Severe Thunderstorm Warning 166, NWS Shreveport, LA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SHREVEPORT LA
1030 PM CDT SAT MAY 9 2009

...A QUICK UPDATE TO THE FORECAST WILL BE COMING...

.DISCUSSION...
PLENTY OF RAINDROPS CONTINUE TO FALL ON THE HEADS OF RESIDENTS
ACROSS NORTHEASTERN TEXAS AND SOUTHERN ARKANSAS...AS A FRONT REMAINS
NEARLY STATIONARY NEAR THE IH-20 CORRIDOR.  CONVECTIVE COVERAGE HAS
DECREASED SOMEWHAT OVER THIS REGION...AT LEAST TEMPORARILY.  I
EXPECT ADDITIONAL ELEVATED CONVECTION TO DEVELOP OVERNIGHT ACROSS
THIS REGION AS BOUNDARY LAYER MOISTURE CONTINUES INTERACTING WITH
ISENTROPIC UPGLIDE.

A LACK OF STRONG FORCING OF INSTABILITY SHOULD KEEP MOST
THUNDERSTORMS /SURFACE-BASED OR OTHERWISE/ AT BAY OVERNIGHT.  ANY OF
THE STRONGER STORMS MAY BE CAPABLE OF PRODUCING SOME HAIL.

WITH THIS UPDATE I HAVE ADJUSTED FIRST PERIOD PRECIPITATION
PROBABILITIES TO BRING THEM INTO BETTER ALIGNMENT WITH OBSERVED
TRENDS.  FLASH FLOODING REMAINS A GOOD BET IN SEVERAL AREAS
OVERNIGHT DUE TO TRAINING CONVECTION AND SOGGY GROUND CONDITIONS.
IN FACT...A COCORAHS OBSERVER IN BOWIE COUNTY HAS REPORTED OVER 5
INCHES OF RAINFALL SINCE THE RAIN BEGAN.

I HAVE ALSO MADE SOME ADJUSTMENTS TO THE SKY COVER...AS WELL AS
HOURLY TEMPERATURE AND DEWPOINT GRIDS.  THIS HAS RESULTED IN SOME
ADJUSTMENT OF OVERNIGHT LOW TEMPERATURES.

ISC GRIDS HAVE BEEN SENT AND SHOULD BE POSTED TO THE INTERNET.  AN
UPDATED SUITE OF PRODUCTS WILL BE ISSUED SHORTLY.  /21/

&&

.PREV DISCUSSION... /ISSUED 812 PM CDT SAT MAY 9 2009/

..A QUICK UPDATE TO THE FORECAST WILL BE COMING...

DISCUSSION...
FRONT HAS ALL BUT STALLED NEAR THE IH-20 CORRIDOR EARLY THIS
EVENING.  SHOWERS AND THUNDERSTORMS CONTINUE TO BE SEEN NORTH OF
THIS BOUNDARY...AND SOUTH OF THE THE 850MB FRONT /CLOSER TO THE
IH-40 CORRIDOR/.  CONVECTION SHOULD CONTINUE FROM NORTHEAST TEXAS
INTO SOUTH ARKANSAS AT LEAST FOR THE NEXT SEVERAL HOURS.  IN
GENERAL...IT LOOKS LIKE THE SEVERE WEATHER RISK IS JUST ABOUT OVER
THE NORTHERN TIER OF COUNTIES.  INSTABILITY AND MOISTURE REMAIN HIGH
OVER SOUTHERN AREAS...BUT THE EVENING SOUNDING SHOWS A STRONG
CAPPING INVERSION REMAINING IN PLACE.

THAT SAID...I WILL UPDATE THE FORECAST TO REMOVE SEVERE THUNDERSTORM
WATCH 282.  FLASH FLOODING REMAINS A RISK OVER NORTHERN AREAS THANKS
TO TRAINING...AND THE FLASH FLOOD WATCH WILL REMAIN IN EFFECT FOR
THE TIME BEING.

FOR NOW...I WILL NOT MAKE ANY CHANGES TO THE ONGOING FORECAST.  I
MAY MAKE A FEW ADJUSTMENTS LATER THIS EVENING TO THE SENSIBLE
WEATHER ELEMENTS BASED ON OBSERVED TRENDS.  UPDATES MAY BE SENT FOR
THIS LATER.  I WOULD JUST LIKE TO SEE HOW TEMPERATURES/DEWPOINTS
TREND IN SOME OF THE RAIN-COOLED AREAS BEFORE TWEAKING TOO MUCH ONE
WAY OR THE OTHER.

ISC GRIDS HAVE BEEN SENT AND SHOULD BE POSTED TO THE INTERNET.  AN
UPDATED SUITE OF PRODUCTS WILL BE ISSUED SHORTLY.  /21/

AVIATION...
MAINLY VFR FLIGHT CATEGORIES ARE EXPECTED S OF IH-20...WITH POSSIBLE
REDUCTIONS TO MVFR BETWEEN 10/0900-1400 UTC OR SO.  WIDESPREAD
MVFR/IFR FLIGHT CATEGORIES WILL BE PREVALENT AT MOST OTHER TERMINALS
WITH FURTHEY EVENING FOR THE FOLLOWING
     ZONES: ARZ050-051-059>061-070>073.

LA...NONE.
OK...FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR THE FOLLOWING
     ZONES: OKZ077.

