Gravity Waves

[wwickoo]

Earlier today, NWS in springfield, Mo posted the following discussion. What are gravity waves?


000
FXUS63 KSGF 211905
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
205 PM CDT THU APR 21 2005

...SEVERE THUNDERSTORMS LIKELY THIS AFTERNOON AND THIS EVENING...

.MESOSCALE DISCUSSION...

GRAVITY WAVES EMINATING FROM AN MCS THAT DEVELOPED OVER NE CO LAST
EVENING HAVE PROGRESSED ACROSS THE ENTIRE STATE OF
KANSAS...ENCOUNTERED AN INCREASINGLY UNSTABLE AND UNCAPPED AIRMASS
OVER NE OK ALLOWING THUNDERSTORMS TO DEVELOP. MID-LEVEL SPEED MAX
HAS YET TO ARRIVE AND THEREFORE VERTICAL SHEAR PROFILES REMAIN
UNIMPRESSIVE ACROSS THE CWA. DESPITE THE LESS THAN IMPRESSIVE
SHEAR...STRONG INSTABILITY EVIDENT ON THE SPECIAL 18Z SOUNDING
INDICATES THAT MULTICELLULAR SEVERE STORMS ARE LIKELY THIS
AFTERNOON. THE PRIMARY THREAT FROM THESE STORMS WILL BE LARGE HAIL
UP TO THE SIZE OF HALF DOLLARS AND POSSIBLY DAMAGING MICROBURST
WINDS.

IT IS UNCLEAR WHAT WILL HAPPEN ALONG THE FRONT WEST OF THESE
STORMS...AND HOW MUCH THE ATMOSPHERE WILL RECOVER IN THE WAKE OF
THIS FIRST WAVE OF STORMS. TIME WILL TELL...

IZZI

&&

.AVIATION...

FOR THE 18Z TAFS...CUMULUS FIELD SHOULD CONTINUE TO BLOSSOM THIS
AFTERNOON WITH SCT TO OCCASIONALLY BKN DECK AROUND FL030. POCKET OF
STRATUS/STRATOCUMULUS OVER NORTHERN OKLAHOMA WILL MOVE INTO THE JLN
AREA FOR A COUPLE HOURS EARLY THIS AFTERNOON AND BKN-OVC CIGS NEAR
FL030 POSSIBLE. KEPT JLN TAF VFR BUT POTENTIAL DOES EXIST FOR SOME
BORDERLINE MVFR CIGS EARLY THIS AFTERNOON.

PERIOD OF THUNDERSTORMS LIKELY AT THE TERMINALS THIS EVENING AS THE
FRONT/DRYLINE MARCH ACROSS THE AREA. POTENTIAL DOES EXIST FOR LARGE
HAIL AND DAMAGING WINDS AT THE TERMINALS THIS EVENING...HOWEVER KEPT
HAIL/WIND OUT OF THIS TAF ISSUANCE PENDING MORE DEFINITE
TIMING/INTENSITY OF THUNDERSTORMS.

GUSTY NORTHWEST WINDS WILL DEVELOP FRIDAY MORNING WITH GUSTS TO 25KT
POSSIBLE BY THE END OF THIS TAF CYCLE. ROBUST COLD AIR STRATOCUMULUS
DECK SHOULD BLOSSOM FRIDAY MORNING ONCE THE SUN BREAKS OUT.

IZZI