201
FXUS64 KSHV 201549 AAA
AFDSHV
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SHREVEPORT LA
1049 AM CDT FRI SEP 20 2019
UPDATE
WHAT REMAINS OF IMELDA THIS MORNING HAS GENERALLY LOST A CLOSED
CIRCULATION AT THIS POINT, BUT THE REMNANT AREA OF LOW PRESSURE IS
MORE OR LESS CENTERED TO OUR WEST IN NORTH-CENTRAL TX. MOISTURE
ADVECTION AND CONVERGENCE TO THE EAST OF THE LOW IS STILL
RELATIVELY IMPRESSIVE AND DRIVING LOCALLY HEAVY RAINS AND
EMBEDDED THUNDERSTORMS ACROSS EXTREME SE OK, FAR NE TX, AND VERY
SOUTHWESTERN PORTIONS OF SW AR. RAINFALL RATES HAVE BEEN RUNNING
UP TO 2 TO 3 INCHES PER HOUR IN SPOTS THERE RECENTLY, MAINLY OVER
MCCURTAIN COUNTY, AND WE ARE CLOSELY MONITORING THE HEAVY RAIN
SITUATION UP THERE. SO FAR WE HAVE NOT HEARD OF EXCESSIVE RAINFALL
ISSUES (EVEN THOUGH THERE ARE LOCALIZED TOTALS NOW OVER 4 INCHES)
AND ARE HOPING SHORT TERM MODEL TRENDS SHOWING THE HEAVIEST RAIN
SLACKENING THERE OVER THE COURSE OF THE NEXT SEVERAL HOURS PROVE
CORRECT. IF THE LATTER DOES NOT HAPPEN WE WILL LIKELY HAVE TO
START ISSUING FLASH FLOOD WARNINGS.
OTHERWISE, EXPECT THE MOISTURE RICH SOUTHERLY FLOW IN A HIGH
PRECIPITABLE WATER ENVIRONMENT TO DRIVE SCATTERED TO NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS ELSEWHERE IN THE FORECAST AREA
AS WE GO THROUGH THE AFTERNOON. FORTUNATELY, THIS ACTIVITY WILL BE
MOVING AND NOT PRONE TO PRODUCING A FLOODING THREAT. ALL THE
CLOUDS AND PRECIPITATION WILL KEEP TEMPERATURES BELOW NORMAL WITH
HIGHS GENERALLY EXPECTED TO RANGE FROM 80 TO 85 DEGREES IN MOST
LOCATIONS. /50/
PREV DISCUSSION
/ISSUED 728 AM CDT FRI SEP 20 2019/
AVIATION...
A MIX BAG OF ALL FLIGHT CATEGORIES THIS MORNING AS A LARGE AREA OF
PRECIPITATION MOVES ACROSS THE REGION IN CONNECTION WITH THE
REMNANTS OF IMELDA. CEILINGS TO GRADUALLY IMPROVE TO VFR BY
20/18Z BUT ADDITIONAL CONVECTION IS EXPECTED DURING THE AFTERNOON,
WHICH COULD RESULT IN PERIODS OF LOWER FLIGHT CATEGORIES.
EVENTUALLY, MOST OF THE PRECIPITATION WILL EXIT THE REGION BY
21/00Z WITH SOME LOW CIGS MOVING INTO PORTIONS OF THE REGION
DURING THE OVERNIGHT PERIOD. WINDS WILL REMAIN EAST TO SOUTHEAST
AROUND 10 KNOTS INCREASING TO 10 TO 15 KNOTS TODAY WITH GUSTS TO
25 KNOTS ACROSS MAINLY EAST TEXAS TERMINALS BEFORE DECREASING
AFTER SUNSET. /20/
PREV DISCUSSION... /ISSUED 434 AM CDT FRI SEP 20 2019/
SHORT TERM.../TODAY THROUGH SATURDAY NIGHT/
CURRENT REGIONAL RADAR SHOWS A LARGE AREA OF PRECIPITATION MOVING
NORTHEAST THROUGH EAST TX AND NW LOUISIANA THIS MORNING IN
ASSOCIATION WITH THE REMNANTS OF IMELDA. THIS PRECIPITATION WILL
CONTINUE TO SPREAD NORTHEAST INTO THE REMAINDER OF OUR LOUISIANA
PARISHES THIS MORNING AS WELL AS SE OKLAHOMA AND SW ARKANSAS.
ADDITIONAL CONVECTION WILL DEVELOP ACROSS THE REGION TODAY AS THE
REMNANTS OF IMELDA, NOW AN OPEN WAVE, CONTINUES TO MOVE NORTHWARD
OUT OF THE REGION. FORTUNATELY FOR US, IT APPEARS WE WILL NOT SEE
THE RAINFALL AMOUNTS EXPECTED EARLIER WITH THIS SYSTEM. AN
ADDITIONAL 1-3 INCHES WILL BE POSSIBLE TODAY, WITH THE HIGHEST
TOTALS ACROSS THE WESTERN HALF OF THE REGION.
