Wintry Mix 12/31/12

Looking at radar returns this morning, I'm forecasting 2-3" of virga for many locations in our region. That's the only thing guaranteed.

Once the column saturates, precipitation will finally reach the ground. Could start as early as 10:00am in Louisville, most likely by 12:00pm. However, what type of precipitation falls is still 'up in the air'.

Therefore, a bag of wintry goodies will be doled out just in time for party festivities.

I'd like to take a look at the 12z NAM coming out by 9:30 this morning. I'll be more interested in looking at those levels in the atmosphere where the 'goodies' will be coming from.

However, the latest HRRR run shows 12pm 925 mb temps of 1-3 degrees C, should support a cold rain. 850mb levels at 12pm shows the freezing line right through Louisville (-2 to 2 degrees C), supporting snow, rain, and sleet.

This is not an efficient precipitation producer. QPF amounts fairly light. However, anytime a mixed bag that includes a chance of ice is included, travelers will be and should be wary.

More later...

MS

Weather Summary and Forecast 12/30/12

First, the most recent snowfall has been tallied and graded....

The official amounts are listed below for 12/28 and 12/29.

Louisville  2.7"
Evansville 3.0"
Paducah   1.1"
Cincinnati 3.6"
Lexington 3.0"

Final Call for Snowfall amounts listed and graded.

NWS said...

Louisville   2-4"    100
Evansville  2-4"    100
Paducah   1-3"     100
Cincinnati 3-5"     100
Lexington 1-3"     100
GRADE    100     A+

MrHP said...

Louisville   2-4"    100
Evansville  3-5"    100
Paducah    2-4"      85
Cincinnati  3-5"    100
Lexington  1-3"    100
GRADE     97     A

MikeS said...

Louisville   2-4"    100
Evansville  3-5"    100
Paducah   2-4"       85
Cincinnati 3-6"     100
Lexington 1-3"     100
GRADE     97     A

For the most part, this was an easy forecast because snow was the predominant precipitation. Lexington almost surprised everybody because of it's transition to snow sooner along with bands of snow pushing through.

The next storm system is already poised to affect the region. The NAM has trended somewhat cooler during its few runs today. However, it keeps this as a mixed bag of precipitation for Louisville. Some minor icing is possible. Snow could accumulate generally north of the River, from Cincinnati to Seymour IN. Generally south of that should be a mix of all kinds of stuff. Hopefully, future model runs will help determine precip types for these locations, as this will be a busy period for party animals.

MikeS 66 Index  30.7 (12/29/12)
3.4 degrees below normal

Climate Regions:
High Plains:        8.3 degrees below normal
Midwest:            1.6 degrees below normal
Northeast:          0.1 degrees below normal
Southeast:          1.1 degrees above normal
Southern:           7.9 degrees below normal
West:                  3.7 degrees below normal

I'll be posting a monthly report during the first part of the year. The above data was just for one day. As cold as it has been recently, the month of December's temperatures has proven to be above normal for most, if not all of the climate regions, excluding Hawaii and Alaska.

Speaking of temperatures, as of 12/29, Louisville was on pace to record a top ten warmest winter (like 6th). However, today's temperatures and tomorrow's temperatures may knock them out of the top ten list.

Two locations in my MikeS 66 Index have posted impressive snow totals for the month.
Sault St Marie Michigan   27.9"
Burlington Vermont  24.3"

Again, speaking of snow, Mt Rainier's Paradise Ranger station in Washington state has recorded 246.5" for the season, starting July 1, 2012. Normal for this date should be 259".

More on our next wintry weather event coming soon...
MS

'Overachiever' 12/29/12

Generally, this storm put out more than expected, what we like to call an overachiever, a surprising surprise.

So far, the highest amounts I found in the region include 8" at French Lick IN and 7" in Paoli, both in Orange County.

In Louisville, amounts varied as expected, due to its proximity to the rain/snow line and the infamous dry slot that nosed its way into the area. I recorded 1.5" in Valley Station in southwest Jefferson County (more possibly fell, since temperatures remained at or just above freezing the entire event; therefore, settling occurred during the dry slot because I was not able to measure at that point). However, up to 4" fell in the Lyndon area in eastern Jefferson County. The NWS at the Airport, which is the official site for precipitation measurement, has been 2.7" as of 7:00am.

Lexington proved to be the biggest winner, relatively speaking. Already near 3" as of 7:00am this morning, additional snow showers this afternoon may produce another inch or so for them. In Anderson county at Lawrenceburg, had a report of 3.5".

