Thursday, January 24, 2013

Stormy, Cold February Could Vindicate Winter

It appears that the potential for a stormy and cold February could vindicate at least part of what has been lost this winter, with some snow and intense cold hitting the nation throughout the incoming month of February.

The Madden Julian Oscillation, or MJO, involves placement of enhanced convection over certain areas of the Indian Ocean, Pacific Ocean and even the far western Caribbean. These different areas are divided into 8 different regions, called phases, which each affect the national weather differently. Their effects change with each season as well. Above is the ECMWF Ensemble Prediction System's MJO forecast from January 24th to February 7th. It is predicting a decrease in intensity in coming days as we remain in Phase 7, and the weakening is exhibited by the forecast line moving closer to the circle in the middle of the image, called the 'Circle of Death', because the MJO is too weak at that point to impact the weather significantly. We see that the ECMWF predicts the MJO to move into Phases 8 and 1 as we enter February. These two phases are widely acknowledged as the best phases for cold and snow during the winter, with the cold hitting the hardest across the Central and East US, and snow hitting the same areas. It is for this reason that I support a cold and potentially stormy open to February.

Something else we must keep in mind is that we have recently had a historic sudden stratospheric warming. In the sudden stratospheric warming (SSW), warm air is suddenly forced up from lower levels of the atmosphere in an act that greatly weakens the polar vortex. The polar vortex is the machine that essentially maintains control of the cold air in the Arctic. If you recall, much of the nation experienced very cold temperatures just a couple days ago. This happened as the polar vortex skirted by Southern Canada. Imagine what it could do if it was inside the US. As we enter February, the 2-4 week lag time between SSW and cold air from the stratosphere reaching the surface (because the warm air has displaced it down to the troposphere) becomes valid, meaning we could see another cold shock, and this one could be stronger, depending on where the polar vortex goes this time around.

Finally, I have been a big advocate of the proven theory that snow cover observed in Siberia during the month of October can have a big effect on the Arctic Oscillation come the following winter. We have seen this theory verify, with warmer than normal temperatures in December and early January correlating with below normal snow cover in the first half of October. However, as we enter February, we find that there was a spike in snow cover in late October, which does count as February in this sense. If we use this snow cover theory, I do see a legitimate possibility for strong, sustained cold to last in the US, but only if the rest of the atmospheric pattern cooperates.

It's certainly looking good for cold and even snow in much of the nation to kick off February, and some indications even suggest this could persist to end the final month of winter.

Andrew

6 comments:

QuietBear said...

Thanks for the insightful info you bring us...
I know that the central & east part of the country will be experiencing a deep cold soon. Can you tell yet, what it's going to be like in the greater Boise area of Idaho?
I'm an organic farmer and info like this is invaluable, as to predict when it's best to start our seedlings to get ready for planting...

Thanks again, Andrew

Steve Mims said...

Thanks for the accuracy in your forecasting Andrew. I've learned a lot from reading your analysis, especially with regard to the intracacies of the polar vortex. I look forward to learning more from you!

Anonymous said...

so what area has the best shot of seeing winter weather before spring is here???
northeast, midwest, plains
any info would be great

Anonymous said...

That's great news for some, and though I don't mind the mildness here on the Front Range, the unbelievable dryness we have had this entire winter (less than 30% of normal precipitation) tells me this...that none of these events, being the SSW, or the MJO, mean a single thing for those of us on the Front Range, here's what I am thinking, there will be few storms that will swing by our area for the rest of winter, and even the few that do will be swept swiftly eastward by unusually strong prevailing westerlies.
Temps will remain erratic, soil moisture for summer will continue to deplete rapidly, and the wildfires that have begun to spring up again over the last couple of weeks will only increase, and the danger of exponentially more developing will skyrocket in coming months.
In short, those of us along the Front Range of the Rockies better prepare for a virtually snowless end to winter, an even drier spring, with many damaging wind events, and possibly the hottest and driest summer ever recorded and unless an unbelievably huge storm hits, this drought will only worsen to the point of no return...so unless you have some good news specifically for us Andrew, I am afraid I am going to just give up all hope that we will ever return to normal, love your forecasts, just wish the stupid atmosphere would quit giving us the shaft every time.

Anonymous said...

SOMEONE ANSWER QUICK PLEASE: I live in danville, va and this is urgent! WE have had 1/10-2/10 of an inch of ice already and it doesn't look like it's slowing down. Even though theres all this ice theres not even a special weather statement for us! It says its snowing but it isnt and my street has already had an accident on it. WHAT DO I DO!?!

Anonymous said...

PRAY............. IT CANT HURT
BE THANKFULL A LEAST YOUR GETTING MOISTURE OF SOME TYPE
MANY OF US WOULD GLADLY TRADE PLACES WITH YOU CAUSE EVEN THE FREEZING RAIN WOULD GIVE MOISTURE TO OUR DRY FIELDS