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Winter Storm Set to Impact the Northern Plains Christmas Day and Boxing Day

Posted by Near Zero Probability Chasers on December 22, 2016 at 1:25 AM Comments comments (0)

As questions came pouring in this morning about the upcoming storm system for Christmas Day and Boxing Day, here is an update on what to expect. Before you read this, please keep in mind that a slight shift in the track of the Low pressure system could mean that you could possibly not be impacted at all by this system. Also, while we generalize “southern Manitoba”, your exact location may experience less or worst conditions, this isn’t a specific forecast. Please keep in mind that we will refine the forecast as the storm nears and finer-scale models come in range.



Feel free to skip to the conclusion if you want to quickly get the main points.




Northern Plains



The European model depicted above has been somewhat consistent in the placement of the Low. As it sits right now, it’s looking like a Sunday to Monday type of storm for the Northern Plains. For southern Manitoba, I’m thinking snow should start sometime Sunday morning with light snow throughout the day and moderate to heavy snow through the evening and overnight hours. This could impact your Christmas Day drive  from whichever celebration you are coming back from!



I have attached a picture of the American model below. After looking at several model runs, this looks fairly consistent. However, the placement of the Low is again critical to which areas receive the highest snowfall. The picture below depicts a typical area of highest snowfall just north of the Low in North Dakota and on the backside of the Low somewhere south of Bismarck, ND. The backside of the Low is usually where blizzard conditions are possible. 




Personally, I think it is far too early to talk about snowfall totals without the NAM model and its finer-scale depiction of the situation. Please monitor our Facebook page daily as we update you on the situation. Here are the thoughts of the National Weather Service in Grand Forks, ND:


 

"FINALLY...CONFIDENCE IS INCREASING IN A SIGNIFICANT WINTER STORM IMPACTING THE AREA FOR CHRISTMAS DAY. HEAVY SNOW...BLOWING SNOW AND MIXED PRECIPITATION ARE ALL POSSIBLE WITH THIS SYSTEM BUT DETAILS AS TO WHERE ARE STILL UNCERTAIN AT THIS POINT. REGARDLESS...IMPACTS TO TRAVEL WILL BE LIKELY FOR THE CHRISTMAS DAY HOLIDAY AND INTO MONDAY." -NWS



I have also attached below The Weather Network's opinion on the subject, which I tend to agree with, as well as the link for the entire article:


https://www.theweathernetwork.com/news/articles/boxing-day-blizzard-to-batter-parts-of-central-canada-/77172/





Conclusion


You will start seeing several media outlets and weather pages on Facebook advertising snowfall totals and forecasting blizzard-like conditions for the Northern Plains, however keep in mind that Colorado Lows are highly unpredictable. Even though models have actually been pretty good this year forecasting the several major storm systems we have seen so far, a small change could mean a very different snowfall amount for your location.



What we know


A storm system should impact most of the Northern Plains this weekend. Main impacts should be felt Sunday (Christmas Day) and Monday (Boxing Day). Tight pressure gradients could lead to blizzard-like conditions on the backside of the Low in the Dakotas and maybe southern Manitoba depending on the track. Will this be the storm of the century? Probably not.



Potential Impacts and timeframe


Potential impacts are pretty high simply due to the fact that there will be a lot of people travelling during this storm. Therefore, even only a few inches could be impactful. People travelling anywhere in southern Manitoba, North Dakota, South Dakota, Minnesota and parts of northwest Ontario on Sunday night should monitor road conditions or make alternative plans to stay put. However, southern shift in track of the Low could mean minimal impacts for Winnipeg and surrounding areas.


Timing should be from Sunday to Monday (generally). For southern Manitoba, you're roughly looking at Sunday evening/night seeing the most snowfall and blowing snow (possibly blizzard-like conditions) on Monday, especially in the southeastern part of the Province.

Severe Weather Threat for the Prairies; Daily Breakdown

Posted by Near Zero Probability Chasers on June 7, 2016 at 1:15 AM Comments comments (0)

It's warm, humid and nice out in the Prairies! Well that also usually means that storm season is upon us. It looks like this year has been an early one for Saskatchewan and Manitoba with multiple reports of funnel clouds, landspouts and severe thunderstorm watches & warnings being issued. The first major threat for severe weather as advertised by us almost a week ago, will be this upcoming week. The main culprit will be this upper level trough set to eject from the west coast into the eastern Prairies. Usually, we see this pattern starting to set up in the end of June and into July. This is the earliest I have seen the Prairies get a "big setup". Below is the daily breakdown of what to expect. 


