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

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663
FXUS64 KLIX 201514
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1014 AM CDT SUN JUL 20 2014

.UPDATE...
VISIBILITIES HAVE IMPROVED OVER THE AREA AFTER SOME UNCHARACTERISTIC
FOG FOR THIS TIME OF YEAR. WITH ADDITIONAL SHOWER AND WET GROUND...
WE WILL LIKELY SEE ANOTHER ROUND OF FOG MONDAY MORNING. MAIN AREA
OF CONCERN TODAY IS HOW MUCH CONVECTION WILL MOVE FROM THE COASTAL
WATERS NORTH. HRR AND WRF 3KM INDICATE AN INCREASE IN ACTIVITY FROM
THE SW INTO THE AREA. THE PREVIOUS BOUNDARY AND LOW LEVEL
CONVERGENCE ZONES WILL FOCUS THIS ACTIVITY. WV AND MODELS DO INDICATE
SOME DRIER AIR MOVING IN THUS SHOULD SOMEWHAT LIMIT HOW FAR NORTH
THE CONVECTION WILL GET. MORNING SOUNDING MEASURED PW VALUES OF
1.84 INCHES THUS DEEP MOISTURE TO WORK WITH. HOWEVER THIS IS DOWN FROM
2.13 YESTERDAY. RAIN WILL STILL BE HEAVY NEAR STORMS BUT THE
INFLUENCE OF THE DRIER AIR ALOFT CAN ALREADY BE SEEN.

&&


.MARINE...
AREAS OF CONVECTION IS THE MAIN AREA OF CONCERN IN THE COASTAL WATERS.
THE MAIN THREAT IS HEAVY RAIN...BRIEF GUSTY WINDS AND LIGHTNING. THIS
WILL CONTINUE FOR MUCH OF THE DAY.


&&

.PREV DISCUSSION... /ISSUED 331 AM CDT SUN JUL 20 2014/

SHORT TERM...
THE MAIN FORECAST CONCERN IN THE SHORT TERM IS THE CONVECTION
EXPECTED ACROSS THE AREA TODAY. WATER VAPOR IMAGERY EARLY THIS
MORNING INDICATES THAT DRIER AIR IN THE MID AND UPPER LEVELS IS
FINALLY BEGINNING TO PUSH INTO THE NORTHWESTERN SECTIONS OF THE
FORECAST AREA. TO THE EAST AND SOUTH OF THIS DRIER AIR...DEEP
MOISTURE CONTINUES TO PREVAIL WITH PRECIPITABLE WATER VALUES STILL
IN EXCESS OF 2 INCHES. CONVECTION IS ONCE AGAIN FIRING ACROSS THE
COASTAL WATERS IN AN AREA OF LOW LEVEL CONVERGENCE ASSOCIATED WITH
A LAND BREEZE AND/OR THE REMNANTS OF A WEAK SURFACE FRONT/TROUGH.
DIVERGENCE IN THE UPPER LEVELS WAS ALSO EVIDENT IN THE SATELLITE
IMAGERY LOOP IN THE AREA WHERE THE CONVECTION WAS DEVELOPING. A
SIMILAR SCENARIO WITH REGARD TO THE CONVECTION IS EXPECTED TODAY
WITH THE SHOWER AND THUNDERSTORM ACTIVITY CURRENTLY IN THE
COASTAL WATERS DEVELOPING/MOVING INLAND ACROSS THE COASTAL AREAS
EARLY THIS MORNING...AND THEN FURTHER INLAND AS THE MORNING
PROGRESSES. THE BEST CHANCE FOR RAIN TODAY WILL BE ACROSS THE
SOUTHEAST HALF OF THE FORECAST AREA AS THE DRIER AIR WORKING IN
FROM THE NORTHWEST ACTS TO LIMIT CONVECTION IN THOSE AREAS. THE BEST
RAIN CHANCES AND COVERAGE WILL LIKELY BE IN THE MORNING TO EARLY
AFTERNOON HOURS TODAY AS THE DRIER AIR SLOWLY ADVANCING TO THE
SOUTH AND EAST DURING THE COURSE OF THE DAY SQUEEZES THE DEEPER
MOISTURE TO THE FAR SOUTHEASTERN SECTIONS OF THE FORECAST AREA BY
LATE AFTERNOON.

