Friday, December 28, 2012

4:35pm Weather Update

Latest snow fall projection from hi-res computer model. Light blue is 2"-4". Dark blue is 4"-6".



- Posted from my iPhone

10:45am Weather Update - New Snow

Another southern storm will be passing much of the Midwest to the south.  While the storm may stay south, it will try to send moisture up to the Midwest and bring additional snow Friday night and Saturday morning.

Initially, it looked like this system might bring an inch or two to parts of the Midwest but overnight data started to ramp up the numbers.  According to some computer models, there could be a swath of 4"-6" snows from southern Illinois in to southern Indiana.

Here is the latest high resolution 4km RPM computer model (12z).
(Click the image to see larger version.)

The light blues indicate 2"-4" and the blueish/purple is 4"-6".  This shows snowfall through 9am ET Saturday.

The feedback I received was that people enjoyed looking at the snow matrix I put together for the storm earlier this week so I've created another for tonight's round of snow.

CITY
9z RPM
12z NAM
12z GFS
AVG
Cape Girardeau
1.1”
9.3”
4.9”
5.1”
Cairo, IL
0.6”
0.1”
4.3”
1.7”
Columbus, IN
3.4”
8.3”
4.2”
6.3”
Bloomington, IN
2.4”
11.8”
4.8”
6.3”
Dyersburg, TN
0.3“
0.6”
1.5”
0.8”
Indianapolis
1.4”
5.2”
4.1”
3.5”
Lafayette, IN
1.6”
1.0”
2.5”
1.7”
Marion, IL
1.7”
8.1”
4.3”
4.7”
Muncie, IN
2.5”
4.6”
2.6”
3.2”
Paducah, KY
1.6”
1.8”
4.1”
2.5”
Poplar Bluff, Mo
0.7”
3.8”
4.7”
3.0”
St. Louis
0.2”
0.0”
1.8”
0.6”
Union City, TN
0.6”
0.7”
1.2”
0.8”

When looking at the average snow column, keep in mind this is an average of the three computer models listed.  The averages are skewed up due to the 12z NAM coming in MUCH wetter.  I do believe the NAM is overdoing things, but that's the NAM's MO.

There are some areas of southeast Missouri, western Kentucky and northwest Tennessee that will start out as rain.  The rain/snow line will have bigger impact than the storm earlier this week.

Winter Weather Advisories or other products are not out from the National Weather Service offices yet, but I suspect we will see something issued during the afternoon.

FREAK-OUT-METER
  • Southeast Missouri: 4
  • Southern Illinois: 4
  • Western Kentucky: 3
  • Southern Indiana: 5
  • Central Indiana: 3

Tuesday, December 25, 2012

10:50pm Weather Update - Final Snow Matrix

This storm is upon us and there isn't much more to do from a forecasting stand point except for sitting back and watching things develop.  Winds are already starting to pick-up in western Kentucky and southeast Missouri.  Scattered power outages are already being reported in the Missouri bootheel.

My thinking as to ETA's haven't changed since my previous post and for the most part, the models are staying relatively consistent with snow totals.

Click image to see larger version.
One thing to keep in mind however, there is drier air getting sucked up in to the storm behind the line of convection (thunderstorm) down along the gulf coast.  One thing that could happen, and does so often, is the convection could rob some of the moisture resulting in lower snowfall totals.

Also, while looking at the thermal profile of the atmosphere, temperatures are expected to hover near 32 degrees F for part of the morning in southern Indiana.  This could allow for some melting and the precipitation to fall as sleet.

Having said all of that, here is a snow matrix with numbers from this evening's computer model runs, the NAM and the GFS.
CITY
0z NAM
0z GFS
AVG
Cape Girardeau
15.1”
9.4”
12.2”
Cairo, IL
14.4”
10.5”
12.4”
Columbus, IN
11.1”
7.9”
9.5”
Bloomington, IN
15.0”
6.8”
10.9”
Dyersburg, TN
7.2
4.3”
5.7”
Indianapolis
12.7”
9.0”
10.8”
Lafayette, IN
3.3”
5.8”
4.5”
Marion, IL
16.6”
9.6”
13.1”
Muncie, IN
12.6”
9.8”
11.2”
Paducah, KY
13.6”
8.6”
11.1”
Poplar Bluff, Mo
13.8”
8.0”
10.9”
St. Louis
0.0”
1.3”
0.6”
Union City, TN
7.4”
3.5”
5.4”

8:30pm Weather Update - ETA's

The evening runs of the computer models are starting to come in.  There has already been reports of freezing rain and sleet in northeast Arkansas, southeast Missouri and western Kentucky.  The precipitation will continue to spread northeast across the Midwest over the coming hours.

There appears to be a warm layer of air at 5,000 feet above the ground.  When I say "warm layer" I mean temperatures above freezing (32 F).  This is causing the precipitation to fall as liquid and then freeze either before or as it reaches the ground.

The Storm Prediction Center highlights parts of northeast Arkansas, southeast Missouri, southern Illinois and parts of western Kentucky for blizzard like conditions and heavy snowfall.
(Click image to see larger version.)

