5 AM Tuesday 12-h Forecast for the U.S. GFS model
(pressure-solid lines, and precipitation-colors)
Although most of the action is about to happen, we are close enough to note that the long-term forecasts of the U.S. global model, the GFS, were quite excellent, superior even to the vaunted European Center model, which generally has superior forecast skill. Really good forecasts 5-6 days out.
Confidence in the forecast models has grown so much that airlines recommended passengers alter their plans on Friday and they cancelled most flights into the Northeast a day ahead of the storm (today).
A few decades ago, we could not offer such skill. But today, enhanced U.S. weather satellites and improved numerical forecast models make all the difference. And now, the Trump administration is talking about massive cutbacks in both of these critical elements.
Let's talk satellites. The storm that is developing off the southeast U.S. as I write this note developed out of two main ingredients: an upper level trough that moved in from the west, and a large low-level temperature gradient (difference) between cold air over the eastern U.S. and the warm Gulf Stream waters.
I have created a graphic showing the upper level flow field (500 hPa) and have indicated the position of the critical trough (where the height lines curve). Troughs cause upward motion and storm development.
At 11 PM tonight the trough is along the coast, resulting in the storm to rev up over the SE U.S. coastal zone. But the same trough was approaching Seattle on Saturday (giving us rain in the lowlands!). And 5 PM Thursday the trough was WAY over the Pacific, north of Hawaii. Yes...a weather disturbance north of Hawaii, will lead to snow over the NE U.S. a few days later.
That is why the Trump administration's plan to cut 1/2 billion dollars from the U.S. government entity responsible for weather satellites (NESDIS) is very worrisome. The loss of that much funding would undoubtedly terminate or delay new satellite launches, such as the critical polar orbiter satellite replacements planned for the new few years or the second, next-generation polar orbiting satellite.
Now, let me show you how the U.S. model "locked into" the storm. Here is the short-term (12h) forecast again..which should be very close to reality. The low is due east of Delaware.
The 72 hr prediction--pretty much the same.
144hr out, still a snow event, but more diffuse
This kind of forecasting demands state-of-science numerical models and data assimilation (use of weather observations to produce a description of the atmosphere). The National Weather Service has greatly improved their data assimilation approach during the past year (an ensemble-based method called ENVAR) and they are working to replace the aging GFS global model.
Much of the new model and data assimilation development work occurs at NOAA's OAR (Office of Atmospheric Research). Guess what organization is slated to take a 26% reduction in the proposed budget plan? You guessed it, OAR.
Excellent weather forecasts as for the upcoming storm save lives and have very positive economic impacts. Hopefully, the needless undermining of U.S. weather prediction capacity will be stopped by wiser folks in Congress.