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Rain creeping slowly toward us.

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Thursday afternoon

The upper level waves of energy are slowly working into position to finally visit the lower Ohio Valley.  Today’s system is slowly spinning southward along the east side of the Mississippi from Illinois to western KY.  I expect it to drift  southward and fade away this evening and tonight, so it poses very little threat to our area.  However, I’m still concerned about of couple of upper air remnants from today’s system.  The GFS continues to bring the energy across KY in two pieces – the first one being the system tonight which I expect to have minimal impact here. The trailing energy pocket should take direct aim on us, with a high chance for showers/thunderstorms tomorrow from about 10 A.M. until 4 P.M. or so.  Yesterday, the NAM wasn’t buying that scenario but has moved closer to the GFS reasoning today.

Another problem has popped up for the weather Saturday.  The GFS has picked up on another weak pocket of energy coming over the Rockies.  While the general trend is to weaken this system, it is projected to move over(or near) us Saturday.  Thus, my previously dry Saturday forecast doesn’t look like it’ll hold up.  Tomorrow’s system will take some of the upper air moisture along as it heads east.  Less moisture and a weakening energy pocket should still be able to at least generate some scattered thunderstorms.  But, let me emphasize the scattered, hit ‘n’ miss nature expected Saturday as compared to a longer, more widespread outbreak expected Friday.

With thunderstorm outbreaks you can never be certain what’s going to happen, but that’s how it looks for me now.

Rosetta arrives!

A few days ago, we mentioned the European Space Agency’s (ESA) space probe Rosetta approaching comet 67P.  After a ten year journey it arrived about 130 km away from the comet core and will now spend the next month or so jockeying into an orbit about 30 km (20 miles) from the surface.  Here’s how the comet looked at a distance of 130 km from Rosetta…photo courtesy of ESA.

rosetta

 

As humidity grows, so does the chance for rain.

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Wednesday morning

Little change from yesterday except the humidity has finally reached uncomfortable levels again.  So, with higher humidity to work with we have to start taking those ever present “rain chances” a bit more seriously.  But it takes more than heat and humidity to make it rain.  The upper level wind patterns have a lot to say about it as well.  For instance, yesterday we had a weak upper air disturbance pass over – plenty of clouds, but the lower atmosphere was so dry that rain didn’t form.  A similar disturbance today, would probably bring us some rain.  So, now that the surface air is “primed” the upper air energy becomes critical.

In general, the models seem pretty consistent with their placement of the next several of these minor upper disturbances.  However, the timing does vary.  Trying to make some sense out of this for Louisville’s weather, I think it’ll come down to something like this…

This afternoon: Partly cloudy and muggy…upper 80’s (no rain)                                                 Tonight:  Partly cloudy warm and muggy…low…72                                                          Thursday:  Partly cloudy, hot and humid…high near 90   (1st day of PGA looks good)           Then things get more complicated.  The upper air energy is expected to turn its attention toward our part of the Ohio Valley.  Now the timing becomes important.  We know how rain/storm systems tend to fade quickly after midnight and then regenerate the next afternoon.  The NAM brings the primary energy pool and chance for rain through the area during late night/morning Friday with NO afternoon regeneration here.  On the other hand, the GFS brings the energy through in two pieces.  The first pretty well matches the NAM, but the second should produce some afternoon thunderstorms.  I lean toward the GFS and expect the primary time for rain Friday to be during the afternoon.  Either way, I’d expect some rain delays during the PGA Friday.   Beyond that, it still looks likely that the weekend should remain dry.

Noctilucent clouds

Noctilucent clouds (NCL’s) are probably the rarest clouds in our atmosphere and are certainly the HIGHEST seen over Earth.  These thin, electric blue clouds are naturally seen about 30-50 miles above the Earth in polar regions during their summer seasons.  (In comparison, the tops of extremely strong thunderstorms only reach 12-13 miles high.)  They are believed to be formed as moisture condenses around “meteor dust.”  Few people have ever seen them.  The pictures below are from www.spaceweather.com  This one was taken by P.M. Heden of Sweden.  heaven_strip

We also have man-made varieties of NCLs.  This picture was taken yesterday at Cape Canaveral about an hour and a half after AsiaSat 8 telecommunications satellite was launched by a SpaceX Falcon 9 rocket.  The photographer was Mike Bartils.            nlcs_strip

Spaceweather.com  has a library of photos of NCLs if you’d like to see more.

Heat and humidity return for the weekend.

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Friday afternoon

August is off to a warm start, but at least the humidity is still low.  That all changes for the weekend as both the temperatures and the humidity will be on the rise.  And the models continue their slow decline in rain chances.  So, it looks like a pretty typical late summer weekend…hazy, very warm and humid.  Rain/thunderstorm chances are not zero, but pretty close.  Best chance still looks like tonight, but only at 20% or less.  Saturday and Sunday rain chances will max out under 10%.  Temperatures tonight should drop to around 70 and about 72 Sunday morning.  High temperatures should reach the upper 80’s.  Similar weather should continue early next week.

