STATUS: IOP

The evolution of today’s weather is very uncertain.  There is a squall line to the west of the area that could advance through the study area this afternoon.  Or it could weaken/dissipate, and be followed by new activity late this evening/tonight.  Or… name your scenario.

Because of the uncertainty, the sounding systems will be deployed near TTU Stesonet fixed surface observing sites, and study the evolution of CAPE.  It should be noted that at least on set of numerical guidance suggests that CAPE will remain small, and then go to zero for the remainder of the day as the cold pool from convection to the west advects across the area, or is renewed if the convection persists.

The in situ observing platforms will remain close to Huntsville until the evolution becomes more clear, and a target storm can be identified.  The MAX mobile Doppler radar will be deployed to Courtland AL airport, and the Purdue X-POL likely will go to the Tanner site later this afternoon.

STATUS: IOP

We are still expecting convection tomorrow (Wed) evening.  Observing is expected to begin midday to monitor the evolution of the boundary layer and mesoscale features.  There will be a PI science planning meeting to design the day’s observing strategies at 10 AM at UAH SWIRLL.

Another episode or two of convection may occur as the week goes on and into the weekend, so the current plan is for this IOP to continue until the weather settles down, or project resources/participants are exhausted.

STATUS: IOP

The final VORTEX-SE IOP for the Spring 2016 campaign will begin Wed 27 April.  Current guidance suggests the possibility for HP supercells and/or a QLCS system Wednesday evening or night.  We will have a science planning meeting at UAH on Wed morning or midday.  The time of this meeting will be decided in the usual 1 PM conference call on Tue 26 April and will be posted on this blog as well.

There should be a continuing period of occasionally sufficient mid- and upper-tropospheric flow for supercells, and occasionally augmented low-level flow and shear, as well as CAPE, between the Wednesday event and ~ Sunday 1 May.  Thereafter, it looks like general ridging in the central US and a deepening trough to the east will bring cooler, drier continental air into the VORTEX-SE domain.  So this IOP will probably involved 2-3 observing periods.

(Dates corrected… thanks to the observant VORTEX-SE fan in Kansas.)

STATUS: IOP Watch

We continue to watch the weather expected between about Thur 28 April and 2 May.  A decision is expected tomorrow on a possible deployment to N AL for observations beginning Thursday.  At this time, it appears that the first system will likely be very marginal for tornado potential, but a stronger system at the start of May has larger potential.

STATUS: IOP watch

We are watching two systems.  The first is the major wave that will move into the Plains on Tuesday, and then begin filling and moving northeast on Wednesday.  It’s possible that the southern end of this strong forcing will be in ~ eastern AR, in a region where roads and terrain do permit mobile operations.  We would not have 100% of the platforms participating because of conflicts with academic schedules.  Another wave follows this first one, and right now it appears that this one will take a more eastward track and possibly move through northern AL with an attendant week surface boundary around May 1.  If the investigators decide to operate in the MS Valley mid-week, they would retreat toward N AL for the weekend.

Right now, neither scenario looks particularly promising for tornadoes.

A decision on the mid-week MS Valley deployment will be made tomorrow 24 April.

STATUS: IOP Watch

The atmosphere is making a valiant effort to hold off severe weather until just after this year’s VORTEX-SE observing period.  We continue watching the last half of next week.  It looks like one of strong systems that will impact the Plains early next week will be lifting out over the Ohio Valley, and a trailing front may make it into N AL ~ Thur 28 April.  CAPE should be present, but flow (especially in the lower troposphere) may be too weak for sufficient shear.  There are hints that eventually one of these systems will move eastward into the lower MS Valley with quite a bit of energy.  But this may be too late for this year’s campaign.

STATUS: IOP Watch

It is starting to look like the stronger flow and better CAPE will remain to the north and west of the VORTEX-SE domain through much of next week.  We are continuing to monitor the trends.  This time of year, we would normally not expect the strong subtropical ridge to be “permanent”, but we will see.  Daily briefings continue.

STATUS: IOP Watch
We are starting to watch the potential for observations beginning around 27 April.  At that time, it appears that the airmass over N AL will have sufficient CAPE, and modest shear.  The shear may be enough for supercells, given the CAPE.  This may be an extended IOP, with observations every day or two for a period of 5-6 days.

Daily briefings will resume today at 1 PM, with a STATUS update after the briefing.

STATUS: Down

Tony Lyza writes:

We are currently watching the 27 April – 3 May time frame for a potential
increase in severe weather chances across the VORTEX-SE domain.  The
blocking pattern currently in place across North America is progged to
break down over the next week, with the GFS, Euro, and their respective
ensembles indicating a good likelihood of a more progressive western
troughing pattern setting up after the 25th.  Many of the ensemble and op
guidance runs indicate the subtropical ridge breaking down, allowing for
ample PBL recovery to occur and shortwave troughing to make its way into
the Tennessee Valley region.

Our current plan is to resume 1 PM forecast briefings within 7-8 days of a
potential IOP system.  Currently, our thinking is that these briefings are
likely to resume toward the end of this week or this weekend.  24 hours
notice will be given to the restarting of briefings.