Joe’s Weather Irma: Irma now a Category 5 (for now) + record lows? (TUE-9/5)

Good morning. Over the weekend I was banging the weather drum about all the smoke in the air from fires burning in the western part of the country…yesterday it seemed folks were surprised that it was in the air. I get that…not many meteorologists were talking about the situation over the weekend at least…plus with it being a holiday a lot were doing other things…but IF you follow me on twitter I probably had about a dozen references to the smokey conditions. In all my years here I don’t remember seeing as much persistent smoke out there as I have over the last few days…it actually goes back to last Friday.


Forecast:

Today: The smoke should fade a bit more today, as cooler air now takes over the region. Temperatures will be cool for September with highs in the low-mid 70s

Tonight: Fair skies and very cool with lows down into the low-mid 40s. The record is 43°. I don’t think we get that low…but we may get close, and some of the outlying areas may dip to near 40° north of the KC metro area.

Wednesday: Mostly sunny and cool again with highs approaching 70°

Thursday: Sunny and cool with highs near 75°


Discussion:

Let’s start with the smoke…getting smoke wafting through our skies in the KC region isn’t that unusual really. It’s more or less tied to the amount of smoke being created from the seriousness of wild/forest fires in the western parts of the US and up into Canada. We’ve actually had some thin smoke out there off and on this year already. The amount though from SAT>yesterday though was compelling to see on the satellite picture.

Also of note was the scope of it…going from the NW to the NE part of the country with even some drifting into the SE part of the country.

Here was a picture I took of the smokey sunset, one hour before sunset…

You may have noticed not only was the sun very “orange” but the rising almost full moon was rather “orange” as well. There’s a lot going on with that but the simple reason is that when the sun and moon are higher in the sky…the light from the sun and the illuminated moon are going through “some” smoke (in yesterday’s case). BUT when the moon and sun are lower in the sky…like towards sunrise or sunset the light coming from the sun, at least, is going through a whole LOT of smoke and other pollution in the atmosphere so the light is being filtered considerably compared to when the sun is directly overhead.

There is actually good information from Stephen Corfidi from the Storm Prediction Center on all this…

“At sunrise or sunset, sunlight takes a much longer path through the atmosphere than during the middle part of the day. Because this lengthened path results in an increased amount of violet and blue light being scattered out of the beam by the nearly infinite number of scattering “events” that occur along the way (a process collectively known as multiple scattering), the light that reaches an observer early or late in the day is noticeably reddened. Thus, it could be said that sunsets are red because the daytime sky is blue. This notion is perhaps best illustrated by example: A beam of sunlight that at a given moment helps produce a red sunset over the Appalachians is at the same time contributing to a deep blue, late afternoon sky over the Rockies (Figure 1).”

“Now what happens when airborne dust and haze enter the view? Typical pollution droplets such as those found in urban smog or summertime haze are on the order of .5 to 1 um in diameter. Particles this large are not good Rayleigh scatterers as they are comparable in size to the wavelength of visible light. If the particles are of uniform size, they might impart a reddish or bluish cast to the sky, or result in an odd-colored sun or moon (it is this effect that accounts for the infrequent observation of “blue suns” or “blue moons” near erupting volcanoes). Because pollution aerosols normally exist in a wide range of sizes, however, the overall scattering they produce is not strongly wavelength-dependent. As a result, hazy daytime skies, instead of being bright blue, appear grayish or even white. Similarly, the vibrant oranges and reds of “clean” sunsets give way to pale yellows and pinks when dust and haze fill the air.

But airborne pollutants do more than soften sky colors. They also enhance the attenuation of both direct and scattered light, especially when the sun is low in the sky. This reduces the total amount of light that reaches the ground, robbing sunrises and sunsets of brilliance and intensity. Thus, twilight colors at the surface on dusty or hazy days tend to be muted and subdued, even though purer oranges and reds persist in the cleaner air aloft. This effect is most noticeable in an airplane, shortly after take-off on a hazy evening: A seemingly bland sunset at the ground gives way to vivid color aloft as soon as the plane ascends beyond the haze. When the haze layer is shallow, a similar effect sometimes is evident at the surface, as shown by the sunset sequence in Figure 2. The photographs show a sheet of billowed altocumulus that erupts into a blaze of fiery oranges and reds once the sun has dropped far enough below the horizon that it no longer directly illuminates the thin veil of surface-based haze present below the clouds. The haze layer appears as a dark band just above the horizon in the last (enlarged) view.”

Here is the complete article with additional pictures.

