Alert archive / Louisiana / Special Weather Statements in 2012

Special Weather Statement, NWS Jackson, MS

April 20, 2012Catahoula Parish, Concordia Parish, Louisiana

NWS Jackson, MS issued this special weather statement at Apr 20, 2012, 9:30 PM CDT for Catahoula Parish, Concordia Parish, Louisiana. It was in force for 60 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Apr 20, 2012, 9:30 PM CDT (02:30 UTC)
Expired: Apr 20, 2012, 10:30 PM CDT
In force: 60 min
Issued by: NWS Jackson, MS

Counties Catahoula Parish, LA, Concordia Parish, LA

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 2.5 hours before the alert went out and 190 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 629 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 988 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: -10 m²/s²
0-3 km storm-relative helicity: 18 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Jackson, MS wrote its last area forecast discussion before this special weather statement went out at Apr 20, 9:03 PM CDT, 27 minutes earlier.

Area forecast discussion, Apr 20, 9:03 PM CDT, 27 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
903 PM CDT FRI APR 20 2012

.DISCUSSION...WE ARE DEALING WITH A COMPLEX WEATHER SITUATION THIS
EVENING AS AN UPPER TROUGH DIGS ACROSS THE DEEP SOUTH. AT THE
SURFACE...A COLD FRONT NOW EXTENDS FROM NEAR TUP TO TVR TO JUST EAST
OF AEX. BEHIND THE FRONT...A COMPLEX OF SHOWERS AND SOME TSTORMS
EXTENDS ACROSS WESTERN TN...NW MS...SE AR...AND MUCH OF WESTERN AND
CENTRAL LA. JUST A FEW HOURS AGO...THERE WAS A MUCH BETTER ORGANIZED
MCS MOVING EASTWARD ACROSS THE TX/LA BORDER...HOWEVER THIS ACTIVITY
HAS RAPIDLY WEAKENED OVER THE PAST HOUR. AS THE UPPER TROUGH
CONTINUES TO DEEPEN INTO THE NORTHERN GULF...AN UPPER LOW WILL CUT
OFF AND SFC CYCLOGENESIS IS EXPECTED ENSUE OFFSHORE...SHIFTING THE
GREATER FOCUS OF CONVECTION IN THAT DIRECTION. HOWEVER...EXISTING
SHOWER AND TSTORM ACTIVITY WILL CONTINUE TO WORK ITS WAY INTO THE
AREA BEHIND THE FRONT THIS EVENING AND OVERNIGHT. THE BEST CHANCE
FOR RAIN WILL BE OVER CENTRAL AND ESPECIALLY WESTERN PORTIONS OF THE
AREA. THERE IS QUITE A BIT OF UNCERTAINTY AS TO HOW MUCH RAIN WILL
GET INTO EASTERN PORTIONS OF THE AREA. THERE IS AN INCREASING CHANCE
THAT SOME AREAS ALONG THE I-59 CORRIDOR WILL SEE LITTLE TO NO
PRECIPITATION WITH THIS SYSTEM.

HAVE UPDATED THE OVERNIGHT FORECAST TO DELAY THE ONSET OF PRECIP BY
A FEW HOURS AND TO DECREASE POPS MAINLY OVER EASTERN PORTIONS OF THE
FORECAST AREA. OTHERWISE MOS GUIDE IS PREDICTABLY DOING A POOR JOB
WITH HOURLY TEMP AND DEWPOINTS TONIGHT...WITH A FRONT IN THE AREA.
ADJUSTED GRIDS USING THE RAW NAM AND RUC OUTPUT...WHICH SEEMED TO BE
MORE REALISTIC AND PERFORMING BETTER AT THIS TIME. NO OTHER MAJOR
ADJUSTMENTS WILL BE MADE. UPDATES ARE BEING SENT AT THIS TIME. AN
UPDATED AVIATION DISCUSSION AND PERTINENT PORTIONS OF THE PREVIOUS
DISCUSSION FOLLOW BELOW. /DL/

&&

.AVIATION...CONCERNS WILL REVOLVE AROUND A COLD FRONT
THAT WILL BE MOVING ACROSS THE FORECAST AREA THE REST OF TONIGHT
THROUGH EARLY SATURDAY. CLOUDS/SHOWERS AND A FEW THUNDERSTORMS
ACCOMPANYING THE FRONT WILL BRING MVFR CONDITIONS WITH OCCASIONAL
IFR CONDITIONS IN ASSOCIATION WITH ANY STORMS. THE BEST CHANCE FOR
GETTING STORMS WILL BE AT GLH/GWO/HKS/JAN/..BUT EXPECT DRIER AIR TO
KEEP A MORE STABLE AIRMASS AS YOU GO FARTHER EAST AND NORTH THUS
LIMITING TSTM AND OVERALL RAIN POTENTIAL. EXPECT RAINFALL CHANCES TO
DECREASE RAPIDLY SATURDAY MORNING FROM WEST TO EAST...BUT A BLANKET
OF MVFR CATEGORY STRATUS CLOUDS MAY LINGER INTO THE EARLY AFTERNOON
AT MOST SITES (ASIDE FROM PERHAPS GLH). VFR CONDITIONS WILL DEVELOP
AS WE GO INTO SATURDAY EVENING...WITH VFR CONDITIONS EXPECTED TO
PREVAIL FOR SUNDAY. /BB/EC/