TX...FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR THE FOLLOWING
     ZONES: TXZ096-097.

&&

D. BUTTS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SHREVEPORT LA
1146 AM CDT SAT MAY 9 2009

ARZ050-051-059>061-070>073-LAZ001>006-010>014-OKZ077-TXZ096-097-
108>112-124>126-136>138-149>151-101200-
SEVIER-HOWARD-LITTLE RIVER-HEMPSTEAD-NEVADA-MILLER-LAFAYETTE-
COLUMBIA-UNION AR-CADDO-BOSSIER-WEBSTER-CLAIBORNE-LINCOLN-
UNION LA-DE SOTO-RED RIVER-BIENVILLE-JACKSON-OUACHITA-MCCURTAIN-
BOWIE-FRANKLIN-TITUS-CAMP-MORRIS-CASS-WOOD-UPSHUR-MARION-SMITH-
GREGG-HARRISON-CHEROKEE-RUSK-PANOLA-
1146 AM CDT SAT MAY 9 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
ARKANSAS...SOUTHWEST ARKANSAS...NORTH CENTRAL LOUISIANA...
NORTHWEST LOUISIANA...SOUTHEAST OKLAHOMA AND NORTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT...

STRONG TO SEVERE THUNDERSTORMS MAY DEVELOP EARLY THIS
AFTERNOON...ALONG AND NORTH OF I 20...WHERE A FRONTAL BOUNDARY
LIES. THE THREAT WILL SHIFT TO JUST SOUTH OF I 20 AS THE FRONT
SLOWLY DIPS SOUTHWARD THIS EVENING. STRONG INSTABILITY FROM
DAYTIME HEATING WILL AID IN THUNDERSTORM INITIATION THIS AFTERNOON.
EVEN WITH THE LOSS OF DAYTIME HEATING...EXPECT THUNDERSTORMS TO
CONTINUE AS THE LOW LEVEL JET KICKS IN TONIGHT...WITH LOCALLY
HEAVY RAINFALL AND THE POSSIBILITY FOR LARGE HAIL AND DAMAGING
WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...

THE SEVERE WEATHER AND HEAVY RAINFALL THREAT WILL CONTINUE THROUGH
AT LEAST SUNDAY NIGHT. FLASH FLOODING WILL BE A POSSIBILITY...
CONSIDERING THE RAINFALL EARLIER IN THE MONTH.

ANOTHER STORM SYSTEM AND ASSOCIATED COLD FRONT WILL ARRIVE LATE ON
WEDNESDAY INTO THURSDAY WITH YET ANOTHER POSSIBILITY OF STRONG TO
SEVERE THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND TONIGHT.

LAZ017>022-TXZ152-153-165>167-101200-
SABINE LA-NATCHITOCHES-WINN-GRANT-CALDWELL-LA SALLE-NACOGDOCHES-
SHELBY-ANGELINA-SAN AUGUSTINE-SABINE TX-
1146 AM CDT SAT MAY 9 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
LOUISIANA...NORTHWEST LOUISIANA AND EAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT...

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS MAY DEVELOP THIS
AFTERNOON...AS A SOUTHWARD MOVING COLD FRONT ENTERS A MODERATELY
UNSTABLE ENVIRONMENT. THIS ACTIVITY WILL LIKELY DISSIPATE SHORTLY
AFTER SUNSET.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...

THUNDERSTORMS ARE EXPECTED TO DEVELOP ONCE AGAIN SUNDAY AND
MONDAY...AS THE FRONTAL BOUNDARY CONTINUES TO SLOWLY PUSH
SOUTHWARD. SOME STORMS MAY REACH SEVERE LIMITS...WITH LARGE HAIL
AND DAMAGING WINDS AS THE MAIN THREATS.

ANOTHER STORM SYSTEM AND ASSOCIATED COLD FRONT WILL ARRIVE LATE ON
WEDNESDAY INTO THURSDAY WITH YET ANOTHER POSSIBILITY OF STRONG TO
SEVERE THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL LIKELY NOT BE NEEDED THIS AFTERNOON OR TONIGHT.

12

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
554 PM CDT SAT MAY 09 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0259 PM     TSTM WND DMG     GARLAND                 33.36N 93.71W
05/09/2009                   MILLER             AR   LAW ENFORCEMENT

            TREES AND POWERLINES DOWNED ALONG HWY 196 AND 134

0300 PM     TSTM WND DMG     KIBLAH                  33.05N 93.90W
05/09/2009                   MILLER             AR   LAW ENFORCEMENT

            TREE DOWNED ON HWY 71 NEAR THE LOUISIANA/ARKANSAS STATE
            LINE

&&

12

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
640 PM CDT SAT MAY 09 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0440 PM     TSTM WND DMG     1 NE HUTTIG             33.05N 92.17W
05/09/2009                   UNION              AR   LAW ENFORCEMENT

            TREE DOWN OVER THE ROAD BETWEEN THE COMMUNITIES OF HUTTIG
            AND FELSENTHAL.

&&

15

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
650 PM CDT SAT MAY 09 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0215 PM     TSTM WND DMG     8 E ASHDOWN             33.67N 93.99W
05/09/2009                   LITTLE RIVER       AR   LAW ENFORCEMENT

            TREES DOWN ALL AROUND MILLWOOD LAKE

&&

12

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