Tuesday, May 29, 2012

Mess of Watches and Storms Lights Up Northeast

Real Time Watches
Several severe thunderstorm watches and even a tornado watch are in place in the Northeast as strong showers and storms move through the region. It is worth noting that a moderate risk remains in effect for portions of New England, as seen below.

The main risk for these storms are damaging winds, as shown by the Storm Prediction Center. It is well warranted, as many severe thunderstorm warnings indicate that the storms are able to produce winds in excess of 60 MPH.


Can a High Pressure in the US Provoke Tropical Activity in the Atlantic?

The concept was brought to my attention that a high in the eastern US or close to the tropics can heighten the potential for tropical systems to form. Today, I decided to act on that concept and see if it was true.

I decided to look at the 2011 hurricane season and use the date of formation to view 500mb maps. Sure enough, in a surprising majority of cases, the tropical system did form when a high pressure system was somewhere in the eastern half of the US.

Now, this was only discovered by me today (although I'm quite sure many others know about this topic), so I don't have too much information on it for now. However, high pressure in the eastern US would most likely act to divert the jet stream north to block any strong winds that may otherwise head to the Gulf and Atlantic. Lack of strong upper level winds is key to have tropical systems form. Additionally, it provides room for the moist, warm Atlantic and Gulf air to possibly rise and give off showers and storms, that may eventually turn into tropical systems.

I looked over the latest ensembles for today, and it does look like a ridge of high pressure will soon return to the eastern US, which may very well give the tropics some room to act up.

Again, this is very preliminary, and I am conducting ongoing research. In my eyes, this could enhance tropical weather forecasts in the future, but let's not get too carried away.


'High' Risk of Storms Outlined for Tomorrow in South Plains

With tomorrow's heightened alert by the Storm Prediction Center, I have decided now is a good time to debut The Weather Centre's new storm alert system. Basically, if I see a risk of severe weather is on the horizon, after peering over the models, I will outline areas using the colors on the lefthand part of the screen. Keep in mind this key is only for the risk of storms, as in thunderstorms. When you get into the 'elevated' region is when severe storms become possible.

I have outlined northern Texas and much of Oklahoma under the 'High' risk of thunderstorms, seeing as instability has skyrocketed from the 0z GFS to the 12z GFS. In addition to as much as 4500 j/kg of instability with very little cap to stop storms from forming, shearing on the order of 30 to 50 knots is possible in these areas, leading me to believe that initial storms forming along the dry line may very well be supercells. Eventually, a more large hail risk should develop, and this will be the big risk. Instability as high as 4500 j/kg will promote very strong updrafts. These updrafts will keep pushing rain back up into the clouds to form larger and larger hailstones.

This is not a product of the SPC, NWS, or any government weather service. This is meant as a guidance product and should not be used in place of official government products.


Moderate Risk Issued for Tomorrow, May 30

Overall Potential for Severe Weather

Probability of severe weather
There is a 45% chance of severe weather within 25 miles of any point in the northern Oklahoma/south central Kansas areas. 

Thunderstorms should fire along a stationary front connected to a nearby low pressure systen and associated dryline in Texas. The tense clashing of air between the stationary front should result in initiation of showers and storms, likely close to the low pressure system. As the storms form, they will be in the midst of a fair 3000+ j/kg of instability. Hail does appear to be a major threat, with a skew-t from north central Oklahoma identifying up to 1.6 inch hailstones falling.

There will be some potential for tornadoes, but that chance is not high. Eventually, these supercells will converge into one or more clusters and become a more hail/damaging wind threat. I will not rule out the potential for these storms to become derecho formations.