Wally’s Weather: October Part 1
Hey folks! Wally again here, bringing you my update for the next two weeks. Since I’ll be doing this sort of things more often (every two weeks), I’ll be following a format in which I’ll dedicate a section to each US region and maybe save the end for something that interests me. Ready? Let’s begin:
I know I said in an earlier post that this winter was to bring a bit of a change for all our peeps near the Atlantic, but these next two to four weeks won’t support that. From the NCEP (Government’s shut down, but weather still runs!):
The figure to the left is the one-month forecast. The dark red, orange, and tan sections show probabilities (70% probability for the darker, 60% and lower probability for the lighter) that the second half of October will bring above-average temperatures. Precipitation will remain normal for the most part, being a little above normal around the Georgia, Florida, Alabama, and Mississippi areas.
The high pressure ridge should be in place now with the remnants of some strong tropical moisture heading north up the coastline through the weekend. Relief for the Northern end doesn’t look possible until the 17th , when we’ll have some strong southern moisture mixing with a small northwestern disturbance pushing east. Florida should have some on/off tropical moisture.
Referencing the NCEP once again, this map is the 8-14 day precipitation forecast. Yikes, a lot more rain than usual on tap for the entire area. This soaking will actually come in two spurts. The first will be another northerly generated disturbance that will reach south to Utah, and will then move northeast and give this area another chance for a large amount of rain and possible snow during the 12th-13th weekend. The southern rain will come just after that from a semi-random tropical disturbance (as they usually are) and then again from the before-mentioned mixing that will provide relief in the East later this month. Temperatures will run close to normal if not a bit warmer at the north and south extremes, and conditions should run normal to a bit drier in the Kansas area.
If you referenced the beginning of the regional forecast for the East and saw that I am prepping everyone for above normal temps, well, here’s the way the US tends to balance weather patterns out. East being warmer than normal = West being colder than normal and that definitely holds true here. The entire West region will see much lower than normal temps for the next two weeks, centering around Nevada and Eastern California. Precipitation-wise, things will be mostly dry with the exception of the Montana area. A bit more precipitation should make its way to the Intermountain region by the middle of the month, but will dry out once again just afterward. Look for the outer Pacific Northwest to have a bit more precip as well toward the end of the month.
ANALYSIS – Arctic Oscillation
Arctic oscillation is an opposing pattern of pressure between the Arctic and the northern middle latitudes. Basically, if the atmospheric pressure is high in the Arctic, that brings lower pressure in the Northern middle latitudes (northern Europe and North America), and vice versa. When pressure is high in the Arctic and low in the middle latitudes, the Arctic Oscillation is in its negative phase. When the reverse is true, AO is in its positive phase. In both their positive and negative phases, wind oscillations are a large factor in what occurs and when.
In the positive phase, the upper winds are so strong that the polar air gets trapped in the upper North of the globe. Conversely, the negative phase means the winds weaken down enough to let that polar air creep down towards the southernmost regions of the Northern Hemisphere. Now, for you winter lovers out there, this means that we want a negative AO during the months of October through April. Also from NCEP once more, here is the year so far and the two-week forecast for the AO:
This shows the AO so far from Jun through the middle of October, and the forecast is the middle of the yellow area. So far so good as things are trending towards neutral and slightly down, which is normal for this time of year.
That’s all from me for now. Please stay tuned for my new weather installment rolling through in a few weeks. Stay cool (or cold)!