Good morning and happy Tuesday!
The heat will continue this week, with afternoon temperatures in the low-to-mid-90s across much of the region, and heat index values exceeding 105F. By Friday, however, an approaching cold front will increase the chances for rain and cool things down slightly for the weekend.
Current Synoptic Picture
The current 500mb geopotential height field shows the position of an upper-level high approximately over the Tulsa, Oklahoma area. This ridge is responsible for some weak upper-level flow out of the east across southwestern Mississippi.
At the surface, ridging from a high pressure off the coast of the Southeast is imparting southerly winds at the surface, providing a constant supply for low-level moisture. This is evident in surface dewpoints, which continue to remain in the 70s for much of the region, and will likely continue to be this high as the week progresses.
These high dewpoints, as well as forecast highs well into the 90s will produce heat index values this afternoon between 105 and 110F!
For this reason, the National Weather Service has issued Heat Advisories for parts of Western Mississippi, as heat index values will remain high through Thursday…
Through Thursday
As hinted at by the wording from the National Weather Service, the region will be stuck in a similar pattern through Thursday, with afternoon temperatures in the mid-90s and dewpoints in the low 70s expected.
As far as chances for rain, no significant forcing mechanisms will sweep through southwestern Mississippi at this time, so any shower or thunderstorm activity will be due to diurnal heating, with storms popping up in the afternoon and then diminishing overnight.
Friday and Beyond
A developing upper-level low currently over the Canadian Prairie will move southeastward and strengthen on approach to the Great Lakes region by Thursday morning – this will result in some significant height falls around the Great Lakes and the northern half of the US, while the upper-level low is squeezed by strong ridging in the west and the subtropical ridge over the Southeast.
As a result, a surface low pressure center will develop northeast of the Great Lakes by Thursday morning, with a cold front developing as the cooler air on the backside of the system forced southward into the Northern US meets the warmer air already in place in the Southern US.
This boundary is expected to move through the region sometime on Friday, bringing an increased chance of rain and notably cooler temperatures. In fact, with the GFS model showing temperatures generally around 5 degrees cooler – particularly to our north, it’s likely that some places will fall just short highs in the 90s.
This boundary struggles to move through the region quickly, thanks to the subtropical ridging to our south and east, and will therefore continue to increase our chances of afternoon storms through early next week – even as temperatures begin to recover to average and above-average levels as the airmass modifies.
Day-to-Day Forecast
Today
Partly cloudy skies with highs in the low-to-mid-90s, with a 30-percent chance of an afternoon storm. Heat index values may exceed 105F.
Tomorrow
Mostly clear skies with highs in the mid-90s, with a 20-percent chance of an afternoon storm. Heat index values may exceed 105F.
Thursday
Mostly clear skies with highs in the mid-90s, with a 20-percent chance of an afternoon storm. Heat index values may exceed 105F.
Friday
Partly cloudy skies with a 40-percent chance of an afternoon thunderstorm. Expect highs in the low 90s.
Saturday
Mostly cloudy skies with a 60-percent chance of a shower or thunderstorm. Expect highs in the upper 80s to low 90s.
Sunday
Partly cloudy skies with a 40-percent chance of an afternoon shower or thunderstorm. Expect highs in the upper 80s to low 90s.
Monday
Partly cloudy skies with a 40-percent chance of an afternoon shower or thunderstorm. Expect highs in the low 90s.
