FXUS64 KLIX 221032
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
432 AM CST TUE DEC 22 2009
.SHORT TERM...
SIMILAR CONDITIONS ACROSS THE AREA FROM YESTERDAY BUT WITH A FEW
CHANGES. GENERALLY...TEMPS AND DEWPOINTS ARE ABOUT 5 DEGREES WARMER.
DEWPOINT SPREADS ARE A LITTLE HIGHER WHICH HAS RESULTED IN LESS
WIDESPREAD FOG DEVELOPMENT SO HAVE TRIMMED OUT MUCH OF AREAS OF
DENSE FOG TO PATCHY DENSE. LOCATIONS ALONG THE PEARL RIVER IN ST.
TAMMANY PARISH AND PEARL RIVER/HANCOCK COUNTIES AS WELL AS HARRISON
ARE THE MOST SUSCEPTIBLE TO MORE WIDESPREAD DENSE FOG. NO PLANS ATTM
TO ISSUE DENSE FOG ADVISORY BUT WILL CONTINUE TO MONITOR.
SURFACE HIGH NOW TO THE EAST OF THE AREA WILL PROMOTE INCREASE
MOISTURE WITH SERLY WINDS ON THE INCREASE TODAY. TEMPERATURES WILL
CONTINUE TO MODERATE WITH INCREASING THICKNESSES. STAYED VERY CLOSE
TO MAV FCST HIGHS DUE TO ITS GOOD PERFORMANCE THE LAST FEW DAYS.
SHOULD SEE HIGHS FROM THE MID TO UPPER 60S WITH A FEW 70S POSSIBLE.
CLOUDS WILL BE ON THE INCREASE FROM THE WEST TODAY BUT SHOULD MOSTLY
BE IN THE FORM OF CIRRUS. THE INTRODUCTION OF SHOWERS INTO THE
FORECAST BEGINS TONIGHT WITH THE FOCUS ON EXTREME NWRN ZONES. POPS
AROUND 30 MAY BE A LITTLE ON THE GENEROUS SIDE. CONTINUED INCREASING
CLOUDS AND MOISTURE WILL RESULT IN SUBSTANTIALLY WARMER LOWS TONIGHT
WITH TEMPS ONLY DROPPING INTO THE MID 50S.
.LONG TERM...
UPPER TROUGH WILL BE DIGGING SEWD ACROSS THE WESTERN HALF OF THE
COUNTRY TODAY AND WEDNESDAY. MODELS HAVE BACKED OFF SOME ON POPS
WEDNESDAY. NO ARGUMENTS HERE AND GOES BETTER WITH UNDERCUTTING
GUIDANCE YESTERDAY FOR THAT PERIODS POPS. SH/TS POTENTIAL WILL
PROGRESSIVELY INCREASE WED NIGHT OUT AHEAD OF APPROACHING COLD
FRONT. MODEL SOUNDINGS SUGGEST PW/S COMING UP TO AROUND 1.5 INCHES
BY MIDNIGHT. THINKING IS THAT A SQUALL LINE WILL DEVELOP ALONG THE
FRONT AND MOVE THROUGH THE CWA THURSDAY AFTN AND INTO THE EARLY
EVENING HRS. THIS COINCIDES WITH THE ECMWF/GFS SPEED AS OPPOSED TO
THE SLIGHTLY SLOWER NAM12. INSTABILITY WILL BE FAIRLY MARGINAL BUT
SHOULD HAVE ENOUGH FORCING ALONG THE BOUNDARY FOR A SVR WX THREAT.
MAIN THREAT WILL BE DAMAGING WINDS WITH ISOLATED TORNADOES.
ONCE THE FRONT CLEARS THE AREA THURSDAY NIGHT...HIGH PRESSURE WILL
BUILD IN FROM THE NW AND PERSIST THROUGH EARLY NEXT WEEK. MEX TEMPS
LOOK TO BE ON THE WARM SIDE FOR SUCH PERSISTENT NWRLY COLD AIR
ADVECTION...SO HAVE UNDERCUT GUIDANCE. MODEL SOLUTIONS DIFFER
TOWARDS THE END OF THE PERIOD. WHILE ECMWF AND GFS BOTH SHOW AN AREA
OF LOW PRESSURE DEVELOPING AND TRACKING ALONG THE GULF COAST...ECMWF
HAS A MUCH STRONGER INVERTED UPPER TROUGH AND SFC LOW TRACKING
DIRECTLY ACROSS CWA WHILE THE GFS KEEPS THE SFC LOW FARTHER SOUTH IN
THE GULF WATERS AND THUS MUCH LESS RAIN ACROSS THE CWA.
MEFFER
&&
.AVIATION...
FOG APPEARS TO BE HELD AT BAY THUS FAR TONIGHT AS DEWPOINT SPREADS
ARE MAINTAINING 2+C ACROSS MUCH OF THE AREA. SOME GROUND FOG NOTED
AT KBIX AND KPQL AROUND 2SM. KMCB BOUNCING FROM 2SM TO 4SM. SUBTLE
BUT STEADY WARM AIR ADVECTION MAY OFFSET SURFACE INVERSION ENOUGH TO
PRECLUDE MUCH FOG IMPACT THIS MORNING BUT TEMPO 1-2 HR OF 1-2SM BR
POSSIBLE BEFORE 1430Z. MID LEVEL CLOUDS SHOULD STEADILY INVADE FROM
THE SOUTHWEST AS NEXT STORM SYSTEM DEVELOPS AND MATURES IN THE
PLAINS STATES NEXT 24 HOURS. VFR CONDITIONS SHOULD PREVAIL THROUGH
18Z WEDNESDAY. 24/RR
&&
.MARINE...
WINDOW OF LIGHT WINDS AND LOW SEAS WILL SLOWLY CLOSE AS RETURN FLOW
GETS UNDERWAY LATER TODAY AND ESPECIALLY TONIGHT. MODERATE RETURN
FLOW NOTED IN THE WEST GULF THIS MORNING WILL SPREAD EAST IN TIME.
STRONG COLD FRONT WITH PRE-FRONTAL SQUALL LINE STILL EXPECTED TO
MOVE THROUGH LA AND MS COASTAL WATERS THURSDAY WITH COLD HIGH
PRESSURE BUILDING IN ITS WAKE THROUGH FRIDAY. SMALL CRAFT ADVISORY
CONDITIONS SHOULD ONSET TONIGHT WITH THE ACTUAL ADVISORY PROBABLY
POSTED WITH AFTERNOON COASTAL FORECAST ISSUANCE. 24/RR
.PRELIMINARY POINT TEMPS/POPS...
MCB 66 53 66 58 / 0 30 30 70
BTR 69 56 72 59 / 10 30 30 60
MSY 68 56 73 61 / 0 20 20 50
GPT 65 53 68 59 / 0 10 20 40
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&
$$