P.S. - We focus on Saskatchewan and Manitoba since this will be the areas we will be chasing in. No detailed discussion will be written about Alberta's severe weather threat even though it does exist for the earlier part of this week. 






Today and Tuesday


- Severe thunderstorms may errupt in Alberta along the foothills due to the extremely warm and unstable airmass. Here is the Prairie and Arctic Storm Prediction Center's (PASPC) forecast for both days: 


 

DESPITE GENTLY FALLING HEIGHTS, WITH THE RIDGE NEARBY, IT WILL LIKELY

TAKE A) SYNOPTIC-SCALE LIFT FROM THE IMPULSE, B) CONVERGENCE NEAR THE

SURFACE TROUGH/LOW, AND/OR C) UPSLOPE EASTERLY FLOW TO INITIATE

CONVECTION. IF STORMS DO INITIATE, THEY WILL BE IN AN ENVIRONMENT OF

1000 TO 1500 J/KG MLCAPE AND 40 KNOTS OF BULK SHEAR, SUFFICIENT FOR

SUPERCELL DEVELOPMENT. HIGH BASES, AROUND 8 KFT AGL, WILL ENSURE THE

MAIN THREATS FROM THE STORMS WILL BE HAIL AS BIG AS GOLF BALLS AND

WIND GUSTS IN EXCESS OF 100 KM/H. STORMS ARE EXPECTED TO FORM

SOMEWHERE IN THE VICINITY OF EDSON TO SLAVE LAKE AND TRACK DUE EAST

OVER THE COURSE OF THE EVENING. NOCTURNAL STRENGTHENING OF THE

LOW-LEVEL JET IS EXPECTED TO OCCUR, AND A STRONG-TO-SEVERE MCS MAY

PERSIST INTO WESTERN SASKATCHEWAN OVERNIGHT.

FARTHER SOUTH ALONG THE TROUGH, INITIATION IS MORE QUESTIONABLE WITH

WEAKER FORCING ALOFT, ALTHOUGH MANY OF THE CAMS DEPICT INITIATION

AROUND 21Z. SHEAR WON'T BE AS STRONG AS FARTHER NORTH, SO IF STORMS

DO INITIATE, EXPECT MULTICELLS OR MARGINAL SUPERCELLS WITH HAIL AND

WIND UNTIL NOCTURNAL COOLING OCCURS.

ON TUESDAY AFTERNOON/EVENING, A ROUND OF SEVERE THUNDERSTORMS IS

LIKELY OVER THE SOUTHERN THIRD OF ALBERTA. A SOUTHWARD-DRIFTING LOW

PRESSURE SYSTEM WILL TAKE THE SHEAR, MOISTURE, AND CONVERGENCE ALONG

WITH IT. DEEP-LAYER SHEAR ON THE ORDER OF 40 KNOTS COBINED WITH

MLCAPE AROUND 1500 J/KG WILL PROMOTE HIGH-BASED SUPERCELLS WITH LARGE

HAIL AND DAMAGING WINDS. THE RISK OF SEVERE THUNDERSTORMS WILL BE

ENHANCED JUST NORTH AND EAST OF THE LOW/NEAR THE EFFECTIVE

FRONT/POSSIBLE OUTFLOW BOUNDARY LATE IN THE AFTERNOON, WHERE THE

SHEAR AND INSTABILITY WILL BE MAXIMIZED. CONVECTIVE EVOLUTION AND

THE LOCATION OF OUTFLOW BOUNDARIES FROM DAY 1 WILL PLAY A VITAL ROLE

IN FOCUSING THE AREA OF CONCERN." - PASPC (http://kamala.cod.edu/Canada/latest.focn45.CWWG.html)


Wednesday


Wednesday the threat shifts into Saskatchewan and Manitoba. Relatively high moisture (dew points) and surface heating should give way to moderate instability, especially near the Saskatchewan and Manitoba provincial border. Supercells (possibly high based) may develop somewhere near Regina and move southeast (similar to last Friday). Tornado threat is relatively LOW at this time due to the lagging of the Low, which should be further west (unless a faster model solution occurs). However, supercell threat is MODERATE due to relaltively high instability. Any storms that pop up during the afternoon and evening hours should have no problem becoming severe and supercellular.


