Severe Thunderstorm Warning 98, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
100 PM CDT SAT MAY 17 2003

MODELS SIMILAR WITH MINOR BIASES. MODELS TRACK H5 LOW SOUTHEAST AND
OVER KMSY AROUND MIDNIGHT SUNDAY WITH GRADUAL WEAKENING OF THE
CENTRAL PRESSURE. THE AVN IS FASTER IN MOVEMENT WHILE THE ETA
WEAKENS THE LOW EARLIER. BY 54 HOURS...18Z MON...ETA OPENS THE LOW
UP IN THE NORTH HALF OF THE MIDDLE GULF WHILE THE AVN (ALSO CALLED
THE GFS) MAINTAINS A BROAD WEAK LOW OVER THE MIDDLE GULF. BOTH
MODELS SHOW A CONTINUATION OF THE SOUTHERN TRACK. MAIN DYNAMICS FOR
TODAY ARE HEATING...45 KT JET AT 850 MB...WEAK DIFFLUENCE ALOFT AND
MID LEVEL SHEAR. CONVECTION OVER THE NORTHWEST PORTION OF OUR CWA
SHOWS SIGNS OF WEAKENING AS IT ENCOUNTERS MID LEVEL DRY AIR. EXPECT
THESE TO FURTHER BE DIFFUSED TONIGHT AS THE SUN SETS BUT WILL KEEP
THREAT OF SHOWERS AND ISOLATED THUNDERSTORMS IN FOR TONIGHT DUE TO
PRESENCE OF H5 VORT MAX IN THE AREA. AS THE LOW DROPS SOUTH SUNDAY
AND MONDAY...CHANCE OF SEVERE ACTIVITY SHOULD ALSO DIMINISH AS LOW
WEAKENS AND SUBSEQUENT LOW LEVEL INFLOW WEAKENS AS WELL. HOWEVER...
HEATING ALONG WITH REMNANT BOUNDARIES COULD TRIGGER A FEW STRONG
THUNDERSTORMS.  SURFACE FRONTAL BOUNDARY EXPECTED TO REMAIN NORTH
AND WEST OF BATON ROUGE TONIGHT AND SUNDAY AND DISSIPATE MONDAY.
WILL MAINTAIN THREAT OF SHOWERS SUNDAY THROUGH TUESDAY BASED ON WEAK
VORTICITY...DAYTIME HEATING. IN ADDITION ANOTHER WEAK SHORT WAVE IS
FORECAST TO MOVE EAST ACROSS SOUTHWEST RIDGE AND OVER MISSISSIPPI
TUESDAY WHICH SHOULD HELP DESTABILIZE THE AFTERNOON ENVIRONMENT.

IN THE LONG RANGE NEXT SHORT WAVE WILL PROGRESS EAST AND DEEPEN
OVER THE MISSISSIPPI VALLEY WEDNESDAY NIGHT AND OHIO VALLEY THURSDAY.
AVN SHOWS A DECENT COLD FRONT MOVING SOUTH TO THE COASTAL WATERS
THURSDAY AM. THIS SHOULD BE PRECEDED BY A STRONG SQUALL LINE
FOLLOWED BY CLEARING AND A MUCH APPRECIATED SPELL OF COOLER AND DRIER
AIRMASS.

IN MARINE ZONES...WILL EVALUATE DATA FURTHER TO DROP SMALL CRAFT
ADVISORY TO EXERCISE CAUTION FOR TONIGHT.

PRELIMINARY NUMBERS...
MCB 69/83/68/86/70 47230  BTR 70/86/70/88/73 45230
MSY 75/87/73/88/76 35330  GPT 77/84/75/85/77 25330

.NEW...SMALL CRAFT ADVISORY...COASTAL WATERS KPQL TO ATCHAFALAYA
       RIVER OUT 60 NM.
LA...NONE.
MS...NONE.

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-181300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1215 PM CDT SAT MAY 17 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST LOUISIANA AND
EXTREME SOUTHWEST AND COASTAL MISSISSIPPI.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A SLOW MOVING COLD FRONT...EXTENDING FROM NORTHEAST LOUISIANA TO
CORPUS CHRISTI TEXAS...WILL DRIFT EAST AND BECOME NEAR STATIONARY
ACROSS CENTRAL MISSISSIPPI TO SOUTH CENTRAL LOUISIANA SUNDAY. A
LINE OF STRONG TO SEVERE THUNDERSTORMS...WHICH FORMED AHEAD OF THE
FRONT...IS EXPECTED TO DRIFT SLOWLY EAST AND WEAKEN THROUGH THIS
AFTERNOON. LOCALLY HEAVY RAINFALL...POSSIBLE HAIL AND DAMAGING WINDS
OF 50 TO 60 MPH ARE STILL POSSIBLE THIS AFTERNOON NORTH AND WEST OF
A LINE FROM TYLERTOWN IN WALTHALL COUNTY MISSISSIPPI TO DENHAM
SPRINGS IN LIVINGSTON PARISH LOUISIANA. THE THUNDERSTORMS ARE
EXPECTED TO DIMINISH TONIGHT.

MARINE...
SMALL CRAFT ADVISORIES ARE IN EFFECT FOR WINDS OF 20 TO 25 KNOTS
OVER GULF WATERS FROM SW PASS MISSISSIPPI RIVER TO ATCHAFALAYA RIVER
OUT 60 NM INCLUDING LAKES PONTCHARTRAIN AND MAUREPAS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THUNDERSTORMS ARE POSSIBLE SUNDAY THROUGH WEDNESDAY. THE NEXT RISK
OF SEVERE WEATHER WILL BE WEDNESDAY AS A COLD FRONT MOVES TOWARDS
THE REGION.

.SPOTTER INFORMATION STATEMENT...

THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS AND EMERGENCY
MANAGEMENT PERSONNEL...IN SUPPORT OF SEVERE WEATHER OPERATIONS...ARE
NOT REQUESTED AT THIS TIME.