In Evansville, which is Paducah's coverage area, I saw a daily climate report listing 10 inches as the new snow amount for December 28 as well as the Preliminary Montly Climate Data.. That would have given Evansville over 17" this month. I thought that seemed overdone. After investigating various storm reports around the area, I saw a report of 4.5" of new snow for a total of 10 inches on the ground (what we know as snow depth). At 5:00am, I informed the Paducah NWS office about the error and it has since been corrected. By the way, as of midnight, Evansville had recorded 2" for a monthly total of 9.7". Still, varied reports of 3-4.5" were reported throughout Vanderburgh County for the entire event thus far. So, Evansville now enjoys double-digit snowfall for the month.

MS

Lightning With Our Snow??? 12/28/12

Just experimenting with the HRRR model, 2-4" snow expected across Jefferson County KY. Of interest was the lightning threat. Some of the heavier bands of snow may contain lightning from Louisville west back toward Evansville and western KY.

This may enhance snow rates for a time over 2" per hour.

It's been a while since Louisville has had thundersnow.

MS

Final Call For Snowfall 12/28/12

Earlier, I posted amounts for 5 locations for snow. I will use the NWS official amounts. The forecast covers the entire storm event through Saturday evening. Therefore, I will be adding up the totals from Friday and Saturday, posting results by Sunday.

MrHP says...

Louisville    2-4"
Evansville   3-5"
Paducah     2-4"
Cincinnati   3-5"
Lexington   1-3"

MikeS says...

Louisville    2-4"
Evansville   3-5"
Paducah     2-4"
Cincinnati   3-6"
Lexington   1-3"

NWS says... (as of 4pm est)

Louisville    2-4"
Evansville   2-4"
Paducah     1-3"
Cincinnati   3-5"
Lexington   1-3"

I might add, keep an eye on the HRRR model. It updates hourly and extends out 15 hours. For example, the 18z run that projects out 15 hours (or about 5am) shows Louisville in a 2-3" range.

MS

Midday Update 12/28/12

At 12:50pm, a few peeks of sunshine here at my location. In addition, NAM 12z simulated radar shows bulk of snow will reside just north of Louisville. Up to 5" for some of us. However, heavy snow is possible locally. Also, during the day, snow showers will develop that may contribute 0.2" - 1.5" additional accumulations across the state. Hard to say where those snow showers will develop. It's not unlikely that isolated areas could record a total in excess of 6" for the entire event through Saturday evening.

Could be adjusting totals in my Final Call for Snowfall coming soon....

MS

First Call for Snowfall 12/28/12

This looks like a slam dunk...Sorry, had to use such terminology since this is a big basketball weekend for the state of Kentucky.

Widespread snow is anticipated with a rather over-achieving southwest system. Models keep increasing QPF totals, mostly snow.

The last run that I saw from the NAM puts an axis of heavy snow along the Ohio River from Owensboro to Cincinnati.

The rain/snow line is critical as it runs through the state, as usual. Just north of the rain/snow line should realize the heaviest snow amounts, in my opinion.

Therefore, this latest run from the NAM looks good. However, they have consistently kept surface temperatures above 32 degrees throughout the event. Accumulations would be confined mostly to grassy surfaces while roadways could become partially snow-covered to slushy depending on how heavy the snow falls.

I've chosen 5 'official' weather locations for this forecast...

Paducah 2-4"
Evansville 2-5"
Louisville 2-5"
Cincinnati 2-5"
Lexington 1-3"

I will issue my Final Call for Snowfall sometime this afternoon, after 3:30pm

MS

Grading MrHP, NWS, and Myself for Winter Storm I

Here are the 'official' snow amounts at the various locations I chose. These amounts will be compared with the forecast solutions presented at least 12 hours in advance for most locations. Then a grade is assigned.

Louisville:    0.0"
Indianapolis: 7.5"
Cincinnati: 2.9"
Evansville: 7.7"
Paducah: 4.6"

Compare these totals to the Final Call for Snowfall forecast made before 4:30pm 12/25/2012

NWS
Louisville <=1"      100
Indianapolis 8-14"   90
Cincinnati 1-2"        90
Evansville 8-14"      90
Paducah 7-11"        85
GRADE                91    A-

MrHP
Louisville 1-3"         50
Indianapolis 6-10" 100
Cincinnati 4-6"        80
Evansville 7-9"      100
Paducah 6-9"          85
GRADE                83    B-

MikeS
Louisville 1-3"         50
Indianapolis 7-11" 100
Cincinnati 2-4"      100
Evansville 6-9"      100
Paducah 5-9"          95
GRADE                89     B+

Next storm system is looming. May need to put out amounts for this one as well. Not expected to be as significant, though. However, NWS Louisville AFD (KLMK271113) says, "a system worth watching and has potential to surprise with snowfall, especially very early Saturday morning across the north."

