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

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497
FXUS64 KLIX 171345
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
845 AM CDT SUN AUG 17 2014

...SOUNDING DISCUSSION...

A MOIST AND UNSTABLE ATMOSPHERE SAMPLED THIS MORNING. THE
PRECIPITABLE WATER VALUE WAS MEASURED AT 2.08 INCHES AND THE LOW
LEVELS ARE QUITE MOIST WHILE THERE IS A BIT OF DRYING IN THE MID
LEVELS BETWEEN 700 AND 500MB. MLCAPE VALUES ARE ALMOST 3000 J/KG
AND THE LIFTED INDEX IS -9...SO PLENTY OF ENERGY FOR THE
ATMOSPHERE TO USE FOR THUNDERSTORMS TODAY. WHILE THERE IS THE
USUAL SURFACE TEMPERATURE INVERSION...THAT WILL NOT INHIBIT
CONVECTION AS IT WILL EASILY MIX OUT WITH A BIT OF DAYTIME
HEATING. MOST OF THE TEMPERATURE PROFILE FOLLOWS THE
PSEUDO-ADIABATIC LAPSE RATE. WINDS ARE LIGHT THROUGHOUT THE
ATMOSPHERE WITH A PEAK WIND OF 20 KNOTS AT A HEIGHT OF 7000 FEET
ABOVE THE GROUND. WINDS WERE FROM THE SOUTHWEST THROUGH 14000
FEET...THEN LIGHT AND VARIABLE ABOVE THIS LEVEL. STORM MOTION WILL
BE 279 AT 9 KNOTS.

12Z BALLOON INFO: A SUCCESSFUL FLIGHT THIS MORNING. THE BALLOON
REACHED A HEIGHT OF 21 MILES ABOVE THE SURFACE BEFORE BURSTING
OVER FAR NORTHWESTERN LAKE PONTCHARTRAIN.

ANSORGE

&&

.PREV DISCUSSION... /ISSUED 425 AM CDT SUN AUG 17 2014/

SYNOPSIS...

LATEST SURFACE ANALYSIS SHOWED A 1018MB HIGH OVER THE CENTRAL GULF
AND 1009MB LOW OVER SOUTHERN ILLINOIS. AS A RESULT...SOUTHERLY
FLOW HIGH TO LOW AND LIGHT SOUTH FLOW HAS ADVECT IN DEWPOINT
READINGS ABV 70F OVER THE FORECAST AREA AND LOWER/MID MISSISSIPPI
VALLEY. PRECIPITABLE WATER VALUE PLOTS SHOWED A SWATH OF 1.8 TO 2
INCHES ACROSS THE SOUTH HALF OF LOUISIANA AND COASTAL MISSISSIPPI
AND ANOTHER SWATH OF 1.8 INCHES FROM NORTH CENTRAL TEXAS TO MID
MISSISSIPPI VALLEY. UPPER LEVEL AIR ANALYSIS SHOWED A TROUGH
AXIS FROM THE MID MISSISSIPPI VALLEY TO CENTRAL TEXAS AND HIGH
OVER THE FOUR CORNERS AND OVER FLORIDA PENINSULA. 18

SHORT TERM...

PRECIPITABLE WATER VALUES WILL REMAIN ELEVATED AROUND 1.8 INCHES
TODAY THROUGH TUESDAY. MODEL SOUNDING FROM GFS SHOW CAPE VALUES
BETWEEN 3 AND 4KJ/KG IN THE MORNING. SOUTHWEST FLOW WILL ADVECT IN
A WARM LAYER BETWEEN 600 AND 500MB. HOWEVER...SURFACE TEMPS AROUND
90F LATE MORNING AND AFTERNOON WILL CREATE MODERATE LAPSE RATES
AND WARMING LAYER SHOULD NOT SERVE AS AN INHIBITOR OR CAP. LIFT
SHOULD REMAIN MODERATE TODAY AND MONDAY. MORNING TEMPS SHOULD
REMAIN IN THE 70S AND SURFACE WITH MOISTURE IN PLAY EACH MORNING. 18

LONG TERM...

