Posted: 6:33 am Thursday, December 1st, 2016
By Kirk Mellish
December 2…UPDATED 5-day rainfall amount forecast map below:
Those who follow me on Twitter @MellishMeterWSB got the heads up on the change to cooler and wetter as far back as November 19th and 23rd.
Before the jet stream pattern change allowed the wet pattern to become established the drought had reached dire levels in much of the Southeast United States including Georgia as documented in previous posts.
Over the past three days 3-6 inch rainfall totals have been common across the area, well above normal for this time of year. The 2.32 inches of rain at the airport Wednesday Nov 30th was the most in one day since Christmas Eve 2015!
RAINFALL TOTALS NOVEMBER 30th:
However, when you NEED over 22 inches in the mountains and over 15 inches in much of Atlanta to eradicate the drought (see map) it’s still just a drop in the bucket. But it sure helps the top soils, creek flows and wildfire situation.
So yes, drought conditions persist as you can plainly see.
However, short-term there is more good news as additional heavy rain is in the outlook over the next 5 days:
And in fact, the general rain outlook for the next 5-10 days is favorable for more drought relief:
Then a drier spell:
The rainfall Outlook for December on average is also promising:
It typically takes three consecutive months of above-normal rainfall to reverse a drought. As of now that is not expected to happen. However, I have said on the radio and in these blogs many times over the years the old axiom that most floods end in drought and most droughts end in flood. So it does not HAVE to take three months of wet weather that’s just the historical average.
So while the longer range winter outlook is for normal to below-normal precipitation it’s obviously always possible the new wet pattern will lock in or return later in winter or spring.
As I discussed in my preliminary winter outlook blog back on OCTOBER 27th “a weak or neutral ENSO would provide closer to normal rain this winter. On the other hand, there is a tendency for more rain and severe weather and stormy episodes in La Nina springs. So there is potential for both a positive and negative impact in the long range”.
The LAST thing we want is a STRONG La Nina in the Pacific. Currently it is neutral to weak and is not expected to strengthen, if anything it may weaken over the winter and spring.
WINTER RAINFALL IN ATLANTA BY ENSO PHASE:
So yes the blocking high pressure aloft that has been over the Southeast U.S. for 6 months to a year has weakened and shifted, allowing a more active jet stream storm track. However, it is far from clear that this is a permanent shift or a transient one. In weather extremes, the rubber band theory often works. You can only stretch a pattern so far so long before it snaps back.