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

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358
FXUS64 KLIX 170152
AFDLIX

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

.SOUNDING DISCUSSION...
NO ISSUES WITH LAUNCH THOUGH THERE WAS A DEVELOPING THUNDERSTORM
ABOUT 15 MILES WEST OF STATION AT LAUNCH. THE FLIGHT STAYED OUT
AHEAD AND MOVED NE AWAY FROM STORM AND WAS ABLE TO SAMPLE PRE-
STORM ENVIRONMENT QUITE WELL. PRECIPITABLE WATER RAMPED TO 2.08
INCHES AND LIFTED INDEX DOWN TO -5.3. CAPE WAS A DECENT 3027 J/KG.
TEMPERATURE PROFILE WAS ADIABATIC TO ABOUT 730MB...THEN PSEUDO TO
TROPOPAUSE AT 135.6 MB WITH AT TEMPERATURE OF -69.6C. MOISTURE
PROFILE WAS TYPICAL WET-MICROBURST LOOKING WITH MODERATE
SATURATION SURFACE TO ABOUT 600MB...A RELATIVELY DRIER LAYER TO
ABOUT 455MB...SATURATED AT 400MB...THEN GRADUAL AND STEADY DRYING
INTO THE LOWER STRATOSPHERE AT ANVIL LEVELS. WINDS WERE LIGHT SW-W
5-15KT SURFACE TO 20KFT...E-SE 5-15KT TO 40KFT...S-SW 10-15KT TO
ABOUT 55KFT...THEN SOLID AND FASTER EASTERLY IN THE STRATOSPHERE.
LAYER AVERAGE LOW LEVEL WINDS BELOW 5KFT WAS 234/11KT. PEAK WIND
WAS A MERE 250/16KT AT 14.5KFT IN THE TROPOSPHERE BUT EAST 35-40KT IN
THE MID TO UPPER STRATOSPHERE.

RAN CHAP ON SOUNDING TO SEE HOW GUSTS WOULD VERIFY. USING A 349K
LIFT YIELDED A RICKS INDEX OF 92 WITH A 46 PERCENT CHANCE OF RAIN
AND GUST POTENTIAL 29KT. KASD MEASURED A GUST OF 23KT AND KNEW
MEASURED A GUST 32KT..SO IT WAS IN THE BALLPARK.

FLIGHT TERMINATED WSW 28 MILES DOWNRANGE NEAR THE CONFLUENCE OF
BEDICO CREEK WITH THE TANGIPAHOA RIVER IN LOWER TANGIPAHOA PARISH
AT A TERMINATION PRESSURE OF 6.5MB OR 21,3 MILES UP. 24/RR

&&

.PREV DISCUSSION... /ISSUED 256 PM CDT SAT AUG 16 2014/

SHORT TERM...
SOUTHERLY FLOW ADDING MOISTURE TO THE LOW LEVELS. PW VALUES DOUBLE
JUST YESTERDAY IS MOST AREA. VISIBLE SATELLITE SHOWS CU FIELD
OVER THE AREA AS RADAR SHOWS COASTAL SHOWERS AND THUNDERSTORMS SOME
OF WHICH HAVE MOVED INLAND. MAIN PLAYER IS CYCLONIC FLOW IN THE GULF
OF MEXICO. THIS TWIST MOST EVIDENT IN THE WATER VAPOR IMAGE AS ENOUGH
CONVERGENCE FORCING IS TAKING PLACE TO KEEP DIURNAL COASTAL SHOWERS
ACTIVE THROUGH MUCH OF THE DAY. A REPEAT OF TODAY FOR SUNDAY AS
NOCTURNAL COASTAL SHOWERS MOVE INLAND IN THE MORNING FROM GULF AND
FROM LAKE PONTCHARTRAIN WITH ANOTHER ROUND RESULTING FROM DAYTIME
HEATING. MAY UPDATE THE QPF BEFORE SENDING THE FINAL GRIDDED
FORECAST PACKAGE AS SOME AREAS MAY RECEIVE HEAVY RAIN SUNDAY WHERE
CELLS CLUSTER OR REPEAT THROUGHOUT THE DAY. AM LEANING TOWARDS OR
HIGHER THAN THE GFS QPF OUTPUT. OVERNIGHT SHIFT WILL HAVE TO
EVALUATE IF POPS NEEDS TO BE HIGHER DEPENDING ON WHERE AND HOW
FAST THE CYCLONIC FEATURE MOVES EAST OF THE AREA. AS OF NOW GOING
30 TO 40 PERCENT OVER THE AREA.

LONG TERM...
HIGH PRESSURE WILL BE THE STORY FOR THE REMAINDER OF THE WEEK. A RIDGE
BUILDS INTO THE AREA MID WEEK AND TAKES HOLD OF THE GULF. A SFC
1020MB HIGH EVENTUALLY CENTERS OVER THE AREA CAUSING LOWER CHANCES OF
RAIN AND HIGH TEMPERATURES. GFS INDICATES A H5 HIGH OF 594DM WITH
THE 1000 TO 500MB THICKNESS PEAKING AT 579DM. HIGH TEMPERATURES WITH
HIGH DEW POINTS COULD BRING HEAT INDEX VALUES CLOSE TO ADVISORY CRITERIA.
H5 TEMPERATURES FORECAST TO BE -6C SO SOME AFTERNOON CONVECTION COULD
BRING SOME RELIEF. HOWEVER... THIS -6C IS DOWN FROM THE PREVIOUS MODEL
RUN. LATER IN THE EXTENDED SHOWS THE AREA ON THE EAST SIDE OF THE HIGH
BRINGING SOME PERIPHERY CONVECTION TO THE REGION LATE IN THE
FORECAST. TEMPERATURES WILL SNEAK UP INTO THE MID 90S ONCE THE
HIGH TAKES CONTROL OF THE FORECAST AREA.

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

MARINE...
SOUTHERLY FLOW OVER THE COASTAL AND OFFSHORE WATERS IN CONBINATION
WITH CYCLONIC FLOW OVER THE GULF OF MEXICO WILL FIRE UP SHOWERS AND
THUNDERSTORMS THROUGH TONIGHT AND SUNDAY. THE CYCLONIC FLOW WILL PUSH
EAST OF THE AREA AS HIGH PRESSURE MOVES SLOWLY WEST OVER THE GULF.
WINDS WILL REMAIN AROUND 10 KTS WITH SOME SOME GUSTS OVER THE OPEN WATERS
TO 15 KTS OTHERWISE SEAS WILL BE 1 TO 2 FEET. AS HIGH PRESSURE
TAKES CONTROL THE CHANCE FOR RAIN WILL DECREASE BY MID WEEK.

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  74  89  74  89 /  10  30  20  30
BTR  76  91  77  91 /  20  30  20  30
ASD  76  91  77  90 /  20  30  20  30
MSY  78  92  79  91 /  20  30  20  30
GPT  77  91  78  91 /  20  40  20  30
PQL  75  90  76  89 /  20  40  20  30

&&

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

$$








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