Good morning! Hope everyone is doing well! After a briefly milder weekend for many, we are settling back to a colder pattern over the next several days. Other than minor disturbances, the main feature many are watching is a southern storm system expected to bring heavy precipitation to the southern U.S. this weekend. The northern edge of this will have the threat to see some wintry precipitation, although questions remain on the northern extent and how much cold air is in place where the moisture is falling. The set-up is a bit unique which makes the forecast more complicated.
A split upper-level flow will be present as this system works across the southern tier of the country. A blocking area of high pressure (at the surface and aloft) to the north will be the big factor in keeping this system shoved further south, with the northern jet stream pulled northward. This gives this storm less of a chance to have an infamous northerly shift. Not saying it can’t happen, but not as likely in this scenario.
The energy with this system is still in the eastern Pacific. As this comes on shore mid/late week, we should see better model convergence.
Looking at surface pressure forecasts Saturday night, we have a strong area of high pressure across the Midwest, which will be another factor to keep the system from getting too far north. If the high can trend weaker, this could possibly allow for some north ticks. However, remember we also have that blocking high aloft, so this system doesn’t have a ton of room to adjust north.
Latest data still honing in on a swath of wintry precipitation from the southern Plains east into parts of the Carolinas/mid-Atlantic. Looking at the latest GEFS ensembles, you can see the increase in snow totals over the higher elevations in the Ozarks of southern Missouri/northern Arkansas. More notably, a very strong signal in the Carolinas and Virginia with a classic cold air damming (CAD) event. This could also for a major snowfall in these areas. The lower Ohio Valley/Tennessee Valley’s are in that “not so certain” area as the systems energy starts to phase into a coastal low, and the marginal temperatures combined with a lack of elevation makes the snowfall forecast tricky. Regardless, this is an impressive early season winter storm unusually far south for this time of year.
Checking out the forecast surface temperatures Sunday, you can see the colder wedge of air damming agains the mountains in North Carolina and Virginia.
Check out the precipitation forecast with this system. A lot of moisture, so where it’s cold enough we can see healthy amounts of wintry precip. Meanwhile, the northern half of the U.S. stays quite dry with that blocking high.
Once we get past this system, we start to usher in a warmer period for a time, along with an increasingly active pattern again mid-month. Here are the forecast temperature anomalies next week off the latest GFS ensemble:
The milder mid-month is associated with a shift in tropical convection and an extended Pacific jet. This will also allow for a more active pattern across the U.S. mid-month. You can see on the correlation maps below, we tend to find a wetter pattern as the MJO (forecast shown below) shifts into phases 3 & 4.
Remember the MJO (Madden-Julian Oscillation) is an eastward-moving pulse of convection along the equator. Different phases of this oscillation correlate to different temperature/precipitation patterns in the U.S. The forecast shifts the convection from Africa into the Indian Ocean. A good way to see this is looking at areas of upward/downward motion. Areas in the blue/purple represent where the convection is centered (upward motion), while the reds represent suppressed convection (downward motion). You can see the area of upward motion shifting east out of Africa into the Indian Ocean, representing our MJO “pulse.”
We see a much milder pattern for the week 2 period, but we are closely watching the progression of things with the MJO, ENSO, AAM, and already seeing the precursors to a stratospheric warming event. We are analyzing all the tools in the tool shed to nail down this pattern. We discuss the details daily in our long-range forecasts! One thing for sure, we see an active time-frame near Christmas with several systems in the Bering Sea correlating to that time-frame. This is sure to make that period interesting. 🙂 This pattern modeled on December 9th (shown below) would correlate to the 23rd-26th time-frame for the U.S. We overlayed the U.S. map over the Bering Sea in the North Pacific which can give us a rough idea of “where” these systems would correlate to in the U.S. This is NOT exact, and in theory, you won’t have lows as intense as shown here. Just gives you an overall idea that these storms would correlate to the central U.S.
Our weather service can provide you with daily You can inquire for our forecasting services by going to bamwx.com/contact-us or e-mail [email protected]! We’d love to help your snow-removal business this winter season! Have a great day!
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