Time to look at the trends...

MS

More Snow For Lexington Than Louisville?

An interesting radar summary, showing a band of moderate to heavy snow rotating along Oldham/Trimble counties pushing east eventually. Could affect Frankfort and portions of Lexington Metro. Reports of 2" out of Trimble county. This band missed Louisville. However, some returns are being picked up just west of Louisville. I can't see more than an inch total now for Louisville. Lexington could get 1-2". We'll see.

MS

Banding of Snow Still Possible

At 1:10pm est, a band of moderate snow rotating through Oldham county; could put down a quick inch in places. Other bands west of Louisville yet to push through. The overall trend though is tapering off the snowshowers. Not expecting too many travel problems locally; however, if snowshowers continue beyond sunset, slick spots will become an issue.

Snow amounts are adding up...
Reports of 10.5" near Evansville, at least 12" in and around Bloomington; 7.2" at Indy airport and still snowing.

More updates forthcoming....

MS

Winter Weather Advisory NOW Louisville

It was supposed to go into effect at 2pm, however, a quicker changeover to snow and sleet is anticipated. I can already see it on the RADAR just across the river literally from Louisville.

One can already see the massive deformation zone to our west. This is where the serious snows are really going to pile up and quick.

Louisville may get in on part of that wide deformation zone. It will be close. Expect more than originally thought if so.

MS

Winter Weather Advisory Includes Louisville and Others

Looks like changeover to snow will occur with minor accumulations, generally 1-3" for Louisville. Therefore, weather offices have combined forces and agree to issue a Winter Weather Advisory for not only Louisville but other locations as well. They include Lexington, Frankfort, Jackson, Pikeville, and West Liberty. Does not include London or Somerset at this time.

Advisories go into effect as early as 2pm near Louisville and 6pm in the eastern part of the state.

MS

MrHP Final Call for Snowfall 12/25/2012

This is such a complicated forecast. I've used my blended MrHP forecast, a Mid-range Highest Probability forecast tool. Unfortunately, it relies primarily on model runs, which are having a hard time with this storm.

In addition, I'm presenting other factors that the models may not be looking at, such as dynamic cooling, dry slotting, and additional thermal profiles besides the proverbial '540' or freezing line.

NWS offices to the north and west are quite robust in snow totals. Totals over 12" are expected in some areas.

NWS office Louisville not expecting much snow at all for Louisville, generally an inch or less.

How to forecast totals with such large spreads over a short distance? They have the tools. Often, though, it takes skill. The NWS has been known to make skilled decisions in their forecasts. They just don't look at the models. They use blends often, but sometimes it just comes down to one's forecasting skill.

Here are a few selected cities...1) NWS says, 2)MrHP says, 3) Mike S says
Evansville IN : 8-14", 7-9", 6-9"
Paducah KY : 7-11", 6-9", 5-9"
Indianapolis IN: 8-14", 6-10", 7-11"
Cincinnati OH : 1-2", 4-6", 2-4"
Louisville KY : <=1", 1-3", 1-3"

* NWS forecasts as of 4:30pm est.

MS

Winter Weather Advisory West of Louisville

A Winter Weather Advisory has been issued for counties just north and west of Jefferson county.

Clark, Floyd, and Harrison counties included in Indiana.
Hancock, Breckinridge, Meade, and Trimble counties in Kentucky.

1-4" expected according to NWS

NWS Louisville admits forecast confidence is not great because Euro model wants to trend colder. Stay tuned to upcoming model runs from the NAM and GFS. More warnings and advisories may be necessary...like for Jefferson county KY?

MrHP Final Call for Snowfall coming up by 4:00 pm

MS

Blizzard Warnings Extended

An unprecedented extension of the blizzard warning now includes most of Indianapolis responsibility. Seymour, Bloomington, Vincennes included. This is in addition to blizzard warnings for west KY and west IN issued from Paducah's responsibility.

Louisville NWS due out with possible advisories or warnings soon...

