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

Home | Current Version | Previous Version | Graphics & Text | 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
468
FXUS64 KLIX 201003
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
503 AM CDT MON APR 20 2015

.SHORT TERM...

SHORTWAVE TROUGH OVER THE LOWER MISSISSIPPI VALLEY EARLY THIS
MORNING WILL MOVE EAST OF THE REGION TODAY. THE ASSOCIATED COLD
FRONT WAS FINALLY PUSHING TOWARDS THE WESTERN PORTIONS OF THE
FORECAST AREA...AND THIS FRONT WILL SWEEP THROUGH THE FORECAST
AREA THIS MORNING. THE ENERGY TO OUR NORTH THAT BROUGHT SOME
THUNDERSTORMS TO SOUTHWEST MISSISSIPPI LATE LAST EVENING HAS
RAPIDLY MOVED WELL NORTHEAST OF THE REGION...HOWEVER THE NOSE OF
250 MB JET WITH 140-150 KNOTS WINDS HAS PROVIDED STRONG LIFT AND
MOISTURE ADVECTION OVER THE COASTAL WATERS WHERE NUMEROUS STRONG
THUNDERSTORMS ERUPTED SINCE MIDNIGHT. A FEW SHOWERS COULD STILL
TRY TO DEVELOP OVER COASTAL LAND AREAS EARLY THIS
MORNING...OTHERWISE CURRENT SHOWERS AND THUNDERSTORMS WILL BE
ENDING FROM THE WEST AND NORTHWEST BY MIDDAY.

SLIGHTLY COOLER AND MUCH DRIER AIR WILL BE FELT OVER THE REGION
TODAY AS SURFACE HIGH PRESSURE BUILDS IN...AND THIS WILL LEAD TO
MUCH COOLER TEMPERATURES TONIGHT WITH LOWS FORECAST TO DROP INTO
THE 50S IN MOST LOCATIONS...EXCEPT NEAR 60 AROUND THE SOUTHSHORE
OF LAKE PONTCHARTRAIN AND THE WARMER COASTAL AREAS...AND POSSIBLY
SOME UPPER 40S OVER THE COLDER NORTHERN LOCATIONS. THE CENTER OF
HIGH PRESSURE WILL MOVE EAST OF THE REGION TUESDAY AFTERNOON
ALLOWING SOUTHEAST WINDS TO RETURN...HOWEVER HUMIDITY LEVELS ARE
EXPECTED TO REMAIN IN THE COMFORTABLE RANGE.

WEDNESDAY INTO WEDNESDAY NIGHT...THE LARGE MID/UPPER LEVEL TROUGH
OVER EASTERN CANADA...THE GREAT LAKES AND THE NORTHEAST U.S. WILL
CONTINUE TO GRADUALLY FLATTEN OUT/WEAKEN AS A SHORTWAVE RIDGE
BUILDS SLIGHTLY OVER THE SOUTHERN PLAINS. A FRONTAL BOUNDARY
SHOULD BECOME ORIENTATED FROM WEST NORTHWEST TO EAST SOUTHEAST
ACROSS THE RED RIVER VALLEY/ARKLATEX REGION TO CENTRAL
MISSISSIPPI. SOUTH OF THIS BOUNDARY...DEWPOINTS WILL RISE BACK
INTO THE 60S AND THE HIGH TEMPERATURES WARM BACK INTO THE LOWER TO
MID 80S. MID LEVEL LAPSE RATES ARE FORECAST TO BE STEEP AND ALLOW
THE ATMOSPHERE TO BECOME MODERATELY TO HIGHLY UNSTABLE. THE MODELS
ARE NOT IN THE BEST AGREEMENT WITH MINOR DISTURBANCES MOVING
THROUGH IN THE WEST NORTHWEST FLOW ALOFT...HOWEVER THE PATTERN
LOOKS FAVORABLE FOR AT LEAST SMALL SCALE MCS/AREAS OF
THUNDERSTORMS TO DEVELOP IN THE ARKLATEX TO CENTRAL GULF COAST
REGION. THE STORM PREDICTION CENTER HAS PLACED OUR ENTIRE AREA IN
A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE DAY THREE CONVECTIVE
OUTLOOK. THE CONFIDENCE IN HOW ORGANIZED AND NUMEROUS
THUNDERSTORMS WILL BE IS LOW AT THIS POINT.

.LONG TERM...

