Operational Forecasting of Landspouts

[Brian Hartmann]

A friend of mine from Nebraska sent me this when it came across her phone from a weather app. It was issued this morning out of the Hastings NWS.

I don't keep really close tabs on operations of the NWS, but I can't recall having seen much in the way of landspout predictions or forecasting in the past. The NWS will issue warnings for them after they have been spotted, of course, but this was new to me. Anyone have more background on the operational side of this?

Brian

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[Warren Faidley]

I always forecast for landspouts when there are limited supercell opportunities ATM. With drought conditions in CO, OK, NM and Texas, a dust-filled landspout can be quite photogenic and are **generally** harmless.

The SPC Mesoscale Analysis page has a forecast for non-supercell tornadoes:

http://www.spc.noaa.gov/exper/mesoanalysis/

From their site:

Non-Supercell Tornado parameter (NST)


The non-supercell tornado parameter (NST) is the normalized product of the following terms:


(0-1 km lapse rate/9 C/km) * (0-3 km MLCAPE/100 J/kg) * ((225 - MLCIN/200) * ((18 - 0-6 km bulk wind difference)/5 m/s) * (surface relative vorticity/8**10-5/s)

This normalized parameter is meant to highlight areas where steep low-level lapse rates correspond with low-level instability, little convective inhibition, weak deep-layer vertical shear, and large cyclonic surface vorticity. Values > 1 suggest an enhanced potential for non-mesocyclone tornadoes.