MS

NAM Having Issues

Despite a prevalent eastward shift, the NAM is not painting a 'colder' solution as should be the case. In fact, according to my ground zero points in my last post, the heaviest snow line appears to have shifted north and west based on the NAM's 12z run and its 850mb forecast. Sounds like the NAM is just as confused as the rest of us.

That's why we can't go by one model run and make a forecast. However, it is about high time for these models, especially the reliable NAM, to start making sense of this storm. We're getting within that 24 hour window, where advisories and warnings should be coming out. This one will give forecasters a fit, for sure.

More later.

MS

Intermediate Post For Heavy Snow Threat

I'll be posting about data from the models a bit later. I wanted to touch base on what I'm looking for today.

Besides the ice threat, which hopefully will not reach critical levels, I wanted to share my thoughts about the heavy snow threat.

I'm looking for the Low to pass just northeast of Cookeville TN near Jamestown to just east of Corbin KY. That is my ground zero points. If the forecast for the low deviates from these points, I know to adjust my snowfall amounts and shift the heaviest snows in the general direction of the deviation.

I do expect sleet and freezing rain to impact some areas, which will cut down on totals. It is the areas just north of the following locations where the most significant snows will occur.

As it stands, here are the areas I'm most concerned with regarding heavy snow potential. Again, this is based on a track of the ground zero points above.

The Harrison/Washington county lines in Indiana - Salem - you're included
Jefferson county Indiana - just north of and including Madison
Boone and Kenton counties KY - just north and including Covington/Cincinnati metro

These are the southernmost extents of the heavy snow threat at this time. Areas just north of those locations mentioned could see almost all snow from this system. Interestingly, a shift of just 25 miles south would bring the heaviest snow into Louisville, based on the track I've set up. Something to think about.

I'll see what the latest runs are showing in a bit.

MS

MrHP Final Call For Snowfall Delayed

Due to the nature of this complex, still developing winter/spring storm system, I've delayed my final call for snowfall till 1pm today at the earliest.

If this was a typical winter storm with just snow and rain, I would have put out a forecast by now. However, several dynamics are at work this morning and will continue throughout the day.

Heavy snow, even crippling amounts, are still in play. In addition, freezing rain, sleet, heavy rain, severe thunderstorms with tornadoes, all of these are part of the same system.

Other factors include energy transfer from one low to another, moisture blocking that could inhibit precip amounts in our region, variable temperature profiles at the surface, 2500ft, 5000ft, and 10000ft above the surface that will determine precip types and duration of precip types

Louisville is right on the edge of this mess. NWS Louisville is doing an excellent job keeping it as simple as possible for its CWA. But the above factors will challenge the skill of our forecasters, with some missing the mark entirely. I don't expect anyone to nail it completely, especially for the Louisville area.

At this point, it could be all rain to 5" snow for the area.

I'll be posting my next update this afternoon.

MS

00z NAM 12/24/2012 Time To Put Out Additional Watches

I think the NAM's last 3 runs have proven that additional WSWatches need to be extended east and south. In addition to a heavy snow threat is an increasing risk of freezing rain and sleet. All precipitation types are highly dependent on temperature profiles at the surface as well as the 925mb, 850mb, and 700mb levels. Warmer air will be drawn into the system, producing warmer readings above while colder air exists at the surface for a time. Sleet could mix in at times if the shallow warm air can be offset by the colder air beneath it before reaching the surface.

If any other precipitation types are realized for an extended period of time, this will adversely affect snow totals. This will be an efficient QPF producer. For all snow, expect up to a foot. for others, expect some type of mix for a time. Dynamic cooling in association with the low can be expected as well. This will produce intense snowfall rates, especially on the backside of the low. It's still hard to tell where all of this will set up.

Stay tuned as this complicated storm structure develops...

MS

The 18z NAM is in (12/24/2012)

The tension is building...I'm on Frame 8 of 15...C'mon already...load. Shows the low along the KY/TN border south of Bowling Green. Whoa! A serious east shift. I'm on Frame 12. If this pans out, many of us are looking at a serious thumping of snow. In fact, crippling might describe the situation for western IN, parts of central and southern IN where up to 12" could occur in places.. Even Louisville may be back in the 2-4" range after all. Places like Lexington could see 1"or 2" as well??

Okay, let's slow the eastward progression already. Quite a dramatic east shift today. WSWatches will likely be covering more real estate. Louisville could be right on the fringe of the Watch. Just across the River, Watches will go into effect where 4-6" at least could occur, based on the recent 2 runs of the NAM.

Still plenty of time to fine-tune the storm system, though.

