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

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108
FXUS64 KLIX 151405
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
804 AM CST SAT NOV 15 2014

.SOUNDING DISCUSSION...

STEEP SFC COLD AIR TEMPERATURE INVERSION THROUGH 6KFT WITH
BELOW FREEZING AT THE SFC AND 41 DEGREES AT 5500 FT.  DRY
AIR AS EXPECTED WITH PW MEASURED AT .56 IN.  TEMPERATURES
THROUGH THE COLUMN GENERALLY HIGHER OVER THE LAST 24 HOURS
WITH THE EXCEPTION OF AROUND 900MB. WINDS NORTHEAST AT THE
SFC THEN WESTERLY THE REMAINDER OF THE SOUDNING. WINDS PEAK
AT 75KT AROUND 35 TO 40KT.

&&

.PREV DISCUSSION... /ISSUED 420 AM CST SAT NOV 15 2014/

SYNOPSIS...
LATEST SURFACE ANALYSIS SHOWED A 1031MB HIGH OVER THE OHIO VALLEY
WITH AN ASSOCIATED RIDGE AXIS EXTENDING SOUTHWEST TO SOUTHEAST
TEXAS. SURFACE DEWPOINT READINGS RANGE FROM THE UPPER TEENS ACROSS
SOUTH MISSISSIPPI TO THE UPPER 20S ALONG THE LOUISIANA COAST. IN
ADDITION...A 1004MB SURFACE LOW WAS NOTED OVER EAST COLORADO AND
SOUTHERLY FLOW OVER THE SOUTHERN PLAINS. UPPER AIR ANALYSIS A
WESTERLY FLOW OVER THE SOUTHERN TIER CONUS AND A POSITIVELY
TILTED WAVE FROM MONTANA TO NORTHERN NEVADA. ISOTACH ANALYSIS AT
250MB SHOWED A JET MAX AROUND 125 KNOTS ON THE BACK SIDE OF THE
WAVE. WATER VAPOR IMAGERY SHOWED A DISTURBANCE DIVING SOUTH OVER
SASKATCHEWAN.

DISCUSSION...
WHILE WE ARE IN THE MIDST OF OUR COLDEST NIGHT THIS FALL...A
PROGRESSIVE PATTERN SWITCH WINTER LIKE TEMPS TODAY TO FALL LIKE
TEMPS BY SUNDAY. UPPER LEVEL WAVES OVER THE NORTHERN PLAINS WILL
TRACK SOUTH AND INCREASE HEIGHTS ACROSS THE CENTRAL GULF COAST.
FLOW ALOFT WILL BECOME SOUTHWEST TONIGHT. WARM AIR ADVECTION WILL
START BY THIS EVENING. SURFACE HIGH OVER THE OHIO VALLEY WILL
SLIDE EAST TO THE VIRGINIA AND FLOW ALONG THE CENTRAL GULF COAST
WILL QUICKLY BECOME SOUTHEAST BY THIS EVENING. DRY AIR WILL PIVOT
NORTHEAST THIS EVENING BEFORE A FULL RETREAT BY AFTER MIDNIGHT.
ERGO...TEMPS MAY DROP QUICKLY AFTER SUNSET TODAY BEFORE CLOUDS
INVADE FROM THE SOUTHWEST. WILL PLACE TONIGHT LOWS AROUND MIDNIGHT
AND TEMPS SHOULD REMAIN STEADY OR INCREASE OVERNIGHT.

