Raleigh Weather Discussion
A general unsettled weather pattern will continue for the next few days. If you have walked outside you can tell today has a totally different feel than yesterday as high pressure over the Northeast has wedged in east of the mountains. This combined with the cloud cover and rainfall is locking in a cold air damming setup for areas east of the mountains and we will likely stay in the 40s all day. Rain will again be mostly concentrated over western and central parts of the state although some showers will likely move through the Triangle at various times.
The wedge front will dissolve and lift north as a warm front tomorrow and we will likely once again zoom up well into the 60s it appears. We could see some rain again, with some partial clearing possible Wednesday night.
The next system of interest approaches the area Thursday evening through Friday morning. The models continue to differ on the evolution of this system as well as the timing. The crux is this, a cut off low will form over Texas tomorrow and move E across the southeast. A surface low will likely form near the Gulf Coast and also move eastward. The air mass in place as this system arrives will be rather bland and for most areas outside of the mountains, it will likely depend on dynamical cooling for any wintry precipitation to fall. I see two likely scenarios for this event.
Scenario #1: A 12z Nam, 00z GFS like scenario where a somewhat potent low pressure develops and the mountains, say above 2000-3000ft see a significant snow event, while most areas outside the mountains see mostly rain, but could change to or mix with snow Thursday night, early Friday with a minor accumulation.
Scenario #2: A 06z GFS/00z ECMWF type solution, where the system is not quite as strong as in scenario #1 and the mountains see a light to moderate snow event with areas east of the mountains likely seeing mostly all rain with perhaps some snow mixed in towards the end of the event but with likely little accumulation.
Right now, this looks like the two best scenarios for this event. Things can obviously change, but for now that is my thinking. I probably favor scenario #2 for now. If it continues to look like this will bring some accumulating snow, I will release a forecast map probably tomorrow.
Behind this event, a monster arctic high will drop into the Plains by this weekend and ahead of this cold air mass we will see a return to southwest/westerly winds and warm up Saturday/Sunday well into the 50s despite cold mornings. But this will be a brief warm-up as the cold arctic front will likely pass through Monday and next week looks to be cold. In fact we could see lows in the teens and highs in the 30s for several days next week.
National Extended and Long Range Discussion
The ensembles show a trough building into western Canada in the 11-15 day period which will allow the cold air in the east to moderate and above normal temperatures to build over the central US. However, we see persistent higher than normal heights near the North Pole and over Greenland which is an indication that cold risks remain particularly across the northern tier, Great Lakes, and Northeast. The central and southern Plains and Deep South will likely see the warmest temps relative to normal.
Both the CFS weeklies and the ECMWF weeklies paint a cold picture for weeks 3 and 4 which take us well into February. The last few forecast hours of the GGEM and GFS Ensembles show a colder pattern re-establishing itself over the Lakes/East by the last few days of January. I do think we see a warm-up in the East from around 1/26 through 1/29 but colder weather may return shortly after that.