FXUS64 KLIX 120249
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
849 PM CST FRI DEC 11 2009
.UPDATE...
...SOUNDING DISCUSSION...
NO PROBLEMS WITH THE FLIGHT THIS EVENING. THE GOOD NEWS IS THAT
THE SOUNDING SHOWS THAT THE ACTIVITY WILL BEHAVE FOR THE TIME
BEING AS THERE IS STILL A WARM NOSE ABOVE THE SURFACE THAT IS
KEEPING THE ENVIRONMENT VERY STABLE DESPITE THE RAIN. THE BIGGEST
THREAT REMAINS THE AMOUNT OF RAIN THAT FALLS AS MANY AREAS ARE
ALREADY SATURATED FROM PREVIOUS EVENTS. RAINFALL HAS SPREAD IN
THIS EVENING FROM THE WEST AND IT IS NOW RAINING AT MOST LOCATIONS
ACROSS THE AREA. THE RAIN THIS EVENING IS PRODUCING RAINFALL RATES
OF GENERALLY UP TO ONE HALF INCH PER HOUR.
98/SO
&&
.PREV DISCUSSION... /ISSUED 352 PM CST FRI DEC 11 2009/
SHORT TERM...
HEAVY RAINFALL THREAT APPEARS TO BE IN EARLY STAGES OF DEVELOPMENT
AS ARCTIC HIGH DOME HOLDS FIRM IN THE CENTRAL APPALACHIANS. LOW
PRESSURE ESTIMATED AT 1013MB IS NOTED IN SURFACE DATA OFF THE
LOWER TEXAS COAST. VERY DRY AIR HAS DRAINED INTO THE LOWER GULF
STATES WHICH SHOULD STEEPEN THE ISENTROPIC LIFT SURFACES ONCE THE
LOW ADVANCES NORTHWARD. PER PREVIOUS DISCUSSION...PRECIPITATION
CALCULATOR AMOUNTS FROM ISENTROPIC MODE INDICATES RATES OF 0.40 TO
0.50 INCHES PER HOUR FOR ABOUT 6 TO 8 HOURS TO YIELD 2.60 TO 3.50
INCHES OF RAINFALL OVERNIGHT IN A RATHER UNIFORM AND LARGE
COVERAGE...GIVEN ABOUT 110-120 MB OF LIFT. HPC GUIDANCE IS
INDICATION SOMEWHAT LESSER QPF VALUES THE NEXT 12 HOURS. AS A
COMPROMISE AND TO STAY CONSISTENT WITH FLASH FLOOD WATCH
BASIS...WILL MAINTAIN GENERAL 1-3 INCHES WITH LOCALLY HIGHER
AMOUNTS 3 TO 5 INCHES...THE BULK OCCURRING OVERNIGHT TONIGHT BUT
STORM TOTALS RUNNING THROUGH SUNDAY MORNING. ASSOCIATED COLD
FRONTAL PASSAGE SHOULD BRING AN END TO RAINFALL...AT LEAST A
REPRIEVE...SUNDAY MID TO LATE MORNING.
LONG TERM...
ANOTHER FRONT MOVES THROUGH THE AREA TUESDAY WITH A SHOT AT HEAVY
RAINFALL ONCE AGAIN MONDAY NIGHT. ONCE THAT FRONT GOES THROUGH...A
STRETCH OF MUCH NEEDED DRIER CONDITIONS WITH SEASONAL TEMPERATURES
ARE EXPECTED INTO THE NEXT WEEKEND.
AVIATION...
18Z TAF ISUANCE...CEILINGS CURRENTLY AROUND 6KFT WILL BEGIN TO LOWER
THIS EVENING AND TONIGHT AS MOISTURE AND RAIN MOVE INTO THE AREA
AHEAD OF A WARM FRONT. BY SAT MORNING...CIGS WILL BE BORDERLINE
MVFR/IFR AROUND 1KFT. FURTHER DEGREDATION OF CONDITIONS IS EXPECTED
THROUGH THE MORNING AS MOISTURE CONTINUES TO INCREASE. CIGS OF 500
FT OR LOWER ARE EXPECTED FROM MID MORNING THROUGH AT LEAST THE EARLY
AFTERNOON. 95/DM
MARINE...
PRESSURE GRADIENT TIGHTENING BETWEEN ARCTIC HIGH SITUATED OVER TEH
EASTERN U.S. AND DEVELOPING LOW PRESSURE OFF THE LOWER TEXAS
COAST. STRONG EAST TO NORTHEAST FLOW TO SWING TO SOUTHERLY FLOW
SATURDAY WITH WARM FRONTAL PASSAGE ONCE LOW MOVES ASHORE IN
SOUTHWEST LOUISIANA SATURDAY MORNING. PERSISTENCE OF EASTERLY FLOW
FOR ABOUT 12 HOURS WILL BRING AN INCREASE IN TIDE LEVELS BUT
SHOULD STAY BELOW COASTAL FLOODING. ANOTHER WEAKER AND BROADER
AREA OF LOW PRESSURE MOVES INTO THE COASTAL WATERS FROM THE WEST
GULF MONDAY EVENING IN ADVANCE OF A COLD FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 41 51 49 70 / 90 100 70 30
BTR 44 54 54 72 / 90 100 70 30
MSY 47 60 60 73 / 90 100 70 30
GPT 45 55 55 73 / 90 100 90 30
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FLASH FLOOD WATCH UNTIL MIDNIGHT SUNDAY FOR THE FOLLOWING ZONES:
ASCENSION...ASSUMPTION...EAST BATON ROUGE...EAST
FELICIANA...IBERVILLE...LIVINGSTON...ORLEANS...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...WASHINGTON...WEST BATON
ROUGE...AND WEST FELICIANA.
GM...SMALL CRAFT ADVISORY UNTIL 3 AM SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO
60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA OUT 20
NM...AND LAKE PONTCHARTRAIN AND LAKE MAUREPAS.
SMALL CRAFT ADVISORY UNTIL NOON SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST
PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 NM...AND
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF
THE MISSISSIPPI RIVER OUT 20 NM.
MS...FLASH FLOOD WATCH UNTIL MIDNIGHT SUNDAY FOR THE FOLLOWING ZONES:
AMITE...HANCOCK...HARRISON...JACKSON...PEARL
RIVER...PIKE...WALTHALL...AND WILKINSON.
GM...SMALL CRAFT ADVISORY UNTIL 3 AM SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA FROM 20 TO
60 NM...COASTAL WATERS FROM THE SOUTHWEST PASS OF THE
MISSISSIPPI RIVER TO LOWER ATCHAFALAYA RIVER LA OUT 20
NM...AND LAKE PONTCHARTRAIN AND LAKE MAUREPAS.
SMALL CRAFT ADVISORY UNTIL NOON SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST
PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 NM...AND
COASTAL WATERS FROM PASCAGOULA MS TO THE SOUTHWEST PASS OF
THE MISSISSIPPI RIVER OUT 20 NM.
&&
$$
