243
FXUS64 KLIX 122117
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
ISSUED BY NATIONAL WEATHER SERVICE MOBILE AL
417 PM CDT WED AUG 12 2020
SHORT TERM
ONGOING SHOWERS AND THUNDERSTORMS ARE PRIMARILY
FOCUSED ACROSS THE SOUTHERN AND EASTERN PORTIONS OF THE AREA,
INCLUDING THE COASTAL MISSISSIPPI ZONES ALONG A SEABREEZE PUSHING
INLAND. THE WET MICROBURST POTENTIAL IS MODERATE, SO A FEW OF THE
STRONGER THUNDERSTORMS STILL HAVE THE CAPABILITY OF PRODUCING
LOCALIZED WIND GUSTS UP TO 40 MPH INTO EARLY EVENING. CONVECTION
WILL DIMINISH BY MID EVENING ACROSS THE ENTIRE AREA, ALTHOUGH
THERE COULD BE A LINGERING LIGHT RAIN SHOWER OR TWO INTO LATE
EVENING. ISOLATED TO LOW-END SCATTERED CONVECTION WILL AGAIN BE
POSSIBLE LATE TONIGHT INTO EARLY THURSDAY MORNING ALONG THE
COASTAL SECTIONS OF SOUTHEAST LOUISIANA AND SOUTHEAST MISSISSIPPI.
THE SYNOPTIC PATTERN CHANGES SLIGHTLY AS THE AXIS OF AN UPPER
SHORTWAVE OVER THE AREA TONIGHT SHIFTS EASTWARD OVER ALABAMA BY
MIDNIGHT THURSDAY, WHILE WEAK UPPER RIDGING BUILDS IN FROM THE
WEST. DESPITE THIS PATTERN CHANGE, THERE WILL BE AMPLE
INSTABILITY FOR CONVECTION AGAIN ON THURSDAY DESPITE THE LACK OF A
FORCING MECHANISM AS THE TROUGH IS LIKELY NOT TO HAVE MUCH OF AN
INFLUENCE. HOWEVER, WILL ADVERTISE SCATTERED TO NUMEROUS COVERAGE
OF STORMS FOR TOMORROW AFTERNOON MAINLY DUE TO DECREASING
STABILITY. THE DEEP LAYER STEERING FLOW WILL BE VERY LIGHT AND
PRECIPITABLE WATERS WILL BE AT OR ABOVE 2". THEREFORE, ANY
STRONGER STORMS THAT DEVELOP WILL CONTAIN STRONG, GUSTY WINDS AND
THE POTENTIAL FOR LOCALLY HEAVY RAINFALL DUE TO THE SLOW MOVEMENT
OF STORMS. HEAT INDICES WILL CLIMB TO 104-107 DEGREES ACROSS THE
REGION ON THURSDAY. THIS IS JUST SHY OF HEAT ADVISORY CRITERIA
(108 DEGREES) BUT WILL CONTINUE TO MONITOR. /22
LONG TERM
FOR THE LONG TERM PERIOD (THIS FRIDAY THROUGH NEXT
TUESDAY), THE LOCAL AREA WILL GENERALLY BE UNDER AN AREA OF UPPER
LEVEL WEAKNESS AS A RIDGE MAINTAINS ITS HOLD ALOFT OVER THE
SOUTHWESTERN CONUS AND AN UPPER LEVEL TROUGH PERSISTS OVER THE OHIO
AND TENNESSEE VALLEYS DOWN THROUGH MISSISSIPPI AND ALABAMA. HOWEVER,
BY EARLY NEXT WEEK THE UPPER TROUGH TO THE EAST WILL BEGIN TO BUILD
BACK WEST OVER LOUISIANA AND EVENTUALLY OVER THE ARKLATEX REGION AS
WELL. AT THE SURFACE, HIGH PRESSURE WILL LARGELY BE MAINTAINED OVER
THE GULF OF MEXICO THROUGH THE WEEKEND. MEANWHILE, A SURFACE
BOUNDARY WILL BE DRAPED OVER THE ARKLATEX AND TENNESSEE VALLEY
REGIONS THROUGH THE DAY FRIDAY. BY SATURDAY, THIS BOUNDARY WILL
PROGRESS BACK NORTH SLIGHTLY, BECOMING A COLD FRONT OVER SOUTHERN
MISSOURI, KENTUCKY, AND DOWN INTO NORTH CAROLINA. THIS FRONT WILL
THEN BEGIN TO BE PUSHED SOUTHEAST BY ANOTHER COLD FRONT TO THE
NORTHWEST OVER THE UPPER MISSISSIPPI VALLEY. THE FIRST COLD FRONT
WILL PROGRESS OVER THE EAST COAST OF THE CAROLINAS, SOUTHERN
GEORGIA, AND THE FLORIDA PANHANDLE BY EARLY MONDAY. THE SECOND COLD
FRONT IS THEN EXPECTED TO MAKE ITS WAY OVER THE ARKLATEX AND
TENNESSEE VALLEY REGIONS DURING THIS TIME, EVENTUALLY MOVING OVER
THE NORTHERN GULF COAST THROUGH THE DAY TUESDAY.