So there you go…

Our weather is quiet for the next 5-10 days or so. It may not rain at all in that time frame. Temperatures will gradually come up but overall average to below average temperatures are expected for awhile it appears. Actually in terms of late summer days go…it’s going to be tough to beat. One note…after soooo much rain over the summer (especially during the flood situations) we’re going into a rather prolonged dry spell. It’s getting dry out there from a topsoil point of view at least. With the combination of dry air…ground…warm sunshine etc…we actually could use some rain for the grasses etc. You may need to start dragging the sprinklers around over the next 10 days.

Onwards…

Irma:

Yesterday Irma really started to get cranked up. Over the weekend it seemed every time it would start strengthening it would sort of whimper again. Yesterday though…that changed. Winds steadily increased from 115 MPH to 140 MPH to now category 5 strength…175 mph!

That is one nasty beast of a storm.

Category 5 hurricanes are still somewhat “rare”. Only 35 have been recorded in the Atlantic Basin. Granted though the the better records of said storms only go back to the 70s and the more modern satellite era. Last year Matthew was at one point a category 5 storms. Before that you have to go back to 2007 when there were 2 category 5 storms.

 

Irma is the 17th Atlantic storm to have winds of at least 175 MPH…

The latest track is for it to rake the Turks/Caicos and the Southern Bahamas (see the previous blog for additional details on the Bahama Islands).

A primer on the islands in the way of Irma…

a bit farther to the SE of there are the US Virgin Islands…

Then as we head towards the weekend…it should be somewhere off the S/SE coast of Florida. There will be some land interactions occurring and I’ve seen numerous hurricanes get weakened by these interactions with the mountainous terrain of the Caribbean. As the wind flow of the storm gets interrupted by the mountains of Hispaniola and to some extent Cuba…the hurricanes circulation can get somewhat interrupted. Right now out over the warm oceans it’s more or less a perfect engine firing on all cylinders and sucking in mostly premium gas (warm water). When it gets into the Florida Straits…other factors can make the “engine” run a little rougher. Also of important note…the errors in the day 4/5 forecast positions on average are between 175-225 miles…hence the cone of uncertainty. The “cone” is always the same size by the way…it’s all related to average errors in tracks over the course of years. These errors though are getting smaller and smaller as more accuracy comes into play.

On the plus side of that though is the water temperatures of the Florida Straits between Cuba and Florida…they are toasty…upwards of almost 90°! That is a lot of “gas” that the storm may try and use to overcome the land effects.

There are questions about how long the storm stays in over the water over the weekend. Does the storm cross over land and rake through Cuba (weakening the storms structure) before turning northwards at some point? Does the storm stay over the open waters and just have it’s circulation disrupted?

Notice the difference in the two operational forecast models…EURO when sliding the bar to the right…and the GFS when sliding left. The pressure is represented in millibars. The GFS is nutty low the EURO weaker since the storm is going through Cuba and the core is away from the “gas” of the warm sea waters.

Various other members of the GFS model (the ensembles) all forecast a HARD right turn (north) at some point…where exactly does that occur? Is it going up or off the east coast of FL…up the middle of FL…up the west coast of FL?

Another model…the Canadian which typically doesn’t do well with tropical systems in my opinion at least…has it more or less off the west coast of FL…

The EURO model has a varied solution…really showing both outcomes possible…an outcome off the west coast and one off the east coast or near the east coast of FL.

It is all connected to the TIME of the turn northwards…a 6-12 hour delay OR advance in the timing over the weekend can dictate which part of the coast in FL gets raked by the potential of 100-120 MPH winds. Good luck forecasting that from 4 days away…any forecast would be merely an educated guess at this point.

Florida obviously needs to take this VERY seriously and they are. A solution off the east coast of FL then brings the Carolina’s into play…a solution farther west off the west coast of FL then brings the FL Panhandle and westwards into play somewhat.

This is going to be terrible storm whoever gets slammed by it. When Matthew skirted off the east coast of FL last year…damage was “relatively” light along the east coast of FL. A 50 mile difference farther west of Matthew’s track would’ve been terribly worse for the east coast of Florida.

Recon aircraft is peppering the storm right now…getting information about a variety of features of the storms structure.

So right now it’s really a “perfect” hurricane. Textbook case.

When looking at the bigger picture there is some data that may suggest some increasing light shear as the storm moves farther east towards the NE leeward Islands…not sure if that will be a deterrent or not though…but when hurricanes are “perfect” it can be difficult to maintain that perfection for more than 24-36 hours or so.

There is a lot more I can write about but the blog is now teetering into epic word length…so I better stop. Our feature photo comes from Sharon Holloway  showing the smoke in the skies yesterday.

Joe

 

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