VORTEX-SE In the Field

STATUS: Down

The next system that we are watching will pass through on ~ Thur 24 March.  If this forecast persists, we will consider starting our IOP watch tomorrow 17 Mar, with an IOP decision around Sunday 20 March.

IOP in progress.

A compact mid-level wave continues to approach from the west.  It is expected to cause an increase in CAPE and shear after ~midnight local time.  Thunderstorms are possible in this environment between about 3 AM and sunrise.  Serial soundings have commenced from the Belle Mina supersite, and at the time of this posting (4:20 PM LT) all other teams are moving toward their observing sites.

No decision has been made concerning extending the IOP through the Tuesday cold front event.

STATUS:  IOP commences midday Sunday

This IOP focuses on the passage of a compact mid-tropospheric wave on Sunday night.  It now appears that shear will begin increasing around midday tomorrow (Sunday 13 March).  This will be followed by an increase in CAPE, albeit to rather mediocre values.  With wave passage between midnight and sunrise Sunday night/Monday morning, there could be convection.  We will commence observations midday Sunday with serial sounding launches from the Belle Mina supersite, with extensive radar, surface, and sounding observations beginning later in the day, and lasting through the night.

The IOP may be extended through much of the day Monday if the current hints of lingering CAPE and shear with a chance of convection persist.

We are still monitoring the evolution of a cold front event on Tuesday when a combination of shear and CAPE supportive of supercells will exist, but it is possible that low-level vertical motion may be insufficient to initiate convection.  There will be additional discussion at the Sunday briefing to design the deployment, as well as to consider observations that bridge that gap between the Sunday night and late Tuesday systems.

STATUS: IOP Sunday 13 March

We continue the IOP declared yesterday.  The Sunday evening/night event still appears marginal, but the overall idea of a compact mid-level wave passage,  an attendant brief increase in flow and shear through the depth, and an increase in CAPE to perhaps 300 J/kg, is enough to motivate us to observe the passage of this system.  We will begin observing the “ramp-up” in CAPE and shear around midday Sunday, with operations likely through part/much of the night.

The next system is a cold front that should pas through northern AL on ~Tuesday.  Significant CAPE, deep shear, and storm-relative helicity (SRH) should accompany the passage of this front.  On Sat and Sunday, we will evaluate the need to extend the current IOP through Tuesday.

STATUS: IOP commencing Sunday morning, 13 March.

The IOP for Saturday has been scrubbed.  Instead, the IOP will commence Sunday morning.  It is anticipated that a compact upper system will pass the study area after sunset on Sunday, with a slight threat of tornadoes.  CAPE may be insufficient, but shear should be adequate.

On Sunday, we will make a decision on whether to have another IOP on Tue/Wed, which will mean that some traveling researchers will likely stay in Huntsville for the duration of these two events.  The mid-week system is a cold front, likely with sufficient CAPE and shear for a tornado threat.  However, at this time the degree of forcing to initiate storms is uncertain.

STATUS: IOP on 12-14 March

We will commence the first IOP of VORTEX-SE Saturday, 12 March.  Observations will ramp up during the day, with boundary layer evolution observations underway by evening.  We are anticipating the passage of two marginal systems during the weekend and Monday, the first on early Sunday morning associated with the remnants of the current deep system over Texas, and the second associated with a sharp mid-level wave on Monday morning.  Potentially, we may stay through Wednesday to observe convection associated with a cold front passage.  Thereafter, long-range guidance is hinting at a quieter pattern through the end of the month.

STATUS:  IOP watch for 13 March and beyond (IOP has been cancelled for 12 March)

The consensus decision today is to not attempt to observe on 12 March because it the forecasted low-level shear is at the low end of the tornado climatology.  Forecasted MUCAPE spans a range from 0 to ~1000, depending on the forecast model.

Another strong vorticity maximum approaches the region on Sunday, and we are now beginning to watch this feature, and watching how the overall pattern evolves beyond Sunday.

STATUS: IOP Watch

We continue to watch the forecast evolution of the lifting/weakening cutoff that will become a negative tilt shortwave late this week in the south, crossing AL early in the weekend.  At this time, the forecast is for negligible chances for tornadoes with this system, primarily because of muddled and weak low-level wind profiles.  We are monitoring to determine if there might be a short window of somewhat more favorable conditions.  If so, studying the evolution of CAPE and shear in this scenario might be scientifically valuable.

Following the Friday/Saturday event, another fairly strong shortwave should pass near or north of AL on the 14th; the development of adequate CAPE remains uncertain.

A final IOP decision will be made in briefing tomorrow, Tue 8 March.

IOP Watch

We continue to watch for a short window of opportunity sometime toward next weekend, when an upper low weakens and lifts northeast from TX.  There is a chance that a weak warm front will exist near the observing area, with light east-southeast winds beneath strong southerly flow aloft, leading to sufficient low-level shear for tornadoes.  An IOP decision is anticipated around Tuesday.

The remainder of March appears to offer additional deployment chances, but the forecast uncertainty continues to be very large.