Severe Thunderstorm Warning 569, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
130 PM CDT SUN AUG 20 2000

ON VAPOR IMAGERY THE UPPER RIDGE PREVALENT ACROSS THE SOUTHERN US
WITH A WEAKENING CONVECTIVE COMPLEX OFF THE GULF COAST. ALSO SOME
ISOLATED SHOWERS WERE OCCURING NORTH OF THE FOREAST AREA. ON THE
SURFACE THE FIRST WEAK BOUNDARY EXTENDED ACROSS SOUTHEAST ARKANSAS
THROUGH SOUTHERN MISSISSIPPI TO SOUTHERN ALABAMA. THE SECOND WEAK
BOUNDARY WAS OFF THE GULF COAST.

THE LOWER MISSISSIPPI VALLEY WILL CONTINUE TO BE ON THE EASTERN END
OF THE UPPER RIDGE DURING THE SHORT TERM PERIOD. A SERIES OF WEAK
SHORTWAVES WILL TRACK OVER THE REGION IN NORTHWEST FLOW. THE BEST
MEAN MOISTURE WILL BE ACROSS THE SOUTH. THE FIRST BOUNDARY WILL
DISSIPATED THIS EVENING...WHILE THE SECOND ONE WILL LIFT INTO THE
SOUTHERN SECTIONS. THE SECOND BOUNDARY WILL HANG AROUND THE
SOUTH...BEFORE DISSIPATING IN SOUTHERLY FLOW MONDAY NIGHT. IT WILL
PROVIDE SOME LIFT...ALONG WITH SEABREEZE AFFECTS FOR CONVECTIVE
ACTIVITY IN THE SOUTH. THIS WILL BE WHERE THE BEST LOW LEVEL
MOISTURE...PRECIPITABLE WATER(1.5 TO 1.9 INCHES) AND WEAK VERTICAL
VELOCITIES WILL OCCUR. ALL MODELS INITIALIZED THE CONVECTION IN THE
GULF PRETTY WELL...ESPECIALLY THE NGM...UNFORTUNATELY IT HAS SOME
FEED BACK PROBLEMS WITH ITS CONVECTIVE COVERAGE IN THE SHORT TERM.
THE AVN MODEL SEEMED TO SHOW TOO MUCH MEAN MOISTURE MOVING OVER THE
FORECAST AREA AROUND THE UPPER RIDGE. THE BEST UPPER DYNAMICS WILL
BE GENERALLY EAST AND OVER THE GULF COASTAL REGION DURING THE
PERIOD. SO WILL STICK CLOSE TO THE MESO-ETA IN THIS FORECAST.

FORECAST TEMPS REMAIN WARM ABOVE SEASONAL NORMALS...ESPECIALLY IN
THE DELTA REGIONS...WHILE AREAS TO THE EAST WILL HIT THE MID TO UPPER
90S. THE MESO-ETA 2METER TEMPS LOOK TO BE ON THE MARK FOR THIS
FORECAST AS FAR AS HIGHS ARE CONCERNED. OTHERWISE ALL MODELS WERE
GENERALLY SIMILAR ON NIGHT TIME TEMPS. AS FAR AS POPS ARE CONCERNED
WILL STICK WITH LOW POPS IN THE NORTHEAST AND SOUTH FOR
TONIGHT...WITH CONCERNED FOR OUTFLOW BOUNDARIES FROM PREVIOUS
CONVECTION IN THE NORTH AND SEA BREEZE AFFECTS FROM THE SOUTH. FOR
THE REST OF THE PERIOD WILL STICK WITH LOW POPS WITH LIMITED
DYNAMICS IN PLAY.

QPF DISCUSSION:NONE OF SIGNIFICANCE EXPECTED.

EXTENDED FORECAST DISCUSSION:LOOKING AT WEDNESDAY THROUGH FRIDAY. UPPER
RIDGE WILL MAINTAIN ITSELF THROUGH THE PERIOD...AS A SERIES OF WEAK
SHORTWAVES COMES THROUGH NORTHWEST FLOW. LOW LEVEL SOUTHERLY FLOW
WILL BECOME WESTERLY BY THURSDAY AND FRIDAY. THE BEST MEAN MOISTURE
WILL BE CONFINED TO THE SOUTH. THE ONLY DIFFERENCE IN CONVECTIVE COVERAGE
IS THAT THE NOGAPS TRIES TO BRING IN SOME COVERAGE UP THE CENTRAL
SECTIONS DURING THE DAY. SO WITH THAT IN MIND WILL GO WITH SLIGHT CHANCE
OF THUNDERSTORMS IN THE EXTENDED.

PRELIM NUMBERS:
JAN 73/99/72/98 -21
MEI 73/99/72/98 -21

.JAN...
AR...NONE.
LA...NONE.
MS...NONE.
17