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QBO in a two dimensional framework

The Quasi-Biennial Oscillation (QBO) is a cycle of zonal wind in the equatorial stratosphere with a period that varies between 24 and 30 months. This oscillation is a product of downward propagating alternating wind regimes. The current method of monitoring this oscillation is through an index, calculated by the zonal wind anomaly at 30hPa averaged along the equator. This method excludes information on the vertical structure of winds in the stratosphere, and presents the QBO as a one-dimensional

OKpowdah

OKpowdah

 

Current Evolution of the QBO and Implications on the Atlantic Hurricane Season

To start, here's the equatorial zonal wind anomalies so far this spring. Can see the -QBO holding on by its thumbs, with the westerlies starting to descend and near 30mb (first days with a + anomaly since July 2011 WOW) The current profile fits the 330 degree phase of my "index" pretty well. Descending westerlies above 30mb, easterlies centered around 70mb, and neutral right around 30mb. The phase I would be keying in on for hurricane season based on average "residence time" is 60 degrees.

OKpowdah

OKpowdah

 

Weekend Severe Possibilities (2/9-10)

The big consensus among model guidance at this point is that a piece of energy from the trough over the Northwest Pacific will jump to the Gulf of Alaska by Wednesday morning, then drop southeastward into California Thursday night into Friday. Similar to the last event, there is a weak disturbance in the southern stream that gets ejected out ahead of the trough dropping into the Southwest ... and able to lift northeastward as the polar vortex over southeast Canada retreats poleward. So the resu

OKpowdah

OKpowdah

 

Broadening our use of the QBO

The Quasi-Biennial Oscillation (QBO) as defined by the AMS: The QBO provides a good first-order look at the background state of the stratosphere, which can be significant for seasonal prediction. It's reliable periodicity (probably the most consistent atmospheric oscillation known today) also makes it a useful tool in forecasting.The QBO is measured by the anomaly of the winds at 30mb averaged along the equator. Here we run into the problem which is the joy with which people embrace one-dimensi

OKpowdah

OKpowdah

 

Increased storminess for last week of January

Stuck in northwest flow for the next week, any current weather discussion here at OU has not been able to escape the use of the word "boring". However, a change is gonna come. One of the distinct characteristics that I'm seeing of the pattern over the next week is that within this wave system, the sub-polar vortex over eastern Canada and the Northeast overwhelms the ridging over western North America. I compared it to RKW theory and the balance of vorticity in the system ... In this case the st

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OKpowdah

 

Holy bombogenesis (W Pac 1/15/2013)

Surprised I haven't seen any discussion about this bomb on the board. Check out the DT pressure map I attached below. You'll never see a better signature of a tropopause fold. And obviously all sorts of upper level support with massive divergence aloft. From Ryan Maue:

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OKpowdah

 

Prolonged negative QBO

This latest easterly QBO period is on track to become the "strongest" episode on record. Below I have plotted the QBO along with an integrated QBO index which very simply sums the monthly QBO across each full easterly period. So far this current -QBO period has an integrated magnitude of -280.62 ... which falls just short of the 2001 -QBO period with a magnitude of -280.79. The mean is -191.6 and standard deviation is 48.6. Data so far for January 2013 suggests the monthly QBO should come in

OKpowdah

OKpowdah

 

12-27 Snowfall forecast for New England

For posterity's sake, here is my final call for snowfall totals for the New England area. Expect maximum accumulations in the Monadnocks region of southwest NH and in a swath from eastern NH through western and central Maine ... where up to 18" could fall.

OKpowdah

OKpowdah

 

Exploring Ensemble Sensitivity Analysis for Dec 27th Winter Storm

Using 00z NCEP (including 20 ensemble members), let's begin by defining the EOFs describing the greatest amount of variance in the ensemble forecasts: Alright what is this telling us? First of all, note the asymmetry in the mean/spread ... there is a maximum in the spread over E PA and NJ ... to the west-northwest of the mean low. EOF1 -- explains 46.6% of the variance -- describes the depth of the low for the cluster of solutions to the NW of the mean ... in general the average SLP across

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OKpowdah

 

Eastern U.S. Winter Storm Threat Dec 27th

Let's begin with the state of winter right now. Where is it? Recent reports say Russia has found it (http://rt.com/news/r...emperature-379/). In other news, the planetary reconfiguration that is occurring right now. Major ridging burgeoning from the Aleutians to the Bering Strait and right up over the North Pole by Saturday. The effect? Well at 22/00z that's 125kts at the DT crossing the NP toward the western hemisphere. Clear at this stage the magnitude of nonlinear processes leading to an

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OKpowdah

 

The catalyst for a pattern change

A significant cyclogenesis event in the North Pacific will be the primary catalyst of a pattern change over the next few days. Let's take a look at the evolution over the Pacific into western North America. Notice our N Pac storm gets dual jet support and really goes to town over the Aleutians. Wait isn't that where a massive ridge was last week? ... or for that matter the last three months. Well that's one thing that changes. The ridging once over the Aleutians and Bering Straight retrogrades

OKpowdah

OKpowdah