What has been suspected for quite some time was officially proclaimed today by the Climate Prediction Center: El Nino is alive and well. The warming of the waters in the equatorial Pacific Ocean directly impacts weather across the globe, and the forecast for spring represents what we would expect during an El Nino year. Here in the Southeast we can expect above normal rainfall along with temperatures that could go either way. Chances are it will turn out cooler than normal.
So what exactly is El Nino? As stated above it is a warming of the waters along the equatorial Pacific.
The warmer sea surface temperatures have an effect on the upper level winds that form over the Pacific Ocean, and eventually cross the United States. What typically happens is a split in the jet stream develops along the West Coast with a large ridge of high pressure developing across the west in the northern branch of the jet. The southern branch of the jet stream dives across Mexico and the Southwest transporting Pacific moisture into Texas, and eventually collecting Gulf of Mexico moisture that makes it here to the Southeast. With that in mind we usually expect to see wetter conditions which is what is expected this spring. Along with the wet weather, slightly cooler temperatures can be expected as well. This typically keeps the number of severe weather events lower than in a non-El Nino year. This doesn’t mean that severe weather won’t happen, it simply means that the number of severe weather events should be less.
With a stronger and more active southern branch of the jet stream present we can also expect a quieter than normal tropical season. Stronger than normal winds in the upper levels of the atmosphere crossing the tropics from west to east are counter productive to the development of tropical systems.
The last time we had an El Nino during the tropical season was the summer of 2009. That summer we wound up with the average number of named storms (10), but only had 3 hurricanes compared to the average of 6, and came out with 2 major hurricanes compared the average of 3. None of the hurricanes hit the United States. Just like with tornadoes this in no way implies that a catastrophic hurricane will not impact the US. In fact one the costliest hurricanes ever, Andrew occurred during the El Nino summer of 1992. Stay tuned.
So far this month the pollen count here in Atlanta has been flirting with the lower end of the high category as we notice the area trees starting to bloom. Today’s pollen count was 188 which places it in the lower end of the high category that ranges from 90 to 1499. These numbers by the way represent the amount of particles per cubic meter of air. When added up that’s a lot of particulates floating in the air around you. For the rest of the week our numbers should remain about the same with lower numbers coming with the rain on Thursday and Friday.
Typically we see the numbers skyrocket by the end of March and the beginning of April. Each year the readings soar into the thousands with the peak usually hitting the 5,000 to 6,000 mark. Last year’s highest reading was 5231 on April 4th with the peak numbers lasting for about two weeks. The all-time highest reading was 9367 on March 20th, 2012! Let’s hope that doesn’t happen again this year, but remember the pollen season has just begun and will only get worse.
After a sunny and milder weekend rain will return next week.
WEEKEND: Sunny skies will continue on Sunday with temperatures warmer than they were on Saturday. Our high today reached 63 here in Atlanta, and tomorrow we should see reading in the upper 60s to near 70. The normal high for the date is 62. As the rain moves in next week temperatures will remain mild with highs generally in the 60s.
RAIN: Upper level flow coming out of the Southwest will bring lots of moisture to the Southeast beginning on Monday. The pattern will remain the same for all of next week, so it looks like a good chance of showers each day. By the end of the week a wedge of cool air will form east of the mountains giving us cooler temperatures by Friday. It should be brief with temperatures returning to above normal next Saturday and Sunday.
DAYLIGHT SAVING TIME: Remember that we return to DST Sunday so be sure to change your clocks ahead one hour before you go to bed so that you are not late for whatever you have planned in the morning.
Fog and drizzle will make for a soupy night and then t-showers possible by Wednesday.
RAIN: Light rain continues tonight with dense fog across all of north Georgia. Visibility at times will be reduced to a quarter of a mile or less so be careful driving. A few showers will be with us early on Wednesday and then a round of stronger showers and t-showers will return for late Wednesday and early Thursday. Nothing severe, but a rumble or two of thunder can’t be ruled out. Rain totals will generally be less than a half inch.
TEMPERATURES: Today we saw a huge range of temperatures with the northeastern part of the state stuck in the 40s while areas south near Macon and Columbus soared into the mid-70s. A more even distribution of temperatures will return tomorrow with highs area wide in the 70s. Enjoy it because much colder air returns by Thursday with temperatures in the afternoon only in the low 40s!