This is Joe Renken following up on Josh's 04OCT15 post regarding
As you can see below, the 30SEPT15 & 02OCT15 500mb charts from the OPC Archived Charts
Here is the 12z 17OCT15 GFS 500mb Anomaly chart for 19OCT15.
Please note the numbers in the first OPC chart and the GFS chart.
- Trough over the PAC NW.
- ULL in the SW.
- Ridge over the Mississippi Valley
- Trough over the Grand Banks off Newfoundland.
Now look at the same GFS anomaly chart for 21OCT15!
The OPC chart on the right matches up with the above.
- Trough off the PAC NW.
- ULL cut off in the SW.
- Ridge over the Mississippi Valley.
- ULL just South of Hudson Bay.
- Slight trough over the TN Valley.
- Stationary/zonal flow over Florida.
- Warm front over the extreme NE CONUS.
Look at the latest surface forecast from the WPC for day 5.
On a side note, the BSR team has created a few graphics based on a Fourier Analysis of the daily PNA numbers since 1/1/1951.
The graphs are going to show you wave number on the x-axis. This is for 1/1/1951 – now or 23623 days. So to get a period for the wave you take the total days and divide by wave number.
So 100 would be 23623 / 100 = 236 days.
Or 38 days you’ll see as 23623 / wave number 620 on the second graph. I graph wave numbers out to 2500. Which is roughly 8 days. Note there is less “power” in the PNA index with smaller periods. This is normal.
We are looking forward to presenting at the 40th CPCDW located in Denver this year!