Comments from Conference Call

Just got off a conference call with forecasters from the  National Weather Service office in Paducah, Kentucky.  They brought up some very good things to consider, especially when it comes to nighttime severe weather.

Here are a couple of comments Warning Coordination Meteorologist Rick Shanklin made during the call that I found noteworthy to pass along.

• Have more than one way to be warned of severe weather overnight.  Along with a weather radio, call family/friends that are in the path of the warned storm.  They found that having someone be warned by a phone call made the person(s) more likely to “wake-up” and take action.
• Leave mobile homes when a watch is issued for your area instead of waiting for a warning.  This is especially true with overnight storms.  71% of deaths from tornadoes in southeast Missouri, southern Illinois, western Kentucky and southwest Indiana occurred in mobile homes.

TIMING

New data continues to come in from high-resolution computer model data.  Here are windows of when the RPM computer model is projecting storms to arrive.

• St. Louis: A few storms around 7pm CT.  Main line arrives around 8pm CT.
• Poplar Bluff:  Line of storms arrive between 9:00pm-10:00pm CT.
• Cape Girardeau:  Line of storms arrive between 9:30pm-10:30pm CT.

Note:  These are projected time from a single run of a computer model.  These are definitely NOT set in stone.

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Nighttime Severe Weather

Severe weather at night is never a good thing.  People are asleep and often don’t have a way to be alerted to warnings.

Unfortunately, severe weather often finds a way of happening at night in southeast Missouri, southern Illinois, western Kentucky and southwest Indiana.  Northern Illinois University has published findings from research of night time severe weather.

• The public is less likely to receive warnings issued at night.
• The public is more likely to be in more vulnerable housing and building structures at night.
• Mobile homes are the leading location for tornado fatalities.
• Tornado deaths are enhanced during the late fall and winter.
• Nighttime tornadoes are twice as likely to kill as daytime tornadoes.

The region I mentioned earlier has among the highest percentage of nighttime tornadoes and nighttime tornado fatalities of anywhere in the United States.

According to the National Weather Service in Paducah, 43 of the 52 tornado deaths since 1996 have occurred at night.  Of those, 69% occurred between midnight and sunrise.  Thirty-seven of the 52 tornado deaths were in mobile homes.  Eleven occurred in permanent homes.

We say this not to scare you, however we do want you to take note that nighttime severe weather can be dangerous and we want you to keep alert to changing weather.

I think the most important take-away from the finding by NIU is that nighttime tornadoes are twice as likely to kill as daytime tornadoes.

A special thanks to Rick Shanklin at the National Weather Service office in Paducah, Kentucky for publishing the findings.

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11:30am Weather Update

All eyes are focused on tonight’s severe weather potential.  I’m going to try to keep this direct and to the point with information you can use and not get too much in the weeds of meteorology for tonight’s setup.

First, the Storm Prediction Center has upgraded southeast Missouri, southern Illinois, western Kentucky and western Tennessee to a “Moderate Risk” in their latest severe weather outlook.  Also, eastern/central Missouri, central Illinois and much of Indiana are included in a “Slight Risk”.

The above outlook is valid through 6am CT Wednesday.

The main threat from tonight’s storms will be damaging wind.  Winds 5,000 feet above the surface will be roaring at 70-90 mph.  Any thunderstorm that gets going will easily interact with that wind and could bring it down to the surface.

Here is the latest outlook for damaging thunderstorm winds.

Note the hatched area.  That indicates a 10% or greater probability of wind gusts 74 mph or greater within 25 miles of any point within the area.

I know many of you will not like to hear the next threat but yes, having a couple tornadoes is a real possibility.  Here is the latest outlook concerning the probability of a tornado occurring within 25 miles of a point.

Again, note the hatched area.  That indicates a 10% or greater probability of strong tornadoes (EF2 – EF5) within 25 miles of any point within the area.

Hail is also a threat but I believe it is much lower compared to the other two modes of severe weather.

TIMING

Here are a couple of images from the 12z run of the high-resolution 4km RPM computer model.  Again, these are not radar images, they are what the computer model projects the radar will look like.

7pm CT Tuesday:

12:30am CT Wednesday:

4am CT Wednesday:

Yesterday on Twitter I mentioned the area I "liked" for storms tonight.  I've made a slight adjustment but it isn't much.  The area I like for storms tonight is a corridor that runs from Chester, Illinois to Malden, Missouri to Star City, Arkansas.
 
FREAK-OUT-METER

• Southeast Missouri: 5/6
• Missouri Bootheel: 6
• Southern Illinois: 5/6
• Western Kentucky: 5
• Eastern Arkansas:6/7
• Western Tennessee: 6
• St. Louis metro: 4
• Central Indiana: 4
• Southern Indiana: 4/5

BOTTOM LINE

• I expect tornado watches to be issued late today and overnight.
• Warnings are likely anytime from late this afternoon through early AM Wednesday.
• It is IMPERATIVE that you have a way to be alerted to severe weather this evening/overnight.
• Take a couple of minutes and think about what you need to do and where you need to go if a tornado warning is issued this evening or overnight.  After the kids get home from school, discuss it with them, but make sure not to scare them.
• If you don't know what county you live in, take 30 seconds and find out.