Instability chart



Simulated radar for 4pm CDT 





Thursday


Thursday is the bigger day out of the week essentially because all the ingredients for tornadic supercells seem to be in place. Significant instability values in the upper 3000 to 4000J of Convective Available Potential Energy (CAPE) is forecast. Instability is the spark that makes storm explode as they form, this is the first thing to look at for thunderstorms and more specifically severe thunderstorms. We already know the forcing is there (first image above), so the trigger for the storms to form should not be an issue. The main difference with Thursday is that the Low will be near the instability, therefore mid to low level winds will support any storm that explodes and will make it rotate, thus creating supercells. If supercells do emerge, they should have no problem being long-lived supercells with lower cloud bases. For this reason, tornado threat is MODERATE with any storms that errupt and is sustainable in that environment. Supercell threat is HIGH due to the impressive kinematics and thermodynamics in place in southern Manitoba. Hard to say at this time where the storms will errupt. It could be anywhere in southern Manitoba at this time and even near the SK/MB border. If the Low can manage to get closer to the SK/MB border as the first image below depicts, then a higher tornado threat could arise. 


Moisture content & positioning of the Low (two different models)





Instability chart




700MB Shear chart




Friday

Southern Manitoba could still see the threat of strong to severe thunderstorms as the Low slowly moves east. A bigger threat may be further south into North Dakota depending on how fast the Low moves east. Still a few discrepancies in models so won't go into too much details. Supercell threat is MODERATE, especially for the southeast corner of Manitoba and tornado threat is LOW due to lack of model input but could be higher as the day nears.



Instability chart





Saturday & Beyond

Low should move out the Prairies and give us fairly quiet weather. Some strong to severe thunderstorms will be possible further south into the Northern Plains, however the threat could easily shif north and impact southern Manitoba. Will keep you updated. 





Keep updated to our facebook page where we will post regular updates as each individual event nears: https://www.facebook.com/NZPChasers/



SOURCES


http://weather.cod.edu/forecast/

http://www.pivotalweather.com

http://www.twisterdata.com


After the omega, severe weather ramps up

Posted by Near Zero Probability Chasers on April 15, 2016 at 4:40 PM Comments comments (1)

The "omega blocking pattern" currently in place in the US should dominate the weather pattern until around mid week next week where it should slowly move east and out of the Plains but not before delivering several rounds of severe weather to the Plains as well as very heavy rain. Once it moves out, more robust severe weather should take place as the peak of the tornado season arrives. As it sits right now, there seems to be two major troughs ejecting almost one after the other behind this omega pattern.


"Omega blocking pattern" depicted below:




WHAT WE KNOW:


There seems to be a pretty potent and significant severe weather event in the latter part of April. Right now, it seems to have been pushed back later than we previously thought due to the slow progression of the omega blocking pattern set to affect the central Plains this weekend and linger up until early next week. Once this trough finally moves out of the CONUS, another more potent trough should eject (see images below) in the west sometime around mid next week and ramp up near next weekend. The omega pattern this weekend isn't as favorable due to relatively stationary feature of the front giving lots of clouds and favoring heavy rain events, therefore limiting instability and the general severity of the event. However, should see some tors regardless. Next weekends trough looks very different.




WHAT WE DON'T KNOW:


The exact timing of next week's omega pattern moving out of the CONUS and the second major trough ejecting is still relatively unknown at this time. Too many variables can affect which days this big severe weather event will occur (if it even occurs). The biggest concern is the flow aloft and the timing of the trough which is too far out to know with certainty with using only medium-range models (GFS/ECMWF/ensembles). High CAPE values depicted could very well mean strong cap inversion preventing storm development as well, it's not because high CAPE & high dews that storms will occur.



GENERAL SETUP DISCUSSION (from what we know):


As previously mentioned, the significant trough seems to eject later than previous thought. It seems to start to appear on the west coast around the 21st or 22nd of April. So why are we looking at this weekend if it will be near the west coast or deserts? Well pre-frontal instability and moisture return ahead of the trough should build up to (it seems like) pretty significant numbers as early as the 22nd (Friday). This could eject multiple dryline/warm front setups as well as pre-frontal troughs into the central Plains regions allowing for a multi-day event before the actual trough itself reaches the Plains allowing for kinematics to be maximized. Whether these will have enough forcing to initiate convection in the high-CAPE & dewpoints environment is less certain, but if storms do form in this environment you're looking at some pretty impressive storms. High-CAPE'd environments usually favor photogenic supercells and very large hail, however, as I have witnessed in Simla, it can always spawn multiple tornadoes as well due to high updraft and dews (4500J & 20kts of shear day).




