Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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917
FXUS64 KLIX 121307
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
807 AM CDT FRI SEP 12 2014

...SOUNDING DISCUSSION...

THE WARM LAYER IN THE MID-LEVELS THE LAST FEW MORNINGS IS MOSTLY
GONE WITH ONLY A VERY SLIGHT TEMPERATURE INVERSION AROUND 470MB.
THE ATMOSPHERIC COLUMN/S PRECIPITABLE WATER VALUE REMAINS ABOVE
NORMAL FOR THIS TIME OF YEAR AT JUST OVER 2 INCHES. WITH THE LOSS
OF THE WARM NOSE...THE FRONT MOVING IN FROM THE NORTH AND MLCAPES
AROUND 2100 J/KG...WE SHOULD SEE MORE COVERAGE OF THUNDERSTORMS
THAN YESTERDAY. STORM SPEED WILL BE AROUND 5 KNOTS. WINDS ARE
GENERALLY FROM THE SOUTHEAST IN THE LOW AND MID-LEVELS AND THEN
PRIMARILY FROM THE EAST IN THE UPPER LEVELS WITH A MAXIMUM WIND
SPEED OF 34 KNOTS AROUND 41400 FEET ABOVE THE GROUND.

12Z BALLOON INFO: A ROUTINE FLIGHT WITH NO ISSUES THIS MORNING.
THE BALLOON BURST 32 MILES DOWNRANGE SOUTHEAST OF HAMMOND AT A
HEIGHT OF 21 MILES ABOVE THE GROUND.

ANSORGE

&&

.PREV DISCUSSION... /ISSUED 350 AM CDT FRI SEP 12 2014/

SHORT TERM...COLD FRONT CONTINUES TO SLOWLY WORK SOUTH THROUGH NRN
LA AND INTO CNTRL MS. THE FRONT IS ALREADY STRUGGLING MIGHTILY TO
MAKE IT MUCH FARTHER BUT SHOULD APPROACH OUR DOORSTEP THIS AFTN.
LGHT SHRA OVER THE COASTAL WATERS ARE TRYING TO PUSH INLAND BUT
OVERALL THE NIGHT HAS BEEN QUIET. TEMPS ARE A FEW DEGREES COOLER
TONIGHT COMPARED TO LAST NIGHT AT THIS TIME.

TODAY LOOK FOR FAR GREATER COVERAGE OF SHRA AND TSRA. THE COMBINED
EFFECTS OF THE APPROACHING FRONT...WEAKENING RIDGE...WEAK
SEABREEZE...HIGHLY MOISTENED AIRMASS (PWS ABV 2")...AND WEAK
DIVERGENCE ALOFT SHOULD PROVIDE LITTLE RESISTANCE TO NUM STORMS THIS
AFTN AND INTO THE EVNG HRS. NOT ANTICIPATING MUCH IN THE WAY OF
STRONG/SVR BUT HEAVY RAIN COULD BE AN ISSUE.

HEADING INTO THE WEEKEND THERE ARE A FEW THINGS TO KEEP AN EYE ON.
FIRST THE EVENTUAL PLACEMENT OF WHATEVER IS LEFT OF THIS FRONT. IT
LOOKS LIKE IT WILL STALL PRETTY MUCH OVER THE CWA...MAYBE RIGHT
ALONG THE COAST. SECOND FEATURE IS THIS WEAK TROPICAL WAVE MOVING
ACROSS THE FL PENINSULA. THIS WAVE WILL CONTINUE TO MOVE TO THE WEST
OVER THE WEEKEND AND AS IT INTERACTS WITH THE OLD FRONT COULD LEAD TO
SOME VERY HEAVY RAINFALL. GLOBAL MDLS ARE NOT HITTING THIS FEATURE
VERY HARD KEEPING IT AN OPEN WAVE BUT SOME OF THE HIGHER RES MDLS
ARE A LITTLE MORE BULLISH WITH IT. HOWEVER THESE ONLY INDICATE A
TROPICAL DEPRESSION TO WEAK TROPICAL STORM AT BEST AND THE MAJORITY
OF THEM ARE WELL TO THE SOUTH. AT THIS TIME NHC IS ONLY INDICATING 40%
THAT IT COULD DEVELOP INTO A TROPICAL CYCLONE OVER THE NEXT 5 DAYS.
THE ENVIRONMENT IS NOT OVERLY FAVORABLE FOR DEVELOPMENT AND EVEN IF
SOMETHING DOES AND MOVES INTO THE NRN GULF THE MAIN RISK IS GOING TO
BE HEAVY RAIN BUT VERY HEAVY RAIN COULD BE A SIGNIFICANT ISSUE. IF
THIS OCCURS IT WOULD BE MORE LIKE SUN AND INTO MON. AGAIN THE MDLS
THAT DO DEVELOP A CYCLONE KEEP IT WELL TO THE SOUTH AS THE RIDGE
REMAINS RATHER STRONG OVER THE GULF COAST STATES.

