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

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473
FXUS64 KLIX 232121
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
421 PM CDT SAT AUG 23 2014

.SHORT TERM...

DEEP LAYER HIGH PRESSURE OVER THE REGION WILL CONTINUE TO SUPPRESS
SHOWERS AND THUNDERSTORMS AND BRING SOME OF THE HOTTEST TEMPERATURES
OF THE SEASON THROUGH SUNDAY. MUCH OF THE MODEL GUIDANCE/MOS FROM
EARLIER FOR TODAY IS LOOKING TO BE TOO HOT DUE TO A BIT HEAVIER
CLOUD COVER AND ISOLATED SHOWERS AND THUNDERSTORMS. THIS TREND COULD
CARRY FORWARD INTO SUNDAY...HOWEVER ANY ISOLATED SHOWERS AND
THUNDERSTORMS WILL ONCE AGAIN BE DEVELOPING IN THE EARLY TO MID
AFTERNOON HOURS...SO THERE WILL BE AMPLE TIME FOR STRONG HEATING.
WITH THAT IN MIND...THE 100 DEGREE HIGHS FORECAST BY THE MAV FOR
KBTR AND KPQL ARE NOT LIKELY...HOWEVER THE MODEL FORECAST
TEMPERATURES AT 850 AND 925 MB ARE SUFFICIENTLY WARM...IF THEY
VERIFY...TO PRODUCE UPPER 90S OVER MOST LOCATIONS IN THE FORECAST
AREA. HAVE CONTINUED THE HEAT ADVISORY AS FOR NOW...THAT SHOULD BE
SUFFICIENT UNLESS LATER FORECASTS EXPECT HEAT INDICES OVER 110 IN
MORE THAN THE TYPICAL HIGH BIAS STATIONS LIKE AUDUBON PARK.

THE HOT AND DRY PATTERN IS EXPECTED TO BREAK FROM EAST TO WEST ON
MONDAY AS A EASTERLY WAVE UNDER THE MID/UPPER RIDGE MOVES ACROSS THE
FORECAST. SOME AREAS TO THE WEST MAY AGAIN HAVE AMPLE TIME TO HEAT
UP TO THE MID 90S WITH HEAT INDICES NEAR 105...HOWEVER EASTERN AND
CENTRAL LOCATIONS SHOULD SEE MUCH LOWER HIGHS DUE TO SCATTERED
SHOWERS AND THUNDERSTORMS DEVELOPING THROUGH THE MORNING AND EARLY
AFTERNOON. PROPAGATION OF THE STORMS INTO HOT AIR AND INITIAL DRY
AIR ALOFT COULD ALLOW SOME OF THE INITIAL THUNDERSTORMS TO PRODUCE
STRONG WIND GUSTS...FREQUENT LIGHTNING...AND HEAVY RAINFALL. MOST OF
THE STORMS SHOULD REMAIN BELOW SEVERE LIMITS.

.LONG TERM...

WILL CONTINUE TO MONITOR WHAT HAS RECENTLY BECOME TROPICAL
DEPRESSION FOUR NEAR THE TURKS AND CACOS ISLANDS. THERE IS QUITE A
BIT OF UNCERTAINTY AND MODEL SPREAD ON HOW FAR WEST THIS SYSTEM WILL
GET BEFORE RECURVING NORTH. REFER TO THE LATEST DISCUSSIONS AND
ADVISORIES FROM THE NATIONAL HURRICANE CENTER FOR DETAILS.

ON TUESDAY...RAIN CHANCES ARE EXPECTED TO REMAIN ELEVATED WEST AND
SOUTH OF NEW ORLEANS...HOWEVER DRIER AIR WILL FOLLOW THE EASTERLY
WAVE EAST AND NORTH OF NEW ORLEANS. HAVE SHOWN A GRADIENT OF POP
ACROSS THE FORECAST AREA TO ACCOUNT FOR THESE TRENDS. THIS TREND IS
EXPECTED TO CONTINUE INTO WEDNESDAY AND THURSDAY WITH HIGHER RAIN
CHANCES...MOSTLY IN THE LOW CHANCE RANGE...TO THE SOUTH WITH MORE
ISOLATED COVERAGE NORTH AND EAST. THE GFS REMAINS MORE PROGRESSIVE
WITH A SHORTWAVE TROUGH MOVING ACROSS THE CENTRAL STATES AND
MISSISSIPPI VALLEY WEDNESDAY THROUGH FRIDAY MORNING. THIS PUSHES A
FRONTAL BOUNDARY PRETTY FAR SOUTH INTO THE GULF COAST STATES. THE
ECMWF HOLDS THE TROUGH AXIS BACK OVER THE PLAINS THROUGH FRIDAY
MORNING BEFORE FINALLY MOVING EAST INTO THE MISSISSIPPI VALLEY LATE
FRIDAY AND FRIDAY NIGHT...AND THE ASSOCIATED COLD FRONT REMAINS WELL
NORTHWEST OF THE GFS POSITION AND IS SLOWER. HAVE GENERALLY FAVORED
THE ECMWF BECAUSE IT APPEARED BETTER INITIALIZED. AM NOT EXPECTING A
GREAT DEAL OF CHANGE GOING INTO FRIDAY AND NEXT WEEKEND...HOWEVER
THE MODELS ARE IN DECENT AGREEMENT SHOWING MORE TYPICAL...HIGHER
END SCATTERED DIURNAL SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
SEABREEZE...LAKE BREEZE...AND CONVECTIVE OUTFLOW BOUNDARIES...AND
NEAR NORMAL TEMPERATURES. 22/TD

