Sunday Afternoon Forecast Update 2 PM

Here's a current look at visible satellite imagery across the state as of 2 PM. Notice cloudiness in southeastern parts of the state, contrasted with splotchy clouds across northwest and west Alabama. That's because the 'splotchy' clouds are more convective in nature, since they're more directly associated with the upper-level low center located to our north of the Ohio Valley.

Here's a look at the GFS forecast at 1 pm tomorrow at 500mb. We are looking at vorticity. Notice we have a ribbon of vorticity stretching from Mississippi through AL up to Ohio. All along this corridor, at least isolated to scattered showers and storms are possible tomorrow afternoon.

Here's a look at the jet stream level valid Wednesday afternoon. Notice an unseasonably strong jet streak (100kts) stretching from Memphis up to the Great Lakes. Parts of MS/AL are in the favorable right-rear quadrant for uplift at the surface. However, the primary convergence axis and deepest moisture axis may not be collocated with this feature just yet, but a general increase in the coverage of storms is expected for Wednesday afternoon.

However, by Independence Day, the Bermuda High over the western Atlantic will be slowly building west, causing the aforementioned upper level to actually retrograde, or move west. As this happens, the highest moisture axis is expected to be over Alabama for Thursday into Friday. While it may not rain all day both these days, confidence continues to remain fairly high at seeing showers and storms at times.

So, while that may not be what people want to hear that have outdoor plans for the 4th, we can be thankful that we are not dealing with the 115+ degree heat that parts of the Southwestern states are dealing with right now!

Have a great Sunday, and God Bless!

IW

June 28 Severe Weather Update...

After some morning clouds, temperatures have skyrocketed into the upper 80s and low 90s across west Alabama with a mostly clear sky. This has allowed the airmass to become very unstable across northwestern sections of Alabama into adjacent portions of northeast MS.

Here's the surface CAPE chart valid right now from the SPC mesoanalysis page. Notice the values exceeding 4500 j/kg from west Alabama to near Memphis, TN. This is an environment that is very unstable, and with an outflow boundary moving south noted in visible satellite imagery, thunderstorms could initiate at any time in this regime. The National Weather Service in Birmingham is particularly concerned with the areas of Fayette, Lamar, Marion, and Winston Counties for potential thunderstorm initiation (seen below; source NWS Birmingham).

However, uncertainty remains to the actual aerial extent and coverage of these storms should they develop. It could be one or two intense storms, or several strong to potentially severe storms. There is, however, some concern about storm coalescence into an MCS and/or bowing segment and accelerating southward. Given northerly flow aloft, these storms would move due south, and if organization occurs, a wind damage threat would certainly be in the cards. Initially, should any storms develop, large hail will also be a potential threat as well.

The 4km WSI RPM develops isolated storms by 3pm over northwestern sections of central AL and moves them southward. Like I said earlier, it remains to be seen if storms can actually develop, but if they do, they will pack quite a punch.

Throughout the afternoon and evening, another thunderstorm complex should develop over portions of Kansas and track southeastward. The 4km and 12km RPM shows this feature making it into north-central MS overnight but dissipates it before it enters west Alabama. This complex will need to be monitored, but for now it appears it will not impact west Alabama.

For tomorrow, a frontal boundary will be sinking in from the north, and as the airmass becomes at least moderately unstable, scattered to numerous showers and storms will develop in association with this feature. Local enhancement of storms may occur where pockets of stronger heating occur and/or where any outflow boundary interactions occur as well and in these areas strong to potentially severe storms will be possible.

Keep an eye to the sky, and God Bless!

IW