Status: GO for Saturday IOP

Teams are enroute, or will soon be, to the Monroe LA subdomain of VORTEX-SE. This is one of two subdomains we will use this year, depending on the forecasted weather.

A narrow mid-tropospheric jet is forecast to be advancing toward Louisiana from the west-northwest on Saturday. To the north of this jet, lift will be strong, likely leading to quite a bit of precipitation and low-level cooling. To the south, the air will be sinking which should enhance the “lid” and possibly limit convection. Between these two regions, there should be a narrow goldilocks zone of sufficient CAPE and strong shear that could support some low-level rotation. Of course, many things can go wrong (and usually do, to the benefit of the general public) with this scenario and any convection may be non-rotating.

We will deploy one mobile C-band “SMART-Radar” from OU to pair with the U. Louisiana-Monroe S-band research radar, and ULM mobile sounding teams. The NOAA P-3 aircraft will likely take off midday Saturday and head toward Louisiana, if this forecast holds up. They will make radar observations of the most interesting storms, and will focus on storms over the ground radar domain near Monroe when storms are present there.

There is a slim chance that there will be tornado potential in the Georgia/N Florida area on Sunday. Although we don’t have a ground subdomain there, the P-3 aircraft may fly a mission to observe storms in that region.

Thereafter, we expect quiet conditions until the following weekend.

One more time with the caveat: forecasting conditions for a field observing program are very different than forecasting for more general purposes. We are generally fine with a “busted forecast”, especially if we are able to obtain data to tell us why we busted. Learning what processes reduce tornado potential are almost as interesting as catching tornadic events. Because tornadoes are rare, we have to observe most everything that comes along with even a little potential. And this spring, our focus is not so much on the physical processes in the atmosphere in the Southeast, but learning how to make much better observations in this difficult region.

STATUS: IOP Watch

We are anticipating a possible IOP on Saturday and Saturday night.

A trough will deepen across the northern High Plains late Friday, causing an acceleration of the flow in the upper atmosphere across OK on Saturday. This trough will consolidate somewhat as it approaches MO/AR, and a surface low will deepen fairly rapidly somewhere in the region centered near Memphis.

The developing southerly flow should bring Gulf moisture back into the Arklatex region Friday night, although the confidence in the “quality” of this moisture is not high. A series of runs of the operational GFS show a subtle decrease with time in the forecasted dewpoints across the region on Saturday, and an associated decrease in CAPE. We expect that drier air will remain in place across GA, and perhaps parts of AL, because the pattern and fast-moving wave will not allow moisture to return to those areas. So any complex of storms that develop in the Arklatex region Saturday will eventually run out of juice as they race east.

Another question (seemingly always a major issue in VORTEX-SE) is the likelihood, timing, and effect of an MCS in the Gulf of Mexico. These systems are probably associated with subtle waves in the jet stream, and those waves may not be well forecast until within 24 hours of passage because prior to that time they are somewhere out over the Pacific.

The current best guess is that storms will form in far east Texas on Saturday, with at least some tornado potential, and roll east across Louisiana in the evening, and perhaps into MS/AL during the night. We expect that our most likely subdomain for combined airborne and surface radar observations will be the U. Louisiana-Monroe subdomain.

Bear in mind when reading these discussions that we are forecasting conditions required for successful research operations. We have a very high tolerance for erroneous forecasts of possible tornadoes; they are a rare phenomenon and it is a lot more painful to miss an observing opportunity than it is to be operating and nothing happens.

A final IOP decision will be made Thursday afternoon, 8 March.