3/2 - 3/3 update

Snowfall total closer to 3 inches appears more likely at this time due to later snow changeover and best dynamics being a bit to the north.... Expect snow to continue to fall until about 4-5 AM. The heaviest snow will fall between 11:30 AM and 1:30 AM... The best dynamics will be to the northeast of the triangle where 5-7 inches are possible.

2:30 update

NWS in Raleigh has issued a winter storm warning for Wake County and other surrounding counties... but they haven't made it public yet. This implies 3 + inches are likely overnight tonight.

update

NWS Raleigh is now expecting a changeover to all snow by 4:00 PM. I still expect to see some mixing before we head close to sun down. Expect little if any accumulation before sunset. Also... the best dynamics and heaviest snow should fall between 8:00 PM and 4:00 AM. I will update if that changes. Local NWS is also thinking about upgrading to a winter storm warning. I personally think we will see that sooner rather than later.

observations update

Snow is already mixing in with the rain southeast of the triangle.. This is an interesting development.

3/2 -3/3 snowfall update

I need to move up the time frame of the snowfall... just a mistake on my part.

I think we will see a changeover from rain/rain snow mix to all snow between 7 and 9 AM... especially if the precip amnts are heavy enough. The biggest deterrent is the warm boundary layer... however this above freezing layer will be fairly shallow later this afternoon. With potential for some heavy precip starting between 7 and 9 I think there's a good chance it will change to snow at that time... and then will remain snow from there. Also... snow is already being reported to our west.

The GFS puts down less qpf than the NAM with the deform band.. but the important thing is that the deform band exists and it is located over the triangle. This band is producing snow right now in Atlanta. It should rotate and move into our area by about 8 PM... and exit the region by around 3-4 AM.

As Bradley Marshall Phelps pointed out... I don't have any support right now from the NWS or the local mets.. They certainly have much better data than I do. So I'm a bit worried that I may be incredibly wrong here... but what the hell.. Will go with only 3 inches if the changeover begins later than expect and up to 8 inches if the changeover starts when expected.


This Afternoon: Rain, Mixing with Snow after 4:00 PM

Tonight: Rain/Snow changing to all snow between 7:00 and 9:00 PM. The snow could be heavy at times.... some thunder will also be possible. Snow easing up by 4:00 AM. Snow should end by day break.

Total accumulations of 3-8 inches mainly in the grassy areas, but covered roads are possible if the snow is heavy enough... Higher amounts are possible where the heaviest bands set up.

3/2 - 3/3 snow potential update

12z NAM model run is out and it does show the deformation band moving through the triangle between around midnight and sun rise. This band will likely contain a 5-6 hour period of moderate to heavy at times precip. This would likely be all snow for the triangle at the time the deform band moves through. 6-9 inches could be possible. Surface temps and a chance of precip issues could negate this total as presented by the NAM in liquid equivalency. Surface temps could be slightly above freezing through the event... Most if not all accumulation will be on grassy surfaces. Expect any snow accum on roadways to melt quickly on Wedns morning. But again I expect most accum. will be on grassy surfaces. Although with the timing and potential intensity of the event I do think we'll see accumulation on most everything else. The best chance for accumulation snow will be between midnight and 6 am. Before midnight we probably won't see much snow if any at all. It will be mostly rain before that time. The local NWS office in Raleigh has been putting more stock in the NAM... and I've felt that the models were underperforming on the deformation band... therefore I do think the NAM is onto something here.

I'll check the 12z GFS along with the soundings (vertical profile of the atmosphere)... Hopefully the GFS will come into agreement with the NAM and show this band of precip.

I'll make my first forecast this afternoon. T

3/2 - 3/3 snowfall update

I've felt that models were underdoing precip a bit with this system and the latest guidance is starting to suggest I may be right. The upper level dynamics with this system are pretty good and combine that with a strong and well positioned surface low... I'm having a tough time believing that this won't result in a band of very heavy precip somewhere over the eastern piedmont/coastal plain. I think any thermal issues in the boundary layer over the piedmont would be overcome by this heavy band, but there may still be issues over the coastal plain.. although with rates of up to 2-3 inches per hour I think temp issues will even be overcome in this region.

Models struggled to pick up the precip during the Carolina Crusher in January of 2000... And now they are starting to catch on to a strong... what we in the business call... deformation band to the west of the surface low... The potential exists for amounts close to 20 inches in the jackpot zone depending upon when, where and if this band develops. Look for a tight gradient in amounts... much like January 2000. Here's a look at the snowfall map with this storm. Right now this heavy band looks to be further east... so I'm not saying we will see these snowfall amts and especially at this location. But I do think a tight band of snow like the one shown below could develop. We will have some solar issues since this is March after all... so even if precip is heavy expect totals to be lessened a bit... I'll check the models later today to get a better idea where this band of heavy snow could develop... if it does... although I think it will.