I will show you in the maps below how the national weather pattern and our weather changes as the soupy steamy tropical air mass of Barry leaves the scene allowing a high pressure ridge aloft to build a dome of hotter than normal air over much of the country.
ATLANTA will come under the influence of high pressure surface and aloft with an air flow from the Southwest bringing in more moist air for high humidity while the high pressure provides the heat.
The MAP ABOVE is the projected heat index or “feels like” factor next Saturday July 20th.
The chance of a thunderstorm will not be zero with the heat and humidity providing a potentially unstable air mass, but the chance will be 10-20% below-normal for this time of year.
Ironically some of the highest temperatures may end up being from I-40 Northward including places like Chicago.
The heat comes on as the global wind energy budget changes from -AAM to +AAM as the Pacific El Nino signal weakens.
See how the upper level jet stream pattern evolves in the days ahead (ECMWF model 500mb level ~18,000ft):
SURFACE WEATHER CHART DAYS 3-7:
3 GLOBAL MODELS ENSEMBLE TEMPERATURE GUIDANCE OUTPUT:
They disagree on specific numbers but there’s consensus the heat wave reaches a crescendo next weekend:
STATISTICAL BLEND OF MODELS:
I think the GEFS and CMC are too extreme as of now so my forecast will reject those numbers for now, but I’ll revisit it when I am back to work Monday.
For more follow me on Twitter @MellishMeterWSB.