Active Weather is Back for Wednesday June 12, 2013

An incoming warm front ahead of a deep area of low pressure will set the stage for rounds of showers and thunderstorms Wednesday afternoon into Thursday. Below is the convective outlook for Wednesday issued by the storm prediction center out of Norman, OK.

Photo 1. Convective Outlook for Wed. June 12th, 1013

All of Michiana is under a SLIGHT RISK for severe weather. An area of low pressure moving in from the west will have plenty of moisture from Monday's rain (some areas received over an inch) to develop numerous showers and storms heading into Wednesday evening. There will be a chance for strong storms developing hail, isolated tornadoes (but not as likely) but there will mainly be a threat for damaging winds from outflow diving out of mature storms.

The ingredients needed for strong to even severe storms will all be in place for for tomorrow. You need three things for a thunderstorm to develop: (1) Moisture, (2) Lift and (3) Instability. But for severe storms, you need something extra to get the storm to strengthen and even rotate to the point of potentially developing a tornado. That thing is (4) Wind Shear - which is rotating winds withing the atmospheric column.

For moisture, dewpoint is the best way to go to find the true amount of moisture over an area. Below shows the dewpoints across the nation at 2 PM Wednesday.

Photo 2. NAM of dewpoint values at 2 PM June 12th

Dewpoints are well into the 60s with this model showing levels getting into the mid to even upper 60s. That air is almost tropical. So there will be plenty of water to fuel thunderstorm development.

For lift, a warm front ahead of an area of low pressure with a trailing cold front with do a great job of vertically developing copious amounts of moisture into t-storms. Below shows an image of the approximate location of the low and fronts tomorrow evening.

Photo 3. Front and Low Locations at 8 PM June 12th.

Instability will be well in place with the highest levels of CAPE making its way to Michiana tomorrow. CAPE - Convective Available Potential Energy is a way to see how efficiently thunderstorms grow vertically. The higher the value the more unstable the environment and sometimes leads to a higher likelihood of strong storms. Below shows CAPE levels over 3000 J/kg already in place at 2 PM before the low pressure center arrives. This is the highest I've seen our instability values get so far this season.

Wind shear is very important for severe storm development. It will be present through multiple levels of Michiana's stretch of atmosphere. It is required for both storm strength and it can stretch rotating air into the vertical...possibly developing tornadoes. Below is an image of low level helicity (rotation in lower atmosphere).

Values over 100 m^2/s^2 show up over Michiana along the warm front. That suggests there will be a lower-end strength of rotation present within developed storms. This suggests a possibility of isolated tornadoes.

There will also be a risk for heavy rain from the passing storms as the low lingers into Thursday morning. Below is an image for the Hyometeorological Prediction Center forecast for rainfall from Wednesday through Thursday morning.

Numerous strong storms developing over the region may bring rainfall totals anywhere from the 1" to even 3" range from Wednesday through Thursday. Local areas of flash flooding may be possible. So be mindful of spots you know of or live near that floods from even a quick inch of rain.

Vernal Equinox and Egg Balancing

Photo provided by: crazialchemist

Every year, on one particular day, you may witness a very strange spectacle: people kneeling on pavements, people at tables and desks and counters, all trying to balance an egg on its end.

It's the Vernal Equinox, the day of approximately equal darkness and light. And more importantly, the only day you can balance an egg on its end. Well, supposedly...perhaps this piece of information is too egg-centric for you. Let's start from the very beginning.

What's The Vernal Equinox?

We observe an interesting, astronomical event during our first day of spring and fall on Earth when the Sun crosses the celestial equator. When that happens, we experience night and day of about equal length. This phenomenon is called an equinox and it occurs twice a year.

The path the Sun follows a path called the ecliptic. The two points on the ecliptic that are the farthest away from the celestial equator are called solstices. During the Winter Solstice the Sun is at its farthest point below the equator (aphelion); from this point on the Sun follows an increasingly elevated path through the sky daily until it intersects the equator. This is called the Vernal (Spring) Equinox. On this day, the axis of the Earth is perpendicular to the Sun, causing the Sun's rays to hit directly onto the equator. On this day the Sun rises exactly in the east, journeys across the sky for 12 hours, and sets exactly in the west, giving us a day of equal day and night along the equator. The exact date for the Vernal Equinox varies year by year, but is usually on or around 20-21-22 of March. 