LONG TERM...MEDIUM RANGE MDLS STILL IN FAIRLY GOOD AGREEMENT
THROUGH MUCH OF NEXT WEEK. IT LOOKS LIKE WE WILL MOVE BACK INTO THE
ERN CONUS L/W TROUGH AND THIS WILL SEND ANOTHER SLIGHTLY STRONGER
COLD FRONT INTO THE REGION IN THE MIDDLE OF THE WEEK. RAIN CHANCES
WILL BE AT OR ABV NORMAL THROUGH MUCH OF THE WEEK AS MOISTURE WILL
CONTINUE TO BE ABUNDANT. TEMPS WILL START TO COOL JUST A TAD MAINLY
THX TO INCREASED CLOUD COVERAGE AND RAIN. /CAB/

MARINE...SURFACE RIDGE THAT HAD BEEN EXTENDING INTO THE NORTHERN
GULF FROM THE WESTERN ATLANTIC WILL BE BREAKING DOWN TODAY AS A COLD
FRONT WILL BE APPROACHING THE AREA FROM THE NORTH. ONSHORE FLOW
CURRENTLY IN PLACE WILL PERSIST TODAY BUT WEAKEN AND BECOME EASTERLY
AS THE BOUNDARY APPROACHES OVERNIGHT. NORTHEASTERLY FLOW WILL
DEVELOP SATURDAY AS THE WEAKENING BOUNDARY SLIDES SOUTH INTO THE
GULF. MEANWHILE...A TROPICAL WAVE THAT IS CURRENTLY JUST EAST OF
FLORIDA WILL BE TRACKING WESTWARD ACROSS THE CENTRAL GULF. SATURDAY
NIGHT THROUGH SUNDAY NIGHT THIS FEATURE SHOULD BE STEADILY MOVING
WEST TOWARDS THE WESTERN GULF OF MEXICO. ITS LOWER PRESSURE WILL
TIGHTEN THE PRESSURE GRADIENT OVER OUR COASTAL WATERS WHICH WILL
BRING EASTERLY WINDS TO NEAR 15 KNOTS IN THE OFFSHORE WATERS.
LIGHTER WIND REGIME WILL RETURN NEXT WEEK AS HIGH PRESSURE BUILDS
BACK IN FROM THE NORTHEAST.

MEFFER

AVIATION...VFR CONDITIONS WILL PREVAIL AT THE TERMINALS FOR THE
BALANCE OF THE TAF FORECAST PERIOD. CURRENT RADAR SHOWS ISOLATED
SHOWERS ALREADY PASSING IN THE VICINITY OF KHUM...KMSY AND KNEW.
MOST OF THE SHOWER AND THUNDERSTORM ACTIVITY WILL HOLD OFF UNTIL THE
PERIOD FROM MID MORNING TO LATE AFTERNOON FOR THE REST OF THE TAF
SITES. PATCHY FOG MAY RESTRICT VISIBILITIES INTO THE MVFR CATEGORY
PRIOR TO AND AROUND SUNRISE AT KMCB. A COLD FRONT WILL BE
APPROACHING THE NORTHERN SECTIONS OF THE FORECAST AREA LATE
TONIGHT.

MEFFER

DECISION SUPPORT...
DSS CODE...GREEN.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT..

DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN  = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE   = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
         VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
         WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
         TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED    = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
         AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
         SIGNIFICANCE.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  90  71  87  68 /  60  50  40  20
BTR  91  72  88  69 /  60  50  40  30
ASD  91  74  89  72 /  50  40  50  30
MSY  91  77  90  77 /  50  40  50  30
GPT  89  76  89  73 /  50  40  40  30
PQL  90  73  90  71 /  40  30  40  40

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

$$







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