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, September 11 at 6:58 AM EDT.
Messages
Most locations will be dry today with isolated showers and storms mainly in the north.
Saturday looks to be the best day for shower and storm coverage. Then more isolated again on Sunday. Saturday, locally heavy rainfall is the main threat due to elevated PW values of around 2 inches.
Above normal temperatures expected through the forecast period. Yesterday, CHA tied the record for consecutive days at or above 90 deg set back in 1993. With drier conditions now expected for today, the probability that CHA breaks the record, with day 39, is very high.
Discussion
In the upper levels, a weak ridge remains over GA/SC as a trough develops over the Lower Mississippi Valley. At the surface, the slow moving weak cold front is over Kentucky slowly drifting southward. Showers and maybe a few storms will be isolated today, mainly in the Upper Cumberland Plateau and Southwest Virginia as the decaying front lingers. Instability will be a little higher today around 500- 1000 J/kg. Some thunder and gusty winds will be possible in the stronger storms.
Rain chances are the highest Saturday as the shortwave moves into the region. The weak surface boundary will also be lingering over or near the region on Saturday. Deep layer moisture advection is likely with high pressure over the Atlantic bringing southerly surface winds and a trough to the west bringing higher level moisture from the Gulf. the blend-of-models forecast has very high rain chances on Saturday with waves of showers and storms possibly starting before noon.
The best chance for strong to severe storms will be Saturday with good instability around 2000-2500 J/kg. With weak shear and high freezing levels the primary threat will be gusty winds. With good moisture advection, Pwat values will be elevated around 2 inches on Saturday so heavy downpours will be likely at times that may cause some isolated flooding. Steering flow around 10-15 knots should help keep showers and storms moving, so overall the flooding threat is low.
By Sunday, the shortwave has moved east and a weak ridge builds into the Southeast. Therefore, showers and storms will be more isolated on Sunday lingering to the east and northeast near the mountains.
Early next week, a ridge will be over the Southeast. Monday looks dry with low chances of showers and storms returning Tuesday and Wednesday in and near the east Tennessee mountains. Tennessee Valley locations will remain dry. Thursday rain chances will be isolated in the Tennessee Valley and maybe scattered in and near the terrain.
Afternoon highs will be above normal throughout the forecast period with mainly upper 80s expected near Tri-Cities and lower 90s for Knoxville and Chattanooga areas, generally about 6 to 8 degrees above normal. Chattanooga is expected to exceed 90 degrees again today. If that happens, they will break the record for consecutive days with a high temp of 90 or greater. The current record is 38 days back in 1993. The streak may be broken on Saturday with the forecast at 88 for Chattanooga since convection may begin in the morning hours. If the timing ends up later or coverage is not as widespread as expected, the streak may continue.
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.