Friday, February 28, 2014

Winter's Biggest Punch Yet to Come

Winter is not over yet. Stay tuned.

I took a brief look at the latest run of the NAM. By the way, this is NOT the most accurate run of the NAM. However, now that the storm system is coming onshore, data sampling is taking place and shows a disturbing shift of the primary low pressure system.

A southward shift is not good for most Kentuckians. The 12z NAM run shows that by Sunday evening, widespread freezing rain will be commencing across western, north-central, and central Kentucky. Heavy amounts are forecast, at least 0.25" in places. This is just through Sunday evening. Additional amounts are expected overnight.

More details later today.

MS

Thursday, February 20, 2014

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
=================

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


Wednesday, February 19, 2014

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

Friday, February 14, 2014

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.

Wednesday, February 12, 2014

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

Monday, February 10, 2014

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

Saturday, February 8, 2014

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

Friday, February 7, 2014

The Cold and Snow

It looks like another in a long line of disturbances to affect the region later tonight. I will be reviewing the 36 hour NAM forecast or the 6z run as the graphics become available this morning. For me, this will be about as accurate as the NAM will be.

Also, I am excited about looking at the next run of the Euro. The last run on day 6 shows low pressure developing along the Gulf coast and riding up the east coast by day 7. This has BIG snow written all over it. It looks as if Kentucky will get in on some of this action. The best location for highest accumulations looks to be along and east of I-65, especially eastern KY. Remember, I like the Euro at 6-7 days out. I don't even look at the GFS until day 5 and that's just to compare the tracks of the models. I believe the Euro handled the ice system quite well at 6 days out.

More updates on these two systems later on this page.
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9:55am UPDATE
I've reviewed the 06z/07 run of the NAM
As expected, this looks like a nuisance snow for some of us. I will not be including any future runs of the NAM in the short term from here on out except to compare them to the short term models like the Rapid Refresh Model. The NAM has a history of overdoing QPF amounts and sometimes undercutting them within 24 hours.

Generally snow accumulations of 0.5" to 1.5" will be common, especially south of I-64.
Here are a select few locations:
Louisville 0.6"
Lexington 0.8"
Bowling Green 1.3"

I will say that this forecast from the NAM may have a measure of bust potential as snow to liquid ratios appear relatively high like 14 to 16:1. Therefore, some of these totals may have to be adjusted upward but still think most locations will not get out of a range of 1-3".

However, will be following the next several runs of the NAM as a system dives in Saturday night/Sunday morning, which may produce a quick-hitting large swath of snow mainly along and north of I-64, that may bring a couple more inches of accumulation for some.

Next, I'll be studying the latest Euro run for the storm system that may potentially impact our region mid-week.

MS


Thursday, February 6, 2014

What to Expect the Next 14 Days (Feb 5 - 19)

Cold. That should about sum it up.

I've analyzed the 500mb forecast for the next 10-14 days and a persistent pattern will be prevalent.

This is different than the pattern we saw for much of January, when the Arctic region and Alaska were much above normal regards to temperatures. In addition, the Pacific Northwest felt the effects of the ridge. Our region was impacted as cold air dove deep into the nation's midsection, producing Arctic outbreaks.

There will still be a good deal of ridging along the Pacific coast. Also, there will be an impressive ridge near Siberia. However, there will also be a broad cyclonic flow near Alaska, with stormy conditions.

So, the cold air will be coming from Siberia, thanks to weaker winds associated with their ridge, through Alaska and the Arctic into the Great Plains, which promises to produce very cold readings over the next several days. Therefore, which would you rather have? Arctic or Siberian?

The only saving grace for this period will be the higher sun angle which may help mitigate or modify the cold air intrusions from the north. Still, single digit temperatures could still exist in our region, even by the middle of the month.

And what about that sunlight to help modify our temperatures? The next two weeks should be characterized by active weather patterns. With below normal temperatures expected, we could be looking at an onslaught of precipitation, yes, wintry precipitation as well.

Arctic Oscillation is expected to go negative, very negative.
PNA will be mostly negative as well.

