If you haven’t been outside this week make sure to do so today because the quiet weather is going to come to a screeching halt next week.
A massive upper level ridge will be building across the eastern United States as we head into next week. This will combine with a large upper low over the desert southwest to create what we call a blocking pattern. What does this mean for our forecast? The short answer is rain and lots of it.
What is an Omega Block?
In our case we are looking at an omega blocking pattern, named after the capital Greek letter (Ω).
In a typical omega block, the dominant feature is a massive ridge aloft and the associated high pressure at the surface. On either side, low pressure’s get stuck in the jet stream and are unable to pass though the area due to the stubborn high pressure.
The areas of the country under the ridge typically see very quiet yet warm weather. The unfortunate souls (Arkansas…) stuck on the western side of the ridge typically experience cloudy, cool, and VERY wet weather. The citizens caught on the east side of the ridge, get stuck in northwest flow. This typically brings cooler and sometimes drier weather.
Next Week’s Set-Up
In the upper levels of the atmosphere, we will be positioned on the western side of the ridge and eastern side of the trough. This set-up will place us in southwesterly flow aloft which will allow the rich moisture from the eastern Pacific to stream into the region. The counter clockwise rotation around the low pressure and the clockwise rotation of the high will stick our region into deep southerly flow at the surface.
At the same time a surface frontal boundary will stall out across the area. Multiple upper level waves will interact with the boundary to produce multiple rounds of showers and storms.
Since we get “stuck” in this pattern, we will be very moist and the atmosphere will be very soupy. The high moisture content will allow heavy rainfall to become a possibility.
High Precipitable Water Values
Precipitable water, a measurement of the water vapor content in a column, will be be close to 2″ (yellow/orange color) in some locations over the area. This means if you were to condense the entire column of water vapor to liquid, it would measure close to 2″ across the area. With precipitable water values, the higher the value is, the more efficient the storms will be in producing heavy rainfall.
Weather Prediction Center (WPC) 7-Day Totals
We are looking at widespread possible rain totals of 3-5″ regionwide. This is some impressive totals this far out. More rainfall is expected towards the end of the week beyond the next 7-days so expect the totals only to climb as we get closer to the event.
Rain Chances Likely Through Much of Next Week.
This type of pattern looks to bring several rounds of heavy rain throughout the week. Flash flooding, areal flooding, and even some river flooding will all be possible. Make sure to be prepared for this possibility. Listed below are several Weather 101s and Weather Blogs that will be helpful in preparation.
Find out if you live in a flood prone area using this ArcGIS Map application from FEMA. Just type in your address and drop a pin. Click HERE to begin!
Keep it here with Your Weather Authority Team for the latest on the impacts expected from this massive rain event!