&&

.PREV DISCUSSION... /ISSUED AT 251 PM CDT FRI APR 20 2012/
SHORT TERM...THROUGH SUNDAY NIGHT...BEST ASCENT WILL MOVE TO THE
SOUTH AND EAST WITH THE MID/UPPER LEVEL ENERGY SATURDAY WITH
COOLER/DRIER AIR MOVING IN SATURDAY. A FEW LEFT OVER SHOWERS MAINLY
IN THE MORNING WILL GIVE WAY TO DECREASING CLOUDS...ESPECIALLY IN
THE WEST BY THE AFTERNOON. DEVELOPING SURFACE LOW PRESSURE IN THE
NORTHERN GULF WILL ALLOW PRESSURE GRADIENT OVER THE CWA TO TIGHTEN
RESULTING IN GUSTY NORTHERLY WINDS UP TO 25 KNOTS POSSIBLE AT TIMES.
GRADIENT LOOKS TO RELAX AFTER SUNSET AS THE LOW QUICKLY MOVES EAST.
SUNDAY LOOKS DRY AND COOL./GRG/

LONG TERM...MONDAY THROUGH FRIDAY...A QUIET LONG TERM PERIOD
EXPECTED WITH BELOW NORMAL TEMPERATURES SUN-TUES WITH PASSAGE OF DRY
RE-ENFORCING COLD FRONT. A WARMING TREND IS EXPECTED INTO THE LATE
WEEK WITH SLIGHT INCREASE IN RAIN CHANCES.

A DEEPLY AMPLIFIED ERN CONUS TROUGH/WRN CONUS RIDGE PATTERN WILL BE
IN PLACE MON-TUES. A STRONG RE-ENFORCING COLD FRONT WILL SWEEP
THROUGH EARLY MONDAY MORNING...PIVOTING A NORTH TO SOUTH GRADIENT OF
0-4C 850MB TEMPS ACROSS THE ARKLAMISS BY THE AFTN. DESPITE THE FULL
SUNSHINE EXPECTED...SFC TEMPS ROUGHLY 10 DEGREES BELOW AVERAGE MON
AFTN ARE PROBABLE WITH READINGS IN THE MID 60S TO NEAR 70. HAVE CUT
A COUPLE OF DEGREES FROM MEXMOS AND TRENDED CLOSER TO EC MOS OUTPUT.

THE ARKLAMISS WILL CONTINUE TO BE UNDER DRY...SUNNY...AND DEEP NW
FLOW TUES AS PATTERN SLOWLY TRANSITIONS BY MID TO LATE WEEK. JUST
HOW QUICK THE TRANSITION WILL OCCUR IS THE QUESTION. THROUGH
WED-FRI...MODELS DIVERGE WITH OPS GFS MORE PROGRESSIVE ON BUILDING
IN H5 RIDGING OVER PLAINS/SE WHILE EC IS SLOWER AND INDICATES
CONTINUED BUT FLATTER NW FLOW REGIME WED BEFORE SOME SLIGHT
RE-AMPLIFICATION OF THE ERN TROUGH THURSDAY. THE GEM/GENS AND
INDIVIDUAL MEMBERS SUGGEST A SLOWER PROGRESSION OF THE RIDGE
BUILDING THAN THE OPS GFS GIVEN POTENTIAL RIDGING STRENGTH AND
ENHANCED BLOCKING. HAVE THUS GONE WITH AN EC/GENS BLEND. EC ENSEMBLE
MEAN FURTHER SUPPORTS STRONGER BLOCKING AND SLOWER MIGRATION OF
RIDGE THROUGH THURS-FRI ACROSS CNTRL CONUS. WITH THAT STATED...SFC
DEWPOINTS SHOULD BEGIN TO RECOVER THU/FRI HAS SFC HIGH SHIFTS FROM
NRN GOM TO SUB-TROPIC ATLANTIC. BY THU...DIURNAL SHOWERS/TSTORMS
LOOK TO BE POSSIBLE AS INSTABILITY INCREASES. WILL HAVE TO KEEP AN
EYE ON ANY POSSIBLE SE DIVING COMPLEX FROM THE MID-MS VALLEY
WED-FRIDAY IF STRONGER BLOCKING OCCURS. HAVE PLACED SOME SLIGHT
CHANCE WEATHER WORDING IN FOR THURS AND FRI AFTN AS HIGH TEMPS
RECOVER INTO THE U70S/L80S. /ALLEN/

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&

DL/BB/EC/GRG/ALLEN

Hazardous weather outlook, Apr 20, 2:37 PM CDT, 6 hours 53 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
237 PM CDT FRI APR 20 2012

LAZ015-023>026-MSZ053-059>062-211945-
RICHLAND-FRANKLIN LA-CATAHOULA-TENSAS-CONCORDIA-CLAIBORNE-
JEFFERSON-ADAMS-FRANKLIN MS-LINCOLN-
237 PM CDT FRI APR 20 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL MISSISSIPPI...
NORTHEAST LOUISIANA...AND EXTREME SOUTHEAST ARKANSAS.

