000 FXUS64 KLCH 231541 AFDLCH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 941 AM CST MON NOV 23 2009 .UPDATE... VISIBILITIES HAVE IMPROVED ACROSS THE FORECAST AREA AS THE FOG BEGINS TO LIFT WITH SOME DAYTIME HEATING. THEREFORE...HAVE ALLOWED THE DENSE FOG ADVISORY TO EXPIRE. OTHERWISE...MORNING SOUNDING SHOWS PLENTY OF DRY AIR ALOFT...SO SKIES SHOULD BE MOSTLY SUNNY THIS AFTERNOON WITH MILD TEMPERATURES. UPDATED ZONES HAVE ALREADY BEEN SENT. RUA && .PREV DISCUSSION... /ISSUED 617 AM CST MON NOV 23 2009/ DISCUSSION... 12Z TAF ISSUANCE DISCUSSION. AVIATION... SATELLITE IMAGERY AND SFC OBS INDICATE PERSISTENT LOW CLOUDS HOVERING OVER THE FORECAST AREA THIS MORNING WITH CEILINGS RANGING FROM 500 FEET AT KAEX TO ALMOST 3000 FEET AT KLFT/KARA. VISIBILITIES HAVEN'T BEEN THE PROBLEM PREVIOUSLY THOUGHT WITH READINGS BASICALLY BOUNCING AROUND ANYWHERE FROM 1/2SM TO 10SM. FORECAST SOUNDINGS INDICATE THAT THE LOW CLOUDS SHOULD GRADUALLY MIX OUT THIS MORNING LEAVING BEHIND JUST SCATTERED CLOUDS THROUGH THE AFTERNOON HOURS. HOWEVER MODEL TIME-HEIGHT SECTIONS INDICATE INCREASING LOW-LEVEL MOISTURE WHILE MOS GUIDANCE SHOWS HIGHER DEWPOINTS BY 12Z TUESDAY SO HAVE INCLUDED SOME RESTRICTIONS TO VISIBILITY FOR LATE IN THE FORECAST. 25 PREV DISCUSSION... /ISSUED 448 AM CST MON NOV 23 2009/ SYNOPSIS... WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS SHOWS UPPER LOW LIFTING OFF TO THE NE WITH THE AREA UNDER PRIMARILY ZONAL FLOW ALOFT. ANOTHER UPPER LEVEL LOW LOCATED UPSTREAM IS MOVING OVER THE NRN ROCKIES. AT THE SFC...HIGH PRESSURE RIDGING OVER THE AREA IS PROVIDING LIGHT VARIABLE WINDS. A LARGE SWATH OF STRATUS PERSISTS OVER THE LOWER MS VALLEY WEST INTO THE SABINE VALLEY UNDER A SUBSIDENCE INVERSION. THESE CLOUDS HAVE DEVELOPED WESTWARD DURING THE NIGHT WITH THE WESTERNMOST EDGE EXTENDING FROM ROUGHLY LFK TO BPT. MOSTLY CLEAR SKIES WERE NOTED EARLIER TONIGHT OVER SE TX AND WRN LA WHICH ALLOWED FOR THE DEVELOPMENT OF SOME PATCHY DENSE FOG. VISBYS HAVE IMPROVED SOME EARLY THIS MORNING...BUT REMAIN HIGHLY VARIABLE IN TIME AND SPACE RANGING FROM LESS THAN ONE MILE TO FIVE MILES. A DENSE FOG ADVISORY REMAINS IN EFFECT THROUGH MID MORNING...MAINLY WEST OF A MARKSVILLE TO CAMERON LINE. FURTHERMORE...IN AREAS WHERE SKIES WERE MOSTLY CLEAR...ENOUGH COOLING HAS TAKEN PLACE TO LOWER TEMPERATURES INTO THE LOWER 50S...WHILE ACRS THE ERN ZONES WHERE SKIES HAVE REMAINED OVERCAST...TEMPERATURES HAVE BEEN STEADY IN THE UPPER 50S. DISCUSSION... EXPECT THE PERSISTENT LOW CLOUD LAYER TO BEGIN MIXING OUT TODAY...WITH SKIES GRADUALLY CLEARING FROM WEST TO EAST. SFC HIGH PRESSURE WILL CONTINUE TO SHIFT EAST OF THE AREA WITH LIGHT SOUTHERLY WINDS DEVELOPING. WILL BEGIN TO SEE A MODEST RETURN OF LOW LEVEL MOISTURE AS WELL. EXPECT TEMPERATURE TO WARM INTO THE UPPER 60S OR NEAR 70 BY THIS AFTN. HOWEVER...THIS IS DEPENDENT UPON HOW QUICKLY THE CLOUDS DISSIPATE WITH HIGH TEMPERATURES POSSIBLY A BIT COOLER THAN FCST OVER THE ERN ZONES WITH OVERCAST ANTICIPATED TO LINGER HERE A BIT LONGER. THE UPPER LOW CURRENTLY OVER THE ROCKIES WILL MOVE INTO THE CNTRL PLAINS THE NEXT COUPLE OF DAYS...BRINGING A COLD FRONT THROUGH THE AREA TUESDAY. HAVE GONE WITH SCT POPS FOR TUESDAY...A COMPROMISE BETWEEN THE HIGHER MET AND THE LOWER MAV POP GUIDANCE. THIS MAY BE A BIT HIGH HOWEVER...WITH RATHER MEAGER MOISTURE RETURN AND LIMITED INSTABILITY. THE INITIAL LOW WILL LIFT NE THROUGH THE REMAINDER OF THE WEEK...WITH ANOTHER LOW DROPPING OUT OF CANADA INTO THE CNTRL CONUS TROUGH BY THURSDAY. THIS WILL PUSH A REINFORCEMENT OF COOL DRY AIR ACRS THE AREA. HIGH PRESSURE AT THE SFC AND DRY NWRLY FLOW ALOFT WILL BRING AN EXTENDED PERIOD OF DRY COOL WEATHER FOR THE THANKSGIVING HOLIDAY INTO THE WEEKEND. TEMPERATURES WILL BE NEAR OR A BIT BELOW SEASONAL NORMS. ANOTHER SYSTEM WILL BE TAKING SHAPE OVER THE WRN US LATE NEXT WEEKEND WITH A CHANCE FOR SHOWERS RETURNING SUNDAY AFTN AHEAD OF THE NEXT FROPA ON MONDAY. MARINE... LIGHT WINDS AND LOW SEAS WILL PERSIST THROUGH LATE TUESDAY. SOUTHEAST WINDS WILL GRADUALLY SHIFT TO A NORTHERLY DIRECTION BY TUESDAY NIGHT AS A COLD FRONT MOVES ACROSS THE COASTAL WATERS. BEHIND THE FRONT...OFFSHORE WINDS WILL STRENGTHEN BY WEDNESDAY MORNING TO 15 TO 20 KNOTS...WITH SEAS BUILDING TO 5 TO 6 FEET. MODERATE TO STRONG OFFSHORE FLOW WILL CONTINUE THROUGH FRIDAY. HIGH PRESSURE WILL MOVE EAST OF THE AREA SATURDAY WITH ONSHORE FLOW RESUMING. && .PRELIMINARY POINT TEMPS/POPS... KLCH 70 53 73 50 67 / 0 10 40 20 10 KBPT 72 56 74 48 67 / 0 10 40 10 10 KAEX 69 48 71 45 65 / 0 10 40 10 10 KLFT 70 53 74 51 68 / 0 10 40 20 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$