More climate talk

Yesterday, I closed with a statement about the headlines concerning a return to “an ice age is coming” within the next ten years.  That was not said in jest to mock the climate claims of the past century.  Rather, it’s based on observations of past reactions of weather to ocean currents.  Yes, ocean driven weather cycles.  The two major patterns are the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO).  Both the PDO and the AMO have two phases – positive(warm) and negative(cold).    The PDO was generally in a positive mode from the mid 70’s (when recent global warming began) until it flipped to the cold negative mode around the year 2000.  The Earth hasn’t warmed since.  (What a coincidence!) Meanwhile, the AMO has been generally positive much of the past 25-30 years.  A few years back it started “flipping” but hasn’t settled into the cold mode yet.  It’s expected to definitely become a cold phase over the next year or two.  Historically, when both the PDO and the AMO are in their cold phase, the Earth cools.  (Coincidence?  our warm Earth climate leaders think so.)

Another possible contributer to cooling could be sunspots.  The sun, of course, is the reason why we a here.  But, for centuries we looked for the “solar constant” the exact amount of energy the sun sends our way each day.  For some reason, the scientific community thought this number had to be a constant.  It’s extremely difficult to measure the sun’s energy through the atmosphere, so the answer was never found…until satellites arrived.  Then, we could easily measure that solar constant.  But, it turns out there is no solar constant – the sun’s output varies on a cycle that closely matches the number of sunspots.  Currently we are at the end of a “solar max” that has been the weakest since around 1900.  Low sunspot numbers then were associated with a “cooling Earth”.  Even lower minimums have occurred.  The most well known is the Maunder Minimum – a period of over 100 years of very low sunspot numbers centered over the 1700’s – right in the middle of the period known as the Little Ice Age.  (Another coincidence?  you betcha! says the warm Earth society.)

ALL the CLIMATE MODELS our country’s so-called experts use project temperatures on a straight line upward from 2000 until 2020.  Well, we’re 70% of the way there and temperatures haven’t budged.  Let’s see how things stand in 6 years – I’m betting on colder.

Rain/storm chances dropping (quickly)

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Saturday Morning

A quick look at the morning model runs continues the trends noted yesterday.  The HIRES NAM model doesn’t even produce ANY rain for the Louisville area – keeping the heavy rain/storm threat from northern IN to SW Ohio, eastern KY (east of I-75) and West Virginia.

The NAM continues yesterday’s trend, but in a much weaker fashion.  It now pushes a line of showers/t-storms through the region after midnight with the majority of rain (on the light side) ending before Noon.

The GFS as usual is the slowest.  It is also a weakened version of yesterday.  It holds off the rain/storm cluster until well after Midnight with all rain wrapping up shortly after Noon. Again the rain totals predicted are much lower than yesterday’s prediction.

So, here’s my latest forecast:

Afternoon:  partly cloudy, hot and humid…high 90ish (a highly technical term

Tonight:  20% chance for thunderstorms until midnight.  After Midnight, showers and thunderstorms are likely.  Gusty winds possible.  Rain chance 60%.  Low…72.

Tomorrow:  Showers end during the morning, then sunny and breezy in the afternoon…high…87.

Severe Storm Threat

Most, if not all, of the severe weather will occur over eastern Indiana and SW Ohio (and southeast from there).  An isolated severe thunderstorm is possible,  but not likely, within 35 miles of Louisville.

There is also talk of a second chance for severe storms tomorrow afternoon or evening.  To me, this seems like someone’s idea of a bad joke.

Big Change in August outlook

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Friday afternoon

I’m not much of a fan of extended outlooks and/or long range forecasting.  Nevertheless, I do check a model that portends to go out weeks and months.  That model is known as CFSv2.  I like to see the slow, usually subtle, forecast changes the model picks up.  But today I noticed a big shock – a dramatic one week change in August’s outlook.

Below is the forecast from July 17.  The top left image is the raw computer output.  The upper right is a statistically “normalized” version of the raw data.  The bottom images are probabilities of occurrence.  Notice the eastern U.S.  Forecast for an above normal surface temperature (2 meters) is quite evident.

CFSv2Aug

That was July 17.  Here’s the same image from today’s run…

CFSv2AugNEW

An amazing flip-flop!  If correct, we’re looking at a very nice August.  But, if it flips once, it can flip again.  This is a perfect example why I don’t like forecasting beyond 3 days.

Hello…Again

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Almost five years into retirement, I find I can’t keep my mouth shut concerning our local weather, some climate matters (and other stuff).  But, now its a hobby, not a job.  So, I won’t post every day.  However, on days when the weather gets “interesting”, I plan to get my two cents in along with everyone else.  After 40 years of forecasting our local weather and watching it closely for another five, I feel I’ve learned a few things to add to weather discussions.  I’ll finish this re-introduction with one of my favorite quotes.  It’s attributed to Neils Bohr, Nobel Prize winning developer of quantum physics and probably, along with Einstein, one of two best physicists of the first half of the 20th century.

“Prediction is very difficult, especially about the future.”