Friday, January 2, 2009

1/2 - 5:45pm - Can I Get a Stable Storm Track Please?

The last 24 hours have been absolutely nuts on the forecast models with our Tuesday storm. Right now I can't say what kind of precipitation we'll see, but I think we'll see a mix of multiple types. Yesterday's model runs showed it to be too warm for any freezing precipitation, but now the area of low pressure is trending slightly east on the GFS and DGEX (derivative of GFS), which starts us out with some wintry precipitation and then goes to rain before a transition to snow on Wednesday. Snow accumulations would be very small, if any, with this solution.

The Louisville NWS office was thinking we'd see mostly rain yesterday, but this trend eastward has made them rethink that. They're saying its unknown what we'll see at this point and would have to be determined based on the low pressure track. I completely agree with that, but all sorts of bells and whistles are still going off in my head.

When I see this kind of variation between the models and their runs at 4 days out, it reminds me of December 2004 and March 2008. We had all sorts of monkey business happen in the models just a few days before those storms, similar to what's happening now. My gut is telling me something is very wrong here and that doesn't happen often. I think we're in for a wild mix of forecasts over the next couple days, but we'll have a correct solution by late Sunday.

For now, I'll stick with mostly rain on Tuesday and a bit of mixed precip at the onset and backside of this storm. BUT, be ready for massive changes in that forecast if the low pressure track goes southeast more. In any case, frigid air is on the way for late next week, but not before a shot at 60 on Sunday!

1 comment:

Anonymous said...

Maybe not as tough a call? We know 2 things. One, we almost certainly will transition to rain as dominant p-type on Tuesday afternoon. Possible we start as a mix. Two, there will be a transition to snow on Wednesday. What I think is still up in the air is, how much snow on the backside. Wet ground and temps looking to be a bit above freezing much of Wednesday, make me believe only little through Wed. afternoon. However, are you noticing the hints at a "double low" structure? If a low forms south of the main low, that would enhance our accumulation chances. Kind of feeling the 1-3" range here be the end of next week. Even with model shifts, the above scenario has been pretty stable the last couple of days. Of course this could change. Maybe our snow chances are better in the 8-12 day range, when some of that really cold stuff gets down here. -53 F in the Yukon right now.