Flash Flooding and Flooding in Louisiana, June 8 to 13, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS/BATON ROUGE LA
340 AM CDT FRI JUN 8 2001

...HEAVY RAINFALL EXPECTED TO CONTINUE WITH FLASH FLOOD/FLOOD WATCH
EXTENDED THROUGH TONIGHT...

STATUS QUO IS THE WAY TO GO...ALTHOUGH THE AMPLIFYING UPPER PATTERN
ACROSS NORTH AMERICA WILL SLIGHTLY CHANGE THE ORIENTATION OF THE
DEEPER MOISTURE AND HEAVY RAIN POTENTIAL AREAS ACROSS THE LOWER MS
VALLEY.

18 HOUR WATER VAPOR LOOPS SHOW THE MID/UPPER LOW ASSOCIATED WITH THE
REMNANTS OF TROPICAL STORM ALLISON MOVING SLOWLY SW FROM E CENTRAL
TO SE TX. A SLIGHTLY DISCONTINUOUS 30-35 KNOT 250 JET MAX EXTENDS
FROM W CENTRAL/NE MEXICO INTO THE NW GULF...AND FROM SE LA ACROSS SE
MS...AND MERGING WITH A STRONG POLAR JET IN THE MID ATLANTIC COAST
REGION. THIS PATTERN SHOULD CONTINUE TO PLACE THE FORECAST AREA IN
AN AREA OF MID/UPPER DIVERGENCE. TO ADD TO THE TROUBLE...ANOTHER IN
A SERIES OF SHORTWAVE TROUGHS/VORT LOBES IS SWINGING NE ACROSS THE
NW GULF WHICH IS AIDING IN ANOTHER MOISTURE SURGE FROM THE SW GULF.

LOOKING BACK AT THE LAST FEW DAYS...THE AVN HAS HAD SOME SUSPICIOUS
LOOKING STRONG VORT MAXIMA MOVING NORTH FROM THE GULF ACROSS THE
FORECAST AREA...HOWEVER MANY OF THESE FEATURES HAVE VERIFIED INTO
MASSIVE MCS BLOWUPS AND RESULTANT FLOODING ACROSS E CENTRAL/SE LA.
MODEL TIMING OF THESE FEATURES AND QPF WILL NEVER BE PERFECT...BUT
THE OVERALL IDEA IS GOOD. TO SUM THINGS UP...WILL MAINTAIN THE FLASH
FLOOD/FLOOD WATCH FOR THE CURRENT AREA AND EXPAND IT IN TIME THROUGH
TONIGHT. FLASH FLOOD GUIDANCE IS STILL FAIRLY HIGH ACROSS HARRISON
AND JACKSON COUNTIES...SO WILL LEAVE THEM OUT OF THE WATCH FOR NOW...
HOWEVER...THEY MAY NEED TO BE ADDED TO THE WATCH LATER TODAY IF
ENOUGH HEAVY RAIN THREATENS THE AREA. ADDITIONAL RAINFALL AMOUNTS OF
2 TO 4 INCHES CAN BE EXPECTED THROUGH TONIGHT WITH LOCAL AMOUNTS UP
AROUND 5 INCHES. AS WITNESSED YESTERDAY...RAINFALL RATES OF 3/4 INCH
PER HOUR AND 1.25 TO 1.5 INCHES IN 3 HOURS WILL RESULT IN STREET
FLOODING WITH SLIGHTLY HIGHER AMOUNTS THREATENING PROPERTY IN SOME
AREAS.

RAINFALL CHANCES SHOULD STAY IN THE LIKELY CATEGORY TONIGHT AND
ESPECIALLY SATURDAY AS ANOTHER SHORTWAVE AND ENHANCED UPPER
DIFFLUENCE AREA AFFECT THE FORECAST AREA. FALLING HEIGHTS IN THE
EASTERN U.S. WILL HELP PUSH A WEAK SURFACE FRONT SOUTH INTO S MS
TONIGHT AND SAT WHICH SHOULD HELP TAPER OFF RAINFALL AMOUNTS
SLIGHTLY IN THE SW MS ZONES SAT AND SAT NIGHT. SUN INTO TUE...THE
REMNANTS OF ALLISON MAY CONTINUE TO JUST DRIFT SOUTH ALONG THE LOWER
TX COAST/W GULF. WE SHOULD CONTINUE TO HAVE AT LEAST SCATTERED
MAINLY AFTERNOON CONVECTION NEXT WEEK. THIS SHOULD RESULT IN LIGHTER
DAILY RAINFALL AMOUNTS.

KMCB 83/69/86/68 8663   KBTR 83/71/86/70 8675
KMSY 83/74/85/72 9776   KGPT 83/72/84/72 9775

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

22

LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-081600-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
645 AM CDT FRI JUN 8 2001

.SYNOPSIS...THE REMNANTS OF TROPICAL STORM ALLISON ARE EXPECTED TO
MOVE SLOWLY SOUTHWEST OVER SOUTHEAST TEXAS TODAY AND TONIGHT.
DEEP TROPICAL MOISTURE AND UPPER LEVEL DISTURBANCES MOVING NORTH OUT
OF THE GULF OF MEXICO WILL CONTINUE TO BRING SCATTERED AREAS OF HEAVY
RAIN ACROSS MUCH OF THE CENTRAL GULF COAST REGION THROUGH TONIGHT.

.THUNDERSTORMS...
THUNDERSTORMS WILL INCREASE IN COVERAGE AND INTENSITY THIS MORNING
INTO THE AFTERNOON. SCATTERED THUNDERSTORMS ARE EXPECTED TO
PERSIST THROUGH MOST OF TONIGHT. THE MAIN THREAT FROM THUNDERSTORMS
WILL BE VERY HEAVY RAINFALL...OCCASIONAL CLOUD TO GROUND LIGHTNING
STRIKES...AND WIND GUSTS UP TO 40 MILES AN HOUR...HOWEVER...A FEW OF
THE STRONGEST STORMS COULD PRODUCE A BRIEF TORNADO.

.HEAVY RAIN AND FLOODING...
PERIODIC HEAVY RAIN IS EXPECTED ACROSS THE ENTIRE AREA THROUGH
TONIGHT. A FEW OF THE HEAVY RAIN AREAS COULD BECOME STATIONARY...
CAUSING RAINFALL RATES OF 1 TO 2 INCHES PER HOUR. ADDITIONAL
RAINFALL AMOUNTS OF 2 TO 4 INCHES ARE EXPECTED THROUGH TONIGHT
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
ORGmANIZED THUNDERSTORM DEVELOPMENT IS OBSERVED.

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