WeatherNation Blog

Groundhog Day Storm On The Way!

Precipitation Type Forecast Animation

Precipitation Type Forecast Animation

Gobbler's Knob Credit: Groundhog.org

Gobbler's Knog Credit: Groundhog.org

Punxsutawney Phil! Credit: Groundhog.org

Punxsutawney Phil! Credit: Groundhog.org


The developments we mentioned yesterday for next week are beginning to come together with the possibility of a Candlemas (ref) or Groundhog Day storm!

This type of development is typical during this time of the season, where an area of lower pressure forms near or over the Gulf of Mexico and treks northward over the northeastern United States becoming a Nor’easter if the track is appropriate, and can be quite potent in snowfall potential, similar to a Panhandle Hook which generally has less snowfall and potency due to the track relative to the Gulf Low, and to a lesser degree a Colorado Low.

To get an idea of timing of formation and general track available at this hour, view our Precipitation Type Forecast Animation. As you walk the loop forward, note the “curving” of the isobars over southeastern Texas and Louisiana around Monday morning (F060 or 06z Monday (1am eastern)).

Advance the frames individually and note that by 00z Tuesday (midnight, for eastern time minus 5 hours or 24-5=19=7pm Monday) the possibility of snow is projected to occur from Monday morning over southeastern Oklahoma, propagating through Arkansas (who has already suffered considerably from the ice storm), covering all of northern Mississippi, and into portions Northern Alabama and Georgia by the time the Animation ends at 06z Tuesday morning.

I recall living in Mississippi in, I forget the year might have been 1998 or 1999 when a few inches of wonderfully thick, heavy snow fell (high moisture content based on relative temperature = large snowflakes), so basically everything was canceled since it is such an unusual event for them =) Having been born in Chicago and lived quite a bit of my life in various states in the north, I found the cancellations quite a shock, but welcome!

While this storm has the potential for heavy snow totals, especially as it treks to the north, it will not equal the big one of 1993 which developed in a generally similar scenario. Arguments are being made as to the exact track the storm will take, I tend to wait until later model runs to make such judgments unless a box of cigars are made in the offing!

Note on the last frame that our Precipitation Type Animation says that on 6z Tuesday morning (-5 for eastern 1am) snows are projected to fall extending from Northern Georgia through Eastern Ohio and banking trough the northeastern states. It will be interesting to view further runs and track the development of this system to see how New York City will be affected.

As we enter the weekend as mentioned yesterday things will generally be quiet. Our Advisory Center currently shows a blizzard watch for eastern North Dakota and western Minnesota, but this is not related to new snowfall, simply high winds that will fling about powdery fluff from the ground.

Please be sure to view our Advisory and Radar Centers for the latest updates and developments.

As always stay tuned to your favorite weather outlet, stay informed, and stay safe!

cheers,

–patrick

Record Power Outage For Kentucky

Stop For Ice! Credit: lets_exist Flickr

Stop For Ice! Credit: lets_exist Flickr


Frozen Power Lines Credit: Kentucky Post

Frozen Power Lines Credit: Kentucky Post

Forecast Precipitation Type Animation

Forecast Precipitation Type Animation

The storm we discussed on Monday certainly left a trail of destruction in its wake. I have tried to find something representing a correct number of people left without power from the event, but can not seem to find definitive sources, so I will simply list a few references of interest for you.

The Kentucky Post (ref) has an article from this afternoon with an updated total of 607,000 people without power, which is the largest power outage in the state’s history, with the previous total occurring in last September as a result of hurricane Ike.

In Little Rock, Arkansas Channel 7 KATV reports that more than 350,000 people are still without power in the state and a total of five deaths were reported related to the event.

The Star in Indianapolis, Indiana reported today that nearly 90,000 people are still without power in Evansville, Indiana and the surrounding communities still suffering from structural damage caused by hurricane Ike last September.

American Electric Power (AEP) of Ohio reported that at one point the highest number of units without power in their sector was 108,705 On January 28, with that number being reduced to 86,517 by this afternoon.

A final note is a Reuters article that lists the highest number of people without power from the event at 1.3 million.

Today through the weekend will be generally quiet. Our Forecast Precipitation Type Animation shows a few light snow showers popping up in the northern tier as the result of a few “zippy clips” that will not produce anything overly dramatic, while on Monday Morning something looks to be coming together for the South starting around eastern Texas to Arkansas and Louisiana.

Please be sure to view our Advisory and Radar Centers for the latest updates and developments.

As always stay tuned to your favorite weather outlet, stay informed, and stay safe!

cheers,

–patrick

The Ice Man Makes a Statement!