They suggest snowfall rates will be 1" to 2" per hour at times overnight.  The expect the onset of blizzard like conditions to start in southeast Missouri between 9pm CT and 11pm CT, and near the Mississippi/Ohio River confluence between 10pm CT and 2am CT Wednesday.

Other ETA's:

  • Southern Indiana (Columbus, IN and south):  Precipitation should reach the Kentucky/Indiana border (near Evansville, IN) around 11:30pm ET.  The moisture will continue to spread northeast reaching Columbus, IN around 3am Wednesday.
  • Central Indiana:  Precipitation should begin to move in to Indianapolis metro's south side around 5am ET and reaching the north side around 6am ET.

3:10pm Weather Update - Blizzard Warnings

I hope everyone is enjoying their Christmas day.  I don't know about you, but the storm has been at the front of my mind all day so lets get to it.  Lets talk some weather!

While watching Uncle Eddy hit the egg nog a little hard, I hope you were also keeping one eye on the weather.  Winter Storm Watches have been updated to Blizzard Warnings, Winter Storm Warnings and Winter Weather Advisories across eleven states stretching from Texas to Ohio.
(Click the image to see larger version.)

For many, when you hear "Blizzard" many thoughts pop in to your head.  Let me help clear up what is a blizzard.  By definition a blizzard is:  The following conditions are expected to prevail for a period of 3 hours or longer:

  • Sustained or frequent wind gusts to 35 mph or greater
  • Considerable falling or blowing snow (visibilities less than 1/4 mile)

Travel is likely to be very treacherous starting later tonight and through Wednesday.  If you have family in town that plans on leaving Wednesday, you should consider kicking them out this afternoon/evening.  There really is no reason for people to be on the road tomorrow.  Stay home.  Stay warm inside or go out and play in the snow.

Time for some numbers.  The new 18z run of the high-resolution RPM computer forecast model is coming in and it is going heavy on snow.  Here is a look at the 4km run of the model (ultra-high resolution).
(Click the image to see larger version.)

Yes, that is right.  The model is suggesting there could be areas with 16" or more.  The one thing I want you to notice how relatively narrow the band of heavy snow (6"+) is.  Now, pick up the band and move it north or south by 60-70 miles.  That is what can happen to snow totals if the storm tracks slightly north or south of the current projection.

How about the other forecast models?  Here is the latest snow matrix from this morning's 12z (6am CT) runs showed.

CITY
12z RPM
12z Euro
12z NAM
12z GFS
AVG
Cape Girardeau
6.2”
8.9”
10.5”
11.2”
9.2”
Cairo, IL
8.3”
8.8”
7.0”
10.8”
8.7”
Columbus, IN
5.1”
10.5”
13.7”
4.6”
8.5”
Bloomington, IN
8.5”
10.5”
11.7”
5.5”
9.0”
Dyersburg, TN
2.7”
4.5”
2.5”
2.4”
3.0”
Indianapolis
7.4”
9.0”
14.4”
6.2”
9.2”
Lafayette, IN
3.1”
4.1”
2.1”
1.1”
2.6”
Marion, IL
6.8”
9.7”
12.5”
8.1”
9.2”
Muncie, IN
4.5”
9.6”
13.0”
3.9”
7.7”
Paducah, KY
6.2”
9.8”
1.7”
1.1”
4.7”
Poplar Bluff, Mo
3.2”
6.1”
9.4”
16.7”
8.8”
St. Louis
0.0”
0.3”
1.6”
0.1”
0.5”
Union City, TN
3.3”
2.0”
0.4”
0.3”
1.5”

Along with the specific models, I have also included a 4-model average.  All along I've been saying someone somewhere from southeast Missouri to central/south central Indiana could see a foot or more of snow.  I still feel that is going to be the case.

With the snow, some places will also see a lot of rain to start.  This will likely be the case in places like northwest Tennessee, western Kentucky and southern Indiana.  Eventually, it should change over to snow.  Places in southern Indiana, like Columbus, could also get a little freezing rain.  This could make things a mess.  At this moment, I don't anticipate major icing to be a problem.  Also, if it takes longer to change the rain over to snow, it could cut down the snow totals.  This won't be known until the event gets underway.

TIMING:

  • Southeast Missouri:  Moisture should begin to stream in to the Missouri bootheel from the south/southwest within the next couple hours.  This may start out as rain before changing over to snow.  It should make it as far north as Cape Girardeau before midnight.
  • Southern Illinois:  Moisture should arrive from the south/southwest around midnight and reaching Route 13 by 2am.
  • Western Kentucky:  Rain should begin to arrive from the south/southwest by 6pm with the leading edge reaching Paducah by 8pm.
  • Southern Indiana: (Bloomington/Columbus and south):  Moisture should begin to cross the Ohio River by 2am Wednesday.  The leading edge of the moisture could be in the form of rain, freezing rain, or a rain/sleet mix.  The moisture should reach Columbus by 5am.
  • Central Indiana (Indianapolis):  Moisture should begin to reach the Indianapolis metro area by 6am and reaching the north side by 7am/8am Wednesday.

