Using analogs is a useful way to identify signals for severe weather days, and here is a good example of their use. FRENCH FRIES site to show where dangerous weather may be coming. Normally we use this the same way as when we use aggregation (i.e. when forecasting over a longer period), but this shows where (to the left) an area within 110km of the point grid can see 1 severe weather report (hail, wind, tornado) and (right) in the exact same situation, except it’s 5 severe weather reports. Originally, the main areas of interest being emphasized are the Southern Plains and the IL.
Dive into the general evolutionary process:
At 300 mb, an intense streak of rays will surround the bottom of a long wave trough, which will spread across the Plains and into the Midwest tonight and into tomorrow. This jet streak will allow for enhanced surface divergence.
At 500mb we can see the “big picture”, as it says a lot in this case. The trough is pushed out of the Southwest and raised to the Northern Plain with a negative (slightly progressive) inclination. Up ahead, the strong upward thrust in the form of an active eddy current shifts down the trough axis and into the Midwest.
Ignoring the surface, this corresponds to the formation of an expression cycle on the Front Band and begins to strengthen as it enters the NE today before turning to IA tomorrow morning, before finally following follow MI on Friday to Saturday nights.
On the surface, this would allow a warm front up much of the Plains and Midwest, with a developing cold front that would droop from the lows and eventually shift eastward. The key here is that as the low surface moves north/northeast, as the warm front moves north, its southern positions will become warm areas tomorrow; This makes sense as warm and humid air will begin to move northward and with it cloud cover – cloud cover impedes instability so we see some uncertainty about CAPE .
Jumping back up in the atmosphere to 850mb, we saw an impressive low-level jet, extending from the Gulf and cutting through the warm region. This implies moisture transport, along with vertical lift with warm airflow.
Speaking of humidity, what we can see is transport in the form of dew points as it heads north. Widespread 60-degree dew points will be transported to the IL, extending from eastern NE, OK and IA to the Midwest and MS River Valley, where it may be more favorable to support strong to severe storms .
So we have strong upward thrust, humidity, instability and now we need to see if we have a storm organization and in what form. Below, we now have the longitudinal wind shear of the deep layer, which is important to allow separation of upwinds and downwinds to keep a thunderstorm mature. We will not lack shear, as is usual with any supercell where we consider whether the 0-6km shear value exceeds 35-40 knots. This threshold usually indicates whether a storm is likely to become hypercellular, and we should see more than 60 knots of deep tomographic force spread over a large area in the warm region.
So we know dynamics since this inclement weather setup is not only a boon for inclement weather and all its modes, we now need to see if we have enough instability to allow for an even environment more favorable or not. Below, we see MCAPE rising northward in our warm region and an approaching cold front shifting eastward (where there is a clear line between CAPE values close to zero and where it is growing). However, tomorrow morning cloud cover will form due to lift, which could limit the extent of any particular supercell – however, in cases like this where stability is lacking, dynamics strong force (cutting) can make up for this! However, we found that more than 500 j/kg increased to the IL center, spread east to TX, up the Ozarks, and shifted eastward into the Midwest. Literally, we’ll probably have enough tomorrow to have some sporadic, open warm regional supercells before high growth occurs with a convection wind forming pushing eastward in front of the cold. . While the pressure could be further north with better instability in the south (ArkLaTex), both areas are likely to experience severe weather as we will now see all sorts of serious hazards. Important factors include gusts, large hail and tornadoes – although the latter is much more favorable to form near the lower surface in IA and has a better chance of forming further north in places such as north of MO and east of IA.
Here’s how it’s going to be starting tomorrow morning and during the day. Mixed modes of superlayers and linear segments will form (the former is closer to the lower surface with the latter more south). starting around late morning to midday. Then, as the cold air moves eastward, high-grade development begins, and convection currents then push eastward into the TN River Valley from tomorrow night to tomorrow night.
Strong winds and damaging tornadoes with individual hail would accompany any severe storm, with a higher risk of tornadoes near the triple point (low on the surface), expected. there will be a large area of damage and strong gusts of wind.
Here are some modeled gusts verbatim, with values in excess of 40 – 50 mph, especially with any strong-severe storm. Additionally, late Saturday, due to the tightening pressure gradient, we should see gusts continuing to blow across the Northern Plains and into the Midwest.
So to recap:
-An outbreak of severe weather will peak tomorrow across the ArkLaTex region, through to IA, IL and MS River Valley.
Strong gusts, isolated heavy hail, and few tornadoes are preferred with warm superclasses (although it remains uncertain about fragmentation and what might manifest among some of the cloud cover), with linear segments becoming the dominant storm regime in the afternoon.
-Risk starts 10am – 12pm east along OK, TX, NE and then turns eastward with convection sections prevailing in the afternoon and evening before shifting east .
- Take precautions if you live in this outlined common area and be prepared to take action!
About the author
Hello! My name is Armando Salvadore and I am a Mississippi State graduate with a Bachelor of Professional Meteorology and an Activity Meteorologist working in the Private Sector. Stay tuned if you like technical, exotic, and general weather tweets! Also big on long-range forecasting as well! Twitter: @KaptMands