What the forecast actually says — NWS Area Forecast Discussions, decoded into plain English.
Plaincast decodes the National Weather Service's Area Forecast Discussion — the real forecast, written 3 to 4 times a day by the meteorologist on shift — into plain English. The discussion is where a forecaster explains their reasoning: which models disagree, what they are watching, and how confident they are. Below is the current edition for Morristown, with its shorthand expanded. The full experience — an AI plain-English summary beside the annotated original — loads with JavaScript, and every one of the 68 forecast offices has its own edition.
Area Forecast Discussion · National Weather Service Morristown (MRX) · issued Friday, November 13 at 6:34 AM EST.
Messages
Rain showers will continue to transition to snow across the higher elevations with the best coverage being from mid afternoon through tonight.
Snow accumulations of 1 to 4 inches are expected at or above 3,000 feet in the Tennessee mountains with locally higher amounts along the highest peaks. A Winter Weather Advisory goes into effect this morning.
Dry and cool conditions are expected this weekend with lows deep into the 20s Sunday morning. Then, a gradual warming trend is expected into next week but still with cool mornings.
Discussion
Currently, broad troughing is deepening across the eastern U.S. with an embedded shortwave over the western Great Lakes. At the surface, Canadian high pressure is progressing south from upper Ontario with the recent surface low off the east coast. This has put the region in a northwesterly flow pattern with CAA dropping the freezing level to near 4,000 feet ASL confirmed by high elevation obs. Morning showers will remain as snow for places this high with a lull in activity for the first half of the day. By mid-afternoon, the reinforcing shortwave will arrive from the north with moisture fetch from Lake Michigan supporting another increase in showers. By this time, freezing levels are expected to drop to near 3,500 feet and then to 3,000 feet and lower after sunset. With the continued moisture and persistent 20 to 25 knots of northwesterly flow, snow will be focused along the higher elevations with potential for sprinkles and flurries in the lower elevations. Between about 1 AM and 4 AM EST, moisture above 850mb will become a lot more limited, inhibiting additional high elevation snowfall. As the Canadian high builds in from the west, moisture will shift towards the northeast Saturday morning before area-wide clearing. All in all, the latest high-res model guidance continues to suggest similar snow accumulations focused near and above 3,000 feet above ground with some lighter amounts possible for lower elevation places.
As the Canadian high settles over the region, strong subsidence will make for notably cold temperatures falling into the 20s by Sunday morning. By the day on Sunday, high pressure remains in place with troughing continuing to shift eastward, leading to a recovery of highs into the 50s as opposed to mainly 40s on Saturday. High pressure will remain in place through next week with gradual height rises continuing the warming trend. As 500mb heights rise above normal to 5,750m by Tuesday, daytime highs will likely reach into the 60s for lower elevation places, followed by higher values Wednesday and Thursday. Continued subsidence will still make for cool mornings, in addition to potentially low humidity's in the afternoons.
This is the plain-text edition, decoded without AI so it loads anywhere. Read the whole Morristown discussion at /o/MRX/, see what changed since the last one, or open The National Desk for where the weather is today.