Friday, March 8

[NorthGeorgiaWX]

Larry Cosgrove
 

"Forecasting winter to spring transitions is hard enough. But when you add a fairly steep change from an El Nino to a La Nina, things can get really difficult. Note that the sea surface temperature anomalies in ENSO 1.2 and 3 are already rapidly dropping, which tells us that we should be in a negative neutral anomaly further west in the Pacific Basin by August 1. Since hydrothermal patterns are forecast to concurrently warm greatly in the Atlantic Basin, the incentive for heat ridge formation will soon be evident. The southern branch jet stream will then have to gain in latitude (see the AMJ 2m Temperature Anomaly from ECMWF), taking communities in the south central and Dixie states from normal/cool to hot. The transition could set off a staggering amount of severe thunderstorms, with the "Panhandle Hooker "B" favored track in the near term and medium range going over to the Colorado/Limon and Trinidad A/B during April and May. Before we get there, however, the chance for absolutely miserable weather will exist along the Interstate 10, 20 and 40 corridors.

I note that the European panels want the chill to hang on in the Midwest and Eastern Seaboard longer than the outlooks of the GFS and GGEM members. Blocking signatures tend to fragment more quickly the later you go in March, and there are few cases where an entrenched cold can set up. The exceptions, like 1993, 2015 and 2017 are not in the analog list for this year, however, so I see a progressive 500MB pattern with perhaps two or three transient cPk (not cAk) intrusions. We will have to watch for severe weather potential, as return of both hot/dry air from Mexico and warm/moist values out of the western Atlantic Basin is very likely to appear. The dryness over the High Plains and Corn Belt only adds to the drama, so to speak, as its continued presence may point to a rapid turn to heat ridging as we move closer to summer."

 

[Alen]

Yep! My memory of all the bad summers here in Georgia, a lot of them were when we were transitioning from a strong El Niño to a La Niña! A great example was the 2016 summer season! Absolutely brutal! 56 days of 95+ here in Athens and over 100 90+ days from April through October! Seriously dreading summer this year especially since it has warmed up so early!

[Asperman1]

What sort of advice can be given in regards to the weather expected this evening?