Wrap up of the 2014-15 Winter
(03/27/2015 − 04/02/2015)
STRAT_K has been on time and accurate. First two peaks of STRAT_K took place on 03/24 and 03/29 and several rounds of aftermath minor peaks will take place within the next 10 days. These aftermath minor peaks will cause several rounds of below-normal temperature events circulating the mid-latitudes (see Forecasts for more details). All of these are consistent with our forecasts for the STRAT_K event, which was first issued on 02/18.
STRAT_L appears to be the strong circulation event that would diminish the last attempt of the restoration of the 2014-15 stratospheric polar vortex above Arctic. Associated with STRAT_L, there will be another round of below-normal temperature events over a large portion of both continents.
Forecasts Made on April 2, 2015
Follow up on Forecast Made in Previous Weeks:
As we move into the first week of April, the first aftermath peak of STRAT_K (which already caused the break-up of the polar vortex around 03/27) will deliver yet another round of below-normal temperatures across the mid-latitudes in this weekend.
The duration of STRAT_K is expected to be long lasting and is followed by multiple aftermath peaks due to the break-up of the polar vortex. In our forecasts first issued on 02/18, we envisioned that STRAT_K would be similar to STRAT_E event, a long lasting event with multiple peaks due to the break-up of the polar vortex. It is very unlikely the polar vortex would be rebuilt back to its full strength at this time of the year as the sunlight comes back to the polar stratosphere. The aftermath events would continue to take place in the next 7-10 days as the remnants of polar vortex dispersed into synoptic scale waves after it was squeezed out of the polar circle around March 27 by the first two peaks of STRAT_K. The lingering synoptic scale vortexes spurning off from the dispersion of the exiled polar vortex will cause the continuation of the below-normal temperature conditions over a large portion of the area over both Eurasia and North America in the next 7-10 days.
STRAT_L appears to be the last strong stratospheric circulation event for the 2014-15 winter (in NH), which would deliver the last punch to the stratospheric polar vortex above Arctic and diminish its hope to rebuilt itself before the sunlight is coming back to the polar stratosphere in the full strength. STRAT_K, which will be weak but can still bring in below-normal temperatures.
New Forecasts Made on April 2, 2015
No new events are forecasted in this week's forecast.