Final Call for Snowfall tomorrow morning. At this rate, many areas will at least double my initial MrHP forecast. Nice....

Stay safe out there everybody.

MS

The 12z NAM Is In (12/24/2012)

Hoping for that westward shift to end, the NAM finally came through on this run.

In fact, a much snowier solution for those areas north of the Ohio River. A slight shift east with this track now has put Indy in a sweet spot for lots of snow, over 6". Louisville could get in on at least 1-2". I'll have to digest the data first and update snow totals in my Final Call for Snowfall tomorrow morning.

Things are looking better...

MS

MrHP and Model Time

After being teased by a couple of analogs, I say it's time to look at the models. Top 15 analogs were showing a decent stripe of snow setting up north and northwest of Louisville. Heavy snow for Indy to Louisville, anywhere from 2-8" in that region  (less south and more north)

The latest NAM model is in...
It's warmed over the previous runs, showing a low traveling through central KY, keeping the warmest readings just to the east and south of low pressure. Another low forms in the Carolinas. It looks like a transfer of energy from KY low to Carolinas. Generally, that means lighter snows for most of us. Mostly a rain maker. Wow, a lot of rain. The NAM at times has been too wet with QPF in the past.

According to the 00z GEM...
Shows a similar track displayed by the latest NAM. Total precipitation from Louisville to Indy about 1.10-1.18". Most of that will be rain for Kentucky and parts of southern Indiana. Even Indy will see some rain or a rain/snow mix from this for a while. However, potential snow amounts may be robust toward Indy by the time the storm moves on.

MrHP is back. It's my Mid-range Highest Probability forecast. Admittedly this one will be a tough one to call. Generally, within 24 hours of a snow event is my most accurate forecast. We're still not there yet. But I like to put out at least 2 of these MrHP forecasts and compare them.

So, don't put too much into the first forecast. The next one will be my final call.

Although this is a wet system, I'm looking for where accumulating snow will occur. Here's how I see it for some locations on this first call for snowfall.

MrHP First Call for Snowfall says....

Indy 3-5"
Louisville 1"
Vincennes 2-4"
Evansville 1-3"
Cincinnati 1-3"
Lexington <1"

Again, the trend has been to warm up this system. We'll see how the next few model runs pan out.

MrHP Final Call for Snowfall out first thing tomorrow.

MS

Analog Time Sunday Edition

Yesterday, I featured a 2006 analog that showed heavy snow lining up along the Ohio River from Louisville to Cincinnati, at least 2-3" for Louisville because rain was the dominant precipitation.

I mentioned the possibility for at least 5" for Louisville if the air mass is colder than the one in 2006.

Today's featured analog is from December 16, 2007. Shows mostly a rain event for most of Kentucky with total precipitation nearing 0.75". Less than 0.50" of additional precipitation is expected with temperatures going below freezing. That could mean 1-4" for Louisville.

However, the top 15 analogs suggest an interesting solution. Snowfall 2-4" for Louisville. Just north of Louisville across southern Indiana 4-6". Near Indianapolis at least 6"

Rain will be a feature of this storm system. When will the changeover begin? If that changeover is sooner then more snow for Louisville. So far, looking at yesterday's analogs along with today's, the best scenario at this time would be 2-4". However, any shift in the storm track will be critical as to storm amounts.

This is for the time frame just after Christmas. So, it's still looking like no White Christmas for 2012.

MS

How To Measure Snow

It's that time of year, finally.

'The flakes have floated,
The ground is coated,
But the snow amounts
Are often bloated.'

Ok, I'm not much of a poet, but it is that time of year when we'll put our yardsticks to good use and attempt to measure the snow that is falling or has fallen.

Over the years, I've seen winter storms come and go. Yet, weather enthusiasts still don't know how to measure the snow properly and report amounts accurately.

I harp on this subject because such information is vital for the professionals to get a handle on how their forecast is performing and whether adjustments need to be made for others who are about to receive impacts from the snow.

I praise the NWS office for helping us prepare for the upcoming winter weather season. During their Winter Weather Awareness Campaign, the good folks there have provided a basic tutorial for how to measure snow, where to measure snow, and when to measure snow.

I've provided a couple of lists below that you will find 'enwhitening', as Elmer Fudd would say.

Snowfall Measuring Procedures

"In Depth" Snow Measuring

More to come on our possible winter storm for the day after Christmas.

