background image

AIM

10/12/17

7

−1−16

Meteorology

SOUTHERN MISSOURI
FAR EASTERN OKLAHOMA
*EFFECTIVE THIS MONDAY MORNING FROM 1250
AM UNTIL 600 AM CDT.
...THIS IS A PARTICULARLY DANGEROUS SITUA-
TION...
*PRIMARY THREATS INCLUDE
NUMEROUS INTENSE TORNADOES LIKELY
NUMEROUS SIGNIFICANT DAMAGING WIND GUSTS
TO 80 MPH LIKELY
NUMEROUS VERY LARGE HAIL TO 4 INCHES IN
DIAMETER LIKELY
THE TORNADO WATCH AREA IS APPROXIMATELY
ALONG AND 100 STATUTE MILES EAST AND WEST OF
A LINE FROM 15 MILES WEST NORTHWEST OF FORT
LEONARD WOOD MISSOURI TO 45 MILES SOUTH-
WEST OF HOT SPRINGS ARKANSAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64
KWNS WOU2).
REMEMBER...A TORNADO WATCH MEANS CONDI-
TIONS ARE FAVORABLE FOR TORNADOES AND
SEVERE THUNDERSTORMS IN AND CLOSE TO THE
WATCH AREA. PERSONS IN THESE AREAS SHOULD
BE ON THE LOOKOUT FOR THREATENING WEATH-
ER CONDITIONS AND LISTEN FOR LATER
STATEMENTS AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...THIS TORNADO
WATCH REPLACES TORNADO WATCH NUMBER 237.
WATCH NUMBER 237 WILL NOT BE IN EFFECT
AFTER
1250 AM CDT. CONTINUE...WW 239...WW 240...WW
241...WW 242...
DISCUSSION...SRN MO SQUALL LINE EXPECTED TO
CONTINUE EWD...WHERE LONG/HOOKED
HODOGRAPHS SUGGEST THREAT FOR EMBEDDED
SUPERCELLS/POSSIBLE TORNADOES. FARTHER
S...MORE WIDELY SCATTERED
SUPERCELLS WITH A THREAT FOR TORNADOES
WILL PERSIST IN VERY STRONGLY DEEP SHEARED/
LCL ENVIRONMENT IN AR.
AVIATION...TORNADOES AND A FEW SEVERE THUN-
DERSTORMS WITH HAIL SURFACE AND ALOFT TO 4
INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI
WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 26045.

5.

Status reports are issued as needed to show

progress of storms and to delineate areas no longer
under the threat of severe storm activity. Cancellation
bulletins are issued when it becomes evident that no
severe weather will develop or that storms have
subsided and are no longer severe.

h. Center Weather Advisories (CWAs)

1.

CWAs are unscheduled inflight, flow control,

air traffic, and air crew advisory. By nature of its short
lead time, the CWA is not a flight planning product.
It is generally a nowcast for conditions beginning
within the next two hours. CWAs will be issued:

(a)

As a supplement to an existing SIGMET,

Convective SIGMET or AIRMET.

(b)

When an Inflight Advisory has not been

issued but observed or expected weather conditions
meet SIGMET/AIRMET criteria based on current
pilot reports and reinforced by other sources
of information about existing meteorological condi-
tions.

(c)

When observed or developing weather

conditions do not meet SIGMET, Convective
SIGMET, or AIRMET criteria; e.g., in terms of
intensity or area coverage, but current pilot reports or
other weather information sources indicate that
existing or anticipated meteorological phenomena
will adversely affect the safe flow of air traffic within
the ARTCC area of responsibility.

2.

The following example is a CWA issued from

the Kansas City, Missouri, ARTCC. The “3” after
ZKC in the first line denotes this CWA has been
issued for the third weather phenomena to occur for
the day. The “301” in the second line denotes the
phenomena number again (3) and the issuance
number (01) for this phenomena. The CWA was
issued at 2140Z and is valid until 2340Z.

EXAMPLE

ZKC3 CWA 032140
ZKC CWA 301 VALID UNTIL 032340
ISOLD SVR TSTM over KCOU MOVG SWWD
10 KTS ETC.

7

−1−7. Categorical Outlooks

a.

Categorical outlook terms, describing general

ceiling and visibility conditions for advanced
planning purposes are used only in area forecasts and
are defined as follows:

1. LIFR (Low IFR).

Ceiling less than 500 feet

and/or visibility less than 1 mile.

2. IFR.

Ceiling 500 to less than 1,000 feet

and/or visibility 1 to less than 3 miles.

3. MVFR (Marginal VFR).

Ceiling 1,000 to

3,000 feet and/or visibility 3 to 5 miles inclusive.