I like to keep my seasonal forecasting short and sweet, so here it is:
- Latest model guidance and ENSO trends suggest DJF will likely be a weak El Nino.
- +PDO to support ridging in the western U.S. and troughing over the Midwest/eastern U.S.
- +AMO could help keep the Southeast milder (read: less cold).
- -QBO will allow for a greater chance for blocking in the Atlantic (-AO/-NAO) as well as stratospheric warming events. This would promote colder temperatures in the eastern half of the country.
- Drought conditions in the West will promote warmer and drier conditions there.
- The western U.S. could go warmer given favorable +PDO and long term drought.
- If -NAO/-AO becomes the main forcing mechanism for the U.S. weather pattern, it could bring colder air into the Midwest, Mid-Atlantic and Southeast while providing warm and wet risks in New England.
- If a moderate Nino develops, a stronger subtropical jet associated with it could allow for wetter conditions across the southern U.S. and Mid-Atlantic.
A note on my track record… I have been about 50/50 with long-range forecast skill since I started in 2010. There are many others out there with more long-range knowledge, reasoning and a better understanding of how the atmosphere works on a longer timescale. That said, nearly every forecast I have seen so far favors a warmer West and cooler East, so I’m not exactly breaking the mold with this forecast. It looks like we’re all in the same boat with this one. The only thing left to see is if we can sail to victory or go down with the ship in defeat.
As always, the forecast anomalies are based off the latest 30-year normals (1981-2010).
I’ve had a few opportunities to chase storms in April, and I grabbed a handful of images and uploaded them to Flickr. They’re in my 2014 East Coast Chases album, which I will keep updating with images if/when I get more.
I head out to the Plains for two weeks… IN two weeks! Same crew as last year, but with my own new-to-me personal vehicle (2010 GMC Terrain) instead of a rental. Like last year, I will be posting daily blog on the U.S. Tornadoes site, and I’ll have a post with the link and details later on.
Not much change from the last map… mostly some expansion of the 4-8″ contour over the mountains and cutting back totals a little bit on the parts of the fringes. I don’t trust how bullish the models are on the snow maps because it looks like temperatures may end up a bit warmer than the raw 2mt in the evening, taking the snow longer to start accumulating. Maybe the front-end stuff will be heavy enough to stick earlier, but I have my doubts.
Still some wiggle room with this, but models are coming to a nice consensus regarding the track, which is pretty much where my snow map is now and was yesterday. There appears to be more upside potential than downside with this event in the 1-4″ areas and up in the mountains, especially if you trust the higher QPF model solutions.
With what is hopefully our last snow threat for the season in the greater D.C. area, there is still a fair amount of uncertainty with the ultimate track of the system in addition to how wet it is. Lower than normal confidence with this forecast, which favors the Euro more than the GFS.
My forecast seems somewhat conservative compared to what some of the models are showing, so I imagine there is probably more upside potential than downside with this disturbance. This thing could still shift some 30-50 miles north or south, so don’t get too hung up with exactly where all the contour edges are at this point.
UPDATE March 2nd, 2pm EST: After seeing the latest model forecasts and trends, I would probably shift the 4-8″ and 8-12″+ contours south by about 15-20 miles.
Shifting everything a bit south from the initial forecast and added locally 12″+ wording for the mountains. Accumulations are for snow and sleet, though it will be a mostly snow event in the higher total areas.
If the sleet holds out for longer in the morning then totals may be cut down, but on the flip side once the cold air does arrive, we could start to see some higher ratio snowfall.
Models may continue to drift south, but I don’t think it will go much further south if they do. For the DC area, expect some rain to start tomorrow afternoon, which may briefly change over to freezing rain before the sleet moves in. After some sleet, over to all snow probably a little before morning rush hour… then snow through the afternoon hours.
And then we get hit by frigid air. Joy.
Meteorological spring is here, but winter isn’t done with us yet. Most of the region will actually start off as rain, but a very strong cold air mass will push southward, bringing the low-level air below freezing and changing areas over to freezing rain and sleet before finally transitioning to snow. The models are handling the speed of this cold air push differently, so there is still a fair amount of wiggle room with the snow totals.
There is still room for this to move north or south by a decent margin. I’ll have a final update after the 18z models come in.
A trough will traverse the Ohio Valley today and will start to take on a negative tilt as it reaches the East Coast, with a nice vort max developing over the Carolinas that will allow for a rapid strengthening of the surface low once it moves off the coast. Cold air aloft and the upper-level dynamics will be fairly supportive of snow, but somewhat-limited moisture and a warm boundary layer (despite the snowpack) will prevent a bigger snowfall within the forecast region.
Risks are more towards the lower side across the region with this system, though there is some upside potential near the coast if the low can strengthen faster. A little event to top off this snowy period before temperatures jump well above normal next week.