VORTEX-SE In the Field

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.

Status: Down

VORTEX-SE is still in a down mode.  We watch the numerical guidance carefully every day, looking for signs of sufficient shear, CAPE, and initiation mechanisms.  Right now, there are hints that a weak system may cause storms late next week (~April 21) with a marginal possibility of severe weather.  And there are hints of additional relatively weak episodes in the last week of the month.  Regular briefings will resume early next week if the late-week system shows signs of being stronger than currently forecast.  Otherwise, briefings will resume about 7 days before the next expected severe weather episode.

STATUS: Down

The long-range numerical guidance suggests that ridging will dominate the Southeast, with strong troughs moving through the SW US and lifting into the Midwest for the next week or so.  Eventually, these waves may start making it into the V-SE domain with enough energy to support severe storms… perhaps around April 20 and beyond.

The UAH briefing team will resume weather briefings about 7 days prior to the expected resumption of severe weather in the domain.

Status: Down

The IOP watch has been ended; the investigators have decided not to make the Monday night/early Tuesday event a V-SE IOP.  All available guidance suggests the probability of surface-based CAPE over 500 J/kg is low, and the probability of low-level shear supportive of tornadoes is also low.  These low probabilities imply that it is not worth using one of the two remaining IOPs for this event.

Briefings are now suspended until the UAH forecast team believes an IOP is possible within about 7 days.  Watch this blog for an announcement of the resumption of daily briefings.

STATUS: IOP Watch

We continue to watch the period from overnight Monday into early Tue morning (APR 12).  There will be a weak front passing N AL, but right now it appears that CAPE and shear will be below the climatological thresholds for tornadoes.  Further, the best CAPE and best shear are probably not going to overlap well in time.

A final decision on this IOP will happen at the 1 PM Saturday briefing, but odds are very slim.  Thereafter, there are no other events looming on the horizon, but that picture is likely to change from day to day.

STATUS: IOP Watch

We are watching for the possibility of an IOP ~ Tue Apr 12.  The odds of an IOP with this system are pretty marginal, but remote investigators need to be considering how they would make travel arrangements with the event occurring early in the week.