454
FXUS64 KSHV 162108
AFDSHV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
408 PM CDT TUE JUL 16 2019
SHORT TERM
/TONIGHT THROUGH WEDNESDAY NIGHT/
THE CENTER OF POST-TROPICAL CYCLONE BARRY CONTINUES TO MOVE
NORTHEAST INTO THE OHIO RIVER VALLEY. THE HEAVY RAINFALL THAT
DEVELOPED LAST NIGHT AND CONTINUED THROUGH MUCH OF THIS MORNING
OVER SOUTHWEST ARKANSAS HAS LARGELY DIMINISHED AND EXITED THE
AREA, WHILE MORE SCATTERED CONVECTION CONTINUES ACROSS DEEP EAST
TEXAS AND CENTRAL LOUISIANA. THIS REMAINING ACTIVITY SHOULD WEAKEN
THIS EVENING AND GRADUALLY END WITH THE LOSS OF DIURNAL
INSTABILITY. SINCE THE THREAT OF ADDITIONAL HEAVY RAINFALL HAS
LARGELY COME TO AN END, THE FLASH FLOOD WATCH FOR PORTIONS OF
SOUTHWEST ARKANSAS WAS CANCELLED.
A BUILDING UPPER RIDGE OVER THE SOUTHEAST CONUS AND A SURFACE HIGH
OVER THE NORTHEAST GULF OF MEXICO WILL QUICKLY ASSERT THEMSELVES
BEGINNING ON WEDNESDAY LEADING TO A RETURN OF MOSTLY DRY WEATHER
TO THE REGION. VERY ISOLATED CONVECTION COULD OCCUR WITH THE SEA
BREEZE DURING PEAK DAYTIME HEATING WEDNESDAY, BUT COVERAGE WILL BE
VERY SPOTTY.
UNDER THE INFLUENCE OF STRONG RIDGING, THE HEAT WILL ALSO BUILD.
THE HIGH AMOUNTS OF LOW-LEVEL MOISTURE SHOULD KEEP DAYTIME HIGH
TEMPERATURES IN THE MID 90S. ON THE FLIP SIDE, THIS WILL ALSO
RESULT IN HEAT INDEX VALUES VERY CLOSE TO 105 DEGREES F AND
FLIRTING WITH HEAT ADVISORY CRITERIA FOR MUCH OF THE AREA.
HUMIDITY LEVELS COULD BE LOCALLY ENHANCED BY EVAPORATION IN
PORTIONS OF SOUTHWEST ARKANSAS ON WEDNESDAY DUE TO THE VERY WET
SOILS AND SEVERE FLOODING THAT OCCURRED TODAY. THUS, I WOULD NOT
BE SURPRISED TO SEE VERY ISOLATED INSTANCES OF HEAT INDEX VALUES
WELL ABOVE 105 DEGREES F IN THESE AREAS. HOWEVER, DUE TO THE
UNCERTAINTY AND HOW BORDERLINE HEAT INDEX VALUES ARE EXPECTED TO
BE FOR THE MAJORITY OF THE FORECAST AREA, A HEAT ADVISORY WAS NOT
ISSUED FOR WEDNESDAY.
