| 000 FXUS64 KLIX 011029 AFDLIX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 529 AM CDT THU JUL 1 2010 .SYNOPSIS... WEAK FRONTAL BOUNDARY OR TROUGH OF LOW PRESSURE EXTENDS FROM JUST OFF THE ALABAMA COAST TO NEAR THE EXTREME SOUTHEAST LOUISIANA COAST. A STRONGER SLOW MOVING COLD FRONT HAS MOVED SOUTH INTO EXTREME SOUTHERN ARKANSAS...NORTHERN MISSISSIPPI...AND NORTHERN ALABAMA. WEAKENING HURRICANE ALEX CONTINUES TO MOVE WEST AND INLAND OVER NORTHEAST MEXICO. DEEP TROPICAL MOISTURE REMAINS OVER THE CENTRAL GULF COAST REGION WITH PRECIPITABLE WATER /PW/ VALUES AROUND 2.5 INCHES. AREAS OF RAIN...SHOWERS...AND TROPICAL RAIN BANDS WITH ISOLATED THUNDERSTORMS ARE DEVELOPING NORTH OVER COASTAL AND EXTREME SOUTHEAST LOUISIANA AND THE COASTAL WATERS. && .SHORT TERM... THE SURFACE BOUNDARY OVER THE REGION WILL ALSO BE ASSOCIATED WITH A SIMILAR CONVERGENCE BOUNDARY UP TO 850 AND 700 MB. THESE BOUNDARIES AND THE HIGH PW NEAR 2.5 INCHES WILL LINGER OVER THE FORECAST AREA TODAY. OTHER SURFACE BOUNDARIES FROM WEAK SEA AND LAKE BREEZES AND OUTFLOW BOUNDARIES WILL ALSO HELP TO FOCUS CONVECTION...SOME POSSIBLY SETTING UP IN STATIONARY OR SLOW MOVING BANDS RESULTING IN A TRAIN ECHO EFFECT OF HEAVY RAINFALL. GIVEN THE HIGH RAINFALL EFFICIENCY...HAVE OPTED TO EXTEND THE FLOOD WATCH IN AREA AND TIME...NOW INCLUDING ALL PARISHES IN SOUTHEAST LOUISIANA INTO COASTAL MISSISSIPPI THROUGH 7 PM TODAY. SHOWERS AND THUNDERSTORMS SHOULD WEAKEN AND GRADUALLY DISSIPATE OVER LAND THIS EVENING...WITH RENEWED ACTIVITY EXPECTED AGAIN OVERNIGHT NEAR THE COAST AND OFFSHORE. THE GFS CONTINUES TO SHOW A FAIRLY STACKED LOW PRESSURE SYSTEM FROM THE SURFACE TO 500 MB FORMING TONIGHT AND FRIDAY. THIS MODEL HAS BEEN THE MOST CONSISTENT SHOWING DEVELOPMENT...BUT THE LOCATION HAS SHIFTED FROM MODEL RUN TO MODEL RUN. THE 00Z RUN TODAY SHOWS THE LOW FORMING ALONG A SURFACE BOUNDARY OVER THE CENTRAL FLORIDA PANHANDLE THIS EVENING...THEN THE LOW DEEPENS AND MOVES WEST-SOUTHWEST OVER THE NORTHEAST GULF OF MEXICO ON FRIDAY. THE 06Z NAM AND 00Z ECMWF SHOW A WEAKER LOW FORMING OVER THE NORTHEAST GULF OF MEXICO DURING THIS TIME FRAME...WHILE THE 00Z CANADIAN GEM IS SIMILAR IN STRENGTH AS THE GFS BUT SLOWER. AM FAVORING THE WEAKER NAM/ECMWF SOLUTIONS AT THIS TIME. THIS MEANS THERE SHOULD NOT BE AS MUCH DRY AIR PULLED SOUTH INTO SOUTHEAST MISSISSIPPI ON FRIDAY AS INDICATED BY THE GFS AND MAV GUIDANCE. THERE WILL BE DRIER/HOTTER AIR AND SUBSIDENCE CLOSE TO OUR NORTHERN BORDER DUE TO THE PROXIMITY OF A BUILDING MID LEVEL HIGH/RIDGE OVER THE MID MISSISSIPPI VALLEY/LOWER OHIO VALLEY AND MID SOUTH AREA. .LONG TERM... THE LONG TERM FORECAST STARTING WITH THE HOLIDAY WEEKEND WILL DEPEND ON THE STRENGTH AND TIMING OF ANY SURFACE LOW OR WAVE THAT MOVES WEST NEAR THE CENTRAL GULF COAST REGION. THE GFS IS SHOWING A STRENGTHENING AND SLOW MOVING SURFACE LOW /TROPICAL?/ MOVING RIGHT TOWARDS THE SOUTHEAST LOUISIANA COAST THIS WEEKEND WITH HEAVY RAIN RETURNING TO AT LEAST COASTAL SECTIONS OF THE FORECAST AREA. ONCE AGAIN...AM FAVORING THE WEAKER NAM/ECMWF SOLUTIONS SHOWING EITHER A WEAKER LOW OR WAVE/INVERTED TROUGH FEATURE MOVING AT A FASTER SPEED TO THE WEST/NORTHWEST OVER THE WEEKEND. FOR THE SENSIBLE WEATHER...THIS WILL KEEP THE RAIN CHANCES ON THE HIGH SIDE WITH A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY AND SUNDAY...THEN DROPPING OFF SLIGHTLY ON MONDAY AS HIGH PRESSURE BUILDS BACK INTO THE AREA. MODEL DIFFERENCES CONTINUE TUESDAY INTO WEDNESDAY WITH THE ECMWF FAVORING A DRIER PATTERN WITH AN EXPANDING MID LEVEL HIGH TO OUR NORTH...WHILE THE GFS KEEPS MORE DISTURBED WEATHER AND LOWER PRESSURES/HEIGHTS OVER THE GULF COAST REGION. HAVE SPLIT THE DIFFERENCE FOR NOW...INDICATING A LOWER END CHANCE POP FOR DIURNAL SHOWERS AND THUNDERSTORMS. TEMPERATURES ARE EXPECTED TO RETURN TO NEAR NORMAL FOR HIGHS. 