CONCLUSION:


As it sits right now, we're looking at the April 22nd to April 25th time range for chase days, with April 21st possibly a less "big" day but also a possibility. Like I said, these days will most likely fluctuate since it's a week out. Also, there might be another significant trough ejecting after this one near the 25th time range. More info soon!


El Niņo and La Niņa Effects on US Tornado Outbreaks

Posted by Near Zero Probability Chasers on March 29, 2016 at 5:50 PM Comments comments (0)

El Niño and La Niña Effects on US Tornado Outbreaks

Francis Lavigne-Theriault

University of Manitoba

[DO NOT RECOPY]



1. Introduction

The everlasting debate on whether the El Niño Southern Oscillation (ENSO) effects tornadoes in the United States is a hard question to answer. Relatively poor instrumental and observational record and high variability of tornado reports each year make it even harder to identify a correlation between ENSO and tornadic activity in the United States (Allen, Tippett & Sobel, 2015). However, a general trend is found when studying older and newer data. El Niño years are found to have less violent tornadoes as well as less tornado outbreaks, while La Niña years are found to have more violent tornadoes as well as having a higher probability of tornado outbreaks (Knowles & Pielke, 1993). This paper will focus on tornado outbreaks occurring in the United States during both warm (El Niño) and cold (La Niña) ENSO phases. The probability of tornado outbreak occurrences, their intensity and when they are most likely to occur is also discussed. Identification of the cause/consequence relationship of changes in sea surface temperature (SST) and its modification of weather and climate throughout the continental United States will be discussed. These findings are presented as a possible long-range seasonal prediction method to severe thunderstorms (Allen et al., 2015).



2. Methodology

2.1. ENSO-outbreak classification for cold-season tornado outbreaks

In order to classify their results, Nunn & DeGaetanno (1998 ) established a basis for ENSO-outbreak relationships. Outbreaks were classified on a regional scale such as Deep South (Texas, Louisiana, Mississippi, Alabama, Georgia and Florida), Mississippi Valley (Wisconsin, Iowa, Missouri, Arkansas, Oklahoma and Kansas) and the Ohio Valley (Tennessee, Kentucky, Ohio, Indiana and Illinois). The regions were separated based on the similarities between climates. After obtaining the total amount of cold-season outbreaks that occurred in each region such as 90, 47 and 43 respectively, the next step was to classify the events by ENSO phases such as El Niño, La Niña and Neutral. After being classified, chi-squared tests were performed for each region. Expected results were put in brackets, while actual results were also described and classified in two categories such as above mean and at or below mean of the number of tornado outbreaks for each region regardless of ENSO phase. Chi-squared tests were then run based on ENSO phase. X2 values are seen to be a function of phase.



2.2. Tornado outbreaks by ENSO phase

Knowles & Pielke’s (1993) study included data collected from tornado reports between 1953 and 1989 where 1953 was selected as a starting point for the study since this was the first year the weather bureau started issuing tornado watches. Tornadoes occurring during downburst thunderstorms, squall lines, towering cumulus and the supercell were included in the study. The seven strongest El Niño and five strongest La Niña events were compared and classified into categories such as total number of tornadoes per year, median tornado track length in miles for violent tornadoes and number of violent tornadoes per year. A comparison of all El Niño and La Niña years is also included. 14 tornado outbreaks between 1953 and 1989 were also classified by strongest and all El Niño/La Niña phases, whereas a tornado outbreak is defined by 39 or more tornadoes during one event.



3. Results

3.1. Defining the El Niño Southern Oscillation (ENSO)

According to Allen et al. (2015), ENSO is characterized by changes in sea surface temperatures (SST) and atmospheric convection in the tropical Pacific. ENSO phases regulates global weather patterns and climate. Warmer than average Pacific sea surface temperatures is called the El Niño phase. Conversely, colder than average Pacific sea surface temperatures is called La Niña. ENSO influences precipitation and temperatures across the continental United States and Canada (Allen et al., 2015). El Niño usually brings colder than average temperatures to the Southeast United States and warmer than average temperatures to western United States as well as higher rainfall to both regions. Conversely, La Niña usually brings warmer than average temperatures for the Southeast and colder than average temperatures to western United States (Barnston, Livezey & Halpert, 1991). The oscillation between the warm and cold phases are referred to as the Southern Oscillation (Knowles & Pielke, 1993).



