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

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS64 KLIX 260940
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
340 AM CST FRI DEC 26 2014

.SYNOPSIS...

SURFACE HIGH PRESSURE HAS MOVED EASTWARD TO THE ATLANTIC COAST.
ONSHORE FLOW HAS BEGUN WITH DEW POINTS OVER THE GULF AND ALONG THE
LOUISIANA COAST ABOUT 15 DEGREES HIGHER THAN 24 HOURS AGO. OVER
MOST OF THE LAND AREA...DEW POINTS RANGE FROM MID 30S TO MID 40S.
MAINLY HIGH CLOUDS ACROSS THE AREA AT THIS TIME...BUT DO SEE SOME
STRATOCU ON SATELLITE/SURFACE OBS JUST WEST OF THE AREA. WIDE
RANGE IN TEMPERATURES AT 3 AM WITH UPPER 30S AT MCCOMB AND
SLIDELL...TO THE 50S SOUTH OF LAKE PONTCHARTRAIN.

&&

.SHORT TERM...

SHORT TERM CONCERN CONTINUES TO BE POTENTIAL FOR HEAVY RAIN AND
SEVERE WEATHER.

ONSHORE FLOW WILL CONTINUE TO PUMP MOISTURE INTO THE AREA TODAY.
TEMPERATURES WILL WARM AND CLOUDS WILL INCREASE THROUGHOUT TODAY
AND TONIGHT. PRECIPITABLE WATER VALUES AROUND ONE QUARTER INCH
EARLY THIS MORNING WILL RISE TO ABOUT 1.30 BY THIS EVENING...AND
TO ABOUT TWO INCHES BY MIDDAY SATURDAY. THIS IS ROUGHLY 2.5
STANDARD DEVIATIONS ABOVE CLIMATOLOGY. BROAD AREA OF LIFT WILL
ALLOW RAIN CHANCES TO INCREASE BEGINNING THIS AFTERNOON. ANY
PRECIPITATION DURING THE DAY TODAY SHOULD BE RATHER LIGHT AND WILL
ONLY BE CARRYING CHANCE POPS TODAY. RAIN CHANCES RAMP UP AFTER
MIDNIGHT TONIGHT WITH RAIN LIKELY ACROSS THE ENTIRE AREA BY
SUNRISE SATURDAY AS WARM FRONT MOVES NORTHWARD. ANY THUNDER DURING
LATE TONIGHT AND SATURDAY MORNING WILL BE ELEVATED AND ISOLATED.
SOUTH OF THE WARM FRONT THERE IS AT LEAST SOME POTENTIAL FOR
SURFACE BASED CONVECTION TO DEVELOP ON SATURDAY. LAPSE RATES ARE
MARGINAL FOR SEVERE WEATHER...BUT THERE IS A BRIEF PERIOD WHERE
HELICITY WILL BE STRONG ENOUGH FOR ROTATING STORMS DURING THE
AFTERNOON. THUS...THE MARGINAL THREAT FOR SEVERE WEATHER IN SPC
DAY TWO OUTLOOK.

WITH THE DEEP LAYER MOISTURE IN PLACE...UNIDIRECTIONAL
HODOGRAPHS...AND BROAD SCALE LIFT IN PLACE...HEAVY RAIN THREAT
WILL BE IN PLAY...ESPECIALLY DURING THE AFTERNOON AND EVENING
HOURS ON SATURDAY. WIDESPREAD 1-3 INCH RAINFALL TOTALS ARE
LIKELY SATURDAY THROUGH SATURDAY NIGHT...WITH HIGHER AMOUNTS
WHERE THUNDERSTORMS TRAIN. THERE MAY BE A BRIEF PERIOD OF
RELATIVELY LITTLE RAIN LATE SATURDAY NIGHT AND SUNDAY MORNING
BEFORE MAIN TROF PUSHES THROUGH THE AREA LATE SUNDAY...ADDING
POSSIBLY ANOTHER INCH OR SO OF RAIN. SIMILAR MARGINAL THREAT OF
SEVERE WEATHER ON SUNDAY AS OUTLOOKED BY SPC.

WITH ANTECEDENT WET CONDITIONS FROM TUESDAYS RAIN...AND EXPECTED
RAINFALL TOTALS OF 1-3 INCHES AND LOCALLY HIGHER AMOUNTS...WILL
LEAVE FLOOD WATCH IN PLACE AS CURRENTLY CONFIGURED. DEBATED
PUSHING BACK THE START 6 HOURS TO SATURDAY MORNING...BUT WILL NOT
MAKE CHANGES AT THIS TIME.

USED A BLENDED APPROACH TO TEMPERATURE FORECAST...WHICH IS
GENERALLY A LITTLE LOWER THAN MAV GUIDANCE. SUNDAY HIGH
TEMPERATURES ARE LIKELY TO BE DURING THE MORNING IN MCCOMB AND
BATON ROUGE AREAS. 35

&&

.LONG TERM...