.DAY ONE...TONIGHT AND SATURDAY

A COLD FRONT WILL SWEEP INTO THE AREA THIS EVENING BRINGING A LINE
OF SHOWERS AND THUNDERSTORMS. LIMITED MOISTURE AND INSTABILITY WILL
KEEP THUNDERSTORMS BELOW SEVERE LEVELS...HOWEVER A FEW STORMS WILL
BE CAPABLE OF PRODUCING STRONG WIND GUSTS OF UP TO 40 MPH AND DIME
SIZE HAIL BEFORE 900 PM. THE GREATEST RISK FOR GETTING A FEW STRONG
STORMS WILL BE OVER NORTHEAST LOUISIANA...WITH A DECREASING RISK AS
YOU GO FARTHER EAST INTO SOUTHWEST MISSISSIPPI.

.DAYS TWO THROUGH SEVEN...SATURDAY NIGHT THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS IS NOT EXPECTED THROUGH NEXT THURSDAY.

ARZ074-075-LAZ007>009-016-MSZ018-019-025>052-054>058-063>066-
072>074-211945-
ASHLEY-CHICOT-MOREHOUSE-WEST CARROLL-EAST CARROLL-MADISON LA-
BOLIVAR-SUNFLOWER-LEFLORE-GRENADA-CARROLL-MONTGOMERY-WEBSTER-CLAY-
LOWNDES-CHOCTAW-OKTIBBEHA-WASHINGTON-HUMPHREYS-HOLMES-ATTALA-
WINSTON-NOXUBEE-ISSAQUENA-SHARKEY-YAZOO-MADISON MS-LEAKE-NESHOBA-
KEMPER-WARREN-HINDS-RANKIN-SCOTT-NEWTON-LAUDERDALE-COPIAH-SIMPSON-
SMITH-JASPER-CLARKE-LAWRENCE-JEFFERSON DAVIS-COVINGTON-JONES-
MARION-LAMAR-FORREST-
237 PM CDT FRI APR 20 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL MISSISSIPPI...
NORTHEAST LOUISIANA...AND EXTREME SOUTHEAST ARKANSAS.

.DAY ONE...TONIGHT AND SATURDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...SATURDAY NIGHT THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS IS NOT EXPECTED THROUGH NEXT THURSDAY.

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.SRH.NOAA.GOV/JAN.

EC

In the hours before

Special weather statement, Apr 20, 9:30 PM CDT, 0 minutes before

LAZ024-026-MSZ060-210330-
ADAMS MS-CONCORDIA LA-CATAHOULA LA-
930 PM CDT FRI APR 20 2012

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
930 PM CDT FRI APR 20 2012

...LINE OF STRONG THUNDERSTORMS PUSHING NORTHEAST ACROSS PORTIONS OF
NORTHEASTERN LOUISIANA AND FAR SOUTHWEST MISSISSIPPI...

A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING PEA TO DIME SIZE
HAIL AND 40 TO 50 MPH WINDS WAS LOCATED FROM 12 MILES SOUTHWEST OF
WALTERS TO 15 MILES SOUTHEAST OF BLACK HAWK AT 929 PM CDT...MOVING
NORTHEAST AT 20 MPH.

HIGH WINDS CAN BRING DOWN TREES AND LARGE LIMBS RESULTING IN SERIOUS
INJURY OR PROPERTY DAMAGE. EXERCISE EXTREME CAUTION WHEN OUTDOORS
DURING SUCH STRONG WINDS...AND BE ESPECIALLY AWARE OF OLDER TREES.

PEOPLE IN SOUTHWESTERN ADAMS COUNTY...AND SOUTHERN CATAHOULA AND
CONCORDIA PARISHES SHOULD MONITOR THESE STORMS CLOSELY.

LAT...LON 3160 9201 3171 9179 3136 9129 3131 9146
      3122 9149 3121 9153 3123 9156 3121 9158
      3111 9162 3105 9155 3099 9164 3104 9166
      3104 9173 3120 9170 3122 9179 3129 9191
      3128 9194 3123 9191 3122 9198 3128 9203
TIME...MOT...LOC 0229Z 241DEG 18KT 3144 9215 3098 9148

BYB

The office that day

Everything else NWS Jackson, MS issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 21, 12:33 AM CDT	Special Weather Statement	JAN	Jefferson	32 min
Apr 21, 12:40 AM CDT	Severe Thunderstorm Warning	JAN	Claiborne, Copiah, Jefferson	65 min
Apr 21, 1:05 AM CDT	Severe Thunderstorm Warning	JAN	Copiah	55 min
Apr 21, 10:14 AM CDT	River Flood Warning	JAN	Attala, Holmes	45 hr
Apr 20, 10:23 PM CDT	Special Weather Statement	JAN	Concordia	42 min
Apr 20, 10:25 PM CDT	Special Weather Statement	JAN	Catahoula	60 min

Nearby

Special Weather Statements in Louisiana, 2012 Every special weather statement in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.