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

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801
FXUS64 KLIX 161734
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1234 PM CDT SAT AUG 16 2014

.AVIATION...

SATELLITE IMAGERY SHOWS A WELL DEVELOPED CUMULUS FIELD ACROSS THE
AREA. SCATTERED CONVECTION HAS DEVELOPED...ESPECIALLY ACROSS
SOUTHERN PORTIONS INCLUDING KHUM AND THE NEW ORLEANS TERMINALS.
HAVE INCLUDED VCTS AT ALL TERMINALS FOR THE REMAINDER OF THE
AFTERNOON INTO EARLY EVENING. CEILINGS SHOULD GENERALLY REMAIN
VFR...BUT ISOLATED MVFR TO IFR VISIBILITIES IN TSRA WILL OCCUR.
ONCE HEATING IS LOST...CONVECTION SHOULD DISSIPATE EARLY THIS
EVENING. MOISTURE LEVELS SUNDAY WILL BE SIMILAR TO TODAY OR
POSSIBLY A LITTLE MORE MOIST...AND EXPECT A RECURRENCE OF SHOWER
AND THUNDERSTORM DEVELOPMENT SUNDAY MORNING INTO THE AFTERNOON
HOURS. 35

&&

.PREV DISCUSSION... /ISSUED 1127 AM CDT SAT AUG 16 2014/

UPDATE...
TYPICAL DIURNAL CONVECTION NOT ENDING ALONG THE COASTAL WATERS DUE
TO SOME CYCLONIC FLOW ASSOCIATED WITH AN UPPER LOW OVER THE
NORTHERN GULF. WV CHANNEL SHOWS THIS TWIST WHICH WILL CONTINUE TO
SUPPORT SHOWERS AND THUNDERSTORMS MAINLY ALONG THE COAST. SOME OF
THESE WILL MAKE THEIR WAY INLAND AS SEEN ON RADAR OVER THE COURSE
OF THE MORNING. SHOWERS HAVE REACHED AS FAR NORTH AS BATON ROUGE
BEFORE INTERACTING WITH RETREATING DRY AIR. AS A RESULT POPS ARE
BUMPED UP TO 40 PERCENT COAST 30 PERCENT INLAND... WITH A FEW
AREAS LEFT AROUND 20 PERCENT WHERE THE DRIER AIR SHOULD HOLD UNTIL
TONIGHT AND TOMORROW WITH POPS INCREASE OVER THE AREA. ALSO
INCREASED THE CLOUD COVERAGE GRIDS TO REFLECT INCREASE IN TSTMS
OVER THE AREA. TEMPERATURES ARE ON TRACK TO REACH THE LOW 90S IN
MOST AREAS BUT LOWER ALONG THE COAST WHERE SOME AREAS WILL BE RAIN
COOLED.

PREV DISCUSSION... /ISSUED 805 AM CDT SAT AUG 16 2014/

.SOUNDING DISCUSSION...

MOISTURE HAS BEGUN TO RETURN TO SOUTHEAST LOUISIANA AND SOUTHWEST
MISSISSIPPI AS THE SURFACE TO 700MB LAYER IS CONSIDERABLY MORE
MOIST THAN YESTERDAY/S OBSERVED SOUNDINGS. ABOVE 700MB PLENTY OF
DRY AIR EXISTS AND TEMPERATURES ARE 3 TO 4 DEGREES HIGHER THAN
YESTERDAY AT THIS TIME FROM ABOUT 850MB TO 750MB. PRECIPITABLE WATER
/PW/ VALUES HAVE RESPONDED AND WAS MEASURED AT 1.67 INCHES THIS
MORNING. THIS VALUE THOUGH IS STILL BELOW NORMAL FOR AUGUST.

WITH THE MOISTURE RETURN...WE ARE ALSO SEEING AN INCREASE IN
INSTABILITY WITH MLCAPES ANALYZED AROUND 2400 J/KG. THE LIFTED
INDEX IS -6.4 AND THE 500MB TEMPERATURE IS -7C. MEAN STORM MOTION
TODAY WILL BE FROM 271 AT 6 KTS. WE SHOULD SEE MORE THUNDERSTORMS
THAN WE HAVE THE PAST FEW DAYS ACROSS THE AREA...BUT NOT EXPECTING
ANYTHING SEVERE. AS FOR THE WINDS...FROM THE SURFACE TO 700MB THEY
WERE FROM THE SOUTHWEST...THEN FROM 700 TO 450MB LIGHT AND
VARIABLE AND ABOVE 450MB GENERALLY FROM THE NORTHEAST.

12Z BALLOON INFO: NO ISSUES WITH THE FLIGHT. THE BALLOON BURST
BETWEEN LAKE MAUREPAS AND LAKE PONTCHARTRAIN AT A HEIGHT OF 20.9
MILES ABOVE THE GROUND.

ANSORGE

PREV DISCUSSION... /ISSUED 422 AM CDT SAT AUG 16 2014/

SYNOPSIS...

LATEST SURFACE ANALYSIS SHOWED AN OLD FRONTAL BOUNDARY FROM THE
FLORIDA PANHANDLE TO LAKE PONTCHARTRAIN TO NORTH CENTRAL TEXAS.
DRY AIR WAS SLOWLY RETREATING NORTH AS DEWPOINT READINGS RANGE
FROM MID 60S ACROSS SOUTHWEST MISSISSIPPI TO THE LOWER TO MID 70S
ALONG THE SOUTHEAST LOUISIANA COAST. PRECIPITABLE WATER VALUE
PLOTS SHOWED THIS CRADLE OF DRY AIR WITH VALUES AROUND 1 INCH OVER
EAST CENTRAL LOUISIANA...SOUTHWEST...COASTAL MISSISSIPPI AND AREAS
NORTHEAST. DEEPER MOISTURE WITH PW VALUES 1.5 TO 1.7 INCHES SOUTH
OF THIS DRY AIR MASS. WHILE THE BOUNDARY CONTINUES TO LOSE SOME
IDENTITY...AIR MASS DIFFERENCES REMAIN INTACT THIS MORNING.

