Why A More Active Storm Track This Winter?

The big thing I have to point out but haven't recently is that the storm track will be more active than last year this winter. Last year, if you recall, something in the headlines was the 'Greenland Block'. You can see what the Greenland Block is below.

The Greenland Block has a high pressure system form over Greenland. This ridge (area) of high pressure remains over Greenland and pushes the jet stream south as cold air flows south into the US. This block really is a 'block'- in the sense that the Greenland Block creates a traffic jam in the atmosphere. When the jet buckles south, it creates two areas of low pressure- one over the East US, and the other in West Europe. Essentially, this pattern continues until the high pressure collapses. That's why there were not as many systems last year.
This year, however, the Greenland Block is not anticipated to be as prevalent as last year, therefore introducing the prospect for a more active storm track.

2011-2012 Winter: Mid-Upper Level Atmosphere Temperatures at Record Lows

Mid to Upper levels of the atmosphere are currently experiencing all time record lows. As seen in the graph above, you can see how this is the lowest temperature for this time of year in at least the past several years graphed here. Not only is that true, but the same lowest temperature claim can be said for all temperature readings at this time of year since recording began.

What does this mean?
Warm air from storms of any nature rise into the atmosphere. In the summer, this creates instability for thunderstorms. At this point in time going into winter, if these record low temperatures are to continue, one could infer that the warm air rising from a low pressure system would rise higher and faster in the atmosphere, thus creating more energy for the system to work with and in turn creating more snow.


In our eyes, this is a very possible thing to happen. It aligns with basic physics rules and basic temperature movements in the air (warm air rises), so to say.
We will watch this, as it may have a big effect on winter snowfall this year.

Models Continue to Support North Plains Snowstorm Late Next Week

6z GFS Hour 144

0z ECMWF Hour 144

The ECMWF and GFS models are pointing towards a snowstorm for the Northern Plains, including the Denver, CO region. The GFS projects a strong low coming north from the Colorado area and producing snowy conditions for the Dakotas. That blue line is the rain-snow line: anything north will be snow, anything south will be rain, theoretically. The 0z ECMWF takes it to another level, bringing not one, but TWO strong low pressure systems along for the ride. Now, in some aspects, this would mean twice the snow. That is not necessarily true. However, the prospect of 2 lows does indeed increase snow potentials. Below is a snowfall 3 hour accumulation map from the ECMWF. Credit to Wundermap.

Check out how strong the line will be for North Dakota between rain and snow. Accumulations may go as high as 6 inches (of higher), but that remains to be seen. Stay tuned with The Weather Centre, your winter weather service provider, as we track this system across the model boards.

NEW NAM shows First Snow for Midwest!

The newly-printed 0z NAM is producing a possible snowstorm for the Illinois/Missouri/Wisconsin region. The old 18z GFS was NOT producing this solution, so we will have to wait until tomorrow to see if the NAM can sway the GFS, or vice versa. Either way, it is another of two systems that may bring a very early winter to the US like the coastal storm already has for the Northeast.

First Snow of 2011-2012 Winter May be Upon the Northeast

Hour 84 Snow Accumulation 18z GFS

Hour 78 18z GFS (bottom right image is precipitation, top right image is lows/highs. )
Dashed red line on top right is rain/snow line.

The GFS continues to indicate that the first snow of the 2011-2012 winter may be upon the Northeast as soon as October 28th. For the past several days, the GFS has been trending for this solution to come to realization. The ECMWF, considered one of the better models in winter weather forecasting, is bringing over 4 inches of snow to the Northeast. Below is the ECMWF Snowfall for Oct. 27 at 8:00 PM EDT, then October 28 at 2:00 AM EDT.

Get excited, northeast folk- this one looks promising!

Denver, CO under Winter Storm Watch for 2 feet of Snow

120 hour 12z GFS Snowfall Accumulations

Denver, Colorado is one of the cities affected in a multi-state winter storm watch in effect as up to 2 feet may fall in Wyoming and Colorado! Here is the official NWS Watch from the Cheyenne NWS Forecast office, then the Winter Storm Watch from the Denver forecast office.

...WINTER STORM WATCH IN EFFECT FROM TUESDAY AFTERNOON THROUGH  
WEDNESDAY AFTERNOON...  
  
THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A WINTER  
STORM WATCH...WHICH IS IN EFFECT FROM TUESDAY AFTERNOON THROUGH  
WEDNESDAY AFTERNOON.   
  
* TIMING...LATE TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON.  
  
* TOTAL SNOW ACCUMULATIONS...18 TO 24 INCHES ARE POSSIBLE IN THE  
  SNOWY RANGE...WITH 15 TO 20 INCHES OVER THE SOUTHERN LARAMIE  
  RANGE BETWEEN CHEYENNE AND LARAMIE. OVER LOWER ELEVATIONS...SUCH  
  AS CHEYENNE AND LARAMIE...8 TO 12 INCHES ARE POSSIBLE. FINALLY  
  IN THE SOUTHERN PANHANDLE FROM SIDNEY TO KIMBALL...5 TO 8 INCHES  
  ARE POSSIBLE WEDNESDAY MORNING THROUGH THE AFTERNOON.  
  
