Yesterday’s trends in the GFS and NAM were looking promising for a clipper to impact the DC Area with some widespread snow showers. Hell, even our local DC weather folks were mentioning a “chance of snow” with “possible accumulation”.
Then last night’s late-evening run kicked us snow lovers in the stomach to what has already been a disgustingly, snowless (add your preferred word choice) ‘winter’ here in the Nation’s Capital.
Check out our “wonderful” American-made forecast models:
- Yesterday afternoon’s (18z) North American Model (this model run makes you feel like you just won best picture)
Here’s the latest run of the same model: (just kidding… it’s a mistake… this is not a joke… you didn’t win a damn thing)
Global Forecast System model (last 10 runs of the same forecast time of Friday 1pm):
- First New England…
- then New York City…
- then southern Pennsylvania…
- then DC Area…
- then it shears out (weakens and drives even further south)
- NCEP do can you feed these American made models some bi-polar medication?
Looking at the vorticity (spin in the atmosphere) at 500mb (18k feet):
- Vorticity in the upper levels of the atmosphere (18,000 feet) weakens as the jet streak (dark red colors over Virginia) “flatten out”.
And the winner is…. the European forecast model wins (yet again) with its steady trends during this forecast time period.
Scattered snow squalls are still possible Friday afternoon as lapse rates (the rate at which temperatures cool with increasing altitude in the atmosphere) will be higher than normal. So when the sun comes out and heats the surface… the parcel of air will rise and cool rapidly allowing for condensation of water vapor and some scattered snow showers/squalls. Any snow showers/squalls could briefly whiten the grass.