MS

Analog Time

At times, I look at past analogs for help in determining a possible solution for upcoming weather scenarios. I've used it for severe weather, such as the tornado outbreak in March 2012 for our region.

This time, I'm looking at an analog for help in figuring out a possible winter storm for the Louisville area and other parts of Kentucky and southern Indiana.

I've chosen the year 2006. The month is February. A low pressure tracks up the Carolinas with a secondary low traveling up east TN and east KY.

Rain overspreads the commonwealth. Snow filters in behind the front, providing accumulations for southern IN. Low pressure transfer from parent low along the Carolinas to secondary low in east TN and KY enhances precipitation in the region.

As secondary low moves east, colder air pours in changing rain to snow, heavy at times. Heaviest snowfall occurs across northern and north-central KY. Total precipitation amounts exceed 0.50". Snowfall amounts 2-3" near Louisville, 1-4" across southern IN.

If the air mass becomes colder as our upcoming storm affects us, expect more snow, with accumulations exceeding 5" in places, especially near Louisville to Cincinnati. I feel this is where the best chance for deformation may take place.

One of the current model runs suggests the aforementioned track. Continue to monitor the latest. I'm sure other analogs will become available by tomorrow. But, right now, the 2006 analog is the one I'm looking at.

MS

Wintry Pattern Ahead

After basking in above normal temperatures for much of December, the end of the year right on into the first of the new year will feature below normal temperatures and the potential for significant snowfall across our region.

The GFS ensembles are showing a prolonged cold spell with some temperatures deviating some 20-25 degrees below normal across Kentucky during the first part of the new year.

There is the potential for a system to affect the area shortly after Christmas with up to 2" for some of us. Of course, things will change as the upper air data becomes refined. Watch us get nothing at all. Ha ha.

However, the pattern continues to turn colder from there. Every now and then, the GFS sniffs out a possible 'biggie' in terms of snowstorms  for the Louisville area. One of its runs shows over 6" around the Jan 1-3 time frame.

Now, the weather professionals will tell us that it's way too early to forecast amounts this far in advance. The storm has not reached the U.S. yet. We still don't know how strong the storm system will become as it develops.

Typically, a strengthening and progressive storm system draws up much warmer air for our area as the track of the system takes it north of the area, giving us rain.

However, there's already going to be cold air in place. Any warming will be offset by the cold airmass in place at the time. Therefore, snowfall looks increasingly likely or the threat of freezing rain is there also.

More cold air will follow as the snowpack will limit much surface warming. An active weather pattern should bring additional snowfall to the area.

So, things are shaping up for a cold and snowy period for us here in Kentucky.

If you're a fan of winter and snow, have fun.

MS

KY and Southern IN rain, snow, wind, power outage reports

As of 12:00pm est
Last hour, 475 residents with no power in Jefferson county KY. That number is now down to 133.
1,110 LGE customers statewide with largest outages in Ballard and Fayette counties.

Rain totals generally between 0.5 and 0.75". Rain is ending west of I-65

Winds are increasing across western KY:
Paducah 45 mph gusts
Hopkinsvile 47 mph gusts

Expect increasing gusts here in Louisville by 2pm as peeks of sunshine are possible (which will help transport those winds to the surface)

Pressure reading at my house in Valley Station is 29.43"

Will be updating this page today....

MS

Severe Thunderstorm Watch for Louisville 12/17/12

2:30pm est UPDATE
reports of hail between pea and nickel size across the region, still below severe criteria (>=1")
Some drifts of hail reported in Oldham county.
Strongest storms pushing along I65 corridor. Weaker storms to the west, Watch remains in place.
---------------------------

Just issued...
Severe Thunderstorm Watch for most of Louisville CWA till 8pm local time

Pressure readings continue to fall; sunshine is peeking more often; instability should rise.

Large hail remains primary threat.

Updated map in a little bit..

---------------------

1:15pm est UPDATE
Here's the map...

SPC feels pretty confident about a widespread hail event (10 or more severe hail events >95%)
Moderate risk for wind damage (40%)

A Severe T'Storm WARNING now in effect for N Meade and S Harrison counties
Pea-size hail in Lewisburg

MS

Weather and Forecast Summary Louisville 121712

MikeS 66 Index (12/16/2012 data)
45.8
+9

High Plains  +3.4
Midwest  +15.4
Northeast  +8.9
Southeast  +10.6
Southern  +13.0
West   +2.7

12 Days of Christmas - % For White Christmas in Louisville 2012
Dec 14   5%
Dec 15  <5%
Dec 16  <5%
Dec 17  <5%

Other news...
SPC includes Louisville in 15% chance for severe weather (slight risk). Main risk - large hail

Arctic air in Alaska - Yesterday's low temperature at Tanana was -56; high temperature was -47

Buffalo NY's Lake Effect Snow Machine for December so far... 0.3"

International Falls MN High 33; Low 19. An average of 17 degrees above normal (Should be 19 for high and 0 for low)

Forks WA Annual Rainfall to date  121.35"
It has rained 222 days this year
It has rained every day this month
Guess what? Rain is in the forecast for the rest of the week.