While this setup is generally not favorable for a big snowmaker in our region, the placement of the trough relative to the Alaskan coast coinciding with a Siberian ridge funneling cold air across the Arctic regions diving south into the United States may produce interesting storm tracks here in the U.S.

Where those storm tracks interact with the cold air in place will determine who gets heavy snowfall and ice. This should be an interesting , if not wild weather pattern setting up for the next several days, or should I say a continuation of the wild weather pattern.

Old Man Winter looks like he's going for the knockout punch. Stay tuned.

MS

Tuesday, February 4, 2014

Nowcast BIG Storm

Well, this was supposed to be the BIG storm. It's gonna be big for some in our region, however.

A mixture of rain, sleet, freezing rain, and snow. It's all in there, what is called a grab bag of precipitation.

Using the latest RAP short term model and weather observations upstream, this page will be updated frequently during the day.

I will focus mainly on Louisville but may include areas like Lexington and southern parts of Indiana as well.

6:30am
09z/04 run of the RAP shows at the 850mb and 925mb levels liquid precipitation for the most part above Louisville by 5pm. Surface temperatures will become critical by this time. At the onset, a mix of snow, sleet, and rain will be possible for Louisville. However, after a couple of hours, rain and pockets of sleet will dominate the next several hours through 10pm. If surface temperatures remain at or below freezing, accumulation of ice will become noticeable, at least 0.1" by then.
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9:45am
12z run RAP continues to show precipitation moving into the Louisville area between 4 and 5pm. It may start out before then but main shield should hold off till after 4pm. By midnight, total frozen precipitation could reach 0.44". That will not be good if it's all ice. But, it looks like sleet will be mixing in at times. Again, though, temperatures will be key.

Current temperature at my house in Valley Station is 29 degrees.

Interesting side note - The NAM, which is generally the model of choice for the short term, is considered the outlier. Last time the NAM was the outlier, it trumped all of the other models. It shows most of the ice along and just north of the Ohio River.
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Monday, February 3, 2014

Snow Totals

As of 4:00am, snow has nearly exited the Metro area. Minor accumulations are still possible. I have seen reports of snow over 4" widespread for Jefferson County, including my little part in the southwest part of the county.

So far, the RAP model that I use is getting lots of love from my area. It showed an average of 5" for the Metro or 4-6" range. And from reports that I'm seeing, that appears to have verified

J'town and Okolona reports of 6".

I have not seen a recent report from the NWS office in southern Jefferson County yet but sure their total is near 5-6".

Jefferson County schools have just announced they are closed

4.4" in Valley Station
4.0" in Lexington'
5.2" at Louisville Int'l
6.1" at Louisville WFO
6.8" in Shelby County.

Season totals have been updated.

MS

Sunday, February 2, 2014

Nowcast...The Big Storm Before the BIG Storm

The current storm system looks to provide plenty of messy issues for many in our Commonwealth. A great deal of uncertainty continues to be factored into even the short term models.

This is where nowcasting becomes important, not just from a short term model aspect.

The most current observations possible will become critical as far as forecasting what may happen to the next tier of counties.

If you have a thermometer, check it.
If it's still raining outside and the thermometer reads near freezing, put on your rain suit, go outside and feel metal objects, observe any ice building up on branches, bushes.
If you hear or see ice pellets bouncing around or pinging, report that as sleet.
If it's snowing, report that especially as soon as changeover begins.
Report if it's sticking to the grass or to the pavement or not at all.
If it's sticking, measure it, preferably in an open area, away from rooftops. Decks do not count, unless you use the one by the pool, which should be away from the house.
If you're traveling, report road conditions as wet, slushy, icy, snow-covered.
Most important, if you're traveling, BE CAREFUL.

This page will be updated frequently, especially as future short term model runs occur. I will be making many references to terms like 850mb, 925mb readings. These are referencing temperatures between 2,500 and 5,000 feet above the surface. This information will prove to be important because if your thermometer reads 32 degrees, yet the 850mb reading is above 32, then it will be likely raining at your location and freezing on contact at the surface.