The timing is subject to change.

FREAK-OUT-METER:
  • Southeast Missouri: 7
  • Southern Illinois: 7
  • Western Kentucky: 5
  • Southern Indiana: 7
  • Central Indiana: 7


Another Night of Random Thoughts

For some we are less than 24 hours until the start of the Post-Christmas Snow Storm.  Just like the last couple of nights, all kinds of random thoughts are dancing through my head.  Un-lucky for you, you get to read some of them.
  1. First and foremost, Merry Christmas to everyone!
  2. Is anyone else ready to just get this storm started?  I am tired of the talk. Its time to party.
  3. Do I really need to look at so much data?  This happens EVERY winter storm.  Eventually it becomes information overload for me.
  4. I am still concerned about warmer air getting in to a layer of the atmosphere which would bring sleet and/or rain.  Sleet and rain would drastically cut down snow numbers.
  5. Just as the computer models were starting to come in line did the GFS really need to do that tonight?!?  I am sure it has me and many other meteorologists going "Hmm...." tonight.
  6. The "just a bit outside" pitch that the GFS threw tonight will cause many meteorologists to stay up a while longer tonight to see what the relatively consistent ECMWF suggests on the 0z run.
  7. Someone, somewhere is going to get a lot of snow.
  8. I've said the previous thought many times the last couple of days.
  9. I wish there were some BUFKIT data locations in southern Illinois.
  10. There will be a sharp cut-off to the snow on the north/northwest side of the storm.
  11. Not feeling overly confident in producing a hyper-local/specific snow forecast with this storm.  There are sooooo many variables going on with this storm.  PLUS, I'm trying to forecast for three areas (St. Louis, the "Heartland" and central/southern Indiana.  Not sure I will have one with this storm.
  12. I think I just heard sleigh bells out the window.
This storm is still a very fluid forecast (pun intended).  Here is my latest snow matrix which now includes the evening run (0z) of the GFS, NAM and RPM.  You will quickly notice that numbers have dropped for many locations.
CITY
0z RPM
21z RPM
12z GFS
0z NAM
0z GFS
Cape Girardeau
0.0”
8.5”
11.7”
8.6”
3,4”
Cairo, IL
1.0”
10.0”


6.2”
Columbus, IN
4.0”
9.3”


3.7”
Bloomington, IN
2.7”
15.3”

13.1”
5.7”
Dyersburg, TN
6.6”
5.8”


7.6”
Indianapolis
2.2”
10.8”
6.6”
8.9”
5.7”
Lafayette, IN
0.1”
4.5”
4.5”
2.1”
1.1”
Marion, IL
0.0”
10.3”


4.5”
Muncie, IN
3.0”
11.5”
5.9”
8.2”
6.4”
Paducah, KY
4.0”
5.9”
0.6”
11.2”
7.2”
Poplar Bluff, Mo
0.0”
9.9”
11.0”
8.8”
2.8”
St. Louis
0.0”
0.1”
0.8”
0.0”
0.0”
Union City, TN
4.8”
4.9”




What to make of the drop in numbers?  Honestly, I am not sure at this point.  The evening computer models have finally been able to sample the entire storm with upper-air data.  Is this a major shift in the storm?  Time will tell.  As I said, we are less than 24 hours from the start of the storm and things can still shift/change.

Bottom line for tonight/this morning... If you have plans to travel Tuesday night/Wednesday, you should check the latest forecast to see what conditions may be like and plan accordingly.

Freak-Out-Meter:
  • Southeast Missouri: 6
  • Southern Illinois: 6
  • Western Kentucky: 7
  • Central Indiana: 5
  • Southern Indiana (including Columbus): 6
This will be the last update for the night.  I hope to have something new up on the blog by early-mid afternoon time and family permitting.

12:20am Update:  The 0z European computer forecast model is in and I wanted to update the snow matrix.  The Euro is continuing its consistent forecast of a significant snow for southeast Missouri, southern Illinois, western Kentucky and central/southern Indiana.


CITY
0z RPM
21z RPM
0z Euro
0z NAM
0z GFS
Cape Girardeau
0.0”
8.5”
11.7”
8.6”
3,4”
Cairo, IL
1.0”
10.0”
8.8”

6.2”
Columbus, IN
4.0”
9.3”
12.6”

3.7”
Bloomington, IN
2.7”
15.3”
13.7”
13.1”
5.7”
Dyersburg, TN
6.6”
5.8”
3.0”

7.6”
Indianapolis
2.2”
10.8”
10.8”
8.9”
5.7”
Lafayette, IN
0.1”
4.5”
4.8”
2.1”
1.1”
Marion, IL
0.0”
10.3”
11.7”

4.5”
Muncie, IN
3.0”
11.5”
11.4”
8.2”
6.4”
Paducah, KY
4.0”
5.9”
9.4”
11.2”
7.2”
Poplar Bluff, Mo
0.0”
9.9”
6.0”
8.8”
2.8”
St. Louis
0.0”
0.1”
0.8”
0.0”
0.0”
Union City, TN
4.8”
4.9”
3.0”




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