Flash Flood Warning 50, NWS New Orleans, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
708 PM CST MON DEC 14 2009

.UPDATE...
.SOUNDING DISCUSSION...

THE ATMOSPHERE IS VERY MOIST UP TO ABOUT 550 MB AND IS SLIGHTLY
UNSTABLE WITH A PRECIPITABLE WATER VALUE OF 1.80 INCHES AND A
LIFTED INDEX VALUE OF -2.5. NUMEROUS SHOWERS AND THUNDERSTORMS
CONTINUE TO MOVE ACROSS THE CWA NEAR 25 TO 30 MPH WHILE PRODUCING
RAINFALL RATES NEAR 2 INCHES PER HOUR...0 TO 6 KM STORM MOTION IS
OUT OF THE WEST AT 23 KNOTS. A SMALL SURFACE INVERSION IS PRESENT NEAR
675 FEET ALONG WITH WINDS GENERALLY OUT OF THE SOUTHWEST THROUGHOUT
THE ATMOSPHERE.

&&

.PREV DISCUSSION... /ISSUED 412 PM CST MON DEC 14 2009/

SHORT TERM...
A BUSY EVENING IN STORE AS A LARGE BAND OF ORGANIZED HEAVY
RAINFALL IS APPROACHING ACROSS ACADIANA INTO THE GREATER BATON
ROUGE AREA. THIS BAND HAS PRODUCED 2 INCH PER HOUR RATES AND
SHOULD MOVE INTO THE BATON ROUGE METRO AREA BY 5 PM...WESTERN
PORTIONS OF NEW ORLEANS METRO AREA BY 7 PM. MEANWHILE...LARGE SLUG
OF GULF MOISTURE ADVANCING NORTH WITH MORE BANDS OF SHOWERS AND
STORMS DEVELOPING DOWNSTREAM OF THE MAIN BAND. NEEDLESS TO
SAY...THE FLASH FLOOD WATCH IS WELL WARRANTED AND ONLY CHANGE TO
PREVIOUS THINKING IS TO BUMP LOWER END TO 2 TO 3 INCHES WITH
LOCALLY 4 TO 6 INCHES. DENSE FOG SEEMS CONFINED TO NEAR WATER
AREAS AND WILL MAINTAIN MARINE DENSE FOG ADVISORY OF AREA LAKES
AND NEAR SHORE WATERS. OTHERWISE...WILL MENTION FOG IN ZONES BUT
FOREGO DENSE FOG ADVISORY FOR LAND AREAS AT THIS TIME AS
CONVECTION SHOULD OFFSET DENSE FOG FOR A WHILE. AN ADVISORY MAY BE
NEEDED LATER IF RAINS SUBSIDE UNEXPECTEDLY BUT PERSISTENT RAINS
ARE ANTICPATED FOR MUCH OF THE NIGHT. MAY SEE A REPRIEVE IN THE
MORNING FOR A FEW HOURS BEFORE REDEVELOPING DUE TO FRONTAL
FORCING.

LONG TERM...
HAVE NOT MADE MANY CHANGES TO LONG TERM GRIDS WITH GREATER FOCUS
ON THE DAY 1 AND 2 PERIODS. BASICALLY LEFT DRY FORECAST WITH
CLOSER TO SEASONAL TEMPERATURES WEDNESDAY THROUGH SATURDAY. WILL
BE WATCHING MODEL TRENDS WITH GULF LOW FORMATION IN THE WEST
CENTRAL GULF LATER THIS WEEK BUT MODELS ARE DIVERGENT ON SOLUTIONS
WITH THIS FEATURE. IF LOW DEVELOPS...IT COULD PASS WELL SOUTH OF
AREA TO MINIMIZE IMPACTS ON FORECAST AREA OTHER THAN MARINE
ISSUES.

