Severe Weather Outlook for Monday March 30, 2012

The weekend will be quiet and warm.  Highs in the 80′s and 90′s are expected; however, a cold front arrives on Monday night, and that’s causing concern for strong to severe storms.

Both the GFS and the NAM are very similar in story when it comes to Monday’s forecast.  We should be capped throughout the afternoon and quiet.  Moisture and heating will increase during the day causing the instability to rise dramatically.

Showers and storms will likely develop toward the late afternoon along I-35 where the dryline sets up.  The dryline is forecast to move east and will be the focus for showers and storms during the evening.

Those storms off the dryline could produce large hail, damaging winds, and tornadoes.  The timing for the storms looks to be from 6 p.m. to Midnight.

A lot can change from now until then, but if the ingredients do come together, this could be a big severe weather event.

Drew Michaels

“Follow us on twitter at “4029weather”

A Bump In The Road Ahead March 30, 2012

 

This week has been perfect weather wise. Temperatures have been warm, it has been dry and the forecast hasn’t changed much from day-to-day, but that is about to change. Our next storm system will shake things up a bit. The latest computer models are still going back and forth on the severe weather potential. At least for the moment the severe weather threat is there but it isn’t quite as dominate as what it looked like yesterday. The storm system will likely come in overnight Monday into Tuesday. The slow-moving storm wouldn’t completely move out till Wednesday late afternoon or evening. A repeat of the flooding rains we saw a week and a half ago are not expected but cooler weather will make a return even if it is brief. After highs in the 80s and 90s on Sunday and Monday, the temperatures will struggle to get out of the 60s with rain cooled air lingering on Wednesday. Enjoy the brief cool down…a couple months from now we might be wishing we had it

Ross Ellet

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Storms Chances for Monday Night… March 29, 2012

I’m going to piggyback off of Ross’ post from earlier today.  Finally the GFS has shown some run to run consistency.  The models are now trending slower with the passage of Monday’s cold front.  The front looks to arrive late Monday evening into Tuesday morning.

That changes the forecast a lot.  Instability will be maximized ahead of the cold front.  The storms will erupt as the upper level support rolls across eastern Oklahoma and western Arkansas.  The storm system will also increase the wind shear. 

With this type of set-up, strong to severe storms are forecast to develop Monday evening.  The strong wind shear would also support rotating storms capable of producing large hail and isolated tornadoes.

A lot can change with the timing of the next system, so keep checking the blog for further updates.

Drew Michaels

Follow us on Twitter at “4029weather”

Strong Thunderstorms Possible Monday March 29, 2012

There are still some inconsistencies in the weather data for next week’s storm system. The potential for severe weather in the Great Plains is high…the location and storm intensity are still up in the air at the moment. The computer models are showing different storm tracks and timing for the storm system. However, the GFS computer model from overnight (shown above) has the strongest part of the storm system moving over Oklahoma and Arkansas on Monday evening. That could be a bad set up for us here at home with severe weather. We will watch the weather data closely over the next few days for the latest timing and storm track, which could easily change. 

Temperatures are expected to cool down to the upper 60s to low 70s for highs by early next week. Lows could dip into the upper 30s in northwest Arkansas by Wednesday morning. At this point frost is not expected but that could change.

Ross Ellet

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Some Hail Basics….Severe Weather Season March 28, 2012

The severe thunderstorms have been rather limited so far this spring. Keep in mind our severe weather season goes through May, so there will be more opportunities for strong to severe thunderstorms.

Hail is a big threat across eastern Oklahoma nd western Arkansas.  Large damaging supercell thunderstorms have produced softball size hail; sometimes it’s so loud it’s hard for us to hear while we are on the air during severe weather coverage.

This is a graphic I took from the National Severe Storms Laboratory.  This map represents the probability of 2 inch size hail or greater.  Look at the bullseye across central and western Oklahoma! 

According to NSSL, the largest hailstone recorded in the US was in Aurora, Colorado.   It was 7 inches in diameter with a circumference of 18.75 inches. 

