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

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FXUS64 KLIX 050114
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
814 PM CDT FRI SEP 4 2015

...SOUNDING DISCUSSION...
THE SOUNDING THIS EVENING HAS 500 MB HEIGHT JUST A LITTLE HIGHER
THAN 24 HRS AGO AT 592 DM... REPRESENTATIVE OF THE RIDGE OVER THE
AREA. MOISTURE IS STILL ABOVE AVERAGE WITH PW AT 2.04 INCHES. 1200
J/KG OF MIXED LAYER CAPE IS PRESENT. WINDS ARE LIGHT FROM THE SW
NEAR THE SFC THEN MORE VARIABLE ALOFT. BY 500 MB FLOW BECOMES FROM
THE NNW WITH PEAK WIND OF 45 KTS AT 170 MB.

KRAUTMANN

&&

.PREV DISCUSSION... /ISSUED 433 PM CDT FRI SEP 4 2015/

SHORT TERM...ISLTD TO SCT CONVECTION DEVELOPED LATE THIS MORNING
MAINLY SOUTH OF I 10 AND THEN CONVECTION BECAME A LITTLE MORE SCT
AND PUSHED NORTH. IT WAS ANOTHER HOT DAY OUTSIDE OF CONVECTION WITH
TEMPS IN THE LOWER TO EVEN MID 90S. LOOK FOR SHRA AND TSRA TO
QUICKLY DISSIPATE AFTER SUNSET.

COVERAGE OF CONVECTION SHOULD BEGIN TO SLOWLY INCREASE
TOMORROW AND MORE SO ON SUN AS CONDITIONS IMPROVE. THE RIDGE THAT
MOVED OVER THE REGION TODAY LEADING TO MOSTLY ISLTD TO WIDELY SCT
SHRA AND TSRA WILL NUDGE WEST AS A MID LVL LOW WILL SLIDE UNDER THE
NERN CONUS RIDGE AND INTO THE SERN CONUS/GULF COAST STATES BY SUN.
DECREASING SUBSIDENCE WITH ABUNDANT MOISTURE AND A WEAK SEABREEZE
SHOULD LEAD TO SCT CONVECTION. AS FOR TIMING DUE TO THE NRLY FLOW
TOMORROW CONVECTION WILL LIKELY START MID TO LATE AFTN AND PERSIST
INTO THE EARLY EVNG HRS. ON SUN THE RIDGE WILL BE FAIRLY WELL
DISPLACED TO THE WEST WITH MUCH LOWER HGHTS OVER THE REGION AS THE
LOW SITS OVER THE NERN GULF COAST. THE LOWERED HGHTS ALONG WITH A
CONVECTIVE TEMP IN THE MID TO UPPER 80S...DIVERGENCE ALOFT...AND THE
H85 THETA E RIDGE DRAPED ACROSS THE REGION SHOULD LEAD TO CONVECTION
DEVELOPING A LITTLE SOONER THAN SAT.

HEADING INTO LABOR DAY THERE IS A FAIR AMOUNT OF UNCERTAINTY WITH
RESPECT TO COVERAGE. THE LOW WILL MOVE FURTHER WEST LEADING TO
SLIGHTLY LOWER HGHTS BUT WE BE IN A SLIGHTLY UNFAVORABLE POSITION
FOR CONVECTION AS WE MOVE UNDER THE CORE OF THE UPPER JET. WILL HOLD
ONTO SCT CONVECTION BUT POPS WILL BE ABOUT 10-20% LOWER ACROSS
THE BOARD THAN SUN. /CAB/

LONG TERM...NO CHANGES MADE TO THE EXTENDED FCST. LOW OVER THE GULF
COAST OPEN UP AND MERGE WITH THE NRN STREAM WITH A L/W TROUGH
DEVELOPING OVER THE CNTRL CONUS LATE IN THE WORK WEEK. PREVIOUS
LONG TERM PORTIONS OF THE DISCUSSION APPENDED. /CAB/