AVIATION...
MOST TERMINALS WILL BE IMPACTED WITH IFR CEILINGS AND VSBY EITHER
DUE TO FOG OR HEAVY PRECIPITATION OR BOTH THROUGH NEXT 24 HOURS.
FRONTAL PASSAGE EXPECTED TO MOVE ACROSS AREA TERMINALS GENERALLY
BETWEEN 18Z AND 00Z FROM WEST TO EAST.

MARINE...
DENSE SEA FOG SEEMS CONFINED TO SHORE AREAS AND A DENSE FOG
ADVISORY IS IN EFFECT UNTIL FRONTAL PASSAGE TUESDAY. ONSHORE FLOW
EXPECTED TO STAY AT MODERATE LEVELS THROUGH TUESDAY AND THEN SHIFT
NORTHWEST WITH FRONTAL PASSAGE TUESDAY AFTERNOON AND EARLY
EVENING. WINDY CONDITIONS WITH OCCASIONAL GALE FORCE GUSTS
PROBABLY IMPACTS TUESDAY NIGHT THROUGH WEDNESDAY EVENING WITH
MODIFIED ARCTIC AIRMASS DENSITY OVER RELATIVELY WARM WATERS.
MODELS SUGGEST ANOTHER LOW PRESSURE SYSTEM DEVELOPS IN THE WEST-
CENTRAL GULF AND MOVES EAST ACROSS THE CENTRAL GULF. THIS MAY
BRING AN INCREASE IN GRADIENT WINDS ACROSS THE NORTH GULF LATER IN
THE WEEK.

HYDROLOGY...
MANY RIVERS ARE IN FLOOD OR IN HIGH FLOWS. WE ARE CONTINUING TO
MONITOR RAINFALL TRENDS WITH RIVER MODELING INCLUSIVE OF 2 INCH
AREAL AVERAGED BASIN RAINFALL NEXT 24 HOURS...HEAVILY WEIGHTED TO
THE NEXT 12 HOURS. RIVER FLOODING WILL BE A CONCERN FOR THE NEXT
FEW DAYS OR INTO THE NEXT WEEK FOR THE LONGER REACH RIVERS LIKE
THE PEARL.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  65  67  39  59 / 100  90  10  10
BTR  63  65  42  60 /  90  90  10  10
MSY  70  72  46  61 /  90  90  20  10
GPT  66  68  45  61 /  90  90  20  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR LAZ034>040-
     046>050-056>070.

GM...DENSE FOG ADVISORY UNTIL NOON CST TUESDAY FOR GMZ530-550.

     DENSE FOG ADVISORY UNTIL 6 PM CST TUESDAY FOR GMZ555.

MS...FLASH FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR MSZ068>071-077-
     080>082.

     DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR MSZ080>082.

GM...DENSE FOG ADVISORY UNTIL NOON CST TUESDAY FOR GMZ550.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
605 PM CST MON DEC 14 2009

GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077-
080>082-160015-
LAKE PONTCHARTRAIN AND LAKE MAUREPAS-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA OUT 20 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER OUT 20 NM-
COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER
TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO 60 NM-
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER FROM 20 TO 60 NM-POINTE COUPEE-WEST FELICIANA-
EAST FELICIANA-ST. HELENA-TANGIPAHOA-WASHINGTON-ST. TAMMANY-
IBERVILLE-WEST BATON ROUGE-EAST BATON ROUGE-ASCENSION-LIVINGSTON-
ASSUMPTION-ST. JAMES-ST. JOHN THE BAPTIST-UPPER LAFOURCHE-
ST. CHARLES-UPPER JEFFERSON-ORLEANS-UPPER PLAQUEMINES-
UPPER ST. BERNARD-UPPER TERREBONNE-LOWER TERREBONNE-
LOWER LAFOURCHE-LOWER JEFFERSON-LOWER PLAQUEMINES-
LOWER ST. BERNARD-WILKINSON-AMITE-PIKE-WALTHALL-PEARL RIVER-
HANCOCK-HARRISON-JACKSON-
605 PM CST MON DEC 14 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS
OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST
LOUISIANA AND SOUTHERN MISSISSIPPI.