3.2. ENSO effects on continental weather and climate

Studies of sea surface temperature changes and the thermal response of the atmosphere suggest a “lag time” between SST change and atmospheric changes. According to Knowles & Pielke (1993), a lag of about three to five months is generally observed between the maximum SST in the Pacific and the atmosphere in the continental United States. Rasmusson et al. (1982) further adds that since the usual SST maxima occurs from January through June in the Pacific, the effects of El Niño and La Niña would therefore be felt from March through November in the United States. This time frame coincides with the most active period for tornadic activity in the United States, which is from April to July.



3.3. Defining modification of environmental factors during ENSO

ENSO modification of extratropical cyclones, precipitation, jet stream position and strength, surface temperatures and low-level moisture advection from the Gulf of Mexico can influence the environmental factors needed for tornadogenesis (Allen et al., 2015). Below are environmental factors, which are described to be less favorable for cyclogenesis and tornadoes during El Niño and more favorable during La Niña.



3.3.1. El Niño modifications

According to Allen et al. (2015), El Niño years favor less low pressure systems over the Plains while increasing low pressure system development and impacts in the southeast United States. Surface winds and warm moist air convergence from the Gulf of Mexico are weakened during El Niño years, which in turn allows cold arctic air to surge further south due to the southward shift of cyclogenesis. Significant decrease in moisture advection therefore decreases atmospheric thermodynamic energy needed for severe thunderstorms in the southern Plains. A more specific decrease in mixed-layer convective available potential energy (MLCAPE) and 0-3km storm relative helicity (SRH) is noted during El Niño years, both of which are key ingredients in tornadogenesis. Surface temperatures in the southern United States are cooler than -1°C and warmer further north, which opposes climatological temperature gradients (north-to-south) reducing probabilities of cyclogenesis east of the Rockies. Reduction of resistance to convection also reduces vertical instability. El Niño favors strong/deep ridges and troughs across the central United States, which in turns favors cooler than average temperatures for the southern US and warmer than average temperatures in the Pacific Northwest (Nunn & DeGaetanno, 1998 ).



3.3.2. La Niña modifications

According to Allen et al. (2015), lesser jet stream flow modification during La Niña favor the development of high pressure systems over the southwest due to stronger flow above the continent and reduced flow further south. La Niña favors greater northward moisture advection from the Gulf of Mexico, especially over eastern Texas and the southern United States, therefore increasing thermodynamic energy needed for severe thunderstorms over the continent. Increased southeasterly surface flow results in larger 0-3km storm relative helicity (SRH), giving way to a more favorable environment for severe thunderstorm development and tornadoes. La Niña surface temperature increase of greater than +1°C enhances the climatological north-to-south temperature gradient, which favors cyclogenesis. This increased surface temperature in turn increases MLCAPE and makes for steeper lapse rates, potentially increasing the resistance to convection. This in turn gives for a more favorable environment for tornadogenesis.



3.4. ENSO and tornado outbreaks

Grazulis (1993) defines a tornado outbreak as a series of tornadoes from the same storm system that occur with no more than six hours between each event. According to Nunn & DeGaetanno (1998 ), there were 180 major tornado outbreaks between 1950 and 1995 during the “cold season” in the Deep South (90 outbreaks), in the Mississippi Valley (47 outbreaks) and the Ohio Valley (43 outbreaks). Only outbreaks with F2 to F5 tornadoes were utilized in this specific study. Table 1 divides the aforementioned cold-season outbreaks based on their ENSO phase. Counting the number of seasons from 1950 to 1995, 15 were found to be El Niño, 8 La Niña and 22 Neutral. Each region’s outbreak was then separated by the phase of each season.



Table 1: Cold-Season Outbreaks by Region and ENSO Phase (Nunn & DeGaetanno, 1998 ). The ENSO outbreak were classified as described in methodology section 2.1.


 

Furthermore, statistical analysis of below, normal and above average tornado outbreaks per ENSO phase per year was calculated. Table 2 shows X2 values as a function of phase. All regions indicating an X2 less than one indicates a “normal” tornado outbreak season while X2 values of 5.07 indicates an above-normal tornado outbreak season. For all regions, the La Niña phase shows a strong correlation between a cold ENSO phase and an increase in tornado outbreaks while El Niño and Neutral remains around “normal” with the exception of the Ohio Valley, which sees an impressive increase in tornado outbreaks during Neutral phases.


Table 2: Statistical Distribution of Tornado Outbreaks by Regions (Nunn & DeGaetanno, 1998 ). Results are represented as described in methodology 2.1. Results represent the number of outbreaks per season in each category (above mean or at/below mean) in brackets are the expected number of outbreaks per season. X2 represents chi-squared tests as described in methodology 2.1.