What do you mean...Egg-Balancing?

According to legend, an egg will only balance on its end on the Vernal Equinox - hence all the people trying to stand up their eggs. The origins of this legend can be traced to ancient China, where it was believed that the balancing of eggs is easily accomplished on 'Li Chun,' which is considered to be the Beginning of Spring.

Incidentally, it wasn't the Chinese who insisted that the Vernal Equinox was the only time of the year that you could perform this feat...it was the Americans. This dates back to 1945 when Life magazine published an article by Annalee Jacoby about a large number of people balancing eggs in the city of Chunking, China, and consequently introduced the Western world to the strange behaviour of eggs on the first day of spring or vernal equinox.

Almost 40 years later, Donna Henes, a self-proclaimed artist rallied about a hundred New Yorkers to balance eggs at the exact moment of the 1983 Vernal Equinox at 11.39am. A skeptical reporter returned to the spot with a carton of eggs two days later where, to his chagrin, he discovered that not a single one of his eggs would balance.

After gaining this knowledge, people started digging in their egg cartons and balancing them on each equinox, sharing their egg-balancing eggs-perience with friends and family. Gradually the fad became a tradition. Every year there is a special slot for it in the media, be it television, radio or the papers. It usually centers around climatological or astrological ramifications that on that one day the Earth, Sun-and-egg line up in such a way that it is possible for the balancing act. There may be classrooms of children trying to perform the feat. I'm not exact sure why it's an egg. But it is what it is when it comes to unscientific legends.

Does it Really Work?

Sure it does. You can balance an egg on its end on the Vernal Equinox. Just ask anybody who's ever tried.There are just many problems on trying to explain the pseudoscience behind this apparently miraculous event. According to legend, the gravitational force is at perfect levels only at the precise moment of the equinox of Earth in order to balance the egg on end.

Unfortunately, when you bring gravity into the picture, you are faced with several embarrassing problems, namely:

• Why are eggs the only balance-able objects on this particular day of the year?
• It doesn't put latitude into the equation. Will it be able to work at all of Earth's latitudes.
• While we're on latitudes - contrary to what we were taught in school, the Earth is not round. It's an ellipse. Therefore the gravity in different parts of the world will vary slightly around 9.8 meters per second squared at sea-level.
• Why isn't the moon involved? The Sun's gravitational pull may be strong enough to keep us in orbit, but the Moon should be involved.
• Why is it that the Sun only exerts this force on the Vernal Equinox? There's an Autumnal Equinox as well.

Basically...there should be nothing other than the outside elements from keeping you from this balancing-act on any other day.

Basics on the Very Real Science Behind Gravity

Gravity is among the four fundamental forces and it is indeed everywhere. It's in the coffee you're drinking, the room you are in and even on the computer screen you're currently and attentively looking at right now. At it's most basic principles...it's a force among objects and their interactions.

The force of gravity on Earth at sea level is approximately 9.8 meters per second squared and it decreases the further "up" you travel into the atmosphere. So if you decided to jump toward the sky from where you are...you will fall back towards Earth at a rate of 9.8 meters for every second sqaured.

It is also a force that relates to two or more bodies. The closer lets say TWO objects are from one another...the STRONGER the force of gravity will be between the two. The force of gravity will then decrease the further away the two object become from one another. This is essentially the reason as to why Earth orbits the sun...explained further by Newton's Universal Law of Gravitation and Kepler's Laws of Planetary Motion.

Provided by: About.com

Try it

Go ahead - balance an egg. You'll need:

• One raw egg (or many, if you keep on smashing them)
• One flat surface

 Go and give it a shot...and happy spring!