The most deadly hailstorm on record occurred in India on April 30, 1988, killing 246 people and 1600 domesticated animals.

There is no clear distinction between storms that do and do not produce hailstones. Nearly all severe thunderstorms probably produce hail aloft, though it may melt before reaching the ground. Multi-cell thunderstorms produce many hailstones, but not usually the largest hailstones. In the life cycle of the multi-cell thunderstorm, the mature stage is relatively short so there is not much time for growth of the hailstone. Supercell thunderstorms have sustained updrafts that support large hail formation by repeatedly lifting the hailstones into the very cold air at the top of the thunderstorm cloud. In general, hail 2 inches (5 cm) or larger in diameter is associated with supercells (a little larger than golf ball size which the NWS considers to be 1.75 inch.) Non-supercell storms are capable of producing golf ball size hail.

In all cases, the hail falls when the thunderstorm’s updraft can no longer support the weight of the ice. The stronger the updraft the larger the hailstone can grow.

Drew Michaels

Follow us on Twitter at “4029weather”

 

Another Summer Scorcher? March 28, 2012

The overall pattern has been brining above average temperatures for about the last year. The question is can it slow down or reverse in time for summer?

A moderate to strong La Nina has been partially to blame for the mild conditions. That pattern is now weakening and is expected to dissolve completely by late April to early May. Neutral conditions are expected to remain for the summer with a slight chance for a weak El Nino developing around mid Summer. An El Nino brings our part of the country cooler than normal weather on most years.

Given the current set up, and expected pattern shifts for the summer, we don’t see a clear signal for either above average or below average temperatures. In theory, summer temperatures should be within a couple of degrees of the average.

On the other hand, the Climate Prediction Center is favoring another hot summer.

This is their current summer outlook which shows a 33% chance of above average temperatures. Tell us what you think in the poll at the top of this post. Summer officially begins on June 20th.

Ross Ellet

Follow us on twitter “4029weather” 

30 Day Rainfall Totals March 27, 2012

Average rainfall for the month of March is right around 4 inches.  The entire area is at or above average when it comes to rainfall for the month.

The River Valley and Ouachitas had a surplus of rainfall over the last 30 days.  Mena saw several rounds of showers and storms with a total of over 11 inches.

Thankfully our area is void of any drought conditions, and that should continue throughout the rest of the spring.

Drew Michaels

Follow us on Twitter at “4029weather” 

A Strong Storm Could Rattle Our Streak Of Nice Weather March 27, 2012

A strong cold front is expected to move into the area next Monday. It is too early to know for sure, but that storm system has the potential to bring a round of severe weather before a push of cold air moves into the area. Timing is key for the storms on Monday. If they can hold off until the afternoon, the storms stand a much better chance of becoming severe.

The other issue is the cold air on the backside of the storm. At this point the computer models do not agree on the strength of the cold air. One computer model would only have lows falling to the 40s…the other computer model (shown below) shows the potential for a freeze. A freeze at this point could be destructive given the very early season blooms, and small fruit that has developed on trees.

Ross Ellet

Follow us on twitter “4029weather”

 

Interesting Tornado Stats…. March 26, 2012

I borrowed this graphic from NSSL researcher Dr. Harold Brooks.  2011 was a wild year all across the country when it came to tornadoes.  Here’s an interesting statistic.  The overall total path length for 2011 tornadoes was off the chart. 

There’s a good reason for the spike.  On average the U.S. reports 1,000 tornadoes each year; 2011 had over 1800 reports of tornadoes.  It’s easy to see the correlation between these two graphics.  Let’s hope that 2012 is nothing like last year. So far so good.

Drew Michaels

Follow us on Twitter at “4029weather”

More Record Highs Today March 26, 2012

More warmth will last all week-long. Today’s highs are expected to reach 81 in northwest Arkansas and 84 in the river valley. We will challenge the record highs on the books for today.

Ross Ellet

Follow us on twitter “4029weather”