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

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 32 33 34 35 36 37 38

839
FXUS64 KLIX 270502
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1202 AM CDT SAT SEP 27 2014

.UPDATE...
UPDATED FORECAST TO SHOW CURRENT TRENDS IN FORECAST...OTHERWISE
THE FORECAST IS ON TRACK WITH NO MAJOR CHANGES. AVIATION WISE
EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE FORECAST PERIOD. HAVE
ADDED VCSH FOR LATE IN THE FORECAST PERIOD FOR MANY TAF SITES
ESPECIALLY ALONG THE MISSISSIPPI GULF COAST AND SOUTH LOUISIANA. 13/MH

&&

.PREV DISCUSSION... /ISSUED 358 PM CDT FRI SEP 26 2014/

SHORT TERM...

NO SIGNIFICANT CHANGES IN THINKING FROM THE PREVIOUS FORECAST
PACKAGE CONCERNING THE TIMING OF THE NEXT SYSTEM THIS WEEKEND. IT
STILL LOOKS LIKE A A MID-LEVEL RIDGE AXIS WILL PULL AWAY FROM THE
AREA DURING THE DAY TOMORROW. THIS WILL ALLOW AN INVERTED MID-
LEVEL TROUGH CURRENTLY OVER FLORIDA TO PULL WESTWARD INTO THE
CENTRAL AND EASTERN GULF OF MEXICO TOMORROW.  AS THIS TROUGH
AXIS MOVES CLOSER TO THE GULF COAST RAIN CHANCES WILL INCREASE
THROUGH THE DAY. BY TOMORROW AFTERNOON...SCATTERED CONVECTION
SHOULD BE FOUND ALONG THE LOUISIANA AND MISSISSIPPI COAST WITH
MORE ISOLATED COVERAGE FURTHER INLAND.

TOMORROW NIGHT INTO SUNDAY A POCKET OF SHORT-WAVE ENERGY IN THE
UPPER LEVELS WILL KICK OUT OF TEXAS AND PULL THROUGH THE AREA.
THIS SYSTEM WILL INTERACT WITH THE BROAD MID-LEVEL TROUGH
EXTENDING ALONG THE GULF COAST AND ALLOW FOR THE DEVELOPMENT OF
SURFACE BASED LOW PRESSURE SYSTEM OVER THE FORECAST AREA BY SUNDAY
AFTERNOON. WITH DEEP LAYER MOISTURE AND AMPLE FORCING IN
PLACE...EXPECT TO SEE HIGHER POPS DEVELOP LATE SATURDAY NIGHT INTO
EARLY SUNDAY. AT THIS TIME...IT APPEARS THE DEEPEST MOISTURE AND
GREATEST AMOUNT OF LIFT WILL GENERALLY REMAIN ALONG THE LOUISIANA
AND MISSISSIPPI COASTS AND HEAVIER RAINFALL WILL BE POSSIBLE IN
THESE AREAS. FARTHER INLAND...THERE WILL BE LESS MOISTURE IN
PLACE...SO LIGHTER RAINFALL IS EXPECTED.  HAVE PLACED A GRADIENT
OF POPS OVER THE AREA...WITH LIKELY POPS GENERALLY ALONG AND EAST
OF A HOUMA TO NEW ORLEANS TO PICAYUNE LINE AND CHANCE POPS TO THE
WEST OF THIS LINE.

CONDITIONS SHOULD BEGIN TO SLOWLY IMPROVE SUNDAY EVENING AS THE
SURFACE LOW DEEPENS AND BEGINS TO MOVE EAST OF THE REGION. DRIER
AIR WILL WRAP AROUND THE SYSTEM...AND BEGIN TO SPREAD INTO WESTERN
ZONES BY SUNDAY EVENING. THIS WILL LEAD TO LOWER POPS TAKING HOLD
LATE SUNDAY INTO SUNDAY NIGHT WITH ONLY CHANCE POPS IN FAR EASTERN
ZONES AND SLIGHT CHANCE POPS ELSEWHERE.

THERE WILL CONTINUE TO BE A LINGERING TROUGH AXIS OVER THE AREA ON
MONDAY...BUT A SURGE OF DRIER AIR IN THE MID-LEVELS SHOULD PRODUCE
ENOUGH CAPPING ALOFT TO KEEP MOST CONVECTIVE ACTIVITY AT BAY. HAVE
ONLY TOKEN 10 PERCENT POPS IN FOR THE DAY ON MONDAY. RAIN CHANCES
WILL BE HIGHER OFFSHORE WHERE A WEAK BOUNDARY WILL LINGER THROUGH
THE FIRST HALF OF THE WEEK.

