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

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
226
FXUS64 KLIX 241740
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1240 PM CDT SUN AUG 24 2014

.UPDATE...

UPDATED FOR 18Z TAFS.

&&

.AVIATION...

MOSTLY VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH MONDAY
MORNING...HOWEVER CONDITIONS MAY LOWER TO MVFR TO BRIEFLY IFR
DURING INCREASING SHRA/TSRA THROUGH THE DAY ON MONDAY. HAVE NOT
CARRIED THESE LOWER CONDITIONS AS PREVAILING DUE TO UNCERTAINTY
IN TIMING. ISOLATED TO LOCALLY SCATTERED TSRA ARE ALSO POSSIBLE
THIS AFTERNOON AND TONIGHT...HOWEVER CONFIDENCE IS TOO LOW FOR
MENTION IN THE TAFS AT THIS TIME. 22/TD

&&

.PREV DISCUSSION... /ISSUED 823 AM CDT SUN AUG 24 2014/

..SOUNDING DISCUSSION...

THE FIRST THING THAT CATCHES YOUR ATTENTION THIS MORNING IS THE
DRY AIR RIGHT ABOVE THE SURFACE. AS THE BOUNDARY LAYER BEGINS TO
MIX TODAY...THIS SHOULD ALLOW FOR SOME DRIER AIR TO MIX DOWN
PERHAPS LOWERING THE DEWPOINTS A BIT. NONETHELESS...STILL HOT AND
MUGGY CONDITIONS IN STORE FOR TODAY. OVERALL...THE PROFILE IS
STILL RATHER MOIST. THERE IS ALSO PLENTY OF INSTABILITY WITH
MLCAPES AT 1650 J/KG AND A LIFTED INDEX OF ALMOST -5. SO THERE IS
PLENTY OF ENERGY FOR THE ATMOSPHERE TO TAP INTO. WINDS FROM THE
SURFACE TO 22000 FEET WERE FROM THE NORTHEAST GENERALLY UNDER 10
KNOTS...THEN FROM 22000 FEET TO AROUND 35000 FEET WINDS WERE FROM
THE EAST UNDER 10 KNOTS...AND THEN FROM THE SOUTHEAST UP INTO THE
LOWER STRATOSPHERE. A PEAK WIND OF 44 KNOTS WAS FOUND IN THIS TOP
LAYER AT 45400 FEET.

12Z BALLOON INFO: A SUCCESSFUL FLIGHT WITH NO ISSUES. THE BALLOON
BURST 35 MILES DOWNRANGE SOUTH OF PONCHATOULA NEAR I-55 AT A
HEIGHT OF 20.7 MILES ABOVE THE GROUND.

ANSORGE

PREV DISCUSSION... /ISSUED 409 AM CDT SUN AUG 24 2014/

SHORT TERM...
A HOT DAY IS IN STORE FOR THE FORECAST AREA AS HIGH PRESSURE IS
OVER THE REGION. THIS HIGH PRESSURE ALONG WITH WARM AIR ALOFT
SHOULD ALLOW FOR DAY TIME HIGHS TO REACH INTO THE UPPER 90S ACROSS
THE ENTIRE FORECAST AREA...COMBINE THAT WITH THE DEWPOINTS
EXPECTED SHOULD YIELD HEAT INDICES IN THE 105 TO 110 DEGREE RANGE.
SOME PLACES COULD SEE SOME HIGHER HEAT INDEX READINGS. WITH THAT
BEING SAID...WILL CONTINUE TO MAINTAIN THE HEAT ADVISORY FOR THE
AREA THROUGH TONIGHT. RAIN CHANCES TODAY WILL BE IN THE 20 PERCENT
RANGE FOR AREAS EAST OF INTERSTATE 55 THIS AFTERNOON. WILL HAVE TO
WATCH AND SEE IF THESE POPS NEED TO BE ADJUSTED UPWARD AS STRONG
DAY TIME HEATING AND A POSSIBLE OUTFLOW BOUNDARY INTERACTION COULD
TRIGGER GREATER COVERAGE OF SHOWERS AND STORMS ESPECIALLY ACROSS
CENTRAL AND EASTERN MISSISSIPPI.

THE AFOREMENTIONED OUTFLOW BOUNDARY IS APPARENT ON THE IR SATELLITE
IMAGERY THIS MORNING COMING OFF OF DECAYING THUNDERSTORMS ACROSS
NORTHERN ALABAMA. THIS BOUNDARY IS CHARGING SOUTHWEST THIS MORNING
AND IT WILL BE INTERESTING TO SEE IF THIS COMES INTO PLAY THIS
AFTERNOON. IT IS UNLIKELY TO PLAY A ROLE THIS FAR SOUTH BUT IT
WILL BE INTERESTING TO WATCH. HOWEVER..AS FOR TONIGHT MODELS DO
INDICATE SOME SORT OF BACK DOOR BOUNDARY MOVING INTO THE AREA
TONIGHT. THIS IS ALSO BEING INDICATED ON SOME OF THE SHORT RANGE
MESOSCALE MODELS. FOR THIS REASON HAVE INCREASED POPS TONIGHT INTO
THE 30 PERCENT RANGE OVERNIGHT BEFORE A GREATER CHANCE OF RAIN FOR
MONDAY AS THIS FEATURE GETS SOME HEATING TO WORK WITH ON MONDAY.
THIS BACK DOOR ENERGY SHOULD BE INTO THE AREA MONDAY AS
PRECIPITABLE WATER VALUES ARE EXPECTED TO BE IN THE 2.25 INCH
RANGE DURING THE DAY. HAVE MAINTAINED THE 50 PERCENT POPS FOR
MONDAY AS THUNDERSTORMS COULD PRODUCE STRONG WIND GUSTS...FREQUENT
LIGHTNING...AND HEAVY RAINFALL. MOST OF THE STORMS SHOULD REMAIN
BELOW SEVERE LIMITS. 13/MH