Warnings Center

Warnings Center

Forecast Precipitation Type Animation

Forecast Precipitation Type Animation

Just a quick note today as I have been battling problems all up and down the line since sunup to sundown in a war that makes me feel like the Last Templar!

The ice storm we discussed yesterday morning is holding true to form causing delays and closures all across America’s Heartland. A more indepth discussion of outages, damages, and pictures will be uploaded tomorrow as the system begins to exit the nation.

Currently our Advisory Center shows winter storm warnings, ice storm warnings, and various advisories extend from central Texas all the way through Maine. With the added bonus of a blizzard warning in and around Laramie, Wyoming!

Our Forecast Precipitation Type Animation shows the ice storm continuing its trek through the midwest as it moves notheast into the midatlantic and New England states through Wednesday and Thursday. More significant icing is in store as well as very respectable snow totals as mentioned yesterday.

Please be sure to view our Advisory and Radar Centers for the latest updates and developments.

As always stay tuned to your favorite weather outlet, stay informed, and stay safe!

cheers,

–patrick

Major Ice Storm To Bash U.S.

Advisory Center

Advisory Center

Forecast Precipitation Type

Forecast Precipitation Type

Forecast Temperatures

Forecast Temperatures

Hundreds of thousands of people or more will be without power in the upcoming days as a major ice storm digs its talons into America’s Heartland.

A frontal boundary viewable with the Fronts overlay in our Radar Center will retreat northward from the Gulf pulling warm most air into the deep south as modified arctic air east of the Rockies will form a dense shallow layer of near or below freezing air at the surface that will result in nearly idyllic temperature profiles for widespread sleet and freezing rain.

The resulting setup is the cause for a cornucopia of winter related warnings in our Advisory Center from ice storm warnings to winter storm warnings active from central Texas to the northeastern United States.

Our 12z Forecast Precipitation Type Animation shows the potential for icing to begin in Texas this afternoon then stretching through Oklahoma, Arkansas, and Missouri as tomorrow approaches. As the warmer air advances from the Gulf meeting with the modified arctic air, an elongated area of icing potential will spread across the breadth of the nation’s midsection.

The best potential for the heaviest accumulations over the next few days will extend from the Missouri / Arkansas border in a general northeast track through northern Tennessee and Kentucky where very high accumulations are likely to occur. In the surrounding areas and those highlighted in the animation above, light to significant accumulations are possible.

In addition to the ice storm, heavy snows will also occur just north of the icing line as highlighted in our Precipitation Type Animation, where on a line from the southern Illinois / Missouri border running northeast through centeral and southern Indiana, Ohio, and Pennsylvania accumulations of 4-6″ are likely, over the next few days, with the best chance for highest accumulations along the southern extent of Illinois, Indiana, and Ohio where up to 8″ or so are possible.

Please be sure to view our Advisory and Radar Centers for the latest updates and developments.

As always stay tuned to your favorite weather outlet, stay informed, and stay safe!

cheers,

–patrick

Update: 3pm
Governor Brad Henry of Oklahoma declared a state of emergency for all 77 counties in the state, urging motorists to “slow down or, better yet, stay off the roads if they can.” Read the full article from Channel 5 in Oklahoma City, KOMO.COM.

Rain, Snow, Cold, Warm..

Forecast Precipitation Type Animation

Forecast Precipitation Type Animation

Forecast Temperature Animation

Forecast Temperature Animation


The rains we discussed on Monday certainly have spread the wetness the southwest was so desperate for and moved its way into the intermountain west as predicted. While things have generally been quiet they are about to pick up a bit as rains and snows will continue in the southwest and west as our Forecast Precipitation Type Animation displays. Well while we are on the subject of the animation, I was asked the other day to explain it a bit, so I might as well do so again here.

Open the animation above and hit the stop button on the bottom of your screen. First, note the time stamp on the bottom. If you want to be on the same “frame” as i will be in this discussion, also please click the “first image” button.

OK, the timestamp I place on the images states:
18z F003hr Valid: Thur Jan 22 21:00:00 UTC 2009

18z means the time the “run” was made (and the first data was valid for) to create each of the images in the animation.

F003hr means the current frame in the animation is forecast 3 hours out from the time the run was initialized, or 18z plus 3 hours so it would be 21z.

The valid time is where I have a script that calculates out the valid day and hour that each frame is valid for so it is easier for the general public to understand when the frame is valid. So in other words January 22, 2100 hours (21st hour of the day) UTC (Universal Time Coordinated). At one time I converted the dates to central time, eastern time and so forth but most people who look at the maps have a general understanding of time and prefer Z / UTC since they are accustomed to it, but I of course could go back to recalculating valid eastern time if a majority chose for me to do so.