&&

.AVIATION...

VFR CONDITIONS ANTICIPATED THROUGH THE FORECAST PERIOD. AREAL
COVERAGE OF ANY ISOLATED CONVECTION IS EXPECTED TO BE TOO SMALL FOR
A GENERAL MENTION IN THE FORECAST. HANDLING WITH AMENDMENTS AS
NECESSARY. CUMULUS FIELD DEVELOPING...WITH BASES NEAR FL040 AT THIS
TIME...WITH DISSIPATION AROUND SUNSET. ANTICIPATE SIMILAR CUMULUS
DEVELOPMENTS DURING THE LATE MORNING TOMORROW. 35

&&

.MARINE...

HIGH PRESSURE REMAINS IN PLACE OVER THE COASTAL WATERS. THIS HIGH
WILL REMAIN IN PLACE THROUGH THE WEEKEND. SEABREEZE/LANDBREEZE CYCLE
WILL DOMINATE. EXPECT OFFSHORE WINDS IN THE MORNING HOURS AND
ONSHORE WINDS DEVELOPING DURING THE AFTERNOON HOURS. WINDS AND SEAS
SHOULD REMAIN FAIRLY BENIGN. WINDS WILL GENERALLY BE 10 KNOTS OR
LESS AND SEAS WILL GENERALLY BE 2 FEET OR LESS. WINDS WILL TAKE ON A
MORE PERSISTENT EASTERLY FLOW BY LATE MONDAY AS THE SURFACE HIGH
BECOMES CENTERED NORTH OF THE REGION. EAST WINDS OF 10 TO 20 KNOTS
AND SEAS OF 3 TO 5 FEET CAN BE EXPECTED LATE MONDAY THROUGH THE
MIDDLE OF NEXT WEEK. 35

&&

.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  73  98  74  93 /  10  20  20  50
BTR  76  99  77  96 /  10  10  10  50
ASD  75  98  76  93 /  10  20  20  50
MSY  79  96  81  93 /  10  20  20  50
GPT  76  98  78  92 /  10  20  20  50
PQL  73  99  75  91 /  10  20  30  50

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...HEAT ADVISORY UNTIL MIDNIGHT MONDAY FOR THE FOLLOWING ZONES:
     LOWER JEFFERSON...LOWER LAFOURCHE...LOWER
     PLAQUEMINES...LOWER ST. BERNARD...LOWER
     TERREBONNE...ORLEANS...ST. CHARLES...ST. JOHN THE
     BAPTIST...UPPER JEFFERSON...UPPER LAFOURCHE...UPPER
     PLAQUEMINES...UPPER ST. BERNARD...AND UPPER TERREBONNE.

     HEAT ADVISORY FROM 10 AM SUNDAY TO MIDNIGHT MONDAY FOR THE
     FOLLOWING ZONES: ASCENSION...ASSUMPTION...EAST BATON
     ROUGE...EAST FELICIANA...IBERVILLE...LIVINGSTON...NORTHERN
     TANGIPAHOA...POINTE COUPEE...SOUTHERN TANGIPAHOA...ST.
     HELENA...ST. JAMES...ST. TAMMANY...WASHINGTON...WEST BATON
     ROUGE...AND WEST FELICIANA.

GM...NONE.
MS...HEAT ADVISORY FROM 10 AM SUNDAY TO MIDNIGHT MONDAY FOR THE
     FOLLOWING ZONES: AMITE...PEARL
     RIVER...PIKE...WALTHALL...AND WILKINSON.

     HEAT ADVISORY UNTIL MIDNIGHT MONDAY FOR THE FOLLOWING ZONES:
     HANCOCK...HARRISON...AND JACKSON.

GM...NONE.
&&

$$





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