UPPER LEVEL HIGH/RIDGE ACROSS THE THE WESTERN ATLANTIC AND FLORIDA WILL
SLOWLY EXPAND WEST MONDAY THROUGH WEDNESDAY. ACCORDING GFS AND
EURO...5OOMB HEIGHTS INCREASE 5930 TO 5940M OVER THE NORTH CENTRAL
GULF LATE WEDNESDAY. BOTH SHIFT THE HIGH NORTHWEST ACROSS THE
FORECAST AREA THURSDAY AND FRIDAY. 5H TEMPS REMAIN AROUND -7C ON
TUESDAY AND CONVECTION WILL BE ISOLATED TO SCATTERED IN NATURE.
HOWEVER...TEMPS AT 5H ASSOCIATED WITH THE HIGH WILL INCREASE TO
-6C AND THIS SLIGHT INCREASE AND GENERAL DESCENT WILL SUPPRESS
SOME DEVELOPMENT OF CONVECTION WEDNESDAY THROUGH SATURDAY. DEEP MOISTURE
WILL REMAIN AND INTENSE SURFACE HEATING WILL YIELD ISOLATED
CONVECTION...VERY ISOLATED ON FRIDAY WITH UPPER LEVEL HIGH ON TOP
OF THE FORECAST AREA. A FEW AREAS MAY SEE AFTERNOON HIGHS IN THE
MID TO UPPER 90S WEDNESDAY THROUGH FRIDAY AND LOWS IN THE MID TO
UPPER 70S. HEAT INDEX VALUES ARE EXPECTED MAY EXCEED 105 IN SOME
SPOTS EACH AFTERNOON. THERE IS A GREAT DEAL UNCERTAINTY WITH
SURFACE DEWPOINTS AND RAIN CHANCES PROVIDING RELIEF FOR THE LATTER
PART OF NEXT WEEK...HEAT ADVISORY MAYBE NEEDED FOR PART OF THE
FORECAST AREA...WILL MONITOR. 18

AVIATION...

VFR CONDITIONS WILL BE IN CONTROL AT ALL OF THE TERMINALS THROUGH
THE FORECAST PERIOD.  A WEAK LOW LEVEL INVERSION MAY BRING A PERIOD
OF MVFR VSBY RESTRICTIONS TO KMCB AROUND 12Z THIS MORNING.  ANY FOG
SHOULD CLEAR BY 13Z.  THERE WILL ALSO BE ANOTHER CHANCE OF
CONVECTION DEVELOPING NEAR THE TERMINALS AFTER 15Z. HAVE INCLUDED
VCTS WORDING TO REFLECT THIS RISK. IF CONVECTION DOES IMPACT A
TERMINAL...A PERIOD OF IFR VISIBILITY RESTRICTIONS AND GUSTY WINDS
OF UP TO 30 KNOTS WILL BE POSSIBLE. ANY CONVECTIVE IMPACTS WILL TEND
TO LAST FOR AN HOUR OR LESS. 32

MARINE...

A SURFACE HIGH WILL REMAIN CENTERED OVER THE EASTERN GULF AND
FLORIDA THROUGH MIDWEEK.  THIS WILL RESULT IN A CONTINUED SOUTH TO
SOUTHWEST WIND OF AROUND 10 KNOTS.  SEAS WILL GENERALLY RANGE FROM 1
TO 2 FEET.  WINDS WILL TURN MORE VARIABLE LATE IN THE WEEK AS THE
SURFACE HIGH BECOMES MORE CENTERED OVER THE NORTHERN GULF OF
MEXICO.  32

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  92  74  92  75 /  30  20  40  20
BTR  94  75  94  76 /  40  20  40  20
ASD  92  77  92  78 /  40  20  40  20
MSY  92  77  92  78 /  40  20  30  20
GPT  90  78  90  79 /  40  20  40  20
PQL  90  76  90  77 /  40  20  40  20

&&

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

$$







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