LONG TERM...

A SHORT WAVE RIDGE AXIS WILL SPREAD OVER THE AREA ON TUESDAY AND
WEDNESDAY BRINGING DRIER AIR AND INCREASED SUBSIDENCE TO THE
AREA. WITH THIS RIDGE IN PLACE...HAVE VERY LOW POPS IN PLACE
ACROSS THE REGION. IF ANY CONVECTION DEVELOPS...IT WILL TEND TO BE
ALONG THE COAST WHERE INCREASED LOW LEVEL CONVERGENCE ZONES AND LIFT
DEVELOP ALONG THE SEABREEZE FRONT. HOWEVER...WITH A FAIRLY STRONG
MID-LEVEL CAP IN PLACE...CONVECTIVE CHANCES WILL REMAIN LOW EVEN
NEAR THE SEABREEZE.

THE MID-LEVEL RIDGE WILL BREAK DOWN BY THURSDAY AS A FAIRLY STRONG
LONGWAVE TROUGH DIGS INTO THE PLAINS STATES. A BROAD AREA OF
INCREASING POSITIVE VORTICITY ADVECTION IN THE UPPER LEVELS WILL
BRING INCREASING OMEGA TO THE AREA. AT THE SAME TIME...DEEP LAYER
ONSHORE FLOW WILL DEVELOP ALLOWING FOR GREATER MOISTURE ADVECTION
INTO THE REGION. WITH LIFT AND MOISTURE ON THE INCREASE...RAIN
CHANCES WILL RISE FOR THURSDAY AND FRIDAY. HAVE PLACE CHANCE POPS
IN THE FORECAST EACH DAY...WITH THE CONVECTIVE CHANCES HIGHEST
DURING PEAK HEATING HOURS IN THE AFTERNOON. THE LONGWAVE TROUGH
AND ATTENDANT COLD FRONT WILL SWEEP THROUGH THE FORECAST AREA
FRIDAY NIGHT INTO EARLY SATURDAY.

&&


MARINE...

THE PRESSURE GRADIENT REMAINS FAIRLY TIGHT OVER THE NORTHERN GULF
OF MEXICO TODAY AND SHOULD REMAIN SO THROUGH TONIGHT AS A BROAD
AREA OF LOW PRESSURE OVER THE CENTRAL GULF INTERACTS WITH A BROAD
RIDGE OVER THE SOUTHEASTERN CONUS. THE RESULTANT GRADIENT FLOW
WILL REMAIN ELEVATED IN THE EXERCISE CAUTION RANGE THROUGH TONIGHT
FOR THE OFFSHORE WATERS. CONDITIONS SHOULD BEGIN TO EASE TOMORROW
AS THE HIGH WEAKENS...AND THE TROUGH BECOMES MORE CENTERED OVER
THE GULF COAST. A SURFACE LOW WILL DEVELOP OVER THE WATERS ON
SUNDAY AND QUICKLY PULL TO THE EAST. WINDS WILL GENERALLY BE FROM
THE SOUTH AND SOUTHWEST EARLY SUNDAY...BUT WILL SHIFT TO THE
NORTHWEST AND NORTH IN THE WAKE OF THE LOW. A LIGHT AND VARIABLE
WIND FIELD WILL THEN TAKE HOLD EARLY NEXT WEEK AS WEAK BOUNDARY
LINGERS OVER THE NORTHERN GULF. THIS LIGHT AND VARIABLE FLOW WILL
GIVE WAY TO A MORE SUSTAINED ONSHORE FLOW BY WEDNESDAY AS A LOW
BEGINS TO FORM IN THE ARKLATEX AND HIGH PRESSURE DOMINATES THE
CAROLINAS AND GEORGIA.

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  64  85  67  83 /  10  20  40  40
BTR  66  85  68  86 /  10  20  30  30
ASD  64  86  68  84 /  10  40  60  60
MSY  71  84  73  83 /  10  40  50  50
GPT  67  86  72  82 /  10  40  70  70
PQL  64  86  71  83 /  10  40  70  70

&&

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

$$







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