FXUS64 KLIX 270055
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
655 PM CST SAT DEC 26 2009
.UPDATE...
...SOUNDING DISCUSSION...
NO PROBLEMS WITH THE FLIGHT THIS EVENING. MOISTURE HAS INCREASED
SOME THIS EVENING IN RESPONSE TO A DISTURBANCE MOVING ACROSS THE
GULF OF MEXICO. PW VALUES HAVE INCREASED TO OVER ONE HALF
INCH...UP TWO TENTHS OF AN INCH FROM THIS MORNING. MOISTURE HAS
ALSO INCREASED IN AROUND 6000 FEET WHICH COULD LEAD TO SOME
PRECIPITATION LATE TONIGHT AND EARLY TOMORROW MORNING. THAT
SAID...WHATEVER PRECIPITATION DOES FALL WILL BE VERY LIGHT OR EVEN
JUST VIRGE AS THERE IS A LARGE DRY LAYER OF AIR BETWEEN THAT LEVEL
AND THE SURFACE TO CONTEND WITH. THE BEST CHANCE WILL LIKELY BE
SOUTH OF A LINE FROM BATON ROUGE TO POPLARVILLE AS THE LARGER
CONCENTRATION OF MOISTURE IS SHIFTING SOUTHEASTWARD. A SHALLOW
LAYER OF SOUTHEASTERLY WINDS IS NOTED FROM THE SURFACE TO AROUND
4000 FEET BEFORE WINDS TURN TO THE SOUTHWEST AND WEST.
98/SO
&&
.PREV DISCUSSION... /ISSUED 318 PM CST SAT DEC 26 2009/
SHORT TERM...
DISTURBANCE IN THE SOUTHERN JET STREAM WILL MIGRATE RAPIDLY
ACROSS THE NORTHERN GULF DURING THE NEXT 24 HOURS. WEAK SURFACE
TROUGH HAS FORMED IN RESPONSE TO THE UPPER FORCING AND WILL MOVE
FAIRLY QUICKLY TO ENE. AIRMASS OVER REGION REMAINS VERY DRY AND
WHILE LOW LEVEL FLOW AND BECOME SE IN MANY AREAS THERE IS ONLY A
SHORT WINDOW FOR ANY TYPE OF MOISTURE RECOVERY...SO EXPECT ONLY
LIGHT AMOUNTS OF PRECIPITATION. EXPECT SOME LIGHT RAIN TO
ACCOMPANY THE SYSTEM LATE THIS EVENING THROUGH DAYBREAK SUNDAY.
MEASUREABLE RAIN CHANCES WILL VARY FROM AROUND 20 PCT I-12
CORRIDOR AND MS COAST TO NEAR 40PCT COASTAL SE LA. FOLLOWING THIS
SHORT WAVE PASSAGE...HIGH PRESSURE REBUILDS INTO AREA WITH A
PERIOD OF COOL AND DRY WEATHER EXPECTED INTO TUESDAY AM.
TUESDAY...ANOTHER SURFACE LOW DEVELOPS IN RESPONSE TO ANOTHER
SHORT WAVE TROUGH IN THE MID AND UPPER LEVEL FLOW. AS HAS BEEN THE
CASE DURING THE PAST 4 TO 6 WEEKS...MODELS TAKE THE SURFACE LOW
ACROSS SE LA COASTAL AREAS ON WEDNESDAY. AMPLE MOISTURE RETURN
NOTED ON MODEL SOUNDING TUESDAY NIGHT INTO WED WITH PRECIP WATER JUMPING
TO 1.3 INCHES ACROSS SE LA BY MID DAY WED. COMBINED AFFECTS OF LARGE
SCALE UPPER FORCING...BOUNDARY FOCUS AT LOW LEVELS WITH SURFACE
LOW AND FRONT..AND AMPLE MOISTURE...HEAVY RAINFALL CERTAINLY A
POSSIBILITY. PROGRESSIVE NATURE OF SYSTEM WILL TEMPER LONG
DURATION RAIN TOTALS. CONTINUING TO MENTION HEAVY RAIN POTENTIAL
IN HAZARDOUS WEATHER OUTLOOK.