If the concept of gmt/utc/zulu is new foreign to you, wiki has this article that you may find helpful. Additionally, there is another article on the concept of time zones that may come in handy.

So, now the concept of the image. You may notice that I throw up different types of products from time to time, because I have been working in meteorology so long that I have quite a few of them. Forecasting precipitation type is one of the many pet projects I have been working on for longer than I care to mention, so I also have a suite of related products.

The animation above may be loosely translated as saying based upon data available, at three hour intervals out 84 hours, what might the radar and precipitation type look like?

Let’s think about this for a minute. Essentially what i am saying is that each frame in the animation represents a three hour window of time. Each time interval also represents the end of the time window. So above the 3 hour 21z Precipitation Type graphic means that from the three hours before and ending at 21z what type of precipitation may fall in the future and at what intensity?

Think carefully about that for a moment. My equations must take into account the entire three hour window and decide which type of precipitation to represent i.e. rain / freezing rain / sleet / snow and also interpret the intensities of that projected precipitation.

So when you advance the frames individually think in your mind as to what types of transitions may be occurring in the area you are interested in. Do you for example notice a transition of greens (liquid precipitation), pinks (mixed freezing rain/sleet.. not my color choice by the way!), or blues (snow) or somethign in that nature? If so you may be in a transition zone of temperature differentials at the surface or aloft that may move over your area of interest within each time frame, which is of course an important and interesting issue.

If weather is an interest of yours, keep the animation in mind, save it (I leave the links from the blogs on the server, that is what it is there for) and see how accurate the forecast was keeping in mind what was mentioned above.

When examining the legend for each precipitation type at the bottom, also keep in mind the intensities. The very light blues on the bottom for example, represent very light forecast snow intensities, or that there is a chance for flurries to light snows within that three hour window. The same is of course also true for rains and mixed. Very light greens for example mean the possibility for light rains to drizzle within each window, that may also be viewed from the ground as virga (precipitation falling from a cloud base that evaporates before reaching the surface).

OK, so now back to the animation and discussion of forecast precipitation type. The first frame shows the forecast rains in the southwest and blotches of snow and mixed precipitation embedded within the rain shields representing areas of elevation where orography will induce snows, however what is going on in the north?

Pacific moisture with enhanced vorticity will stream into the area aiding in the creation of snows along the northern tier over the next few days where again orographic process will aid in the higher accumulations in the central Rockies with emphasis in the mountains Idaho, Utah, Colorado, and Wyoming. While overall a wide precipitation shield will extend basically from Montana to the southwest.

As the days progress (advance frames) a little zippity do dah will spread snows and rains extending from the great plains to the midwest and south, which is especially beneficial in the drought ridden areas of the southeast where some reservoirs are still below their nominal levels. Snows with this event will not be overly excessive as the initial push exits east by Saturday evening and a new system comes barreling in from the Pacific Northwest simultaneously and reaching the plains by Sunday Morning.

Colder air is also going to invade the north again. The new Forecast Temperature Animation I have created for you goes out through 8 days instead of the 84 hours I usually put up. The reason I normally don’t put longer scale animations up is because some people still have bandwidth issues, but we will see how people respond to this setup.

A small synopsis of these since I have been asked, is that they represent what the temperatures are forecast to be at the valid time (note above) of the image. I also have what are called Tmin and Tmax images that I may start putting up as well, that represent what is the lowest or highest temperature forecast to occur within each window of time.

Now since this is an 8 day animation what you will see in the loop is that from the first hour (00z, the time of initialization) through F084 (the 84th hour from initialization) are at three hour intervals. Then from F090 through day 8 are at 6 hour intervals.

Hopefully both of the explanations above help you understand the images a bit more =)

So as we view the Forecast Temperature Animation (also handy to have two windows open at once and view the Precipitation Type Animation and Temperature Animation frames together if you are interested in weather) note as the days progress the nasty “purples” start coming into play. Something called Cold Air Advection (CAA – advection meaning horizontal movement of air as opposed to the vertical [convection]).

On initiation (000hr) note Florida has returned to more nominal temperatures than we discussed previously, and texas + the southwest are enjoying warm temperatures, but as we advance notice that as the cold purples are diving south, the red line that you know represents 32ºF is also inching its way south as well. A very normal happenstance this time of year. Fortunately it seems that the extreme may not occur in this run for Florida, but what happens as you continue to advance through next week? Is something interesting in store? Take a look and see!

Please be sure to view our Advisory and Radar Centers for the latest updates and developments.

As always stay tuned to your favorite weather outlet, stay informed, and stay safe!

cheers,

–patrick

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