* WINDS/VISIBILITIES...NORTHEAST WINDS OF 5 TO 15 MPH WITH HIGHER  
  GUSTS...COMBINED WITH HEAVY SNOWFALL COULD PRODUCE NEAR ZERO  
  VISIBILITIES FOR COMMUTERS ON INTERSTATES 25 AND 80 IN SOUTHEAST  
  WYOMING AND SOUTHERN NEBRASKA PANHANDLE.  
  
* IMPACTS...SHOULD THE FORECAST SNOW ACCUMULATIONS MATERIALIZE AS  
  FORECAST...TRAVEL COULD BE SIGNIFICANTLY IMPACTED ALONG  
  INTERSTATES 25 AND 80 FROM SIDNEY TO ARLINGTON. ROADS WOULD  
  BECOME VERY SLICK AND HAZARDOUS WHERE SNOWFALL IS HEAVIEST.  
  HUNTERS AND OTHER OUTDOOR ENTHUSIASTS WILL BE IMPACTED BY THESE  
  WINTRY CONDITIONS AND ARE ENCOURAGED TO EXERCISE CAUTION IF  
  VENTURING OUT TUESDAY EVENING THROUGH WEDNESDAY.  
  
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
  
A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT  
SNOW ACCUMULATIONS THAT MAY IMPACT TRAVEL. CONTINUE TO MONITOR  
THE LATEST FORECASTS.  

Denver, CO Watch Below:

...WINTER STORM WATCH IN EFFECT FROM TUESDAY EVENING THROUGH  
WEDNESDAY AFTERNOON...  
  
THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A WINTER STORM  
WATCH...WHICH IS IN EFFECT FROM TUESDAY EVENING THROUGH WEDNESDAY  
AFTERNOON.   
  
* TIMING...RAIN AND SNOW IS EXPECTED TO DEVELOP BY TUESDAY EVENING  
  AND THEN CHANGE TO ALL SNOW IN THE LATE EVENING HOURS AND  
  CONTINUE THROUGH WEDNESDAY.   
  
* ACCUMULATION/WIND...TOTAL SNOW ACCUMULATIONS IN EXCESS OF 6  
  INCHES WILL BE POSSIBLE. SIGNIFICANT WINDS ARE NOT ANTICIPATED.  
  
* MAIN IMPACT...HEAVY WET SNOW MAY ACCUMULATE ON TREES...RESULTING  
  IN BROKEN TREE LIMBS AND POWER OUTAGES.  
  
* OTHER IMPACTS...ROADS MAY BECOME SNOW AND SLUSH COVERED  
  ESPECIALLY DURING PERIODS OF HEAVIER SNOWFALL.  
  
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
  
REMEMBER...A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR A  
HAZARDOUS WINTER WEATHER EVENT IN AND CLOSE TO THE WATCH AREA.   
SIGNIFICANT SNOW ACCUMULATIONS MAY OCCUR THAT COULD IMPACT  
COMMERCIAL POWER OR TRAVEL. STAY TUNED TO THE NATIONAL WEATHER  
SERVICE OR YOUR LOCAL NEWS MEDIA FOR THE LATEST UPDATES AND  
POSSIBLE WARNING CONCERNING THIS POTENTIAL WINTER STORM.

NCEP CFS Falls Off the Charts

The Average line for how strong this year's La Nina could get has fallen off the charts, or below -3, which would be a very strong La Nina. Luckily, the CFS version 1 is more unreliable than the newer CFS version 2, which is below.

It still predicts a stronger Nina, but not nearly as strong as the CFS version 1.

ECMWF May be Indicating Snowy Period for Lower Great Lakes October 19

The 12z ECMWF model is printing an interesting solution. At 7 am October 19th, the ECMWF shows considerably high relative humidity values fairly close to the surface while the 540 line (line that theoretically separates rain and snow) has collapsed southward, allowing for a rush of frigid air to invade the Great Lakes. These relative humidity readings got me thinking: Does this mean the ECMWF is pointing towards snow? And since this is the best ECMWF in terms of maps we have available, I do believe that there is potential for snow in the areas in green, especially in darker green shades in the lower 2 images, which are relative humidity images.

12z GFS Depicts 3 Stronger Lows Going Thru Central/South Illinois in Eerily Similar Track- Coincidence or Pattern?

The 12z run of the GFS has brought to our attention something potentially significant. This GFS run shows 3 storms (on the stronger side) all going through Central/South Illinois over the course of 16 days. Of those 3 storms, only 2 are considered in the realm of possibility- the 3rd storm is forecast about 13 days away. 13 days away is not reliable in the least.