Strong Thunderstorms possible over portions of Wyoming Thursday afternoon

   Wyoming continues to bounce around under quickly changing weather patterns! We began the week with a strong, upper-level ridge over the region. That, allowed for very WARM AIR to move our way from the desert SW. Every location that keeps records tied or set records. Not only did Monday and Tuesday feature daily highs, but some locations received ALL TIME record highs for the month of April! Sources, click links in BLUE: Central WY & SE WY

   The ridge will begin to break down today as a STRONG UPPER LOW over the Pacific begins its journey over the west. Much need, widespread showers will be likely, and they'll give us WELL-NEEDED MOISTURE, mostly Thursday. This low will divide its energy, one of which with dig over the Colorado Rockies (see Image 3). This will also allow a large amount of Pacific Ocean moisture to flow over the state to end the week (Image 1).

   The below image shows two significant areas of moisture moving over the west, ahead of that strong, upper low. Moisture plumes shown in the water vapor imagery are shown in the darker colors. This moisture will interact with an incoming low to produce likely chances of showers and t-storms over Wyoming, some of which could go severe. You can see the current water vapor at this link HERE

Image 1: Water Vapor Imagery at 9:45 a.m. Wednesday, April 25

   Speaking of severe weather, here is the convective outlook for Thursday, April 26, issued from the SPC based in Norman, Oklahoma. They issued a SLIGHT RISK (or up to 15% chance) of developing thunderstorms reaching severe levels within the yellow area (NE Colorado, western Kansas, SW Nebraska Panhandle & far SE Wyoming). Strong winds of 60 mph and quarter-sized hail will be most likely. A brief tornado can not be ruled out either in these areas.

Image 2: Convective Outlook issued by the Storm Prediction Center (SPC) for Thursday, April 26

   To make thunderstorms, you need generally 3 ingredients: (1) MOISTURE, (2) INSTABILITY and (3) LIFT

   We have already covered Thursday's system will have plenty of moisture from the water vapor imagery Wednesday morning (see image 1). So let's cover lift next. Lift can come from many sources that range from fronts to even mountain barriers (of which Wyoming has a large supply). But an incoming upper low will be the driver, the creator of the lift, as it creates surface cold fronts, directing moisture to and then up mountain barriers of the intermountain west!

   

   Below (image 3) shows a large upper level low developing over the Colorado Rockies. This feature will bring much lower pressure over Wyoming. To image this happening, you can picture a shovel the size of Maine "digging" a hole in the atmosphere that covers the area over Wyoming. This will create a large "disturbance" over the Rockies that will eventually develop fronts, clouds and then showers over Wyoming. So it's a good "rule of thumb" to correlate relatively low pressure with clouds & showers.

Image 3: NAM data of relative vorticity at 500 hPa, approximately 5600 to 5800 meters above ground

   The last ingredient of t-storms & severe weather is INSTABILITY. One measure of this is something called CAPE (Convective Available Potential Energy). Typically to get a good chance of severe weather, CAPE would have to be at least at levels of 2500 Joules per kg. However, this model run is showing value of less than that, and even lower. You can see those maxima of CAPE touching areas of NE and SE Wyoming. Even though this amount of instability is marginal, it is enough to give way for severe thunderstorms, producing damaging downburst winds and large hail.

Image 4: NAM data of CAPE at 6:00 p.m. Thursday, April 26 (00 UTC 27 APR)

   So we'll see a great chance of widespread precipitation. Rain, strong thunderstorms and then eventually mountain snow will fall over the state through the late week & early weekend, all associated with the aforementioned upper-low. You can see below the NAM (North American Model) data for precipitation. You can see there's a chance for showers and t-storms to become widespread tomorrow afternoon and evening. This is great because the state is very dry, with even areas of Laramie County currently under a MODERATE DROUGHT. up to 1-2" of liquid precip. could total over local areas of eastern & northern Wyoming! Again, SE Wyoming will have a chance of thunderstorms turning severe Thursday afternoon!