MEDIUM RANGE MODEL SOLUTIONS ARE MORE IN LINE EARLY NEXT WEEK WITH
THE GFS COMING CLOSER TO THE COOLER AND DRIER SCENARIO PAINTED BY
THE ECMWF FOR MONDAY THROUGH WEDNESDAY. ANOTHER TROF MOVES OUT OF
THE SOUTHWEST TOWARD THE END OF THE WEEK NEXT WEEK WITH RAIN
CHANCES INCREASING THURSDAY OR FRIDAY. STILL SOME TIMING
DIFFERENCES WITH THIS SYSTEM...SO WILL PROBABLY NEED TO INCREASE
RAIN CHANCES AT THE BACK END OF THE FORECAST IN LATER EDITIONS.

AFTER THE SUNDAY/MONDAY FRONTAL PASSAGE...EXPECT TEMPERATURES TO
BE SOMEWHAT BELOW NORMAL THROUGH THURSDAY...BUT NOT EXTREMELY SO.
TEMPERATURES WILL WARM ABOVE NORMAL BY NEXT FRIDAY AHEAD OF THE
NEXT MAIN SYSTEM. 35

&&

.AVIATION...

MVFR CONDITIONS DUE TO A COMBINATION OF PATCHY LIGHT FOG AND/OR CIGS
025-030 SHOULD WILL IMPACT SOME AIRPORTS WEST OF THE MISSISSIPPI
RIVER IN SOUTH LA EARLY THIS MORNING...THEN THE MVFR CIGS ALONG WITH
ISOLATED MOSTLY LIGHT SHRA ARE EXPECTED TO ADVANCE NORTH AND
NORTHEAST ACROSS THE REMAINING TAF AIRPORTS DURING THE LATE MORNING
OR EARLY AFTERNOON. LIGHT SHRA/RA SHOULD INCREASE TO SCATTERED
COVERAGE OVER MOST AIRPORTS BY MID TO LATE AFTERNOON...HOWEVER LOWER
VSBYS SHOULD NOT BE A PROBLEM. NUMEROUS SHOWERS AND ISOLATED TO
SCATTERED TSRA ARE EXPECTED TO DEVELOP DURING THE EVENING TONIGHT
PRODUCING AT LEAST TEMPO REDUCED VSBYS...AND LOWER CIGS ARE LIKELY
TO DROP TO IFR CATEGORY AFTER ABOUT 06Z SATURDAY AND CONTINUE
THROUGH AT LEAST THE MORNING HOURS ON SATURDAY. 22/TD

&&

.MARINE...

HIGH PRESSURE WILL REMAIN ANCHORED ALONG THE MID TO SOUTH ATLANTIC
COAST AND SOUTHEAST STATES THROUGH TONIGHT BEFORE MOVING EAST OVER
THE WEST ATLANTIC SATURDAY INTO SUNDAY. THE PRESSURE GRADIENT WILL
TIGHTEN TODAY THROUGH SATURDAY MORNING AS THE NEXT COLD FRONT
SYSTEM APPROACHES THE WESTERN GULF COAST AND LOWER MISSISSIPPI
VALLEY FROM THE WEST AND A WARM FRONT MOVES NORTH OUT OF THE GULF OF
MEXICO. EAST/SOUTHEAST WINDS ARE EXPECTED TO RISE INTO THE 15 TO 20
KNOTS RANGE LATE THIS AFTERNOON OR EARLY TONIGHT...THEN THE WINDS
ARE EXPECTED TO VEER AROUND TO SOUTH AND WEAKEN LATE SATURDAY
AFTERNOON THROUGH SUNDAY MORNING AS A COLD FRONT MOVES INTO THE
CENTRAL GULF COAST REGION.

CONFIDENCE IN THE TIMING OF THIS FRONT IS BETTER TODAY COMPARED TO
YESTERDAY DUE TO BETTER MODEL AGREEMENT. THE COLD FRONT IS EXPECTED
TO MOVE SLOWLY THROUGH THE TIDAL LAKES AND WESTERN COASTAL WATERS
SUNDAY AFTERNOON AND THE REMAINING COASTAL WATERS BY AROUND MIDNIGHT
SUNDAY NIGHT. NORTHERLY WINDS BEHIND THE FRONT ARE INITIALLY ONLY
EXPECTED TO BE 10 TO 15 KNOTS SUNDAY NIGHT AND ONLY AROUND 10 KNOTS
OR LESS MONDAY AND MONDAY NIGH. STRONGER NORTHEAST WINDS ARE
EXPECTED TO RISE TO NEAR 15 KNOTS ON TUESDAY AND NEAR 20 KNOTS LATE
TUESDAY NIGHT INTO WEDNESDAY MORNING AS COLDER AIR AND HIGH PRESSURE
MOVE IN FROM THE NORTH. 22/TD

&&

.DECISION SUPPORT...

DSS CODE...BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
             ASSESSING FLOOD WATCH POTENTIAL FOR THE WEEKEND

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  62  55  69  60 /  30  60  90  90
BTR  65  59  73  61 /  40  70  90  90
ASD  65  59  70  62 /  40  70  90  90
MSY  67  61  72  63 /  40  70  90  90
GPT  64  58  69  62 /  30  60  90  90
PQL  65  55  69  60 /  30  60  90  90

&&

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

GM...NONE.
&&

$$







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