 

In addition, Knowles & Pielke (1993) notes an average of 750 tornadoes per year occurred between 1953 and 1989, most of which occurred between March and August. However, one must count in the bias of poor reporting methods during this time period and the general “increase” in tornado reports from that time until today. Table 3 depicts the overall tornado summary classified by ENSO phases from strong El Niño to strong La Niña as well as all El Niño and La Niña events between 1953-1989. Tornado outbreaks are also depicted. Tornado outbreaks are hereby defined as 39 tornadoes or more occurring during one event.


Table 3: List of specific Averages by Event Type (Knowles & Pielke, 1993). Summary of overall tornadic activity between 1953 and 1989 in the United States categorized by strongest El Niño and La Niña years as well as all El Niño and La Niña years and related tornado outbreaks during that period. Violent tornadoes are described as F4-F5 strengths only. Tornado outbreaks are shown and classified by phase whereas 39 or more tornadoes occurred in a single event.


 

According to Knowles & Pielke (1993), violent tornadoes (F4-F5) and tornado outbreaks were much lower during El Niño years and much higher than “normal” during La Niña years between 1953 and 1989. El Niño years average around 7.8 violent tornadoes while La Niña years average around 12.6 violent tornadoes. During the 14 tornado outbreaks of 39 tornadoes or more, zero occurred during strong El Niño years and three have occurred during strong La Niña years. Out of the 14 outbreaks, 11 occurred during La Niña events while only three occurred during El Niño events regardless of strength of the ENSO phase.



4. Discussion

As noted by Nunn & DeGaetanno (1998 ), El Niño’s effect on the polar and subtropical jet and the increase in convective activity offshore of Western/Central America leading to the formation of upper-level lows lead to tighter pressure gradients between Central American lows and strong Alaskan high pressures that tend to form during a northward retreating polar jet with a sharp baroclinic zone between the warm tropical Pacific waters and the cool subtropical waters, which were found to increase the speed of the subtropical jet. This, combined with increased moisture transport in the southern United States and northern Mexico has been found to increase storm intensity for northern Mexico and southern California and lead to wetter than normal conditions in the Gulf States. During La Niña years, the polar jet becomes stronger while a generally weaker subtropical jet is observed. The polar jet therefore dominates the synoptic pattern in North America. Warmer and drier conditions are observed in the southern US. Increased baroclinity between warm and cold air masses favor an increase in both strength and numbers of synoptic-scale development.

According to Knowles & Pielke (1993), the year-to-year average of all tornado counts are generally constant, but when studying the violent tornadoes and tornado outbreak criteria, the numbers become statistically significant.

The method for long-range tornado prediction consists of analysing winter ENSO phases and creating a probabilistic forecast for the March to May severe thunderstorm season. According to Allen et al. (2015), there is a clear statistical correlation between March to May tornadoes associated with moderate to strong December to February ENSO phases. This information is then used to create a forecast for tornadoes based on past similar ENSO conditions. This suggests that for moderate to strong ENSO phases, above average or below average tornado activity across the United States can be predictable based on the ENSO pattern into the following spring.



5. Concluding Remarks

Statistical evidence seems to support the fact that ENSO cold phases (La Niña) contribute to environmental conditions that are more favorable for violent tornadoes (F4-F5) as well as significant tornado outbreaks in the United States, while warm (El Niño) and Neutral ENSO phases seem less favorable. However, there are some exceptions such as in the Ohio Valley during Neutral phases, which seem more favorable for tornado outbreaks. Better environmental ingredients conductive to tornado outbreak evolution exist during La Niña events. Environmental conditions such as the weakening of the subtropical jet and domination of polar jet favoring stronger cyclonic development, stronger pressure gradients, better vertical thermodynamic energy such as MLCAPE and 0-3km storm relative helicity (SRH) and better northward moisture transport from the Gulf of Mexico are most favorable for tornado outbreaks and strong tornadoes during La Niña phases. Statistical analysis of both cold-season and spring-season tornado outbreaks found that La Niña years favor more violent tornadoes as well as more significant tornado outbreaks of 39 or more tornadoes. Aforementioned causes of sea surface temperature (SST) modifications and its consequential effects on continental atmospheric conditions in the United States can lead to long-range predictions for severe thunderstorms and tornadoes as proposed by Allen et al. (2015). However, more research would need to be done on ENSO phases and effects on tornadic activity for one to provide any solid conclusions. Our reporting methods and technological advancements in the past 20 years have drastically improved our understanding of tornadoes and ENSO phases and new research such as the one by Allen et al. in 2015 would need to be repeated for long-range prediction methods. Research focusing on spring tornadoes such as the one currently being done by the VORTEX projects in the United States can provide more insights as to how SST changes affect the peak of the tornado season as well as cold-season tornado intensity and outbreaks. I would have liked to also see more research done on ENSO and tornadoes in the northern Plains and Canada. I found almost no research being conducted on the subject in these areas. This would be an interesting subject of future research projects.