SOUTHWEST FLOW ALOFT WILL INCREASE MOISTURE ABOVE 500MB ON
SUNDAY...WHILE SOUTHEAST FLOW IN THE LOWER INCREASE MOISTURE SUNDAY.
UPPER TROUGH AXIS WILL CONTINUE TO DIVE SOUTHEAST OVER THE CENTRAL
PLAINS SUNDAY AFTERNOON. A SURFACE INVERTED TROUGH/LOW IS EXPECTED
TO DEVELOP THE UPPER TEXAS COAST SUNDAY AFTERNOON AND TRACK
NORTHEAST SUNDAY EVENING OVER THE FORECAST AREA. SURFACE DEWPOINT
READING WILL INCREASE TO THE LOWER 60S OVER THE FORECAST AREA. AT
THIS TIME...MODEST MID LAYER INSTABILITY WILL BE PRESENT AND
SURFACE WARMING SUNDAY AFTERNOON WILL INCREASE LL LAPSE RATE. THE
BEST LL SHEAR SHOULD REMAIN NORTH ACROSS CENTRAL AND NORTHERN
MISSISSIPPI/ALABAMA WILL LIKELY BE ELEVATED. THE INTERSECTION OF
SURFACE INSTABILITY AND LL SHEAR COULD LEAD ONE OF TWO STRONG
ROTATING STORMS...THREAT IS LOW RIGHT NOW. ANOTHER COMPONENT IS THE
WIDESPREAD RAIN AND THE POSSIBILITY OF THE SYSTEM PRODUCING 1 TO 2
INCREASE ACROSS THE FORECAST AREA SUNDAY AFTERNOON AND SUNDAY
NIGHT. MANY AREAS ARE EXTREMELY DRY AND SHOULD HANDLE THE HEAVY
RAINFALL...BUT WILL MAINTAIN CATEGORICAL RAIN CHANCES ACROSS THE
NORTH ON SUNDAY. EXPECTING THE TROUGH TO PUSH THE MOISTURE THROUGH
BY MONDAY MORNING. THE SECOND SURGE ASSOCIATED WITH THE WAVE OVER
CANADA WILL ARRIVE MONDAY AND SCOUR OUR THE REMAINING MOISTURE AND
CLOUD COVER. STRONG COLD AIR ADVECTION WILL ALLOW TEMPS DIVE AGAIN
AND POSSIBLY PUSH PARTS OF SOUTHWEST MISSISSIPPI TO A HARD FREEZE
TUESDAY AND SOUTH SHORE TO A NEAR FREEZE. SOME MODERATION WILL OCCUR BY
THURSDAY FOLLOWED BY ANOTHER SYSTEM BRINGING A CHANCE OF RAIN
FRIDAY AND NEXT WEEKEND.

AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE PERIOD AT ALL TERMINALS.
WINDS WILL GRADUALLY SHIFT FROM NORTHEAST TO SOUTHEAST OVER THE NEXT
24 HOURS AS HIGH PRESSURE SHIFTS TO THE EAST.

MARINE...
SURFACE HIGH PRESSURE WILL BEGIN TO SHIFT EASTWARD AWAY FROM THE AREA
TODAY RESULTING IN WINDS TURNING FROM NORTHEAST TO SOUTHEAST OVER
THE NEXT 18 TO 24 HOURS. HEADING INTO SUNDAY...A LOW PRESSURE SYSTEM
WILL MOVE THROUGH THE AREA. INCREASED ONSHORE FLOW WILL DEVELOP IN
ADVANCE OF THIS LOW...AND EXPECT TO SEE EXERCISE CAUTION CONDITIONS
DEVELOP IN THE GULF WATERS FOR SUNDAY AND SUNDAY NIGHT. A STRONG
FRONTAL BOUNDARY WILL THEN SWITCH WINDS TO THE NORTHWEST AND NORTH
DURING THE DAY ON MONDAY. ANOTHER ROUND OF SMALL CRAFT ADVISORIES IS
LIKELY FOLLOWING THIS FRONT WITH SUSTAINED WINDS IN THE 25 TO 30 KT
RANGE. HIGHER GUSTS COULD NECESSITATE GALE WARNINGS.

DECISION SUPPORT...
DSS CODE...BLUE.
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  56  42  67  42 /   0  10  90  90
BTR  57  44  73  42 /   0  10  90  90
ASD  57  44  71  49 /   0  10  60  90
MSY  56  50  74  51 /   0  10  60  80
GPT  56  44  70  55 /   0  10  50  90
PQL  56  40  70  58 /   0  10  40  90

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...FREEZE WARNING UNTIL 9 AM SATURDAY FOR THE FOLLOWING ZONES:
     ASCENSION...ASSUMPTION...EAST BATON ROUGE...EAST
     FELICIANA...IBERVILLE...LIVINGSTON...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...FREEZE WARNING UNTIL 9 AM SATURDAY FOR THE FOLLOWING ZONES:
     AMITE...HANCOCK...HARRISON...JACKSON...PEARL
     RIVER...PIKE...WALTHALL...AND WILKINSON.

GM...NONE.
&&

$$










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