PREV LONG TERM DISCUSSION...THE UPPER LEVEL TROUGH OVER THE
SOUTHEASTERN CONUS WILL BEGIN TO RETROGRADE BACK TO THE WEST BY
TUESDAY AND WEDNESDAY OF NEXT WEEK. AS THIS TROUGH AXIS SLOWLY
MOVES TO THE WEST...INCREASING UPPER LEVEL FORCING AND DEEPER
ATMOSPHERIC MOISTURE PROFILES WILL OVERSPREAD THE FORECAST AREA.
TUESDAY WILL BE A TRANSITIONAL DAY...AND STILL EXPECT TO SEE ONLY
ISOLATED TO SCATTERED CONVECTION OVER INLAND ZONES. HOWEVER...THE
IMMEDIATE COAST AND OFFSHORE WATERS COULD SEE GREATER CONVECTIVE
COVERAGE AS THE DAY GOES ON DUE TO THE INCREASE IN FORCING ALOFT
AND HIGHER THETA E VALUES ADVECTING IN FROM THE EAST. THE TREND OF
INCREASING CONVECTIVE COVERAGE WILL CONTINUE ON WEDNESDAY...AND
HAVE POPS INCREASE FROM 20 TO 30 PERCENT TO CLOSER TO 40 PERCENT
FOR MOST OF THE FORECAST AREA BY WEDNESDAY AFTERNOON.

FARTHER TO THE NORTH ON WEDNESDAY...A FAIRLY VIGOROUS SHORT WAVE
TROUGH WILL DRIVE A FRONTAL BOUNDARY INTO THE ARKLATEX BY
WEDNESDAY NIGHT. A SECONDARY UPPER LEVEL IMPULSE WILL DIVE INTO
THE MIDWEST ON THURSDAY...FORCING THIS COLD FRONT FURTHER TO THE
SOUTH...AND EXPECT TO SEE THIS BOUNDARY SWEEP INTO THE FORECAST
AREA FOR FRIDAY AND SATURDAY. AS THIS OCCURS...THE INITIAL TROUGH
THAT HAD RETROGRADED BACK OVER THE AREA WILL BE SWEPT BACK TO THE
EAST TOWARD FLORIDA AND THE SOUTHEASTERN CONUS. EVEN WITH THIS
TROUGH DEPARTING...A BROAD REGION OF INCREASING POSITIVE
VORTICITY ADVECTION IN ADVANCE OF THE DEEPENING NORTHERN STREAM
SYSTEM AND THE CONTINUED WARM AND MOIST AIRMASS OVER THE AREA
WILL ALLOW FOR HIGH END CHANCE POPS TO DEVELOP OVER THE AREA BOTH
THURSDAY AND FRIDAY. TEMPERATURES WILL COOL DUE TO THE INCREASED
CLOUD COVER AND RAINFALL...AND HAVE HIGHS ONLY CLIMBING INTO THE
UPPER 80S OVER MOST OF THE REGION. /32/

AVIATION...

SCATTERED TS COVERAGE WILL DISSIPATE AROUND 22Z. WILL MAINTAIN TS IN
TEMPO GROUPS THROUGH 22Z. TONIGHT SHOULD SEE MAINLY VFR CONDITIONS
..WITH POTENTIAL FOR MVFR VISIBILITIES AT KMCB AND KHUM. /18/

MARINE...

A SMALL UPPER LEVEL ANTI-CYCLONIC CIRCULATION WAS LOCATED OVER
SOUTHWEST LOUISIANA. PRESSURE GRADIENT WAS RELAXED ACROSS THE GULF.
DEEP TROPICAL MOISTURE WILL REMAIN OVER THE GULF. THIS WEAKNESS WILL
KEEP HIGHER CHANCES OF TS ACTIVITY IN THE COASTAL WATERS THROUGH THE
FORECAST. WINDS AND SEAS WILL BE HIGHER NEAR SCATTERED TS. WIND
GUSTS COULD BE AS HIGH AS 30 KNOTS WITH THE STRONGEST ACTIVITY.
OUTSIDE TS ACTIVITY...CONDITIONS WILL REMAIN RATHER BENIGN WITH A
WEAK PRESSURE GRADIENT. NOCTURNAL ACTIVITY WILL BE THE MOST ABUNDANT
WHILE THERE WILL BE A GENERAL DECREASE IN AVTIVITY DURING THE LATE
MORNING THROUGH LATE AFTERNOON HOURS. /18/


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

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 RISK SVR AND/OR DIRECT
         TROPICAL THREATS; EVENTS OF NATIONAL SIGNIFICANCE

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  73  94  72  93 /  20  30  30  50
BTR  73  93  73  93 /  30  40  30  50
ASD  75  92  74  89 /  20  20  30  50
MSY  76  91  75  89 /  20  30  30  50
GPT  74  91  75  88 /  20  20  30  50
PQL  74  91  74  88 /  20  20  30  50

&&

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

$$


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