Nowcast - SPC - MODERATE Risk Area Includes Louisville

The Storm Prediction Center has provided its Day 1 Convective Outlook and includes Louisville in a Moderate Risk area with accompanying hatched areas. Damaging wind continues to be the primary threat; however, brief tornadic spinups are still possible along a fast-moving squall line programmed to reach the Louisville area well after sundown this evening and tonight.

I will be updating this page throughout the day. This is a nowcast event.

Look for some of these parameters for severe weather support...
Amount of sunshine
Sudden erosion of capped atmosphere
Dewpoint temperatures
Wind shear
Jet streak > 100mph

Squall line to approach the Louisville area between 8 and 11 pm. This may have to be adjusted as the line develops. Again, updates in a little while. Next SPC update before 1pm.

12:30pm
I have updated squall line arrival between 7 and 9pm for Louisville area. Wondering whether we'll see widespread >58mph winds along this line as they approach Louisville. I think best chances reside south of the area. Dewpoints in the mid 50's  and temperatures are nearing 70 degrees. Looking forward to next update from SPC as to placement of moderate risk axis. I don't think Louisville will be included; nevertheless, severe weather will be possible all along this line (depends on where those bowing segments take place).
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3:30pm
SPC Moderate risk remains in place for Louisville; really, no changes made to our region, but additional changes west and south, mainly for hail from SW Tennessee to Texas.
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3:55pm
Pressure readings in southern and eastern MO as low as 29.17" last hour. Non-thunderstorm wind gusts of 50-60 mph being reported post frontal passage with mostly sunny skies.
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4:00pm
78 degrees last hour in Nashville. Dewpoint in Louisville at 54 degrees. NWS Louisville expecting line to arrive in Louisville between 8 and 10pm. Now, that the line has formed, it should take about 4-6 hours for it to reach the I-65 corridor.
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4:30pm
Tornado confirmed in Illinois near Jacksonville
Stay up to date with latest power outages from LGE/KU Energy - see side of the blog Miks Piks
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6:30pm
SPC considering issuing a Tornado Watch for much of central KY and central TN and a part of southern IN.
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7:30pm
Timeline originally was 8-11pm for Louisville. Looking at earlier forecast models caused me to up the time to 7-9pm. However, it looks like it was a line ahead of the main squall that I was looking at. Main squall still expected to arrive. That may have the best chance for high winds. However, these low-topped storms we have presently in the area may affect the main squall's ability to produce long-lived downburst winds because of cooler, stable air ahead of the main squall.







MS

Severe Potential Increasing

The Storm Prediction Center has issued an update to its Day 2 Convective Outlook and includes much of Kentucky in a slight risk for severe thunderstorms. Also, hatched areas for central and western KY from I-65 west indicates an increasing potential for significant severe weather.

Of course, as always, a number of parameters need to come together for this severe weather event to unfold. However, the potential does exist. No need to downplay what may not happen.

Strong winds above the ground, mid 50's dewpoint temperatures, warm surface temperatures will foster a healthy environment for storm initiation and propagation.

However, some things to overcome include precipitation potential from earlier in the day. How quickly can the atmosphere recover with a mid-February increasing sun angle? And will there be sufficient clearing for the atmosphere to destabilize? Any additional showers ahead of the squall may preclude severe weather potential for some.

Nevertheless, the SPC is onboard. Plan accordingly.

MS

Nowcast Northern Snow System

I cannot believe JCPS (Jefferson County Public School) called off school again. When 2-hour delays or, in this case, 2-hour dismissals would have sufficed, the schools are abruptly called off for the day. At least monitor the ongoing forecast or nowcast as the system approaches. Perhaps make a decision by noon. I know there would be buses on the roads even after 3:00pm with an early dismissal, which does coincide with the arrival of snow, but the current RAP short term model continues to indicate the freezing line just above the surface runs right through Louisville. However, you couple that with the daytime heating's effects at the surface, the snow is not going to stick to the pavement right away, especially if our precipitation starts out as a mix of rain and snow.

I raise this issue about abrupt school closings because earlier this week, JCPS closed school before even trying to see if a 2-hour delay would have given more time for the snow to melt from the roadways, especially those non-treated side streets.

Anyway, enough with that rant. We are in nowcast mode. I will say that the NAM 06z and 12z runs from yesterday painted a beautiful swath of 1-4" amounts for southern IN into north-central KY and the Bluegrass.

The RAP model (11z run) shows that the accumulating snow line is very close to Louisville throughout the daytime hours. If we get snow accumulation, it would be confined to the existing snowpack, not treated area roadways as temperatures will be close to the freezing mark.

Based on the current information, any snow falling by late afternoon when the daytime heating's effects will be reduced, area roadways will become negatively impacted. With this nowcast post, Louisville looks to get 1-2".

I will update this page by noon time. Then, we'll see if JCPS made a good decision or not. Coordinating with the NWS, which I'm sure they do, any nowcast leanings toward negative travel by 3pm will hopefully be more clear.