 

 

 

 

 

 

 

 

 

References

Allen, J. T., Tippett, M. K. & Sobel, A. H. (2015). Influence of the El Niño/Southern Oscillation on tornado and hail frequency in the United States. Nature Geoscience.

Barnston, A. G., Livezey, R. E. & Halpert, M. S. (1991). Modulation of Southern Oscillation – Northern Hemisphere Mid-Winter Climate Relationship by the QBO. J. Climate, 4, 203-217.

Grazulis, T. P. (1993). Significant Tornadoes 1680-1991. Tornado Project of Environmental Films.

Knowles, J. B. & Pielke Sr, R. A. (1993). The Southern Oscillation and Its Effect On Tornadic Activity in the United States. Colorado State University: Department of Atmospheric Science, Paper No. 755.

Nunn, K. H. & DeGaetano, A. T. (1998 ). The El Nino Southern Oscillation and Its Role in Cold-Season Tornado Outbreak Climatology. Cornell University, Ithaca, NY, USA. Paper presented to the American Meteorological Society, 1998.

Rasmusson, E. M. & Carpenter, T. H. (1982). Variations in Tropical Sea Surface Temperature and Surface Wind Fields Associated with the Southern Oscillation El Niño. Monthly Weather Review., 110, 354-384

 

 

 

 

 


 

Severe Thunderstorm Watch 33

Posted by Near Zero Probability Chasers on February 29, 2016 at 9:05 PM Comments comments (0)

URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 33

NWS STORM PREDICTION CENTER NORMAN OK

735 PM CST MON FEB 29 2016

 

THE NWS STORM PREDICTION CENTER HAS ISSUED A


 

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

SOUTHWEST THROUGH NORTHEAST OKLAHOMA

WESTERN NORTH TEXAS


 

* EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 735 PM

UNTIL 400 AM CST.


 

* PRIMARY THREATS INCLUDE...

SCATTERED LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL EVENTS

TO 2 INCHES IN DIAMETER POSSIBLE

SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE


Tornado Watch 27

Posted by Near Zero Probability Chasers on February 25, 2016 at 1:50 AM Comments comments (0)

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 27

NWS STORM PREDICTION CENTER NORMAN OK

145 PM EST WED FEB 24 2016

 

THE NWS STORM PREDICTION CENTER HAS ISSUED A


 

* TORNADO WATCH FOR PORTIONS OF

SOUTHEAST MARYLAND

EASTERN NORTH CAROLINA

SOUTHERN AND SOUTHEAST VIRGINIA

COASTAL WATERS


 

* EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 145 PM

UNTIL 900 PM EST.


 

* PRIMARY THREATS INCLUDE...

A FEW TORNADOES LIKELY WITH A COUPLE INTENSE TORNADOES POSSIBLE

SCATTERED DAMAGING WIND GUSTS TO 70 MPH LIKELY

ISOLATED LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE


 

IN PICTURES: South Dakota Blizzard 2016

Posted by Near Zero Probability Chasers on February 4, 2016 at 7:45 PM Comments comments (0)

As you may or may not not, on February 2nd I headed down towards Sioux City, IA area to document the significant snowfall/blizzard event. Although the bulk of the snow had already fallen across the area, namely Nebraska/Iowa/southeast South Dakota, I still headed down to document the high snowdrifts due to strong winds in the area.


I left Winnipeg, MB around 1:30pm CST. At the time, heavy snow was already being reported. Below you can see a 16" snow report in northeast Nebraska. I was headed for Sioux City, however the highway from Sioux Falls to Sioux City (red line below) was closed. Therefore, I stayed around the side roads. 





BEFORE


When I crossed the border and entered North Dakota, I bagged a nice sun halo, but didn't have time to stop!! 


 


DURING




Near Sioux Falls, SD


These were the conditions just south of Sioux Falls around 11pm. This is a town next to where the interstate 29 was closed. At this location I encountered the first person in the ditch requiring assistance.