UPPER LEVEL AIR ANALYSIS SHOWED A WEAK TROUGH AXIS FROM SOUTHEAST
LOUISIANA COASTAL WATERS TO WEST CENTRAL GULF. IN
ADDITION...ISOLATED CONVECTION WAS NOTED IN THE SAME AREA OF THE
TROUGH AXIS. UPPER LEVEL HIGH WAS LOCATED OVER SOUTHWEST CONUS AND
SEVERAL DISTURBANCES FROM THE MID MISSISSIPPI VALLEY TO NORTH
PLAINS TO THE NORTHWEST PACIFIC. 18

SHORT TERM...

SURFACE BOUNDARY WILL DISSOLVE TODAY. AT THE SAME TIME...DRY AIR MASS
WILL RETREAT NORTH AND PW VALUES WILL INCREASE UP TO 1.8 INCHES BY
LATE THIS AFTERNOON ACCORDING TO GFS. SURFACE HEATING WITH
MOISTURE WILL CREATE INSTABILITY ACROSS THE FORECAST AREA TODAY.
NAM SHOWED SOME SMALL CYCLONIC CURVATURE WITH THE TROUGH/WEAKNESS
OVER THE GULF AND THIS FEATURE SHIFT NORTHEAST BUT REMAINING EAST
OF LAND FORECAST AREA AND SHOWING SOME DESCENT AIR NORTHWEST OVER
FORECAST AREA TODAY. ALL THESE FEATURES ARE SUBTLE AND MOISTURE IS
THE MAIN PLAYER ARRIVING IN THE AFTERNOON ACROSS FORECAST AREA.
ERGO WILL MAINTAIN SLIGHT RAIN CHANCES ACROSS SOUTHWEST THIS
MORNING AND OVER THE REST OF THE FORECAST AREA THIS AFTERNOON.
MOISTURE WILL BE IN PLAY TONIGHT AND SUNDAY. SUNDAY MORNING TEMPS
SHOULD REMAIN IN THE 70S AND SURFACE WITH MOISTURE IN PLAY WILL
LEAD TO SCATTERED CONVECTION SUNDAY AND MONDAY. 18

LONG TERM...

RIDGE AXIS ACROSS THE WESTERN ATLANTIC AND FLORIDA WILL SLOWLY
EXPAND WEST MONDAY THROUGH WEDNESDAY. ACCORDING TO GFS AND
EURO...5OOMB HEIGHTS INCREASE 5930 TO 5940M OVER THE CENTRAL GULF
WEDNESDAY AND 5960M JUST WEST OF FORECAST AREA BY FRIDAY. 5H TEMPS
REMAIN AROUND -7 TO -8C...SO ISOLATED CONVECTION WILL ACCOMPANY
THE WARM TEMPS. A FEW AREAS MAY SEE AFTERNOON HIGHS IN THE MID TO
UPPER 90S WEDNESDAY THROUGH FRIDAY AND LOWS IN THE MID TO UPPER
70S. HEAT INDEX VALUES ARE EXPECTED MAY APPROACH 105 IN SOME SPOTS
EACH AFTERNOON. AS FOR HEAT CONCERNS...THERE IS A GREAT DEAL OF
UNCERTAINTY WITH SURFACE DEWPOINTS AND RAIN CHANCES PROVIDING
RELIEF FOR THE LATTER PART OF NEXT WEEK...WILL MONITOR. 18

AVIATION...

EXPECT TO SEE VFR CONDITIONS REMAIN IN CONTROL AT ALL OF THE
TERMINALS THROUGH THE FORECAST PERIOD.  THERE WILL BE A CHANCE OF A
THUNDERSTORM DEVELOPING NEAR KHUM...AND HAVE INCLUDED SOME VCTS
WORDING AFTER 16Z.  OVERALL...NO SIGNIFICANT AVIATION IMPACTS ARE
EXPECTED. 32

MARINE...

A BROAD RIDGE OF HIGH PRESSURE WILL BECOME ENTRENCHED OVER THE
EASTERN HALF OF THE GULF OF MEXICO THIS WEEKEND.  THIS BROAD RIDGE
OF HIGH PRESSURE WILL SLOWLY MOVE WEST ACROSS THE GULF OF MEXICO AND
BECOME CENTERED OVER THE COASTAL WATERS BY THE MIDDLE OF NEXT WEEK.
WINDS WILL BE FROM THE SOUTH AND SOUTHWEST THROUGH THE MIDDLE OF
NEXT WEEK.  OVERALL...NO SIGNIFICANT WEATHER IMPACTS ARE EXPECTED
ACROSS THE COASTAL WATERS THROUGH THE MIDDLE OF NEXT WEEK.  WINDS
WILL BE FROM THE SOUTH AND SOUTHWEST AT AROUND 10 KNOTS AND SEAS
WILL BE AROUND 1 TO 2 FEET. 32

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  92  71  92  74 /  20  10  30  20
BTR  93  74  93  76 /  30  20  30  20
ASD  91  74  92  76 /  30  20  30  20
MSY  91  78  91  77 /  30  20  30  20
GPT  91  74  91  76 /  30  20  40  20
PQL  91  74  91  75 /  20  20  40  20

&&

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

$$







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