Image 5: NAM  3-hour precipitation at 6:00 p.m. Thursday, April 26

   Lastly, I'll mention the likely weather for Friday and through the weekend. That upper-low will eventually travel over the great plains and toward the upper Midwest Friday. Cold, Canadian air will then point to the low, which guides it right into Wyoming. Highs will likely drop into the 50's for lower elevations, east of the continental divide Friday and Saturday. Lingering showers will also wrap behind the low developing mountain snow during this time. Casper last shot for showers appears to be FRI night-SAT morning. Lows could dip below freezing, so snow mixed with rain will be possible for Casper & Casper Mountain but the activity looks very light currently.

Image 6: NAM data of relative vorticity at 500 hPa, approximately 5600 to 5800 meters above ground Friday at 9:00 a.m.

What Makes a Waterspout

We'll be learning a few topics today. We'll mainly learn about specific waterspout formation on this Thursday, January 26th. We'll also touch on topics like: Doppler Radar, Doppler Shift, Radar Reflectivity, What the RADAR actually reads, Layers of the Atmosphere, Ingredients for Thunderstorm Development, Rear Inflow Notch, Bow Echoes, Bow Echoes and Tornado Development, Conservation of Angular Momentum and the Bookend Vortex. Okay, lets get started!

Figure 1. Waterspout image courtesy NWS - Miami

Tornadoes not only develop over land. That statement may be common sense to many. However, they easily occur over many locations that are deemed "safe" due to popular weather folklore. Here I will be talking about tornado development over water ("waterspouts"). So, if you find yourself with a tornado staring you in the face, with nothing but a river between you two; I still recommend you find cover asap!


I will be using today's weather set-up (1/26/12) as the foundation of the waterspout explanation. Waterspouts really are just weaker versions of land-spouts. To put it simply, you need 3 things to develop a tornado-producing thunderstorm: moisture, wind shear, and a trigger. So below (Fig. 2) I show you RADAR imagery scanned 1643 Z (10:43 AM - Alabama time). Below you see a well-developed, squall line feature over the Gulf of Mexico, with a heavy, sporadic organization of heavy rain/t-storms spreading NE over the gulf states. By the way, RADAR stands for RAdio Detecting And Ranging!

Figure 2. RADAR Base Reflectivity Imagery of states bordering the Gulf of Mexico at 1643 Z

What I am highlighting in the image above is the "Rear Inflow Notch" feature. This is the name given to when a line of thunderstorms "bulges" farther eastward (usually) from the parent area of the squall line. This bulge is creating what's called a "Bow Echo." The bow echo is the portion of the squall line the takes on a bow-shape. A rear inflow notch develops when quickly moving air enters the backside of a storm in the middle levels of the troposphere. Inflow notches are related to severe weather if they carry high momentum, dry air into the storm. If the air is dry, evaporative cooling will case the air to cool. This will increase the negative buoyancy of the air and it will accelerate toward Earth's surface. This acceleration can also create damaging wind gusts.


I also highlighted the approximate location of the waterspout (blue triangle) over the portion of the squall line that is bulging into an arrow-like shape. On the north-side of the bow echo, the winds will often rotate north and south through the bow. The winds rotating to the north will cause a counter-clockwise flow to develop here. This is often called a "Bookend Vortex" where tornadoes can develop. The possible waterspout in this case study is likely the result of a north-side bookend vortex. Below (Fig. 3) shows a typical evolution from squall line to Bow Echo & Bookend Vortex.

Figure 3. The evolution of a bow echo due to strong wind shear, courtesy of COMET

One thing to really understand about tornado movement is that they don't just propagate horizontally over the ground (or water in this case). They also rotate! You can measure the direction and magnitude of that rotation with one of my favorite (and necessary) tools, the Doppler RADAR. Over the northern hemisphere, within our atmosphere, tornadoes almost always (but not always) rotate counter-clockwise. In the displays we create from Doppler RADAR data, we can show what's called the Doppler Shift of particles that are scanned within parent thunderstorms. If these particles (rain drops, hail, etc) are moving towards the RADAR, the display shows the particles in GREEN. If they are moving away, they are RED. Below (Fig. 4) I show you the apparent rotation over the Gulf due to the inflow notch's affects on the squall line. You can see there is counter-clockwise rotation! Within that area of rotation would be the best approximation of the waterspout!

