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Forward from Skip forwarded From Mr. Lisisisisisus forwarded from the
Grandmaster Charles Edwards:
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Date: Sun, 14 Sep 1997 11:10:43 -0500 (CDT)
From: MILWAUKEE AREA SKYWARN ASSOCIATION <svoros{at}execpc.com>
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Subject: Major Change At SPC
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MASA ("May-sah")
Promoting severe weather Identification, Evaluation, & Reporting.
*****************************************************************
From Roger Edwards, forecaster at the Storm Prediction Center
(roger.edwards{at}noaa.gov). Credit to breaking the story: Martin
Lisius, TExas Severe Storms Association
(TESSA-http://www.tessa.org):
There are going to be MAJOR changes to SPC outlooks, beginning on an
experimental basis this fall. We are planning a special 11Z issuance
broken down into 2 12-hour periods, for one thing. In that
early-morning outlook, we also plan to test 3 categories of coverage
(tentatively called ISOLD, SCTD and NMRS) and 3 categories of
intensity (MRGL, SGFNT, EXTRM). The result will be a much more
precise forecast drawn from the 9 possible permutations of ISOLD MRGL,
SCTD MRGL, NMRS SGFNT, etc. We're still working on exact numerical
definitions for those categories.
The reason this is being done is because the current SLGT/MDT/HIGH
system, as officially defined, only applies to coverage. Technically,
an event producing widespread reports of dime-sized hail --
threatening nobody's life and doing little or no property damage --
could be verified as a high risk! In the real world, most would agree
that it would be patently ridiculous to actually outlook HIGH for
something like that. Still, to do justice to forecasting severe
storms, intensity MUST be explicitly accounted for in addition to
coverage.
Philosophically among forecasters, and in user perceptions, the
current system has lost much of its meaning. There are way too many
different answers to the question, "What is a SLGT risk?" depending on
who you ask. Also, the new system will help us to better cover the
many situations that produce marginal and/or isolated severe, which
are often not outlooked due to their disorganized or transient nature.
The new categories may seem confusing at first simply because there
are more of them; however, they actually will be more meaningful and
less confusing in the long run. This is because there will be no
doubt as to what they mean. There will be rigid statistical ranges of
severe storm coverage and intensity defined into each outlook
category. Most importantly, they will be verified that way.
[Currently, SPC outlooks are not numerically verified!] We aim to get
these new categories incorporated into all SPC outlooks eventually.
Also, SPC technical discussions (MCD, outlooks, status reports) are
going to switch to plain language format this fall, with abbreviations
only for states, station identifiers and common meteorological terms
(such as CAPE and LI). This will make them longer but hopefully
easier to read.
Finally, SPC is participating in the 50th Anniversary of Tornado
Forecasting celebration, held here and at Tinker AFB this coming
March. For more info, crank open your web browser and point it to
http://www.nssl.noaa.gov/GoldenAnniversary
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