What does this mean?
If this 12z GFS run verifies, it very well could be a new part of the LRC (Lezak Recurring Cycle). The LRC is a pattern that sets up between the October 1st period and November 10th period. This LRC is an annual occurrence and is NEVER THE SAME. While it may possess similar traits as the year before, no one pattern is ever the same. Since we are in the LRC forming timeframe, this does ultimately lead to the question: Is this going to be a pattern for the entire winter??
We will keep you updated with a post on the new 18z run that will come out shortly.

Prospects for Snow in Midwest/Ohio Valley Rising as ECMWF Joins Snow 'Camp'

Pre-Reading Notes:
Vocabulary: 'Camp' is a term you will hear often this winter if you read this blog frequently. In the weather enthusiast world, a 'camp' is defined as a group of models favoring one solution to a weather event over another group. Example: The ECMWF/GFS models are in the snow camp vs the GEM model in the rain camp. In the example, the ECMWF/GFS are favoring snow for an area versus the GEM model favoring rain for the same area in the same time frame.
(end pre-reading notes)

The ECMWF has joined the camp of models favoring a cold blast following a strong low pressure system. In the midst of that cold blast, some precipitation may still be ongoing on the back of that low, introducing the seasons first snow flurries for the region. Here's the latest 12z ECMWF model.

Hour 192 (October 19)

The top right image is the one of most importance. The dashed red line sinking down below the Great Lakes region is referred to as the 540 line. It is basically the line where, theoretically, rain switches to snow for areas north of the 540 line. Another dashed line farther south isn't something we need to worry about.
The 12z GFS is now predicting a slightly higher amount of snow for cities like Chicago and Gary, IN for this 12z run. Below is the predicted snow depth for Hour 192- the same timeframe as the ECMWF image above.

The GFS is predicting as much as over an inch of snow to fall in areas close to Lake Michigan extending eastward into Ohio, Michigan and even into New York. Below is the GFS's take on the 540 line.

The blue area is considered the air north of the 540 line, so the separating boundary/540 line is the green/light blue border on the map above.

What do we expect from this system? We really don't want to say much as it is still a while off and winter weather is harder to forecast for the models, but as of right now, the areas above are looking at a fairly good chance for snow for the time being.

CFS Long-Range Model Depicts East SD with -21 degree temperatures

Pre-reading notes: This image is for November 18th and will not happen. Don't even consider this happening because it is way way too far out.

This is a pretty cool image we uncovered from the ridiculously long range CFS model that shows Eastern South Dakota in the middle of a -21 degree F. temperature on November 18th. We show this because it is considered a pretty cool thing in our eyes. Again- this will not turn out due to its long range extent.

ECMWF showing potential for cold blast into Great Lakes; Could Winter be near?

The latest ECMWF model is showing two strong low pressure systems quickly putting an end to the 80's currently being reached over the Midwest and instead bringing in potentially temperatures near freezing levels. With the forecasted strength of these two lows, I wouldn't be surprised if it turned out. The eventual strength may depend on the forecast tropical system that may develop in the Florida region and potentially move inland at some point.

SnowCAST- September 29, 2011 (Valid September 31, 2011)

We have been watching the potential of snow for the last several days in the Northeast, and it now appears likely there will be some snow, possibly accumulating, in the Northeast region. If there is to be any accumulation, totals will be at or below 2 inches, with the best chance for accumulation in the West Virginia area. The region outlined in lighter blue is where flurries are possible, but where accumulation is unlikely or will be below .5 inches.
Any accumulation that does occur will melt quickly.

Pennsylvania, New York could get in on some Snow by Sunday

There is potential for some snow flakes to begin flying in parts of West New York and Pennsylvania. The image below shows projected surface precipitation on Saturday at 8 AM EDT. The blue dashed line is what's known as the 540 line- the line typically separating rain and snow areas. Places south of the 540 line get rain, regions above the 540 get snow. Below is the image for Saturday at 8 AM EDT.

If you look closely, you can see the blue dashed line sagging southward and encompassing portions of New York and Pennsylvania. That said, there is indeed a potential for snow. The question is- how much?
Many of you probably aren't ready for winter (mentally or physically), but the good thing is that any snow that happens to fall will melt, as that 540 line will fly back north into Canada. Here's the details as of now:

-The models are not forecasting any snow to fall
-There is potential, but it is low
-Flakes flying in the air if this turns out is a possibility
-Accumulation above .1 inches is unlikely for now.

Winter is Coming... Series- What is a clipper snowfall system? Q/A

Average Clipper Track

Q: What is a 'clipper'?
A: Called an Alberta Clipper in its formal name, the clipper is a snowfall system that drops from Alberta, Canada and affects the Upper Midwest. It is a fast-moving low pressure system that can bring much colder temperatures behind its passage. Due to the fast movement, snowfall amounts are typically low, but have been known to go above 6 inches.

Q: How much snowfall can typically be expected from a clipper?
A: Usually 1-3 inches of snow due to the moisture-starved nature and fast movement of the storm. A stronger clipper can put down 6 inches or more, but that is more infrequent.

Q: How much can temperatures plummet after the passage of a clipper?
A: It is typical for temperatures to freefall 30 degrees right after the passage, accompanied by nasty winds.