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

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223
FXUS64 KLIX 302124
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
424 PM CDT SAT APR 30 2016

.SYNOPSIS...
LATEST SURFACE ANALYSIS SHOWED A DEEP 1001MB LOW OVER MISSOURI WITH
A COLD FRONT EXTENDING SOUTH SOUTHWEST TO NORTHWEST LOUISIANA TO
CENTRAL TEXAS COAST. A MODERATE SOUTHERLY FLOW WAS PRESENT OVER
SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI. PRECIPITABLE WATER
PLOTS SHOWED MOISTURE AXIS FROM UPPER TEXAS COAST TO WEST
TENNESSEE WITH 1.50 TO 1.8 INCHES THIS MORNING.

UPPER AIR ANALYSIS SHOWED TWO CYCLONIC CIRCULATIONS...FIRST OVER
NEBRASKA AND SECOND OVER WEST ARIZONA...CREATING A WEST FLOW OVER
ARKLATEX REGION...SOUTHERN AND CENTRAL PLAINS. ISOTACH ANALYSIS AT
250MB SHOWED A NEARLY PARALLEL JETS...FIRST SOUTHEAST ARIZONA TO
CENTRAL OKLAHOMA AND THE SECOND TEXAS BIG BEND TO WEST LOUISIANA.
18

&&

CURRENT RADAR COVERAGE WILL DICTATE THE FIRST 12 TO 18 HOURS OF
THE FORECAST. LINE OF STORMS IS EXPECTED TO RACE ACROSS THE
REMAINDER OF THE FORECAST AREA THROUGH THIS EVENING. WITH THE
UPPER LEVEL FLOW WESTERLY...THE PROGRESSION EAST OF STORMS HAS
BEEN FAST. HOWEVER...RAINFALL RATES ARE HEAVY AT TIMES. MOISTURE
AXIS WILL BECOME MORE WEST TO EAST THIS EVENING AND OVERNIGHT.
THIS MAY SLOW THE PROGRESS OF THE RAIN ACROSS THE SOUTH HALF OF
THE FORECASTER AREA. THE MOISTURE AXIS WILL DRIFT BACK NORTH
ACROSS THE NORTH HALF OF THE FORECAST AREA ON SUNDAY. COVERAGE OF
CONVECTION WILL BE WIDESPREAD THIS EVENING....LINGER OVERNIGHT
AND REDEVELOP AFTER MIDNIGHT AS THE MOISTURE AXIS DRIFT BACK
NORTH. THEREFORE...EXTENDING THE FLASH FLOOD WATCH THROUGH SUNDAY
AFTERNOON WITH SECOND ROUND OF STORMS ALONG THE RETREATING
MOISTURE AXIS AFTER MIDNIGHT THROUGH EARLY SUNDAY AFTERNOON.

CAPE VALUES WILL REMAIN BETWEEN 1000 TO 2500 J/KG THROUGH
TUESDAY. THE MAIN JET STREAM WILL REMAIN WELL NORTH OF THE
FORECAST AREA WITH SOUTHERN STREAM OVER SOUTH TEXAS AND WEST
GULF...CREATING A DISTANT COUPLET. WITH WEST FLOW DECREASING...LL
HELICITY VALUES REMAIN BELOW 150M/S WITH BEST VALUES THIS EVENING
ACROSS THE NORTH HALF OF THE AREA. WILL MAINTAIN LIKELY POPS WITH
HEAVY RAINFALL ACROSS NORTH HALF OF FORECAST FOR SUNDAY. THIS AXIS
WILL BECOME SLIGHTLY DIFFUSE AND SAG SOUTH MIDDAY MONDAY THROUGH
TUESDAY AND RAIN CHANCES WILL REMAIN ELEVATED THROUGH TUESDAY. 18

.LONG TERM...

MID RANGE MODELS CONTINUE TO A WAVE IN THE NORTHERN STREAM DIVING
SOUTH ACROSS THE OHIO VALLEY TUESDAY. MOISTURE AXIS WILL SLOWLY
PUSH SOUTH OF THE THE REMAINDER OF THE FORECAST AREA TUESDAY
AFTERNOON. THIS WAVE WILL ASSIST THE PUSH TUESDAY NIGHT INTO EARLY
WEDNESDAY. GFS SHOWS A SECOND WAVE PUSHING THROUGH THE AREA
THURSDAY AND THURSDAY NIGHT BUT RAINFALL EXPECTED. 18

&&

.AVIATION...
A LINE OF STRONG THUNDERSTORMS ARE CURRENTLY MOVING ACROSS THE
FORECAST AREA THIS AFTERNOON. THIS LINE OF STORMS IS CURRENTLY
IMPACTING MANY TERMINALS WITH WINDS UP TO 40 KNOTS...HEAVY RAIN AND
FREQUENT LIGHTNING. THIS IS YIELDING TEMPO IFR TO LIFR CONDITIONS
FOR TERMINALS AS THE HEAVIEST PORTIONS OF THE STORMS MOVE THROUGH.
OUTSIDE OF THE STORMS EXPECT MVFR TO VFR CONDITIONS TO PREVAIL.
KBTR...KHDC AND KHUM SHOULD SEE IMPROVING CONDITIONS THIS EVENING
NOW THROUGH 22Z. KASD...KMSY...KNEW AND KGPT WILL SEE THE WORST OF
THEIR CONDITIONS NOW THROUGH AT LEAST 0Z. CONDITIONS SHOULD IMPROVE
SLOWLY AFTER 0Z AND WINDS MAY BE SLIGHTLY ELEVATED. 13/MH

&&

.MARINE...

WILL CONTINUE EXERCISE CAUTION HEADLINES THROUGH THE EVENING HOURS
SHOULD SEE SOME WEAKENING OF PRESSURE GRADIENT OVERNIGHT FOR
SEVERAL DAYS. FRONT NOT LIKELY TO PUSH THROUGH COASTAL WATERS
UNTIL SOMETIME AROUND THE MIDDLE OF THE WEEK. A STRONGER FRONT
WILL PUSH THROUGH THE COASTAL WATERS LATER IN THE WEEK.

&&

.DECISION SUPPORT...
DSS CODE....BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...MINOR RIVER FLOODING. MONITOR CONVECTIVE TRENDS.

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  68  80  67  78 /  60  70  30  60
BTR  70  82  69  81 /  60  70  30  60
ASD  70  82  70  83 /  60  60  30  50
MSY  72  81  72  83 /  50  50  30  50
GPT  72  82  71  82 /  50  50  30  50
PQL  70  81  69  81 /  40  50  30  50

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...COASTAL FLOOD ADVISORY UNTIL 6 PM CDT THIS EVENING FOR LAZ040-
     050-058-060>064-066>070-072.

     FLASH FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR LAZ034>037-039-
     040-046>050-056>058-071-072.

GM...NONE.
MS...COASTAL FLOOD ADVISORY UNTIL 6 PM CDT THIS EVENING FOR MSZ080.

     FLASH FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR MSZ068>071.

GM...NONE.
&&

$$



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