UPDATE 10 AM, 10/3: Tropical Storm Karen has formed in the southern Gulf of Mexico. Hurricane watches are posted from Louisiana to the Florida Panhandle. The current National Hurricane Center projected track of the system puts Southwest Virginia near the center of the zone of uncertainty with its inland movement. END UPDATE
In case you’re wondering, the National Weather Service is an “excepted agency” and is continuing to perform mission-critical functions during the ongoing federal government shutdown. This basically means weather service offices, like the one in Blacksburg, will continue to perform functions related to forecasting and the issuance of advisories, watches and warnings, but some forms of information not critical to those tasks will be unavailable to the public, and many outreach activities have been curtailed. Some web sites like the noaa.gov, weather.gov and the National Climatic Data Center are not operational currently — clicking on those sites redirects you to “governmentshutdown.noaa.gov” with a message that “Only web sites necessary to protect lives and property will be maintained.” Others like the Storm Prediction Center, National Hurricane Center, Climate Prediction Center and Weather Prediction Center (precipitation forecasting, primarily) are deemed critical to that mission and are continuing unabated. Local forecast office sites, like the one in Blacksburg, are also still operational. National Weather Service forecasters in the local offices are continuing to report for work but do not know when they will be paid for that work.
Warm, dry weather with highs in the 80s from Roanoke south and east and mid 70s to near 80 to the west will likely continue Thursday, Friday and Saturday — so yes, the Virginia Tech homecoming game and other daytime outdoor events appear likely to go off without downpours . High temperatures are expected to be 6-12 degrees above normal the next 3 days, but the bar on most daily records is even higher, so it appears the historic standards will remains. Our weather focus is going to continue be on the system in the Caribbean that may well become Tropical Storm Karen very soon. As the system drifts northwest into the Gulf of Mexico, it is going to be shunted more northeastward by a jet stream trough in the central U.S. and an associated advancing cold front, and this will likely lead to a rainy period, possibly heavy, for Southwest Virginia Sunday and/or Monday. The relative speed of the cold front and the likely lack of development in the tropical system — there is almost no guidance showing that a Karen would even make Category 1 hurricane status — may limit flooding potential as tropical moisture may become strung out and move through quickly. Another limiting factor is how dry the surface has become in the past 6 weeks or so (seems very odd saying that after such a soaking wet summer). But tropical systems are always puzzles, and there may be some surprises in how this one develops. For now, rainfall projections on the order of 1-2 inches seem like a good starting point for rain Sunday and Monday. Expect those to go down if appears the brunt of the rain will be pushed even farther east, and to go up if it appears a potential Karen will be slower, stronger storm. The latter contingency would also ramp up tornado potential through parts of the South and East, as the remaining spin from a tropical system often creates atmospheric shear to spin storm cells well inland.
Meanwhile, there is big snow expected to fly in the Northern Rockies and Northern Plains. Forecast guidance shows no likely periods of frost/freeze-inducing temperatures through at least the first two weeks of October in Southwest Virginia, and perhaps even longer than that.