AS FOR SENSIBLE WEATHER, A DIURNAL PATTERN WILL CONTINUE THROUGH AT
LEAST THE WEEKEND. MLCAPE VALUES WILL BE RIGHT AROUND 1000 J/KG
THROUGH SATURDAY, WITH AN INCREASE IN INSTABILITY TO BETWEEN 1000-
2500 J/KG FOR SUNDAY THROUGH TUESDAY AFTERNOONS. THUS, EXPECTING
SCATTERED SHOWERS AND STORMS TO BEGIN DURING THE LATE NIGHT/EARLY
MORNING HOURS OVER THE GULF WATERS AND THEN TRANSITION OVER LAND
THROUGH THE DAY. SHOWERS AND STORMS WILL DWINDLE TO BE FAIRLY
ISOLATED THROUGH THE EVENING. IN GENERAL, PWATS WILL RANGE BETWEEN
1.7-2.0 INCHES FOR THE LOCAL AREA THROUGH MONDAY, WITH THE HIGHEST
VALUES EXPECTED AREA-WIDE ON FRIDAY. PWATS WILL THEN DECREASE TO BE
AROUND 1.4 INCHES OVER THE INLAND AREAS AND AROUND 1.8-2.0 INCHES
NEAR THE LOUISIANA AND MISSISSIPPI COASTS ON TUESDAY. THIS IS DUE TO
DRIER AIR BEING BROUGHT IN FROM THE NORTH WITH COLD FRONTAL PASSAGE.
AT THIS TIME, WENT WITH LIKELY POPS FOR FRIDAY AND SATURDAY
AFTERNOONS BECAUSE OF HIGHER DEEP LAYER MOISTURE AND SOUTHWEST TO
WESTERLY WIND FLOW. ALSO, CAPPED POPS AT CHANCE FOR SUNDAY THROUGH
TUESDAY AFTERNOONS DUE TO DECLINING PWATS, A SHIFT TO MORE
NORTHWESTERLY FLOW, AS WELL AS MODEL UNCERTAINTY.
HIGH TEMPERATURES WILL BE IN THE UPPER 80S TO LOWER 90S ON FRIDAY
(DUE TO HIGHER CLOUD COVER AND POPS), THEN TEMPERATURES WILL
INCREASE TO GENERALLY BE IN THE LOWER TO MID 90S THROUGH THE
WEEKEND. HIGHS WILL SLIGHTLY DECREASE TO BE IN THE UPPER 80S TO
LOWER 90S ONCE AGAIN BY TUESDAY. LOW TEMPERATURES WILL MAINLY BE IN
THE LOWER TO UPPER 70S THROUGH SUNDAY NIGHT, WITH AREAS RIGHT ALONG
THE LOUISIANA COAST NEAR 80 DEGREES. LOWS MONDAY AND TUESDAY NIGHTS
WILL THEN BE IN THE LOWER TO MID 70S FOR MOST INLAND AREAS, WITH
AREAS RIGHT ALONG THE LOUISIANA COAST IN THE UPPER 70S; ALTHOUGH, A
FEW SPOTS OVER FAR SOUTHWEST MISSISSIPPI COULD SEE LOWS IN THE UPPER
60S. /26
AVIATION
NOT MUCH OF A CHANGE TO THE AVIATION FORECAST THIS
AFTERNOON AS ONGOING SCATTERED TO NUMEROUS SHOWERS AND STORMS THIS
AFTERNOON WILL GRADUALLY DIMINISH INTO EARLY EVENING. VFR
CONDITIONS WILL PREVAIL THROUGH MUCH OF THE FORECAST, EXCEPT NEAR
THUNDERSTORMS WHEN VISIBILITIES AND CEILINGS COULD DROP TO MVFR OR
IFR CRITERIA. WIND GUSTS OF 15-25 KNOTS ARE POSSIBLE NEAR
THUNDERSTORMS. /22
MARINE
SHOWER AND THUNDERSTORM ACTIVITY HAS WANED OVER THE
COASTAL WATERS THIS AFTERNOON AND GENERALLY LIGHT WINDS AND SEAS
ARE EXPECTED OUTSIDE OF ANY CONVECTION. WINDS WILL CONTINUE TO BE
LIGHT AS HIGH PRESSURE REMAINS OVER THE COASTAL WATERS.
PRELIMINARY POINT TEMPS/POPS
MCB 76 90 75 89 / 40 60 20 60
BTR 77 94 77 91 / 30 60 20 60
ASD 76 93 76 91 / 30 60 20 70
MSY 78 92 79 91 / 30 60 20 60
GPT 78 89 77 88 / 30 60 30 70
PQL 75 92 75 90 / 30 60 40 70
LIX WATCHES/WARNINGS/ADVISORIES
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
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