AFTER MID WEEK SYSTEM CLEARS AREA...HAVE SOMEWHAT A LULL IN
WEATHER UNTIL MID LEVEL TROUGH DEEPENS OVER CENTRAL AND EASTERN
CONUS IN THE FRIDAY AND SATURDAY TIME FRAME...ALLOWING STRONGER
HIGH PRESSURE TO SURGE SWD TO GULF COAST ACCOMPANIED BY COLDER
TEMPERATURES.
AVIATION...
VFR CONDITIONS ARE EXPECTED THROUGH 00Z MONDAY AT ALL FOUR TAF
SITES. WEST TO SOUTHWEST FLOW ABOVE 3KFT WILL BRING MOISTURE AND
CEILINGS...MAINLY ABOVE 8KFT THROUGH 00Z SUNDAY...THIS
EVENING...THEN CEILING MAY LOWER TO 5FT AT MSY...BTR AND GPT BETWEEN
06Z SUN AND 13Z SUN. IN ADDITION...SCATTERED SHRA/-RA AFTER 06Z
SUN...TONIGHT THROUGH SUNDAY MORNING WILL BE MOSTLY LIGHT WITH ONLY
BRIEF PERIODS OF BELOW VFR CONDITIONS EXPECTED. NORTHERLY WINDS WILL
DRY OUT THE ATM SUNDAY AND DEFINITE VFR CONDITIONS EXPECTED AFTER
16Z SUNDAY THROUGH 00Z MONDAY. 18
MARINE...
A TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE WESTERN GULF OF
MEXICO TONIGHT AND MOVE EAST ACROSS THE NORTH CENTRAL GULF OF MEXICO
ON SUNDAY. WINDS ARE EXPECTED TO INCREASE UP TO 15 KNOTS AND GUSTY
AT TIMES LATE TONIGHT THROUGH SUNDAY MORNING...MAINLY OVER THE
WESTERN AND CENTRAL WATERS BELOW 29N LATITUDE. A LULL IN WINDS IS
EXPECTED SUNDAY AFTERNOON OR EVENING...THEN COLD HIGH PRESSURE WILL
REBUILD OVER OKLAHOMA LATE SUNDAY NIGHT INTO MONDAY MORNING WHICH
WILL INCREASE NORTHERLY WINDS TO EXERCISE CAUTION OR POSSIBLY SMALL
CRAFT ADVISORY CRITERIA. THERE WILL BE A SLIGHT BREAK FROM THE
STRONGER WINDS AGAIN MONDAY AFTERNOON THROUGH TUESDAY EVENING...THEN
THE NEXT STRONGER LOW PRESSURE SYSTEM IS LIKELY TO BRING STRONG
WINDS AND LOTS OF RAIN AND THUNDERSTORMS TO THE MARINE AREA LATE
TUESDAY NIGHT INTO WEDNESDAY. THE STRONG SOUTHEAST WINDS OF 25 TO
POSSIBLY 30 KNOTS SUSTAINED MAY OVERCOME THE SHORT DURATION AND
POSSIBLY CAUSE COASTAL FLOODING LATE TUESDAY NIGHT AND WEDNESDAY.
THERE ARE SOME UNCERTAINLY ON WIND SPEEDS BETWEEN HIGHER GFS WIND
SPEED VALUES AND LOWER ECMWF WIND SPEED VALUES AT THIS TIME...ERGO
HAVE NOT INTRODUCED TIDES ABOVE NORMAL IN PRODUCTS YET. 18
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 35 55 30 50 / 10 10 10 0
BTR 37 57 33 51 / 20 10 10 0
MSY 43 58 38 52 / 30 20 10 0
GPT 39 58 34 53 / 20 20 10 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&
$$