CN
LONG TERM
/THURSDAY THROUGH TUESDAY/
UPPER RIDGING OVER THE SRN PLAINS AND LOWER MS VALLEY WILL CONTINUE
TO BUILD E INTO THE TN VALLEY AND SE CONUS THURSDAY THROUGH
SATURDAY, MAINTAINING HOT AND DRY CONDITIONS AREAWIDE, WITH ANY WEAK
SEABREEZE EXPECTED TO REMAIN TO THE S OF S LA. HAVE TRENDED MAX
TEMPS A BIT ABOVE THE BLENDED GUIDANCE FOR THIS PERIOD OF THE
EXTENDED, ALTHOUGH HEAT INDICES WILL RANGE FROM 100-105 DEGREES EACH
DAY, AND WILL BE HIGHLY DEPENDING ON THE EXTENT OF MIXING OBSERVED
EACH DAY. THOSE AREAS OF SW AR WHICH OBSERVED EXCESSIVE RAINFALL
AMOUNTS OF 6-10+ INCHES EARLIER THIS MORNING, AS WELL AS PORTIONS OF
NCNTRL LA, WILL HAVE TO BE WATCHED CLOSELY SHOULD THE MIXING OF
DEWPOINTS NOT BE SUFFICIENT ENOUGH TO KEEP HEAT INDICES BELOW THE
105 DEGREE ADVISORY CRITERIA. THE MEDIUM RANGE PROGS CONTINUE TO
INDICATE THAT A PORTION OF BARRY'S REMNANTS WILL BE PINCHED OFF FROM
ITS ORIGINAL TROUGH AXIS ALONG THE E COAST FRIDAY MORNING, WITH THE
UPPER RIDGING RETROGRADING THIS PIECE OF ENERGY BACK W ACROSS THE SE
CONUS FRIDAY/SATURDAY AND INTO THE LOWER MS VALLEY SUNDAY (MUCH LIKE
HOW IT BEGAN A WEEK AND A HALF AGO, EXCEPT FARTHER S INTO THE NRN
GULF). THUS, ISOLATED CONVECTION WILL BE POSSIBLE SATURDAY AFTERNOON
OVER THE SRN AND ERN ZONES, WITH THE POTENTIAL FOR CONVECTION
SPREADING FARTHER W ACROSS N LA SUNDAY. HAVE EXPANDED LOW
CHANCE/SLIGHT CHANCE POPS FARTHER W SUNDAY, WITH MUCH OF THE
CONVECTION REMAINING DIURNALLY DRIVEN, DIMINISHING BY EARLY EVENING
WITH THE LOSS OF HEATING.
THIS INVERTED TROUGH IS PROGGED TO SHIFT FARTHER W INTO SE TX/N LA
MONDAY, WHICH SHOULD FOCUS MORE IN THE WAY OF SCT CONVECTION OVER
MUCH OF THE REGION THROUGH TUESDAY AS THIS WEAK TROUGH LINGERS ALONG
THE ERN PERIPHERY OF THE UPPER RIDGE ONCE IT RETREATS W BACK INTO
THE PLAINS. WHILE THE ECMWF MAINTAINS STRONGER RIDGING ALOFT EARLY
NEXT WEEK, THE GFS REMAINS A BIT WEAKER WITH THE RIDGE, ALLOWING FOR
A LONGWAVE TROUGH TO DIG SE ACROSS THE OH VALLEY/SE CONUS. THIS MAY
ALLOW FOR A WEAK SFC FRONT TO MIX S EARLY NEXT WEEK AS WELL, WHICH
MAY ALSO HELP FOCUS SCT CONVECTION THROUGH THE END OF THE EXTENDED
PERIOD AS WELL. FOR NOW, HAVE MAINTAINED LOW CHANCE POPS UNTIL
BETTER TIMING/EXTENT OF CONVECTION IS SEEN IN THE MEDIUM RANGE
PROGS.
15
PREV DISCUSSION
/ISSUED 1246 PM CDT TUE JUL 16 2019/
AVIATION...
FOR THE 16/18Z TAFS, THE MAJORITY OF THE HEAVY CONVECTION THAT
HAS PERSISTED ACROSS SOUTHWEST ARKANSAS SINCE LAST NIGHT IS SLOWLY
LIFTING NORTHEAST OUT OF THE AREA. SOME IMPACTS WILL STILL
CONTINUE FOR A FEW MORE HOURS ACROSS SOUTHWEST ARKANSAS, INCLUDING
KELD. MORE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE ALSO
AFFECTING KMLU AND PORTIONS OF NORTH CENTRAL LOUISIANA. MOST OF
THE CONVECTION SHOULD END AT ALL SITES AROUND 17/00Z OR 17/01Z. A
DEEP, MOIST, LOW-LEVEL SOUTHERLY FLOW SHOULD RESULT IN LOW CLOUDS,
FOG, AND MVFR/IFR CEILINGS AND VISIBILITIES AT MOST TERMINALS
BETWEEN 17/06Z AND 17/15Z. FLIGHT CONDITIONS SHOULD RAPIDLY
IMPROVE BACK INTO THE VFR RANGE LATE IN THE PERIOD.
CN
PRELIMINARY POINT TEMPS/POPS
SHV 77 95 75 94 / 20 10 0 0
MLU 74 93 75 93 / 30 10 0 10
DEQ 74 94 74 93 / 20 0 0 0
TXK 76 94 75 93 / 20 0 0 0
ELD 76 93 75 93 / 30 10 0 0
TYR 76 95 76 94 / 0 0 0 0
GGG 76 95 76 94 / 10 0 0 0
LFK 77 95 75 94 / 20 20 0 10
SHV WATCHES/WARNINGS/ADVISORIES
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
09/15
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