The weekend outlook and the future of Isaac
By now I’m sure readers of this blog are well aware of the presence of Tropical Storm Isaac due to the media coverage of this event…but first let’s talk about Fredericksburg’s weekend weather.
While today (Friday) will be sunny a new surface low pressure center – NOT a tropical feature – looks to form near Cape Hatteras as a byproduct of an upper level trough that has been hanging around the East Coast for several days. Both the NAM and GFS forecast models bring this low pressure center westward over central Virginia on Saturday and Sunday which will result in overcast skies and showers both days. After today’s high in the mid-80′s (F) it looks like the weekend will feature the low 80′s with a total of perhaps a quarter- to a half-inch of rainfall for the ‘Burg by Monday morning.
Now for the rest of the weather story. The forecast models have been jumping all over the map (literally) with Isaac’s track and intensity but this morning the same models seem to be converging on a landfall near Mobile Bay Alabama overnight Tuesday.
Now, the question for Fredericksburg is whether we will see any impacts from Isaac. Perusing last night’s run of the GFS model reveals a storm track into the lower Ohio valley by Thursday of next week where the remnants would get swept up into an approaching cold front and provide us rain for the first part of the Labor Day weekend (yay….). However, the middle-of-the-night GFS run radically differs from this solution and has Isaac’s remnants sweeping northeastward off the Carolina coast by Thursday, totally missing Virginia. To confuse matters even more last night’s run of the European model - which has been the maverick outlier for most of Isaac’s lifetime – has the center of circulation over Memphis TN next Thursday night.
So what should we expect from Isaac? Continued uncertainty, but with a decent chance at some rainfall impacts to Fredericksburg and vicinity sometime next week. How’s that for an evasive answer? (Or, I could just point out that forecasters don’t yet have a clue.)