Kahului HI Annual Rainfall to date  5.09" (over 11" below normal)
Phoenix AZ Annual Rainfall to date 4.19"
Both are expecting rain this week.

Death Valley CA has recorded at least 100 degrees for 158 days this year
In July, Death Valley recorded its 3rd highest daily minimum temperature of all time at 107 degrees.
By the way, their record low was 15, in 1913, the same year as their record high 134

MS

White Christmas Percentage Remains the Same

During the 12 days of Christmas, I've been highlighting the percentages of a White Christmas here in Louisville for this year.

Dec 14 :  5%
Dec 15 : <5%
Dec 16 : <5%

I've been watching the GFS ensembles. One persistent feature is a huge block just west of Greenland. Major ridging to take place there. Above normal temperatures expected there.

However, another feature I see on the long-term maps is chunks of cold air dropping into the northwest during the Dec 28-30 time period. How far south can this air mass penetrate? High temperatures in Louisville are expected to dip into the 30's for a time. Even as early as this upcoming Friday or so, temps are expected to turn quite cold before a quick warm up.

If enough blocking can take place over an extended period of time, expect colder air to pour into the U.S. But, we need the PNA to be negative for this to happen.

MS

Severe Weather Possible Monday for Louisville

At 12:30pm today, the SPC came out with their Day 2 Outlook and includes much of the Ohio Valley in a Slight Risk category for severe weather. Despite a 15% probability assigned to the region, which is not a significant risk probability, any low-topped thunderstorms could become robust enough to put out gusty winds and hail. Updates will be forthcoming, but not looking at widespread severe weather.

It's warm enough to support severe weather. Temperatures well into the 60's today with sporadic peeks of sunshine; however, clouds should hang tough for most of us.

While we're talking about severe weather, I've looked at the Tornado reports page from the SPC. Much quieter this year than last year, to say the least. Here's a brief summary for 2012...

Updated December 13...
839 actual tornadoes confirmed this year through September. Now, October through December has seen only 66 preliminary reports of tornadoes; however, even if most of these are confirmed, we're still looking at about 900 or so actual tornadoes. It looks like we're on track to record below 1,000 for the year, much below the 1,691 confirmed last year and the 3-year average of 1,382.

Tornado deaths are much lower this year, thankfully. After last year's record 553 deaths, 68 has been recorded this year, still too much. Unfortunately, 10 killer tornadoes occurred in March taking 41 lives. Most of those deaths occurred in Indiana and some in Kentucky.

MS

Expecting Another Warm Day

Despite a high temperature of only 39 degrees on the 11th of the month, Louisville is still averaging nearly 10 degrees above normal for the month. In fact, only 2 of the 14 days have registered below normal readings.

Tomorrow's temperatures could be nearly 20 degrees above normal for December 16.

We are looking for a cold snap near the end of the month. Our best chances for measurable snow exist by this time as well.

That means the chances for a White Christmas continue to trend negative as of now. My 12 days of Christmas percentage for a White Christmas as of today now stands at less than 5%. Yesterday's reading was at 5%.

MS

12 Days of Christmas - % of White Christmas Louisville KY (12/14/12)

Starting today, I help try to unravel the percentage for a 2012 White Christmas here in Louisville.

Things are still pretty far away. So don't fret when you see these percentages. They will likely change each day based on the latest data suite from the models. Unfortunately, we still have to rely on the GFS this far out.

Right now, based on the data from the CPC, GFS forecast models, and teleconnection indices (AO and NAO primarily), several mixed signals coming in already. However, one thing they all agree on: limited chance for a White Christmas.

At this point, I'm assigning a 5% chance for a White Christmas in Louisville. Again, don't fret. As long as the GFS is in control, expect changes from run to run. In a few days, I'll tap into the data from the Canadian GEM also and eventually the NAM.

There was a better chance for a pattern change by the end of the year (time period of Dec 27-29). But, GFS ensembles were hinting at much above average temperatures by then. And the AO and NAO are forecast to be near neutral.