BY SATURDAY, THE REMNANTS OF IMELDA SHOULD BE WELL NORTH OF THE
REGION, MERGING WITH A FRONTAL ZONE IN THE CENTRAL PLAINS AND
MIDWEST. UPPER LEVEL RIDGING WILL BEGIN TO BUILD INTO THE SE CONUS
AND INTO OUR REGION. DESPITE THE RIDGING, DECIDED TO MAINTAIN
SLIGHT RAIN CHANCES ACROSS DEEP EAST TX AND WEST-CENTRAL LOUISIANA
AS DEEP SOUTHERLY FLOW ALONG WITH DAYTIME HEATING COULD RESULT IN
ISOLATED AFTERNOON CONVECTION. SOME OF THIS CONVECTION COULD MOVE
FURTHER NORTH TOWARD THE I-20 CORRIDOR OF EAST TX AND NW LOUISIANA,
BUT CONFIDENCE IS LOW AT THIS TIME.
TEMPERATURES WILL REMAIN BELOW NORMAL TODAY WITH THE RAIN AND
CLOUD COVER OVER THE REGION. AFTERNOON HIGHS WILL STRUGGLE TO
REACH THE MID 80S. LOOK FOR AFTERNOON TEMPERATURES TO REBOUND INTO
THE UPPER 80S TO NEAR 90 DEGREES ON SATURDAY WITH THE UPPER RIDGE
EXPANDING INTO THE REGION. /20/
LONG TERM.../SUNDAY THROUGH FRIDAY/
BY THE END OF THE WEEKEND, UPPER RIDGING WILL BE SET UP ACROSS THE
SOUTHEAST U.S. WITH THE RIDGE AXIS EXTENDING WESTWARD ACROSS THE
LOWER MISS RIVER VALLEY INTO S TX. A LONGWAVE TROUGH SHOULD BE
MOVING OUT OF THE INTERMOUNTAIN WEST SUN MORNING, FILLING AS IT
EJECTS QUICKLY INTO THE CENTRAL AND NORTHERN PLAINS BY SUN EVENING.
CANNOT RULE OUT SOME ISOLATED, DIURNALLY DRIVEN CONVECTION ACROSS
OUR WESTERN HALF ON SUNDAY WHERE MOISTURE WILL BE A LITTLE MORE
PREVALENT. THERE WILL BE WEAK FRONTAL BOUNDARY IN ASSOCIATION WITH
THIS EJECTING LONGWAVE TROUGH THAT WILL TRY TO BACKDOOR INTO OUR
NORTHERN THIRD MONDAY AFTN/EVNG WHICH COULD HELP TO FOCUS SCATTERED
CONVECTION ALONG AND AHEAD OF IT SO DID BEEF POPS UP TO LOW END
CHANCE VARIETY TO ACCOUNT FOR THIS. WHAT IS LEFT OF THIS BOUNDARY
SHOULD RETURN BACK TO THE NORTH OR WASHOUT ALL TOGETHER TUE INTO WED.
BY WED, THE UPPER RIDGE AXIS WILL BEGIN TO LOSE ITS IDENTITY ACROSS
THE SOUTHERN PLAINS WITH SOUTHWEST FLOW ALOFT DEVELOPING ACROSS THE
PLAINS AS AN UPPER LEVEL TROUGH CARVES ITS WAY ACROSS THE SOUTHWEST
CONUS. KEPT POPS OUT OF THE FORECAST FOR WED BUT DID INCREASE POPS
TO LOW END CHANCE VARIETY FOR THU AS THIS TROUGH EJECTS OUT INTO THE
SOUTHERN PLAINS. THIS TROUGH SHOULD HELP TO TAP DEEPER GULF OF
MEXICO MOISTURE ON THU WHICH SHOULD SUPPORT THE INCREASE IN
CONVECTIONAL COVERAGE. WE ARE BACK TO ISOLATED DIURNALLY DRIVEN
CONVECTION FOR FRI WITH SOUTHWEST FLOW ALOFT CONTINUING IN THE WAKE
OF THE EJECTING TROUGH.
13
PRELIMINARY POINT TEMPS/POPS
SHV 83 70 88 71 / 60 10 10 10
MLU 85 69 90 70 / 50 20 10 10
DEQ 79 70 88 70 / 100 40 10 10
TXK 80 69 88 71 / 70 30 10 10
ELD 81 68 89 69 / 50 30 10 10
TYR 86 71 88 71 / 50 10 10 10
GGG 84 71 88 71 / 50 10 10 10
LFK 85 71 87 71 / 50 10 20 10
SHV WATCHES/WARNINGS/ADVISORIES
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
50/13/20
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