MS
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4:15am
06z RAP
850mb freezing line just south of Louisville by 7pm
925mb freezing line into central KY
Mix of snow/rain by 5pm with complete changeover by 7pm or so for Louisville.
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5:00am
Widespread Winter Storm Warning products out for our region, including Louisville, Lexington, E'town, and points east into eastern KY.
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5:10am
At Louisville, temperature has dropped from 50 to 39 degrees within the past two hours. It is now 39 at my house as well.
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7:50am
10z run RAP
batch of light precipitation may become freezing drizzle, freezing rain along Ohio River before 3:00pm, maybe even change to s-2now across southern IN.
A brief lull then mostly snow for Louisville by 5pm onward. After dark or a little later, accumulations should begin. By 11pm, at least 2" may be on the ground in Louisville.
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12:40pm
RAP model continues to highlight moderate to heavy snow for the Louisville area, perhaps even shifting the heaviest axis into the area while parts of southern IN could be looking at warning criteria. At this time, 4"+ is looking likely for Louisville. However, this is still a developing storm. Many variables still need to be analyzed and come together. There are indications that a thin stripe of very heavy snowfall could occur with rates -approaching 2"/hr. Therefore, 5-6" are possible between Louisville and Lexington. Still monitoring latest runs. Looking out west for observation data. Temperature remains at 34 degrees at my house.
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1:30pm
Heavy snow falling across southern MO like West Plains and Branson. This could be the snow that will impact our area later this evening and overnight. Still looks like Louisville to Lexington could be in for a major accumulation (4-8")
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2:10pm
1-2" common across parts of southern MO, falling within the past couple of hours. Numerous slide-offs.
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2:15pm
3" south of West Plains MO. This kind of snow is heading toward the area for later this evening/overnight.
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3:15pm
2-4" from Branson to West Plains. Numerous accidents. Sleet falling across Western KY. Sleet reported in Louisville.
Latest RAP continues to paint at least 5" in Metro Louisville. That would put them in a 4-6" range. Nevertheless, Lexington and nearby locations stand to receive perhaps 6-9 inches.
Look for parts of southern IN to go under a warning if this trend continues.

Saturday, February 1, 2014

NAM Model Shunts Snow Band Northward

Wow. I don't know what to tell you. A monumental shift in the expected snow band within 12 hours.

What looked like a decent snow event across most of central and east/se Kentucky has now shifted the heaviest snow band from Louisville to Lexington and E'town while still showing a decent accumulation for eastern KY.

At this rate, I wonder if the NAM is overcompensating already or if the northward trend will continue.

Really tough to nail down expected totals when Ole Reliable (NAM) is got a case of the magic jumping beans.

I cannot imagine Louisville being in line for 2-3" when just a few hours ago, we were talking about flurries.

Time to see what the NWS Louisville thinks about this trend.

MS

Preliminary First Call for Snowfall

At at time when most meteorologists have been looking ahead to the BIG system, which looks to bring mostly rain to the Commonwealth, a rather potent winter storm is taking shape and aiming for central and eastern KY for the Sun pm/Mon am time frame.

Using the 06z/01 run of the NAM, here is a preliminary look at snow and ice totals for the region.

Bardstown          1" or less
Bowling Green    1-3"
Corbin                2-4", <0.2" ice
Elizabethtown      less than an inch
Glasgow             1-3"
Jackson              2-4"
Lexington            1-2"
London               3-5"
Louisville            dusting to 0.1"
Pikeville              3-5"
Richmond           1-2"
Somerset            3-5"

Locations from Whitley to Letcher counties could see rain/ice with decent accumulations of one or both.

I would like to see the runs of the 12z and 18z runs of the NAM to make a final forecast for the region.

The NWS Jackson may want to issue Winter Storm Watch products for east to southeast KY.
A sw-ne line from Russell to Lawrence couties representing the northernmost boundary of the Watch product and nearly all points south of that in Kentucky. Again, standby only.

MS

MikJournal Midweek 11/16/2017... A Lot of Data

Good afternoon. My expected midweek post was a little bit delayed. I had an influx of data to pore over and did not have time to write ...