.DAY ONE...TONIGHT
THUNDERSTORMS AND FLASH FLOODING...
A FLASH FLOOD WATCH IS IN EFFECT FOR THE EXPECTED RETURN OF HEAVY
RAIN. IN ADDITION...SOME THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING ISOLATED STRONG WIND GUSTS AND FREQUENT LIGHTNING.

FOG...
DENSE FOG IS EXPECTED TO PERSIST ACROSS THE MISSISSIPPI GULF COAST
AND OVER THE COASTAL WATERS TONIGHT. A DENSE FOG ADVISORY IS IN
EFFECT FOR THESE AREAS THROUGH TONIGHT...WITH VISIBILITY OF 1/4
MILE OR LESS EXPECTED.

RIVER FLOODING...
SEVERAL AREA RIVERS REMAIN NEAR OR JUST ABOVE FLOOD STAGE. PLEASE
REFER TO THE LATEST RIVER FLOOD WARNINGS...STATEMENTS AND RIVER
FORECASTS FOR ADDITIONAL DETAILS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY
THUNDERSTORMS AND FLASH FLOODING...
THE POTENTIAL FOR HEAVY RAINFALL WILL CONTINUE THROUGH TUESDAY.
THE FLASH FLOOD WATCH WILL REMAIN IN EFFECT THROUGH THE DAYTIME
HOURS ON TUESDAY. STORM TOTAL RAINFALL OF 2 TO 3 INCHES IS LIKELY
ACROSS MOST OF THE AREA...WITH ISOLATED HIGHER AMOUNTS OF 4 TO 6
INCHES POSSIBLE. OCCASIONAL LIGHTNING AND GUSTY WINDS WILL ALSO BE
POSSIBLE WITH SOME OF THE THUNDERSTORMS DURING THE DAYTIME HOURS.

RIVER FLOODING...
SEVERAL AREA RIVERS WILL REMAIN NEAR OR ABOVE FLOOD STAGE. HEAVY
RAINFALL EXPECTED THROUGH TUESDAY COULD RESULT IN HIGHER CRESTS
THAN FORECAST...WITH ADDITIONAL RIVERS POSSIBLY RISING TO FLOOD
STAGE BY MID WEEK. PLEASE REFER TO THE THE LATEST RIVER FLOOD
STATEMENTS AND RIVER FORECASTS FOR DETAILS.

.SPOTTER INFORMATION STATEMENT...
PLEASE RELAY REPORTS OF STREET FLOODING OR FLASH FLOODING TO THE
NATIONAL WEATHER SERVICE OR LOCAL LAW ENFORCEMENT. THE NATIONAL
WEATHER SERVICE CAN BE REACHED AT 5 0 4 5 2 2 7 3 3 0...OR 9 8 5 6
4 9 0 3 5 7.

95/DM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1015 PM CST MON DEC 14 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1000 PM     FLASH FLOOD      THIBODAUX               29.79N 90.82W
12/14/2009                   LAFOURCHE          LA   EMERGENCY MNGR

            WATER ABOUT TO ENTER AT LEAST 7 HOMES AT BELLE HELENE IN
            THIBODAUX.

&&

RSW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1057 PM CST MON DEC 14 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1055 PM     FLASH FLOOD      DESTREHAN               29.96N 90.37W
12/14/2009                   ST. CHARLES        LA   EMERGENCY MNGR

            SEVERAL ROADS CLOSED IN THE DESTREHAN...BOUTTE AND ST.
            ROSE AREAS.

&&

RSW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1125 PM CST MON DEC 14 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1120 PM     FLASH FLOOD      METAIRIE                30.00N 90.18W
12/14/2009                   JEFFERSON          LA   BROADCAST MEDIA

            ONE FOOT OF WATER COVERING VETERANS BLVD AT
            CAUSEWAY...AND CONTINUES TO RISE.