A STRONG UPPER LEVEL RIDGE WILL BUILD ACROSS THE FOUR CORNERS
REGION AND CENTRAL AND SOUTHERN PLAINS THROUGH THE MID WEEK
PERIOD. THE LOCAL FORECAST AREA WILL BE ON THE PERIPHERY OF THIS
RIDGE. THE INFLUENCE OF THIS BUILDING RIDGE...ESPECIALLY ACROSS
THE WESTERN SECTIONS OF THE FORECAST AREA...ALONG WITH DRIER AIR
ACROSS THE REGION WILL ACT TO DECREASE CONVECTION COVERAGE MONDAY
AND ESPECIALLY TUESDAY. 11

LONG TERM...
DURING MUCH OF THE WEEK THE SOUTHEAST CONUS WILL BE LOCATED IN A BREAK
BETWEEN THE UPPER RIDGE OVER THE CENTRAL AND SOUTHERN PLAINS AND AN
UPPER RIDGE OVER THE WESTERN ATLANTIC. THE AXIS OF THIS WEAKNESS
ALOFT WILL MIGRATE WESTWARD WITH TIME AND ALLOW DEEPER MOISTURE TO
RETURN TO THE LOCAL AREA DURING THE MID AND LATE WEEK PERIOD. AS A
RESULT...THE CONVECTION COVERAGE WILL INCREASE ONCE AGAIN FOR THE LAST
HALF OF THE WORK WEEK. THE STRONG UPPER RIDGE OVER THE PLAINS WILL
GRADUALLY WEAKEN AND RETROGRADE DURING THE LAST HALF OF THE WEEK.
AN UPPER TROUGH DIGGING ACROSS THE EASTERN CONUS FOR THE END OF
THE WEEK WILL PUSH ANOTHER COLD FRONT INTO THE SOUTHEAST U.S.
FRIDAY AND SATURDAY.

AVIATION...
MAIN ISSUE WILL BE ON LOW CIGS THIS MORNING AND SOME LIGHT SHRA.
BIGGEST ISSUE WOULD BE MVFR CIGS HOVERING AROUND 2-3K FT. THIS
WILL CHANGE LATE THIS MORNING AND MORE SO AROUND MIDDAY AND THIS
AFTN AS CONVECTION DEVELOPS. SCT TSRA SHOULD IMPACT MUCH OF THE
REGION SOUTH OF THE LA/MS BORDER AND ESPECIALLY AREAS ALONG AND
SOUTH OF THE 10/12 CORRIDOR. ANY TERMINALS IMPACTED BY CONVECTION
WILL SEE BOTH VSBYS AND CIGS DROP TO MVFR AND POSSIBLY AS LOW AS
LIFR. CONVECTION WILL TAPER OFF LATE THIS AFTN AND EARLY EVNG.
/CAB/

MARINE...
BROAD RIDGING WILL DOMINATE THE REGION THROUGH MUCH OF THE
FCST. WINDS WILL GENERALLY REMAIN AROUND 12 KTS OR LESS AND OUT OF
THE SOUTHWEST. ONLY REAL ISSUE WILL BE CONVECTION WITH ISLTD TO SCT
SHRA AND TSRA EXPECTED OFF AND ON. /CAB/

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  89  70  90  70 /  30  10  20  10
BTR  90  72  92  71 /  40  20  20  10
ASD  89  72  92  72 /  50  20  30  10
MSY  90  76  91  76 /  50  30  30  20
GPT  90  73  91  73 /  50  30  30  20
PQL  89  72  90  72 /  50  30  30  20

&&

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

$$







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