Severe Thunderstorm Warning 101, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
245 PM CDT SAT JUN 9 2001

...FLASH FLOOD/FLOOD WATCH IN EFFECT THROUGH SUNDAY WITH HEAVY
RAINFALL POSSIBLE THROUGH TUESDAY...

A FEW NEW WRINKLES TO ADD TO THE FORECAST PICTURE THIS AFTERNOON
WHICH DO NOT FARE WELL FOR THE DECLINE OF HEAVY PRECIPITATION ACROSS
THE FORECAST AREA. THE FIRST OF THESE IS THE UNCERTAINTY BUT
POSSIBILITY OF THE RETURN OF ALLISON TO THE GULF WATERS AND THEN HER
RETURN TO SOUTH CENTRAL LOUISIANA EARLY IN THE WEEK. THE OTHER IS A
WEAK FRONTAL BOUNDARY WHICH IS PUSHING THROUGH CENTRAL MISSISSIPPI
WHICH WILL HELP WITH THE SQUEEZE PLAY ACROSS SOUTHERN LOUISIANA AS
TROPICAL MOISTURE CONTINUES TO STREAM NORTH.

COORDINATION WITH TPC VERIFIES OUR FORECAST STRATEGY OF FOLLOWING
THE AVN WITH THE CAVEAT THAT THE LOW LEVEL CIRCULATION IS STILL
LOCKED NEAR PALACIOS TEXAS SO THE TIMING OF LOW LEVEL FEATURES IS
RATHER UNCERTAIN. WITH THIS UNDERSTANDING THE AVN AND CONFIRMED BY
ETA 12Z MODEL SHOWS SIGNIFICANT 200 MB DIVERGENCE ACROSS THE
FORECAST AREA THROUGH TUESDAY WITH AN IMPRESSIVE CONVERGENCE/
DIVERGENCE COUPLET MOVING SW TO NE MONDAY NIGHT. THE 700 MB OMEGA
FIELD ALSO SHOWS IMPRESSIVE FIELDS ACROSS THE AREA FROM THIS
AFTERNOON THROUGH TUESDAY. LOOKING AT RADAR AND SATELLITE TRENDS OF
TODAY APPEARS WE ARE TRANSITIONING FROM A HYBRID TROPICAL/SEABREEZE
REGIME INTO A MORE CLASSIC TROPICAL RAINFALL PATTERN OF STRATIFORM
WIDESPREAD RAIN OVERNIGHT BREAKING UP LATE MORNING INTO MULTI
CELLULAR THUNDERSTORM/RAIN CLUSTERS WITH AN ISOLATED SEVERE THREAT
DURING PEAK AFTERNOON HEATING. HEAVY RAIN THREAT WILL CONTINUE FOR
THE NEXT THREE DAYS BUT FOCUS WILL LIKELY SHIFT TO THE OVERNIGHT
HOURS PER HOUSTON EVENT WITH A THREAT OF VERY HEAVY RAINFALL TIED TO
THE EAST SIDE OF THE SURFACE LOW. THIS SHOULD PLACE SE LOUISIANA IN
VERY HEAVY RAINFALL MON NIGHT INTO TUESDAY WHICH FOLLOWS THE TIMING
OF THE AVN 12Z 500 MB LOW TRACK WHICH THE SURFACE LOW SHOULD STICK
CLOSE TO.

PRELIM NUMBERS...

KMCB 70/86/71/86 9899  KBTR 71/84/72/84 9899
KMSY 72/84/73/84 8899  KGPT 70/84/71/84 7898

.NEW...NONE.
LA...FLASH FLOOD/FLOOD WATCH LAZ034>040-046>050-056>070.
MS...FLASH FLOOD/FLOOD WATCH MSZ068>071-077-080.

13

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-101200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1100 AM CDT SAT JUN 9 2001

...A FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH THIS AFTERNOON
FOR EAST CENTRAL AND SOUTHEAST LOUISIANA AS WELL AS ADJOINING
COUTNIES OF MISSISSIPPI...

.SYNOPSIS...
THE REMNANTS OF TROPICAL STORM ALLISON LOCATED JUST WEST-SOUTHWEST
OF GALVESTON ARE EXPECTED TO MOVE SLOWLY SOUTHEAST AND POSSIBLY EMERGE
BACK OVER THE EXTREME NORTHWEST GULF LATER TODAY OR TONIGHT. DEEP
TROPICAL MOISTURE WILL CONTINUE TO BRING SCATTERED TO NUMEROUS AREAS
OF SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE CENTRAL GULF COAST
REGION THROUGH TONIGHT.

.THUNDERSTORMS...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE THROUGH THIS
AFTERNOON. THE MAIN THREAT FROM THE THUNDERSTORMS WILL BE HEAVY
RAINFALL. IN ADDITION...OCCASIONAL CLOUD TO GROUND LIGHTNING AND
WIND GUSTS UP TO 30 MILES AN HOUR ARE ALSO POSSIBLE.
HOWEVER...WIDESPREAD SEVERE THUNDERSTORMS ARE NOT LIKELY ALTHOUGH AN
ISOLATED TORNADO MAY OCCUR WITH THE STRONGER STORMS.

.HEAVY RAIN AND FLOODING...
AREAS WHICH RECEIVE REPEAT SHOWERS COULD RECEIVE AN ADDITIONAL 2 TO
4 INCHES OF RAINFALL WITH LOCALLY HIGHER AMOUNTS POSSIBLE. HEAVY
RAIN ON ALREADY SATURATED GROUND WILL LIKELY CAUSE FLOODING.

.ACTIONS...REFER TO THE LATEST FLOOD RELATED WATCHES...WARNINGS AND
STATEMENTS. THE ACTIVATION OF STORM SPOTTERS MAY BE NEEDED IF
ORGANIZED THUNDERSTORM DEVELOPMENT IS OBSERVED.

FOR MORE INFORMATION PLEASE VISIT OUR HOME PAGE ON THE INTERNET AT
THE FOLLOWING ADDRESS...HTTP://WWW.SRH.NOAA.GOV/LIX (ALL LETTERS
SHOULD BE LOWER CASE).