&&

TERICKSN

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1154 PM CST MON DEC 14 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1250 PM     FLASH FLOOD      5 ENE GONZALES          30.24N 90.85W
12/14/2009                   ASCENSION          LA   EMERGENCY MNGR

            AMITE RIVER AND SUMMERFIELD ROADS CLOSED TO DUE HEAVY
            RAINFALL.

0130 PM     FLASH FLOOD      3 SE MCCOMB             31.21N 90.43W
12/14/2009                   PIKE               MS   EMERGENCY MNGR

            THE INERSECTION OF RAYBORN AND GUTTER ROADS WAS CLOSED
            DUE TO WATER FLOWING OVER THE ROAD FROM EXCESSIVE
            RAINFALL.

0542 PM     FLASH FLOOD      GONZALES                30.22N 90.92W
12/14/2009                   ASCENSION          LA   EMERGENCY MNGR

            SIX ROADS IN PARISH CLOSED DUE TO FLOODING.

0736 PM     FLASH FLOOD      GONZALES                30.22N 90.92W
12/14/2009                   ASCENSION          LA   EMERGENCY MNGR

            SEVERAL ROADS FLOODED. SOME FLOOD WATERS APPROACHING
            PROPERTY.

0750 PM     FLASH FLOOD      HOUMA                   29.58N 90.71W
12/14/2009                   TERREBONNE         LA   EMERGENCY MNGR

            SEVERE STREET FLOODING WITH SOME STREETS CLOSED DUE TO
            HIGH WATER...MAINLY IN THE CITY. A FEW HOMES THREATENED.
            SOME BAYOUS BEGINNING TO OVERTOP...IN PARTICULAR LITTLE
            BAYOU BLACK.

0750 PM     FLASH FLOOD      RACELAND                29.72N 90.60W
12/14/2009                   LAFOURCHE          LA   EMERGENCY MNGR

            WATER APPROACHING SOME HOMES IN RACELAND.

0917 PM     FLASH FLOOD      DESTREHAN               29.96N 90.37W
12/14/2009                   ST. CHARLES        LA   EMERGENCY MNGR

            BERNICE STREET CLOSED DUE TO FLOODING AND RIVER ROAD IS
            NOW BEGINNING TO FLOOD.

1000 PM     FLASH FLOOD      THIBODAUX               29.79N 90.82W
12/14/2009                   LAFOURCHE          LA   EMERGENCY MNGR

            WATER ABOUT TO ENTER AT LEAST 7 HOMES AT BELLE HELENE IN
            THIBODAUX.

1055 PM     FLASH FLOOD      DESTREHAN               29.96N 90.37W
12/14/2009                   ST. CHARLES        LA   EMERGENCY MNGR

            SEVERAL ROADS CLOSED IN THE DESTREHAN...BOUTTE AND ST.
            ROSE AREAS.

1120 PM     FLASH FLOOD      METAIRIE                30.00N 90.18W
12/14/2009                   JEFFERSON          LA   BROADCAST MEDIA

            ONE FOOT OF WATER COVERING VETERANS BLVD AT
            CAUSEWAY...AND CONTINUES TO RISE.

&&

RSW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1202 AM CST TUE DEC 15 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1156 PM     FLASH FLOOD      5 N THIBODAUX           29.86N 90.82W
12/14/2009                   LAFOURCHE          LA   EMERGENCY MNGR

            5 INCHES OF WATER COVERING JOSHUA STREET.

&&

TERICKSN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1204 AM CST TUE DEC 15 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1202 AM     FLASH FLOOD      5 N THIBODAUX           29.86N 90.82W
12/15/2009                   LAFOURCHE          LA   EMERGENCY MNGR

            WATER COVERING ROADWAYS IN WOODLAND HEIGHTS. MOBILE HOME
            ROAD IS IMPASSABLE.

&&

TERICKSN