A POTENT SHORTWAVE TROUGH IS EXPECTED TO MOVE FROM THE PACIFIC
INTO THE SOUTHWEST U.S. AND BAJA MEXICO REGION THURSDAY AND
THURSDAY NIGHT AS THE DOWNSTREAM SHORTWAVE RIDGE MOVES EAST INTO
THE LOWER MISSISSIPPI VALLEY. ONCE AGAIN...CONFIDENCE IS LOW AS TO
HOW MUCH COVERAGE OF SHOWERS AND THUNDERSTORMS WILL EITHER BE
ONGOING FROM ANY LEFTOVER NOCTURNAL MCS...OR REDEVELOPING IN THE
AFTERNOON FROM DAYTIME HEATING AND INSTABILITY. HAVE MAINTAINED
CHANCE CATEGORY POPS FOR NOW.

A SHORTWAVE TROUGH SHOULD MOVE OUT OF THE SOUTHWEST STATES AND
NORTHERN MEXICO INTO THE SOUTHERN PLAINS ON FRIDAY WITH A SURFACE
LOW PRESSURE SYSTEM MOVING OUT OF THE LEE OF THE ROCKIES INTO
KANSAS OR OKLAHOMA. THE MODELS STILL HAVE THEIR DIFFERENCES WITH
THE ECMWF WETTER OVER THE FORECAST AREA. THE HIGH TEMPERATURES ARE
EXPECTED TO BE WELL INTO THE 80S WITH DEWPOINTS IN THE LOWER
70S...SO THERE SHOULD BE AMPLE MOISTURE AND INSTABILITY FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP. HAVE GONE WITH LOWER END
CHANCES OF RAIN OVER THE SOUTHERN AREAS WITH HIGHER CHANCES OVER
THE NORTH.

A MODEL BLEND SUGGESTS THE PLAINS SYSTEM WILL SHEAR OUT AND
DISSIPATE AS IT MOVES EAST ACROSS MISSISSIPPI VALLEY ON SATURDAY.
BECAUSE OF THIS...RAIN CHANCES SHOULD LOWER AGAIN OVER THE
WEEKEND IF THE MODEL TRENDS ARE CORRECT...AND HUMIDITY LEVELS
COULD ALSO LOWER BY SUNDAY ALTHOUGH TEMPERATURES WILL LIKELY
REMAIN WARM. 22/TD

&&

.AVIATION...

CURRENTLY SEEING VFR CONDITIONS ACROSS THE AREA. THERE MAY BE A
BRIEF PERIOD THIS MORNING OF MVFR TO IFR CEILINGS AND VISIBILITIES
AROUND SUNRISE THIS MORNING...BUT NOT EVEN SEEING INDICATIONS OF
THAT RIGHT NOW. AFTER MID-MORNING...EXPECT VFR CONDITIONS TO PREVAIL
THROUGH THE REMAINDER OF THE FORECAST PERIOD. 35

&&

.MARINE...

THUNDERSTORMS WILL PRODUCE BRIEF WIND GUSTS TO 40 KNOTS EARLY THIS
MORNING...PROMPTING SPECIAL MARINE WARNINGS. A COLD FRONT WILL MOVE
INTO THE COASTAL WATERS TODAY GRADUALLY SHIFTING WINDS FROM
SOUTHERLY...TO WESTERLY AND FINALLY NORTHEAST AS THE FRONT PASSES.
WINDS WILL GENERALLY BE 10 TO 15 KNOTS...BUT COULD GET INTO EXERCISE
CAUTION RANGE FOR A BRIEF TIME EARLY TUESDAY...WITH WAVE HEIGHTS
GETTING UP TO AROUND 3-4 FEET OVER THE OPEN WATERS. WILL NOT RAISE
ANY FLAGS FOR NOW...BUT DAY SHIFT MAY NEED TO CONSIDER THIS
AFTERNOON. WINDS WILL QUICKLY RETURN TO AN ONSHORE TRAJECTORY LATE
TUESDAY AS HIGH PRESSURE PASSES TO THE EAST OF THE AREA. WINDS WILL
REMAIN AROUND 10 KNOTS DURING THE MIDDLE OF THE WEEK...BUT COULD
RAMP UP TO ABOUT 15 KNOTS AT THE END OF THE WEEK AS ANOTHER FRONT
APPROACHES. WAVE HEIGHTS AT THAT TIME COULD GET UP TO 4-5 FEET OVER
THE OPEN WATERS. 35

&&

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

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  75  49  77  55 /  10   0   0   0
BTR  79  53  78  59 /  10   0   0  10
ASD  80  52  77  59 /  10   0   0  10
MSY  78  60  76  64 /  10   0   0  10
GPT  81  54  76  62 /  20   0   0  10
PQL  79  53  77  56 /  30   0   0  10

&&

.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.