There has been considerable examination of the All-Sky LAP products (PW and CAPE) this week, and for good reason – they’re quite good. I wanted to take a quick look at how the All-Sky LAP total PW compared with the merged TPW product. The All-Sky product is on the left and TPW on the right. I overlaid the 20z 1 hour RAP PW forecast for comparison. Ignoring the higher resolution of the All-Sky, the very broad distribution of enhanced and depressed values are similar in location between the two products. However, the TPW values are considerably lower than both the All-Sky and the RAP forecast. Further, pulling the 21z SPC mesoanalysis PW shows that the All-Sky tends to be the better of the two satellite products.

The TPW seems good for very broad generalizations, but if given a choice between the two in operations, I’ll take the All-Sky, All-Day Every-Day.

–Stanley Cupp