I am going to publish another post later this afternoon concerning severe weather at night.

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1:20am Weather Update: Updated F-O-M

Data from tonight's computer model runs are in and there is enough new information to make an update to my "Freak-Out-Meter".

We are less than 24-hours from the start of the event and the computer models should be getting a pretty good handle on the system coming together.  The NAM, GFS and European computer models are all pointing to freezing rain and/or sleet for the St. Louis metro area along with parts of southeast Missouri, south/central Illinois and west-central Indiana.

Having said that, I want everyone to keep in mind that this is going to start as rain, heavy at times, Saturday.  There could even be a few strong to severe storms over Arkansas, the Missouri bootheel and Tennessee.  Further north, north of the cold front, cold air at the surface will begin to undercut warm air 1,000 to 2,000 feet above the ground.

Here is the meteogram for freezing rain accumulation (ice) in St. Louis:

Click image to see larger version.

The data in the above image shows the GFS suggesting 0.5" of freezing rain (ice) accumulation for St. Louis.  That could be enough to cause some power issues if ice collects on power lines.  It also isn't out of the question for there to be a dusting to an inch of snow laid down on top of the ice before the moisture finally exits.

Further south, models are suggesting freezing rain accumulations 0.5" to 1" for a few areas of southeast Missouri.  At this time, I think places in the Missouri bootheel and Sikeston/New Madrid will keep the precipitation as a cold rain and not sleet or freezing rain.

As I have said many times before, if the track of the storm shifts even as little as 40 miles north of south, the end product could change.  Some areas of Missouri, Illinois, Kentucky and Indiana will only see rain, others will see a lot of rain with sleet mixed in and some will see freezing rain and/or sleet.

I mentioned timings in my previous post and I think those still hold relatively the same.

FREAK-OUT-METER:

• St. Louis metro:  5
• Southeast Missouri:  4 - There will be a wide range of precip type from north to south across southeast Missouri and the Freak-Out-Meter could range from 1 to 4 depending on specific location.
• Southern Illinois: 3
• Western Kentucky:  2
• Central Indiana:  3

Bottom line... I do believe there will be freezing rain in some areas.  This won't be of the severity of the 2009 Ice Storm but this could make things slick in some places.

Should you go out and stock up on weeks of supplies?  No.  Would I go out and get a can of deicer to have on hand?  I would.  Worst case... If this doesn't pan out, you end up with an extra $3 can of deicer you can use at a later time.

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3:00pm Weather Update: Shift in Time

The morning computer model data is in and everything appears to be running straight and normal.  That means that all of the various computer models have different solutions to the Sunday-Tuesday time frame.

One thing that is becoming more apparent is the time frame.  Everything seems to be pointing to a slightly earlier and not as long of duration for wintery precipitation.  The way it looks now…

• St. Louis metro:  Saturday night through early Sunday morning.
• Southeast Missouri:  Sunday morning through early afternoon.
• Southern Illinois:  Sunday
• Western Kentucky:  Sunday afternoon through Sunday evening.
• Central Indiana:  Sunday afternoon through Sunday evening.

The precipitation type is still too early to pin down.  I don’t think snow is going to be a big player.  In a few locations there could be a brief period of snow but the bigger deal will be either sleet and/or freezing rain.

A quick breakdown of what the models are suggesting…

• European Forecast Agency global model (ECMWF):  Continues to suggest a layer of warm air (above freezing) a few thousand feet above the surface with cold air (below freezing) undercutting the warm air.  This would be friendly to freezing rain/sleet production.
• NOAA’s global forecast model (GFS):  Is starting to trend the way of the Euro by keeping a layer of slightly warmer (above freezing) over the top of cold air (below freezing).  This would lean more towards sleet with maybe freezing rain.
• North American Mesoscale Model (NAM):  Suggests air type (cold or warm) will arrive through the entire column (both at the surface and a few thousand feet up).  This would keep it either snow or rain depending on location.

Finally, here is the latest meteogram for St. Louis.  This shows computer model projections of freezing rain accumulation.  Each colored line is a different computer model run.  The white line indicates the average of all the forecast models.  Note:  The meteogram does not display European computer model.

Click image to see larger version.

I’m starting to think there could be a band of icing that runs from the Arkansas/Missouri border eastern/southeast Missouri through southern Illinois and in to west central Indiana.  Some of the locations that could be impacted would be St. Louis, Perryville (MO), Carbondale, Effingham, Terre Haute, Indianapolis, Bloomington (IN) and Columbus (IN).  (Before people start to question… No, these are not ALL of the locations, these are SOME of the locations.)