LONG TERM...
THE BACK DOOR BOUNDARY/WAVE SHOULD BREAK THE HEAT WAVE OVER THE
AREA. RAIN CHANCES WILL STILL REMAIN ELEVATED TUESDAY AND INTO
MIDWEEK. THE GREATEST CHANCE OF RAIN THESE DAYS WILL BE IN AN AREA
WEST OF INTERSTATE 55 AND SOUTH OF INTERSTATE 12. HIGH TEMPS
SHOULD ONLY BE IN THE LOW 90S. THE NEXT ORGANIZED CHANCE OF RAIN
LOOKS TO BE ON THE TABLE IN THE FORM OF A COLD FRONT IN THE
MODELS. THERE STILL REMAINS SOME DIFFERENCES IN TIMING AND
STRENGTH OF THIS FRONT THE GFS STILL REMAINS THE MOST PROGRESSIVE
WITH BRINGING THE FRONT INTO PLAY LATE THURSDAY NIGHT INTO FRIDAY.
AT THE SAME TIME THE ECMWF SLOWS THE TROUGH AND KEEPS THE BOUNDARY
WELL WEST OF THE FORECAST AREA AND NOT EVEN PUSHING THE FRONT OUT
OF THE PLAINS UNTIL NEXT SUNDAY. WILL MAINTAIN PREVIOUS FORECAST
FOR THE LONG RANGE PERIOD. 13/MH

AVIATION...
VFR CONDITIONS ARE EXPECTED THROUGH AT LEAST 25/00Z WITH SOME
UNCERTAINTY THEREAFTER. MODELS ARE SUGGESTING A BACK-DOOR FRONTAL
FEATURE THAT MAY ACTIVATE CONVECTION FROM VERY WARM DAYTIME
TEMPERATURES THIS EVENING. THE GREATER IMPACTS WOULD BE FOR
KPQL/KGPT/KASD AND KNEW. AT THIS TIME WILL INDICATE PROB30 GROUP FOR
THOSE LOCATIONS MAINLY AFTER 03Z WITH DEGRADATION TO IFR VSBY/CIGS
IN BRIEF HEAVY RAINFALL. THOUGH NOT EXACTLY ZERO CHANCE...OTHER
LOCATIONS WOULD BE LESS THAN PROB30 AT THIS TIME...BUT UPDATES MAY
BE WARRANTED LATER THIS EVENING. 24/RR

MARINE...
1014 MB HIGH CENTERED OFF THE LOUISIANA COAST WILL MAINTAIN LIGHT
WINDS AND LOW SEAS TODAY. AN UPPER LEVEL DISTURBANCE DEVELOPING IN
THE APPALACHIANS LATER TODAY IS EXPECTED TO MOVE AROUND THE FRINGE OF
UPPER HIGH PRESSURE TO BRING A THREAT OF STRONG THUNDERSTORMS LATE
THIS EVENING THAT MAY MOVE OFF THE COAST OVERNIGHT. THIS WILL LIKELY
BRING INCLEMENT CONDITIONS IN THE COASTAL WATERS AND TIDAL LAKES.
SURFACE HIGH PRESSURE THEN BUILDS OVER THE SOUTHEAST U.S. TO BRING A
TIGHTENING OF THE PRESSURE GRADIENT FOR ENHANCED EASTERLY FLOW OVER
THE NORTHEAST GULF TUESDAY. THIS GRADIENT SHOULD BE A SHORT-TERM
ISSUE AND WEAKEN BY WEDNESDAY FOR LESSER WINDS AND LOWER SEAS FOR
THE REMAINDER OF THE MARINE FORECAST PERIOD. 24/RR

DECISION SUPPORT...
DSS CODE...YELLOW.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...HEAT ADVISORY...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  98  74  91  71 /  20  30  50  40
BTR  99  76  93  74 /  20  20  50  40
ASD  98  76  90  73 /  20  30  60  50
MSY  96  81  91  77 /  20  30  60  50
GPT  98  78  90  75 /  20  30  60  40
PQL  99  77  90  71 /  20  30  50  40

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...HEAT ADVISORY UNTIL MIDNIGHT MONDAY FOR THE FOLLOWING ZONES:
     ASCENSION...ASSUMPTION...EAST BATON ROUGE...EAST
     FELICIANA...IBERVILLE...LIVINGSTON...LOWER
     JEFFERSON...LOWER LAFOURCHE...LOWER PLAQUEMINES...LOWER ST.
     BERNARD...LOWER TERREBONNE...NORTHERN
     TANGIPAHOA...ORLEANS...POINTE COUPEE...SOUTHERN
     TANGIPAHOA...ST. CHARLES...ST. HELENA...ST. JAMES...ST.
     JOHN THE BAPTIST...ST. TAMMANY...UPPER JEFFERSON...UPPER
     LAFOURCHE...UPPER PLAQUEMINES...UPPER ST. BERNARD...UPPER
     TERREBONNE...WASHINGTON...WEST BATON ROUGE...AND WEST
     FELICIANA.

GM...NONE.
MS...HEAT ADVISORY UNTIL MIDNIGHT MONDAY FOR THE FOLLOWING ZONES:
     AMITE...HANCOCK...HARRISON...JACKSON...PEARL
     RIVER...PIKE...WALTHALL...AND WILKINSON.

GM...NONE.
&&

$$







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.