Saturday, September 13, 2014

September 27-October 1 Potential Storm System

The September 27th to October 1st period is being monitored for a potential storm system.

Tropical Tidbits
The image above shows 500mb height anomalies over the West Pacific area on the afternoon of September 21. In this image, blues indicate the presence of below-normal height anomalies, which can then lead to cooler than normal temperatures, as well as stormy conditions. Warm colors are associated with positive height anomalies, which generally bring warm and quiet conditions.

As we see in the image above, a trough is moving through Japan on the 21st, according to the latest GFS Ensembles forecast. We see negative height anomalies across the entire country of Japan, but the real point of interest is the depression in the contour lines. This depression indicates a trough moving through the area, and that's what may provide us with the chance for a storm system in the September 27th - October 1st period.

Forecasted teleconnections can give us an idea of where this potential storm may end up.

On the top-left, we see the forecast for the Pacific-North American (PNA) index. We see that at the end of the forecast period, on September 27th, the PNA is projected to be descending from a strong positive state. This tells us that ridging in place across the Western US may be dissipating by the time this potential storm rolls around. Typically a positive PNA means the Midwest and Ohio Valley are most favored for storm systems, but it could be more for the Plains if the PNA is descending to neutral or negative territory.

Additional updates will be provided in the near future.


1 comment:

Anonymous said...

What kind of precipitation will this be. If it is cold enough, could we see snow in the midwest, great lakes region?