Tuesday, December 25, 2012

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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Monday, December 24, 2012

8:00pm Weather Update - 21z RPM Snow Matrix

Quick update from the mid-afternoon computer models. (The numbers are finally in from the model.)  I am usually not a big believer in the 21z RPM but it is the latest data.  What I want you to notice is the numbers compared to previous versions in the table.  The numbers are starting to get a little more consistent, not as much variance between runs.

CITY
18z RPM
21z RPM
12z GFS
Cape Girardeau
9.3”
8.5”
11.7”
Cairo, IL
11.1”
10.0”

Columbus, IN
7.9”
9.3”

Bloomington, IN
10.9”
15.3”

Dyersburg, TN
3.6”
5.8”

Indianapolis
9.6”
10.8”
6.6”
Lafayette, IN
5.8”
4.5”
4.5”
Marion, IL
13.9”
10.3”

Muncie, IN
5.8”
11.5”
5.9”
Paducah, KY
14.0”
5.9”
0.6”
Poplar Bluff, Mo
4.0”
9.9”
11.0”
St. Louis
0.5”
0.1”
0.8”
Union City, TN
3.9”
4.9”

A Blizzard Watch is out for southeast Missouri, southern Illinois, western Kentucky and southwest Indiana.  Winter Storm Watches are in effect for Indiana.  The NWS is in an interesting spot.  They will upgrade the watches to warnings and advisories.  Usually they wouldn't do the upgrade until Tuesday morning or Tuesday evening, however, with the holiday I am curious to see when they issue them.  If they issue the upgrades Tuesday morning, there is a good chance the public won't see them as everyone is wrapped up in holiday festivities.  It isn't a big issue, but something kind of interesting to watch.

With heavy snow and strong winds expected there could be power outages.  If you've got a generator it might not be a bad idea to dust it off after opening presents in the morning.
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6:40pm Weather Update - Snow Matrix Update

The chunk of energy to spawn the Post-Christmas snow storm is over the four corners region of the United States southwest.  The low is expected to develop early Tuesday morning over eastern Texas and then move northeast.

I am working on my forecast numbers but not sure if I'm going to have them out tonight.  I still have quite a bit of uncertainty as to the placement of heavy snowfall.

I have been talking about a concern for a layer of warm air coming in.  I am seeing data that is confirming that concern.  NOAA's global forecast model is suggesting a layer or temperatures at or slightly above freezing coming in at 3,000 feet and at the surface for 2-3 hours Tuesday evening in southeast Missouri and early Wednesday morning for central Indiana at 3,000 feet .  This would allow for sleet to develop in Indiana and rain in southeast Missouri.  Sleet is a nightmare for forecasters.  It drastically reduces snow totals.  This doesn't mean everyone in the locations mentioned above will see sleet/rain.  In fact, many places will see all snow.  However, the introduction of sleet and rain makes putting together accurate numbers difficult.

The Hydrometeorological Prediction Center has updated their snow probability charts.  These cover 6pm CT Tuesday through 6pm CT Wednesday.

4" or greater snow probability:
(Click image to see larger version.)

8" or greater snow probability:
(Click image to see larger version.)

12" or greater snow probability:
(Click image to see larger version.)

The afternoon run of the high-resolution RPM computer model (21z) is in.  Here is what it is projecting for snowfall through Thursday afternoon.
(Click the image to see larger version.)

Now for the snow matrix.  This is updated with morning and afternoon computer model data.

CITY
18z RPM
9z RPM
12z GFS
Cape Girardeau
9.3”
0.2”
11.7”
Cairo, IL
11.1”
1.5”

Columbus, IN
7.9”
8.0”

Bloomington, IN
10.9”
8.3”

Dyersburg, TN
3.6”
1.5”

Indianapolis
9.6”
5.2”
6.6”
Lafayette, IN
5.8”
2.4””
4.5”
Marion, IL
13.9”
0.7”

Muncie, IN
5.8”
6.6”
5.9”
Paducah, KY
14.0”
4.2”
0.6”
Poplar Bluff, Mo
4.0”
0.1”
11.0”
St. Louis
0.5”
0.1”
0.8”
Union City, TN
3.9”
4.1”


I will try to get updated information out later tonight after the evening data is available.  Not sure how much I will be able to update tomorrow.  Look for an update later in the day.

Have a Merry Christmas!

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