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

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000
FXUS64 KLIX 280126
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
726 PM CST SAT DEC 27 2014

.SOUNDING DISCUSSION...
THERE WERE NO PROBLEMS WITH THE UPPER AIR RELEASE THIS EVENING.
THE 00Z SOUNDING DEPICTED A VERY MOIST PROFILE THAT WAS NEARLY
SATURATED UP TO 500 MB WITH THE EXCEPTION OF A SMALL DRY LAYER
CENTERED NEAR 700 MB. THE PRECIPITABLE WATER VALUE WAS AN
IMPRESSIVE 2.03 INCHES. THE WINDS WERE NEARLY UNIDIRECTIONAL
THROUGHOUT THE COLUMN FROM THE SOUTHWEST. THERE WAS IN INVERSION
NOTED JUST ABOVE THE SURFACE. 11

&&

.PREV DISCUSSION... /ISSUED 300 PM CST SAT DEC 27 2014/

SHORT TERM...
RAINS ASSOCIATED WITH WARM FRONTAL ZONE HAS LIFTED TO THE NORTH OF THE
FORECAST AREA WITH MORE UNIDIRECTIONAL SOUTHWEST FLOW BECOMING
INCREASINGLY DEEPER OVER TIME THIS AFTERNOON AND EVENING. MOISTURE
FETCH EXTENDS ACROSS CENTRAL MEXICO INTO THE TROPICAL PACIFIC WELL
IN ADVANCE OF UPPER SYSTEM CURRENTLY MOVING OVER SONORA STATE OF
NORTHERN MEXICO. LARGE SCALE OMEGA DRIVEN BY JET DYNAMICS
DIVERGENCE COUPLED WITH SURFACE CONVERGENT FLOW FOR A HIGHLY
EFFICIENT RAINFALL PROCESS OVER THE AREA. WILL MAINTAIN THE FLOOD
WATCH FOR THE ENTIRE AREA AS IS BUT WILL ACCOUNT FOR WHAT APPEARS
TO BE GENERAL 1-2 INCHES OF RAINFALL THAT HAS FALLEN IN SEVERAL
LOCATIONS THUS FAR. THE UPDATE WILL MENTION ADDITIONAL 2-4 INCHES
WITH HIGHER AMOUNTS TO 6 INCHES POSSIBLE...SO THE MATH STILL
REMAINS THE SAME FOR THE EVENT THROUGH SUNDAY AFTERNOON.

CATEGORICAL RAIN CHANCES WILL BE MAINTAINED THROUGH SUNDAY MORNING
BEFORE GRADUAL DECREASE IN RAIN CHANCES THROUGH THE AFTERNOON AS A
PERIOD OF LIGHTER OVER-RUNNING PRECIPITATION MAY LINGER UNTIL THE
UPPER SUPPORT FINALLY MOVES THROUGH THE AREA AS A SHEARED REMNANT
IMPULSE LATE SUNDAY. TEMPERATURES SHOULD REMAIN ON THE WARM SIDE
UNTIL FRONTAL PASSAGE...THEN LEVEL OFF DURING THE AFTERNOON WITH
SOME NON-DIURNAL TRENDS FARTHER NORTH AND WEST WHERE FRONTAL
INFLUENCES WILL HAVE LONGER DWELL TIMES.

LONG TERM...
RATHER STRONG CANADIAN HIGH BUILDS INTO THE NATION AND WILL
PROVIDE A FEW DAYS OF DRY BUT COOL CONDITIONS MONDAY THROUGH
WEDNESDAY. MODELS ARE INDICATING A MECHANICAL LOW DEVELOPMENT OVER
THE WESTERN GULF OF MEXICO THAT BECOMES BAROCLINIC WITH WARM
FRONTOGENESIS PROCESS TO BRING ANOTHER ROUND OF RAINFALL FOR
NEW YEAR`S DAY INTO FRIDAY. A VIGOROUS SOUTHERN BRANCH DISTURBANCE
LIFTS NORTHEAST ACROSS THE CENTRAL PLAINS STATES THAT EVENTUALLY
TAPS INTO SOME ARCTIC INFLUENCED AIR POISED OVER LOWER CANADA AND
UPPER TIER OF STATES. NOT SURE HOW FAR SOUTH THIS AIR WILL
PENETRATE GIVEN MODELS SHOWING MORE OF A SHUNT AT THIS TIME...BUT
IT IS CONCEIVABLE SOME COLDER THAN GUIDANCE AIR CAN REACH THE GULF
STATES NEXT WEEKEND. 24/RR

AVIATION...

MARINE...
STRONG CONVERGENT ONSHORE FLOW HAS MANAGED TO KEEP WINDS AT LEAST
IN MODERATE LEVELS THROUGH EARLY THIS AFTERNOON. LATEST
OBSERVATIONS ARE BELOW ADVISORY LEVELS SO WILL CANCEL SMALL CRAFT
ADVISORY WITH THIS PACKAGE. A BRIEF INCREASE IN NORTHWESTERLY
WINDS EXPECTED POST-FRONTAL AS THE HIGH BUILDS SUNDAY NIGHT THEN
RELAX TO LIGHTER NORTH FLOW MONDAY. GRADIENT BEGINS TO TIGHTEN
TUESDAY AND MAY PROMPT SMALL CRAFT ADVISORY ONCE AGAIN AS WARM
FRONTAL ZONE DEVELOPS OVER THE CENTRAL GULF. 24/RR

DECISION SUPPORT...
DSS CODE...BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
             MONITORING RAINFALL AND FLOOD THREAT

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  59  58  45  55 /  90  80  80  10
BTR  60  60  46  58 / 100  80  60  10
ASD  63  71  49  61 /  90  50  60  10
MSY  65  71  52  60 /  90  60  50  10
GPT  64  70  51  61 /  90  50  60  10
PQL  61  73  50  65 /  90  50  60  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FLOOD WATCH UNTIL 6 PM SUNDAY 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...FLOOD WATCH UNTIL 6 PM SUNDAY FOR THE FOLLOWING ZONES:
     AMITE...HANCOCK...HARRISON...JACKSON...PEARL
     RIVER...PIKE...WALTHALL...AND WILKINSON.

GM...NONE.
&&

$$






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