Storm Post-mortem
In general, I feel my final forecast map was pretty decent. There were a lot of reports of 6-12 inches if not more in the area D of my forecast map in NW NC and western Va. Also amounts in the 3-6 inch range were reported in area C in Virginia and the NC border counties. However, amounts in the NC foothills and piedmont particularly east and south of the Triad were not as much as forecast. From the Triangle to the southern piedmont to the southern foothills, a better forecast would have probably been a dusting to an inch or two instead of 2-4 inches.
It seems the problem was that the upward vertical velocities or lift, was not as strong as I thought and some of the model data was showing. Model data had shown strong lift for instance in the Triangle from around 8pm till 2am. With the changeover happening right on time if not a little earlier than thought, the snow forecast seemed good. But the best lift seemed to set up a little further north near the Va border and in southern Va, and was weaker over the NC piedmont areas. Thus the marginal boundary layer warmth, (most areas were 33-34 during the event) resulted in a rain/snow mix late yesterday evening and thus after the initial burst of snow with thunder/lightning occurred yesterday evening, the snow that fell after say 10pm, did not accumulate much. Officially at the RDU airport, as of 1am I saw 0.8 inches was the official measurement. Across Wake county amounts ranged from a trace in southern sections to 1.5 to 2 inches in extreme northern parts of the county. In the escarpment areas of the NC foothills, the bubble of warmth showed by the high-res models proved correct. With these weak upper lows, that are weakening as they pass, it seems the wind components in that area is crucial and actually leads to down sloping and more rain than snow. OH well, live and learn.
Raleigh Weather Discussion
It will be cold today and any remaining slush will re-freeze tonight. However, southwesterly flow ahead of a strong arctic cold front will return tomorrow through Monday with moderating temperatures well into the 50s the next 3 days. This front will pass through late Monday and it looks like Tuesday and Wednesday appear to be very cold. High may struggle to get above freezing both Tuesday and Wednesday with lows in the teens likely on Wednesday. It will start to moderate by Thursday and we be back well into the 50s again by Friday it appears.
Yet another cold front looks to pass later Friday, early Saturday with a chance of rain and cooler temperatures again by late next weekend.
National Extended Weather Forecast/Discussion
The cool down next weekend in the East as of now looks brief. A new trough digs into the Rockies, interior West, the following week (1/27-1/31) popping a ridge in the eastern US leading to a cold west, warm east look again. It does appear however that this will be short-lived.
The ensemble guidance wants to pop a –EPO ridge into the Gulf of Alaska and build it into western North America as that week progresses, which should progress the trough out, and at the same time we see continued positive height anomalies over the poles (blocking). The ensembles are in pretty good agreement today that the trough will move into the Plains/Midwest by 1/29-1/30 and cover much of the eastern half of the nation by 1/31 into early February. The look of the ensembles is pretty cold late in the 11-15 day period. We see a –AO, a –NAO, and a ridge over the west coast of North America. This sets up the polar vortex over Hudson Bay and a cold pattern across much of the eastern half of the nation. This is supported by the latest CFS and ECMWF weekly forecasts which keep a cold pattern through mid-February. So perhaps there will be more snow chances for many of us in the month of February.
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