A week or so ago I mentioned that we would be undergoing three separate jet stream transitions, with the last one being a cold snap. Well, it sure has been cold outside! The third pattern, a digging upper trough, has dominated since this past weekend.

As is often the case in winter, the jet stream will continue to fluctuate in alignment over the next week. Once again, it will be a battle between a northerly branch of the jet and a southerly branch. Here you can see the current (relative) position of each of these steering flows. For the most part, through this week, we will be in the southerly flow which will allow temperatures to moderate. Note the dashed black lines. Each of these “impulses” indicates an upper pulse of energy that will result in a chance of precipitation. They are lined up about 3 days apart.

So, what might we expect for precipitation this week? Here is our MMEFS model showing accumulated rainfall. The time range (bottom axis) extends through February 20th. I have indicated 3 separate rain events, one arriving early in the week, a second later this week, and the third arriving over the weekend. Right now, and subject to change, the first one looks pretty weak as to rainfall amounts, with the second event significantly stronger. Have you noticed I am stating “precipitation” rather than “rainfall.” Due to the current close proximity of the northern jet, a small part of the region could receive frozen precipition with this first event.

In consideration of hydrologic impacts, let’s take a look at this next graphic. The bottom image shows the cumulative rainfall potential over the next 7 days. I have boxed in the more widespread coverage (0.50 – 1.0″), scattered coverage (1.0 – 2.0″) and spotty coverage (2.0 – 4.0″) ranges from the three events.

The image on the top indicates flash flood guidance. It can provide a rough estimate of hydrologic response. Due to the on-going drought, much of the region can take 3- to 5-inches of rain before more significant runoff and hydrologic response occurs. These values are lower over parts of Mississippi, Alabama, North Georgia, and the western Carolinas. It is possible that rivers within this region could experience more robust within-bank rises, and perhaps some minor flooding at a few spots, especially within the Tombigbee River drainage, later this week.