraft. The high-speed wind and directional shear helps generate large values of helicity that can lead to tornadogenesis.

Therefore, as we progress through the weekend, pay attention to any buzzwords like low-level jet and wind speeds at the 850 mB level exceeding 70 knots. This could be a significant indicator for impending severe weather.

Thanks for the info from http://www.theweatherprediction.com/severe/llj/
We'll look at additional severe weather parameters throughout the weekend. Keep checking back.
Have a good Friday evening.
MS

***Severe Weather in Florida***

At the moment, I'm following severe weather in Central Florida...I'll be posting a few updates for the next couple of hours. For you with spring break interests, keep checking back for the latest...

***RECAP 4:00pm edt***
Severe storms are finally exiting and hopefully things will start to calm down. Although now, heavy rain will be the primary threat. Here is a brief summary of storm reports and any injuries:
According to WFTV channel 9, seven people were injured in a tent collapse at the Lakeland Linder airport, where an aviation festival was in session. An  earlier report was that a hangar collapse had occurred.
Over 6" rain has fallen across The Villages, a large retirement community south of Ocala.
Even hail reports in parts of central Florida, suggesting how high the cloud tops must've reached during the peak of the storm.
Near Clearwater, reports of roof and structure damage along with a 300-ft tower collapse.
Overturned vehicles near Brandon in Hillsborough county.
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*** UPDATE 1:35pm edt***
Good news! NO COLLAPSED building in Lakeland
No people trapped. There was damage at the airport.
See what happens when severe weather wreaks havoc???

***UPDATE 1:25pm edt***
Line of storms pushing through at 70 mph.
LIVE video feed is about to end
Tampa has wind damage; trying to confirm up to 70 people trapped in hangar collapse in Lakeland
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For the second consecutive day, severe weather has erupted over parts of central Florida. During the last hour,  reports of damage have been streaming in, especially across Lakeland. Apparently, damage has been fairly widespread. At the airport, a hangar collapse with possible injuries is being reported. I just read that possibly up to 70 people are trapped. Other strong storms located just south of Poinciana, near Kissimmee.

More updates coming...
MS