22/TD && .AVIATION... RAIN AND ISOLD TSRA MOVING BACK INLAND FROM THE GULF. BOUNDARY SOUTH OF INTERSTATE 12 HAS AIDED IN AREAS OF LOW STRATUS PRODUCING OCCASIONAL IFR CONDITIONS MAINLY AFFECTING KMSY...KNEW...KHSA AND KASD. MOIST AIRMASS IN COMBINATION WITH THE BOUNDARY WILL CONTINUE TO ALLOW THE DEVELOPMENT OF TSRA...AT LEAST THROUGH THE MORNING AND EARLY AFTERNOON HOURS. MVFR CIGS AND IFR VSBYS LIKELY WITH STRONGER CELLS. WILL ENHANCE CURRENT MENTION OF TSRA IN SHORT TERM...2 TO 6 HOURS OUT...AS AFFECTED AREAS BECOME MOST APPARENT. EXPECT DIMINISHING TREND BY EVENING. LOCATION OF BOUNDARY BY EVENING WILL DETERMINE WHICH TERMINALS WILL SEE LOCAL STRATUS DEVELOP AROUND 06Z TONIGHT. CURRENT FORECAST TRENDS WOULD INDICATE THIS IS MOST LIKELY AT KGPT...KHSA...KASD...KBTR AND KMCB. 35 && .MARINE... SMALL CRAFT ADVISORIES REMAIN IN EFFECT FOR THE COASTAL WATERS FOR LONG PERIOD SWELLS THAT CONTINUE FROM HURRICANE ALEX. SEA HEIGHTS IN THE 7 TO 9 FEET RANGE ARE EXPECTED TODAY...GRADUALLY DIMINISHING TONIGHT. SOME OF THE OUTER WATERS WEST OF PORT FOURCHON WILL CONTINUE TO SEE EAST TO SOUTHEAST WINDS 15 TO 20 KNOTS TODAY...OTHERWISE...MOST OTHER WATERS WILL BE IN THE 10 TO 15 KNOTS RANGE...EXCEPT HIGHER DURING GUSTS FROM THUNDERSTORMS AND HEAVIER RAIN BANDS. SOME TYPE OF LOW PRESSURE AREA OF INVERTED TROUGH IS LIKELY TO MOVE WEST ACROSS THE COASTAL WATERS OVER THE FIRST PART OF THE WEEKEND...WHICH WILL CAUSE SOME VARIABILITY TO THE DIRECTION AND POSSIBLY AN INCREASE IN SPEEDS TO NEAR 15 KNOTS IN SOME AREAS. A RETURN TO A MORE STEADY STATE SOUTHEAST WIND 10 TO 15 KNOTS IS EXPECTED SUNDAY INTO EARLY NEXT WEEK. $$ .PRELIMINARY POINT TEMPS/POPS... MCB 87 72 88 71 / 80 50 50 40 BTR 88 75 90 74 / 90 50 60 40 ASD 87 74 89 73 / 90 60 60 50 MSY 87 77 87 76 / 90 60 60 50 GPT 87 75 89 74 / 90 60 60 50 PQL 88 74 90 74 / 90 60 60 50 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...FLOOD WATCH UNTIL 7 PM THURSDAY FOR THE FOLLOWING ZONES: ASCENSION...ASSUMPTION...EAST BATON ROUGE...EAST FELICIANA...IBERVILLE...LIVINGSTON...LOWER JEFFERSON...LOWER LAFOURCHE...LOWER PLAQUEMINES...LOWER ST. BERNARD...LOWER TERREBONNE...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 1 AM FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA OUT 20 NM...AND COASTAL WATERS FROM THE PORT FOURCHON TO LOWER ATCHAFALAYA RIVER OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 7 AM FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM BOOTHVILLE LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER OUT 20 NM...AND COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 1 PM FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA FROM 20 TO 60 NM...COASTAL WATERS FROM STAKE ISLAND LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM THE PORT FOURCHON TO LOWER ATCHAFALAYA RIVER FROM 20 TO 60 NM...AND COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON FROM 20 TO 60 NM. MS...FLOOD WATCH UNTIL 7 PM THURSDAY FOR THE FOLLOWING ZONES: HANCOCK...HARRISON...JACKSON...AND PEARL RIVER. GM...SMALL CRAFT ADVISORY UNTIL 1 AM FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA OUT 20 NM...AND COASTAL WATERS FROM THE PORT FOURCHON TO LOWER ATCHAFALAYA RIVER OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 7 AM FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM BOOTHVILLE LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER OUT 20 NM...AND COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 1 PM FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM PASCAGOULA MS TO STAKE ISLAND LA FROM 20 TO 60 NM...COASTAL WATERS FROM STAKE ISLAND LA TO THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER FROM 20 TO 60 NM...COASTAL WATERS FROM THE PORT FOURCHON TO LOWER ATCHAFALAYA RIVER FROM 20 TO 60 NM...AND COASTAL WATERS FROM THE SOUTHWEST PASS OF THE MISSISSIPPI RIVER TO PORT FOURCHON FROM 20 TO 60 NM. && $$ |