Severe Thunderstorm Warning 148, NWS New Orleans, LA

AREA FORECAST DISCUSSION...CORRECTED TIME AND DATE
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
400 AM CDT FRI JUL 2 2004

.DISCUSSION...
MAIN FORECAST CONCERN IS SEVERE THUNDERSTORM AND HEAVY RAIN
POTENTIAL TODAY. WATER VAPOR IMAGERY SHOWS BASE OF UPPER TROUGH NEAR
THE TX/LA BORDER EARLY THIS MORNING. ONE VORT MAX IS JUST OFF THE
SOUTHWEST LA COAST AND IS MOVING EAST. OTHER SHORTWAVE TROUGHS ARE
NOTED NEAR THE BASE OF THE UPPER TROUGH AND TO THE WEST ACROSS TX
AND OK. A COUPLED JET STRUCTURE IS SETTING UP ACROSS THE FORECAST
AREA AND THIS STRONG UPPER DIVERGENCE PATTERN WILL PROBABLY CONTINUE
TO AFFECT THE AREA MUCH OF TODAY. RADARS SHOW AREAS OF MOSTLY LIGHT
RAIN AND SHOWERS OVER THE WESTERN AND SOUTHERN ZONES WITH A FEW
THUNDERSTORMS NEAR THE SOUTHWEST LA COAST. IT IS ANTICIPATED THAT
THIS RAIN WILL CONTINUE TO MAKE SLOW PROGRESS EAST EARLY THIS
MORNING. AS THE SUN RISES...THE BIG QUESTION IS HOW MUCH SUN AND
RESULTANT INSTABILITY THERE WILL BE. THERE IS A CHANCE RAIN AND
CLOUD COVER COULD HOLD TEMPERATURES DOWN WELL BELOW GUIDANCE. IF
THIS OCCURS...THERE WILL LIKELY BE WIDESPREAD LIGHT TO MODERATE RAIN
AMOUNTS WITH ONLY ISOLATED HEAVY RAINFALL TOTALS. ON THE OTHER
HAND...A FEW BREAKS IN THE CLOUDS AND DAYTIME HEATING WOULD MAKE
THINGS QUITE UNSTABLE...AND DRYING ABOVE 500 MB...INDICATED IN WATER
VAPOR IMAGERY AND RUC MODEL SOUNDINGS...WILL ADD TO CONVECTIVE
INSTABILITY. WITH BOTH OPTIONS POSSIBLE...WILL TAKE THE MIDDLE
GROUND AND GO HIGHER THAN MOS POP GUIDANCE...MENTION LOCALLY HEAVY
RAIN...AND A FEW STRONG THUNDERSTORMS IN THE HAZARDOUS WEATHER
OUTLOOK. DRY AIR WORKING IN THE EVENING SHOULD BRING THE THREAT OF
CONVECTION DOWN TO A SLIGHT CHANCE.

THE PASSAGE OF THE MID/UPPER TROUGH SHOULD ALLOW DRIER AIR TO WORK
IN ON SATURDAY...ESPECIALLY OVER THE NORTHERN AND WESTERN ZONES.
WILL LOWER POPS TO 20 PERCENT ALONG THE KBTR-KMCB CORRIDOR...BUT
KEEP 40 PERCENT ON THE MS COAST.

ON SUNDAY JULY 4TH...THE MODELS SHOW AN INVERTED TROUGH ALOFT MOVING
SLOWLY WEST ACROSS THE NORTHWEST GULF OF MEXICO. TROPICAL MOISTURE
ON THE EAST SIDE OF THIS FEATURE SHOULD GET SUPPRESSED BY A WEAK
UPPER RIDGE WHICH IS FORECAST TO BUILD FROM THE SOUTHERN PLAINS
TOWARDS THE CENTRAL GULF COAST. THE GFS MOS LOWER POPS ALL THE WAY
TO 10 PERCENT. THIS SEEMS A BIT OPTIMISTIC...SO WILL TAKE POPS DOWN
TO 20 PERCENT AT THIS TIME.

ON MONDAY INTO WEDNESDAY...THE MODELS SHIFT THE 500 MB HIGH EAST
ACROSS FLORIDA BRINGING DEEP SOUTHERLY FLOW BACK TO THE REGION. THIS
SHOULD BRING POPS BACK AT LEAST TO NEAR NORMAL AGAIN FOR MUCH OF
NEXT WEEK.

&&

PRELIMINARY POINT NUMBERS...
MCB 87 71 90 73 / 70 20 20 10  BTR 87 72 91 75 / 70 20 20 10
MSY 86 73 90 75 / 90 20 30 10  GPT 86 73 88 76 / 80 30 40 10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
MS...NONE.
COASTAL WATERS...NONE.
&&

22

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1010 AM CDT FRI JUL 2 2004

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-031100-
AMITE-ASCENSION-ASSUMPTION-EAST BATON ROUGE-EAST FELICIANA-HANCOCK-
HARRISON-IBERVILLE-JACKSON-LIVINGSTON-LOWER JEFFERSON-
LOWER LAFOURCHE-LOWER PLAQUEMINES-LOWER ST. BERNARD-LOWER TERREBONNE-
ORLEANS-PEARL RIVER-PIKE-POINTE COUPEE-ST. CHARLES-ST. HELENA-
ST. JAMES-ST. JOHN THE BAPTIST-ST. TAMMANY-TANGIPAHOA-
UPPER JEFFERSON-UPPER LAFOURCHE-UPPER PLAQUEMINES-UPPER ST. BERNARD-
UPPER TERREBONNE-WALTHALL-WASHINGTON-WEST BATON ROUGE-WEST FELICIANA-
WILKINSON-
1010 AM CDT FRI JUL 2 2004

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

.THUNDERSTORMS...NUMEROUS SHOWERS ALONG WITH A FEW THUNDERSTORMS ARE
EXPECTED LATER TODAY AS AN UPPER LEVEL DISTURBANCE MOVES ACROSS THE
CENTRAL GULF COAST REGION. A FEW OF THE STORMS MAY BECOME QUITE
STRONG IN NATURE WITH THE POTENTIAL FOR WIND GUSTS TO 50 MPH AND
FREQUENT LIGHTNING. THE STRONGER STORMS MAY ALSO PRODUCE LOCALLY
HEAVY RAINFALL AMOUNTS OF 2 TO 4 INCHES IN A COUPLE OF HOURS WHICH
MAY RESULT IN SOME MINOR STREET FLOODING. THE THREAT OF THUNDERSTORMS
IS EXPECTED TO DIMINISH EARLY THIS EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

DRIER AIR IS EXPECTED TO MOVE INTO THE REGION ON SATURDAY AND
CONTINUE THROUGH SUNDAY. SCATTERED SHOWERS AND THUNDERSTORMS THOUGH
ARE STILL EXPECTED ON SATURDAY WITH A FEW STRONG STORMS POSSIBLE.
THUNDERSTORM COVERAGE IS EXPECTED TO BECOME MORE ISOLATED ON
SUNDAY...INDEPENDENCE DAY...AND THEN INCREASE BACK TOWARD SCATTERED
COVERAGE MONDAY THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

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