Figure43. Base Velocity Display taken at 1643 Z, courtesy of Mobile, AL Doppler RADAR

Why I think Casper will see its first measureable snowfall of 2012 this week!

This Wednesday morning, we’ll see a cold front put an end to the 40’s and even low 50’s early this week. This is a stronger front that will have enough strength behind it to push south across the entire state and much of the region. This front should not only drop temperatures Wednesday and Wednesday night; but it will also drop a chance of accumulating snow.

A trough of low pressure will be digging south over the intermountain west Tuesday into Wednesday morning. You can see the position of the trough at 2 A.M. Jan., 11 below in fig. 1.

Figure 1. Map of NAM model 500 hPa heights and geo. abs. vorticity at 2 A.M. Jan., 11 - Image Courtesy Golden State Weather Service

Ahead of the trough, there should be substantial upward motion, even as the energy becomes spit between the trough and the cut-off low over California. That upward motion should promote cloud and snow growth over Wyoming.

We can also look at the jet stream at the same time using the same model run (12Z – 5 A.M. January 9^th).

Figure 2. Map of NAM model 300 hPa heights, isotachs and Jet Stream at 2 A.M. Jan., 11 - Image Courtesy Golden State Weather Service

I want to show you the jet stream position at this same time as well. A dip in the jet stream will position the jet streak (generally the strongest winds within the jet stream) right over Wyoming. The Right-Entrance Quadrant of the encircled jet streak (shown above in fig. 2) is found to promote the best growth of snowfall. A source on that is below in figure 3. The entrance regions of jet streaks are found to be excellent sources of enhanced winter weather.

Figure 3. Basic dynamics of a jet streak - Photo courtesy of MetEd.

The jet streak position matters to where you could potentially see the heaviest snowfall. I will compare the right-entrance region of the jet streak in figure 2 with the NAM forecasted snowfall below in figure 4.

Figure 4. NAM forecasted 3-hour precipitation at 2 A.M. January 11 - Image courtesy IPS Meteostar

Okay, here is the nitty-gritty…the snowfall forecast. The below images show the NAM forecasted snowfall for the Wyoming area. Generally, 1-3” is possible for areas north and east of a mountain range (Casper, Lander, Sheridan, Buffalo, Glenrock, Douglas, Lusk, Wheatland and Torrington). This model run is also going strong for snow on Casper Mountain (up to 8 inches). The timing looks to be through Wednesday morning. The snow will quickly pass and should be done by the afternoon.

Figure 5. NAM snowfall forecast for west-central WY - Image courtesy wxcaster.com

Figure 6. NAM forecast for eastern WY & northern CO - Image Courtesy wxcaster.com

Webpages I used as data sources: http://wxcaster.com/gis-snow-overlays.htm

                                                             http://ggweather.com/loops/ncep_loops.htm

                                                             http://wxweb.meteostar.com/models/

                                                             https://www.meted.ucar.edu/

Fall Foliage

We are in the middle of September now...and the Wyoming "Leafers" may need to start coming out to view the beautiful fall colors. Isn't it amazing that the trees just "know" when to show off what they have!? Well there is actually a lot that goes into the science of fall.

Cool crisp autumn days usher in the breathtaking colors of Wyoming's fall foliage. From September through November, Wyoming's state parks and forests provide endless opportunities to experience the brilliant transformation of the leaves.

Fall Color Progression
This graph (courtesy of the dept. Environmental Proection) shows the three waves of fall color - yellow, orange, and red. Depending on the region, each wave takes seven to 16 days to progress. In mid-season, where the three colors intersect, the fall display is most colorful.

Fall Conditions for Best Color!!!