Don't jump the gun JCPS. Let the good folks at the NWS help assay the situation. I believe sometimes, our media sites get a little too excited and distort the school system's ability to wait for any change in the ongoing forecast before making a final decision. Perhaps a final decision helps parents coordinate or plan what to do with the kiddos instead of struggling with what to do with an early dismissal? With that said, by the end of the day, the decision to close school will probably be the right call.
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10:15am
Winter Storm Warning for locations just across the River extending into parts of the Bluegrass.
Louisville not included, yet.
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11:00am
NWS Louisville:
4-6" for areas just across from Louisville and rest of warned area
1-4" for Louisville
Wave3 in Louisville has been leading the way
RAP 13z shows heaviest snow just north and northeast of Louisville with little or no accumulation just south of Louisville.
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1:00pm
Still, no precipitation reaching the ground as of noon. But, it does appear Evansville could be shortly. Indy already reporting snow with temperature of 19 degrees.
15z RAP shows moderate snow in southern IN and Louisville area between 4 and 5pm. However, snow totals still look tame according to these runs, generally an inch or two for Louisville with maybe 3-4" north and northeast of Louisville.
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3:15pm
Rain at Paducah, Owensboro, Louisville, Fort Knox with temperatures still well above freezing. Snow has been reported mixing in with the rain at times. It will take some time before cooling at the surface supports snow sticking to the pavement unless a heavy band overcomes the warmer ground. Across the River from Louisville, at least not too far away, snow is falling.
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4:00pm
Light rain at Valley Station and 37 degrees.
RAP 18z still shows heaviest snow just north and northeast of Louisville.
Expected changeover after 5pm.
JCPS should have went with early dismissal; oh, well. Jefferson County Catholic dismissed early, no makeup day for them.
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4:15pm
2.3" snow accumulation in Paoli IN. Floyds Knobs 1-1.5".
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4:40pm
NWS Louisville has Jefferson County in 2-4" range.
I still think parts of the county will only see an inch while others in the county may see  4" or more.
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5:00pm
Rain drops are beginning to take on more of a snow consistency. It's not a true snowflake yet but is beginning to transition in Valley Station.

Power Outages On the Rise In the South

Atlanta power outage map
http://outagemap.georgiapower.com/external/default.html

Wilmington NC and surrounding areas outage map
https://www.progress-energy.com/app/outagemaps/carolinas.aspx

As I write this post, over 130,000 Georgia Power customers in Georgia and 107,000 Duke/Progress Energy customers in the Carolinas.

Over 50,000 Wilmington residents affected. Tens of thousands in Atlanta Metro.

These are the primary sites I'm looking at. However, other major electrical providers may be added soon to this page.

MS

Mt Rainier Paradise Ranger Station Dethroned???

Perhaps you have heard of the western ridge that has greatly limited the snowpack in Washington and California. In fact, one of the snowiest locations in the United States is the Paradise Ranger Station on Mt. Rainier in Washington state. Last year, over 741 inches fell from July 1, 2012 through June 30, 2013 (the official annual snowfall  total).

What a difference a year makes. So far, as of this writing, only 195.6" has been deposited there. Typically, one cannot make too many comparisons to the Station's abundant snowfall seasons, except for some isolated regions in Alaska and California.

Not this year. I have seen at least 4 locations that have surpassed the Ranger Station's total thus far.

Colden NY        196.1"
Highmarket NY 202.9"
Perrysburg NY  240.5"
Hocker NY       241.7"

There's still much of the snow season ahead. Paradise Ranger Station, probably, will come out on top. But, I would not be surprised if a new U.S. Snow King is crowned for this winter. Wouldn't be something if the highest snow totals came  from a location east of the Mississippi river. Now, that would be unusual.

MS

Midweek System Still On the Table

Good Monday. Well, the cold and unsettled pattern continues as expected. Nuisance snowfall amounts over the past few days have not amounted to much. But, this last one that pushed through put down 0.7 at my house, a mild overachiever, considering I was only expecting a half inch or less.

Another small system looks to affect the region today, but it appears to be weakening and may affect our southernmost communities.

However, attention is returning to a midweek system that still looks interesting. Again, the Euro picked up on this feature a few days ago. Some of us though will not be affected by the precipitation. Southern to eastern KY continue to have the best chance at getting any significant snowfall. At least, that's what the NAM is beginning to see now.

We'll see how the next runs of the NAM handle it. Nevertheless, it looks good but don't be surprised if it fails to materialize like we want it to.

MS

Nowcast and Forecast

The snow has moved in, perfectly timed by the Rapid Refresh model. It should remain light, but pockets of moderate snow may develop later this morning for the central part of our region. Up to 0.6" is possible, with perhaps localized 1" amounts from Louisville to Lexington with main shield exiting by shortly after noon in Louisville and 1-2pm in Lexington.

More nuisance snow showers overnight Saturday. These will be looked at in fuller detail as the RAP gathers more data.

Attention turns toward midweek system. The 12z./07 run of the Euro keeps the track of the storm the same, Low along the Gulf that tracks up the east coast. However, moisture appears to be suppressed to the south. Only the eastern part of KY could see the most precipitation. According to the Euro, this is not a storm system that drags much colder air behind it. In fact, 850mb readings warm enough for any leftover moisture could end as drizzle, liquid drizzle.

So far, the run of the Euro looks good for the most part. However, today, I'll be looking at the GFS and the Euro for that system.

MS