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Harrisburg, SD


After gasing up in Sioux Falls, SD and eating, I started to head south until I hit the closed interstate 29 point. I then hit the side roads. The first major encounter was in Harrisburg, SD where people were getting stuck getting home!! The local sheriff was there calling tow trucks and I helped him by searching the surroundings and letting him know if I saw anyone trapped. I stumbled upon this building and it reminded me of The Day After Tomorrow!!


As I ventured around town I stumbled upon this snowplow. The funny thing is the sheriff had called and was waiting for a snowplow to come rescue the stranded people from earlier. Hopefully, he wasn't waiting on him hahah!!




Worthing, SD


As I headed south I encountered intense snowdrifts on the 115 south and almost got stuck a few times as you can see in the video below.


This video is being managed exclusively by Newsflare. To use this video for broadcast or in a commercial player go to: http://www.newsflare.com/video/61780/weather-nature/roads-rendered-impassable-following-heavy-snow-storm-in-south-dakota-usa or email: [email protected] or call: +44 (0) 8432 895 191


I then entered Worthing. A small town in South Dakota that was completely deserted once I got there. Below you can see pictures of a scene seemingly taken from the movie The Day After Tomorrow.





I-29 Closed for Business


As I moved on to other towns, I crossed I-29, which was closed at the time. You can see the conditions on the roadway and why they decided to close it down.





Chevrolet Dealership


After crossing I-29 I stumbled upon an isolated car dealership and the snowdrifts between the row of cars were awesome!!





Canton, SD


East of Worthing I encountered some of the worst conditions of my trip. This car below was abandoned in the middle of an intersection! This was just west of town and pretty impressive.


You can see below in the video the conditions as I entered the town's main street (click link below):


http://www.newsflare.com/video/61782/weather-nature/entering-canton





Cars Abandoned (Video)


Although I didn't film all of them, I encountered at least a dozen cars stranded during my journey. Unfortunately, I made the mistake of crossing the river into Iowa after Canton and spent a good 2hrs trying to find a road back into South Dakota to take I-29 back home. I finally found a road that was passible before getting stuck twice and crossed back into South Dakota. However, the interstate was still closed and had to wait at a truck stop like everyone else until it was reopened at 8am CST. 

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Tornado Watch 4

Posted by Near Zero Probability Chasers on January 17, 2016 at 12:50 AM Comments comments (0)

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 4

NWS STORM PREDICTION CENTER NORMAN OK

1245 AM EST SUN JAN 17 2016

 

THE NWS STORM PREDICTION CENTER HAS ISSUED A


 

* TORNADO WATCH FOR PORTIONS OF

CENTRAL AND SOUTH FLORIDA INCLUDING THE KEYS

COASTAL WATERS


 

* EFFECTIVE THIS SUNDAY MORNING FROM 1245 AM UNTIL 800 AM EST.


 

* PRIMARY THREATS INCLUDE...

A FEW TORNADOES POSSIBLE

SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

Tornado Watch 572

Posted by Near Zero Probability Chasers on December 27, 2015 at 3:50 PM Comments comments (0)

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 572

NWS STORM PREDICTION CENTER NORMAN OK

240 PM CST SUN DEC 27 2015

 

THE NWS STORM PREDICTION CENTER HAS ISSUED A


 

* TORNADO WATCH FOR PORTIONS OF

SOUTHERN ARKANSAS

WESTERN AND CENTRAL LOUISIANA

EASTERN TEXAS


 

* EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 240 PM UNTIL

1000 PM CST.


 

* PRIMARY THREATS INCLUDE...

A FEW TORNADOES POSSIBLE

SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

ISOLATED LARGE HAIL EVENTS TO 1 INCH IN DIAMETER POSSIBLE


Tornado Watch 569

Posted by Near Zero Probability Chasers on December 27, 2015 at 1:40 AM Comments comments (0)

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 569

NWS STORM PREDICTION CENTER NORMAN OK

1235 PM CST SAT DEC 26 2015

 

THE NWS STORM PREDICTION CENTER HAS ISSUED A


 

* TORNADO WATCH FOR PORTIONS OF

WEST-CENTRAL ARKANSAS

SOUTH-CENTRAL INTO SOUTHEAST AND EAST-CENTRAL OKLAHOMA

NORTH-CENTRAL AND NORTHEAST TEXAS


 

* EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 1235 PM

UNTIL 800 PM CST.


 

* PRIMARY THREATS INCLUDE...

A FEW TORNADOES POSSIBLE

ISOLATED VERY LARGE HAIL EVENTS TO 2 INCHES IN DIAMETER POSSIBLE

ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE



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