Raleigh Weather Discussion
The first weather concern is a line of severe storms currently in Kentucky, Tennessee, Alabama, and Georgia. This line of storms will move east and after weakening a little over the mountains, should re-fire and move east through the Carolinas and Virginia this afternoon and evening. High-resolution models show a narrow, but intense line of storms traversing across the piedmont from west to east this evening. I think the line will arrive in the Triangle between 8-10pm. The line will likely be low-topped which means there will not be a great deal of thunder and lightning associated with it. However, it will be accompanied by strong straight-line winds, potentially tornadoes, and heavy rain. The low level wind field is very impressive with the NAM soundings showing 80-85 knot winds as low as 850mb this evening. Wind gust potential values from my company’s in-house high resolution model show widespread 50-60mph wind gust potentials with the line as it moves east. The only thing lacking is thermodynamic instability with CAPE values likely to stay below 500 J/kg but the synoptic scale lift and the strong low level winds are more than enough to produce severe weather. You can already see the damage that occurred overnight in Tennessee and areas west of here, so stay tuned and keep updated.
Temperatures today will be April-like with highs in the mid 70s to perhaps some upper 70s although clouds will likely prevent the upper 70s to near 80 possibilities.
The front plows through tonight and then we see cooler temperatures for late week and into the weekend. Several upper level disturbances will move through over the next week, one Friday, one Saturday night, and another Tuesday, but as of now most model data shows very little to no precipitation. I will mention there is an outside chance we could a rain or snow shower Friday afternoon and/or Saturday night/Sunday morning as the models could moisten up a little in time. However, as of now, significant precipitation looks unlikely. However, the mountains of NC and areas of TN/KY could see a nice 1-3 inch snow fall Friday with the mountains seeing more.
Temperatures will moderate next week as a trough moves into the southwestern US, and the polar vortex lifts into northern Canada. This will allow the polar jet to retreat north and much of the country turns warmer than normal with this reaching the Carolinas late in the forecast period.
National Extended Discussion/Forecast
For cold and snow lovers, especially those of us in the Southeast and eastern US, once we get into February, it feels like we are on the clock. The normal are warming up and that will only continue, and we know that March and Spring is right around the corner, meaning snow chances will decrease rapidly and any winter weather is usually minor, with of course exceptions like the March 93 storm.
So with that said, this time of year you like to see encouraging trends/signs in the ensembles that are now extending out into mid-February for a cold pattern, because if you don’t, you know you are seriously starting to run out of time. Well unfortunately, the ensemble models are showing a good deal of warm signals and very few cold signals as we head into the 11-15 day period. The pattern is showing a strong polar vortex setting up over the Bering Sea/Alaska and another one over central and eastern Europe. However, there is very little evidence in the ensemble data of one in North America. This means that the polar jet stream is going to lift well north into Canada and a strong Pacific jet stream will dominate the pattern with mild temperatures for much of North America. IN fact if you look at the height anomaly forecasts in the 11-15 day period, the only below normal height areas are in the Southwest US and Alaska. That is not a cold signal.
The GFS/GGEM Ensembles do progress the Southwest US trough out in time late in the 11-15 day period and if this does happen, we COULD, see a s/w trough drop in and phase with this producing a big storm in mid-February and perhaps a new polar vortex could form over eastern Canada and portend a colder 2nd half of February. However, for now that is just conjecture.
Things can obviously change, a week ago, it looked like February was going to be a cold month, so who knows what it will look like in a week. But for now, the modeling is overwhelmingly signaling a warm month, once we get past the next several days.