Bottom line… There will be a decent amount of rain falling Saturday.  Eventually the rain should change over to something.  There are still several details that need to be ironed out, but the potential does exist for ice but at this point.  For those in southeast Missouri and western Kentucky this does not look to be anything like the 2009 ice storm.

FREAK-OUT-METER:

• Southeast Missouri:  3
• Southern Illinois:  3
• Western Kentucky:  2
• Central Indiana:  3
• St. Louis metro:  3

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5:10pm Weather Update

Continuing to keep an eye on the Sunday-Tuesday time frame for parts of Missouri, Illinois, Indiana, Arkansas, Kentucky and Tennessee as the possibility of wintery weather exists.

Morning computer model data is in and the battle lines are still drawn.  NOAA’s global forecast model, the GFS, continues to bring in cold air at both the surface as well as a few thousand feet up in the atmosphere.  The European forecast agency’s computer model, the ECMWF (Euro), continues to bring shallow cold air near the ground in under “warmer” air a few thousand feet up.  The GFS suggests rain with a brief changeover to snow before the moisture moves out.  The Euro has moisture overrunning the cold air which would fall as rain and then freeze near the ground.

A couple of quick meteograms.  First, a look at surface the surface temperature in St. Louis.  Pretty obvious when the cold front passes.

Click image to see larger version.

Next, a look at freezing rain accumulation for Evansville, IN.  Note the scale on the left side of the image.  It keeps the accumulation minimal.

Click image to see larger version.

The latest forecast from the Hydrometeorological Prediction Center keeps the possibility of freezing rain/sleet in the forecast from 6pm CT Saturday through 6pm CT Sunday.

Click the image to see larger version.

The above is a probability forecast for 0.01" or more of ice.

There has been a subtle shift to the southeast in this morning’s run of the European forecast model, but I think it is too early to get in to details like that as the data will flip-flop around a bit over the next couple of days.

A forecaster from the National Weather Service office in Paducah, Kentucky described it best in their afternoon forecast discussion… “There is little reason to expect these rather subtle details to be handled well by the models at this time range… Will have to wait for a better, more coherent, clue which may not show up until Saturday.”

FREAK-OUT-METER:

• Southeast Missouri: 3
• Southern Illinois: 3
• Western Kentucky: 3
• Central Indiana: 3
• St. Louis metro: 3

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HPC Puts On Their Skates

Taking a quick glance of data this morning concerning Sunday-Monday and the possibility of freezing rain.  Last night’s European computer model (ECMWF) continues to be bullish on the potential whereas NOAA’s global forecast model (GFS) is downplaying the icing side.

One thing the models are in agreement about, rain, heavy at times, will fall Saturday night through early Sunday morning.  A cold front will be slowly moving through Missouri, Illinois and Indiana at the time.  There will be shallow cold air behind the cold front while a few thousand feet up in the atmosphere winds out of the southwest will keep temperatures above freezing.  There are two big questions at this time:

1. How long will water be available?
2. Where will be the location of the cold front?

Most likely, just north of the front will see freezing rain.

The Hydrometeorological Prediction Center is getting in on some of the freezing rain chatter.  There latest Day 3 Freezing Rain Probability Forecast and Day 3 Freezing Rain Accumulation Forecast is out and includes parts of Arkansas, Missouri, Illinois and Indiana.  The images below look at the Saturday night through Sunday morning time frame.

24-Hour Probability of Freezing Rain Accumulation 0.01”+:

Click the image to see larger version.

24-Hour Probability of Freezing Rain Accumulation 0.25”+:

Click image to see larger version.

48-Hour Freezing Rain Accumulation – 95^th Percentile:

Click image to see larger version.

Notice how HPC keeps the freezing rain out of western Kentucky, southern Indiana and northeast Arkansas.  The European computer model has the freezing rain going further south in to those areas.

Will the models continue the way of the GFS, keeping the freezing rain away, or will they lean towards the Euro, hinting at an ice storm?  We’ll have to wait and see what the runs come in with over the coming days.

FREAK-OUT-METER:

• Southeast Missouri: 3
• Southern Illinois: 3
• Western Kentucky: 2
• Central Indiana: 2
• St. Louis metro: 3

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7:20am Weather Update: Severe Weather

A quick update to highlight the latest severe weather outlook from the Storm Prediction Center.


The SPC has put parts of southeast Missouri, western Kentucky, western Tennessee and northeast Arkansas in a "Slight Risk"for severe weather. The outlook runs through 6am CT Friday.

According to SPC forecasters, the main threat will be damaging winds, however with the amount of winds turning with height a couple tornadoes could be possible.

Instability is somewhat lacking with the setup so the big questions is if organized storms will develop.

The window for the potential severe weather appears to be anywhere from 6pm through just past midnight.


- Posted from my iPhone

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