A severe weather forecast, algorithm explained

[Darrell KSR]

If this doesn't come out readable, go search on Twitter @Wxmanms1 for a nice explanation of the severe weather forecast over the South this weekend.

[Darrell KSR]

@Wxmanms1: A quick thread of what some tools that help contextualize the potential magnitude of a weather system are showing for the weather system across the South the next 48 hours. (1/)

@Wxmanms1: The SLU CIPS Analog system takes model output and runs it through a system that finds analog events based on matching fields to those observed on past dates. (2/)

@Wxmanms1: CIPS has been consistently showing for several days that the top analog for tomorrow night is 2/5/2008 - the start of the Super Tuesday tornado outbreak. (3/) https://twitter.com/Wxmanms1/status/1215459539778265089/photo/1
https://uploads.tapatalk-cdn.com/20200110/572b25660120bc10f29183168c9625c3.jpg8848

[Darrell KSR]

@Wxmanms1: CIPS also produces variety of probabilistic guidance by looking at all the top analog matches. Here is the probability of 10 severe reports within 110 km of a point - these values are quite high (and coincidentally, similar to the SPC day 2 MDT). (4/) https://twitter.com/Wxmanms1/status/1215459548900753408/photo/18849

[Darrell KSR]

@Wxmanms1: Another tool is the NWS Western Region Situational Awareness tool, which takes ensemble model output and determines where various parameters rank in the historical database (1979-2009 reanalysis). (5/)

@Wxmanms1: One thing that has been subjectively apparent watching NWP output for this event is the strength of the wind fields and moisture with this event. The SA tool shows this objectively: MSLP is near the climo min, and wind fields/PW are either maxed out or near the climo max. (6/) https://twitter.com/Wxmanms1/status/1215459568186208258/photo/1

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[Darrell KSR]

@Wxmanms1: The fact that these parameters are so climatologically unusual tells forecasters that impacts - for example, from severe weather and/or heavy rain - are more likely to be unusually significant. (7/)

@Wxmanms1: Of course, none of this guarantees a major severe weather or flood event. But it does provide further support to what is being seen by mets in the various NWP and observational data, and brings awareness to the potential for a higher end impact event. (/fin)

[blueboss]

So is it going to rain?🤓


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[dan_bgblue]

So is it going to rain?��


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MAYBE

[dan_bgblue]

Pretty sure the wind will blow, and even more sure it will be dark tonight

[MickintheHam]

Are we gonna die?

[dan_bgblue]

Do you envision dark as being lethal?

[Darrell KSR]

Are we gonna die?Yes.

Eventually.

[Owenchon]

Hmm, that algorithm helps save a lot of lives.