I'll update the chances tomorrow.

Have a good evening,
MS

America at Night

A neat picture of the United States at night. Interestingly, some of what you see may not be city lights. The satellite detects light from other sources too such as wildfires, volcanoes, and gas flares. Check out the Gulf of Mexico, for example.

Look at other locations around the globe by clicking on the link below....

Night Lights Around the World
(courtesy of Earth Observatory)

MS

UPDATE Rain Totals MSD rain gauges

Since midnight December 4, here are selected rain totals across the county based on rain gauges from MSD, also since midnight December 7...Totals ending December 8 at 10:00 am.

Valley Station just south of Gene Snyder - 3.61"; 3.01"
Fairdale at High School - 3.63"; 2.87"
Okolona just north of Jefferson Mall - 3.65"; 2.73"

Jeffersontown at water quality treatment center - 3.54"; 2.57"
Floyds Fork at water quality treatment center - 3.05"; 2.26"
Cedar Creek wqtc - 2.55"; 1.84"
Fern Creek at Fire Station Three - 2.40"; 1.54"

Louisville Int'l - 3.01"; 2.55"

The front has passed through the county. Steady rains are over for now. Clouds, drizzle, very light rain should be expected throughout the day. I did see a glimpse of sunshine here at my house in Valley Station about an hour ago!

MS

Rain Totals This Week (12/4 - 12/7)

Since midnight, 12/4, here are some rain totals based on MSD rain gauges around the area, ending at 3pm today (12/7):

TR01

D. R. Guthrie WQTC

2.52

TR15

Jeffersontown WQTC

2.64

TR19

Fairdale High School

2.76

Rainfall should taper later, with drizzle and fog dominating. Hopefully, we'll get in on a dry slot for part of the weekend. However, don't make picnic plans just yet.

MS

MikeS 66 Index 120512

Wow. Looking at yesterday's data shows that the above normal temperatures are not just a regional thing. It's national.

All 6 climate centers represented by locations in my index experienced above normal temperatures. Some were very impressive.

Selected cities include Miles City in Montana at 22 degrees above normal; Denver at 23 degrees above normal; Laramie WY at 24 degrees above normal.

Again, here is how it breaks down for the 6 climate regions...

High Plains      43.0
                       16.0 degrees ABOVE NORMAL

Midwest         33.7
                        3.5 degrees ABOVE NORMAL

Northeast       42.9
                        6.6 degrees ABOVE NORMAL

Southeast       62.3
                        9.4 degrees ABOVE NORMAL

Southern         55.1
                        8.6 degrees ABOVE NORMAL

West               51.0
                       10.2 degrees ABOVE NORMAL

The MikeS 66 Index for the U.S. is...
47.5

What does this number mean? Simple math, averaging the 6 climate regions' average temperature (high + low temps and divide by 2 for each climate region)

Departure from normal....9.05 degrees ABOVE NORMAL

...One other factoid. Looking at snow cover across the U.S., we are at 6.0% nationwide. Last year on this date, 38.6% of the nation had some measure of snow cover.

MS

MikeS 66 Index Monthly Report

Here is a breakdown of November's temperatures and precipitation by climate divisions...

High Plains
     39.6 degrees
      3.5 degrees ABOVE
     40.2% of normal precipitation

Midwest
     39.4 degrees
      0.1 degrees ABOVE
     37.6% of normal precipitation

Northeast
     41.0 degrees
      2.8 degrees BELOW
     28.4% of normal precipitation

Southeast
     55.2 degrees
      3.4 degrees BELOW
     33.8% of normal precipitation

Southern
     54.7 degrees
      0.6 degrees ABOVE
     26.3% of normal precipitation

West
     50.7 degrees
      3.4 degrees ABOVE
     95.9% of normal precipitation

Summary:
Although 4 of the 6 climate divisions in the U.S. reported above normal temperatures, the U.S. average was pretty close to normal, according to the MikeS 66 Index.

One outstanding feature in this report is the precipitation deficit across the U.S. The composite index shows that the U.S. received only 43% of its normal precipitation for November.

The driest climate regions belonged to the Southern, Northeast, and Southeast respectively. These areas reported about a third or less of their normal November precipitation.

The West was unusually wet, offset by the southwestern areas where some locations reported less than 10% of their normal precipitation.

United States
     46.9 degrees
      0.4 degrees ABOVE
     43.5% of normal precipitation

MS