• Number of leaves — Many leaves (no early leaf drop)
• Health of tree — No Leaf damage or pests
• Sunlight — More sun and less cloud cover
• Rain — Intermitant light rain - no heavy rain or drought
• Temperature — Cool at night without frost

Fall Color Timing
Autumn changes begin in the mountainous regions and steadily progress south toward lower regions. With expansive deciduous forests, Eastern North America has one of the best fall color displays in the world (image courtesy of steelvalleyoutdoors.info).

How Leaves Change
During the growing months, leaves produce chlorophyll, a green-colored pigment. Through chlorophyll the tree uses the sunlight’s energy to combine carbon dioxide and water to make glucose, which serves as food for the tree. This process is called photosynthesis.

As summer ends, shorter days and colder air alerts the tree that winter is coming. The tree severs the leaves’ connection to water and minerals from the roots. The leaves begin to die and chlorophyll production ends. The sunlight breaks down chlorophyll which reveals carotenoid pigments previously masked by the deep green.

The remaining chlorophyll produces lots of sugar, which is not used up by the tree. Red pigments called anthocyanins are created through excess sugar and more sunlight. Sunny days and cool nights provide the best weather for good anthocyanin production. You may notice that the leaves may be more red where the tree receives direct sunlight. Shaded leaves don’t produce as many anthocyanins and appear less brilliant.

Why I'm worries about 2011 flooding

Wyoming is no stranger to flooding. It is a natural occurence due to melting snowpack every spring. The last decade however, has been nothing short of record breaking. River crest data since 2000 for some locations is shown below:

   -  Saratoga: 2nd highest crest (10.16 ft) on 06/13/2010
   -  Encampment: 4th highest (7.67 ft) on 06/08/2010
   -  Savery: highest (7.10 ft) on 05/22/2008
                    2nd (6.55 ft) on 05/20/2010
                    3rd (6.53 ft) on 05/03/2009
                    4th (6.52 ft) on 06/08/2010
                    5th (6.20 ft) on 05/23/2006
   -  Laramie:  Highest recorded crest (6.60 ft) on 06/14/2010
                       2nd highest  (5.30 ft) on 06/08/2005
                       3rd (4.90 ft) on 06/08/2008
                       4th (4.70 ft) on 06/04/2003
                       5th (4.05 ft) on 06/06/2009
   -  Dubois: 5th highest (5.14 ft) on 06/02/2009
   -  Riverton (Little Wind): Highest (11.91) ft on 06/09/2010
   -  Buffalo: 2nd highest (6.29 ft) on 05/22/2008
                     4th highest (6.12 ft) on 06/08/2010
   -  Kaycee: highest (8.74 ft) on 05/21/2010
   -  Casper:  3rd highest (7.19 ft) on 06/25/2010
 
It is troubling to see these areas have their highest flood levels occur this frequently. There are a few patterns with this data: These crests are among the highest recorded (as far back as the 1800s), they occur during late May - early June, and they've occurred within the last 10 years (in some cases only last year). There is also one loose pattern that will be the topic of a future blog. During the months from March to July of the above years of flooding; the El Nino/Nina pattern has been either neutral to a weak La Nina. This year we have been under a strong La Nina. Source: NOAA. There must be a reason for the recent surge of moisture over the state during the winter and spring months.

We are now entering the 1st full week of June. Already some areas along the North Platte are showing signs of a crest. The reason I'm worred about this year's flooding is simple. The 2010-2011 winter season saw record amounts of snowfall pack atop our mountain ranges. Snow-to-water equivalent levels are some of the highest ever recorded. That moisture will eventually melt and flow into our streams & rivers. There is a possibility some of our rivers may see some of the highest crests on record. Much of the snowpack has yet to melt.

-------------------------- Current Water Levels, Forecasts & Flood Impacts --------------------------


To see Wyoming's current water levels, click here: State

For areas currently (June 7) under moderate flood stage: Ft. Steele
                                                                                      Saratoga

For areas currently under minor flood stage: Laramie
                                                                   Savery
                                                                   Encampment

For areas currently below flood stage/action stage: Slater
                                                                             Buffalo
                                                                             Kaycee
                                                                             Dubois
                                                                             Casper