Alert archive / Louisiana / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 181, NWS New Orleans, LA

October 16, 2009Assumption Parish, Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Oct 16, 2009, 3:42 AM CDT for Assumption Parish, Louisiana. It was in force for 48 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Oct 16, 2009, 3:42 AM CDT (08:42 UTC)
Expired: Oct 16, 2009, 4:30 AM CDT
In force: 48 min
Issued by: NWS New Orleans, LA
Area: Storm-based polygon

County Assumption Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 8.7 hours before the alert went out and 137 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: 3175 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 930 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 96 m²/s²
0-3 km storm-relative helicity: 127 m²/s²
Significant tornado parameter: 1.8
Supercell composite: 8.0

Open this sounding in Storm Lab

What forecasters said that day

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

NWS New Orleans, LA wrote its last area forecast discussion before this severe thunderstorm warning went out at Oct 15, 11:46 PM CDT, 3 hours 56 minutes earlier.

Area forecast discussion, Oct 15, 11:46 PM CDT, 3 hours 56 minutes before

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Hazardous weather outlook, Oct 15, 7:00 PM CDT, 8 hours 42 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
700 PM CDT THU OCT 15 2009

GMZ530-550-555-570-575-LAZ034>040-046>050-056>070-MSZ068>071-077-
080>082-161200-
PASCAGOULA TO SW PASS MISSISSIPPI RIVER OUT 20 NM-
PASCAGOULA TO SW PASS MISSISSIPPI RIVER 20-60 NM OUT-
SW PASS MISSISSIPPI RIVER TO ATCHAFALAYA RIVER OUT 20 NM-
SW PASS MISSISSIPPI RIVER TO ATCHAFALAYA RIVER 20-60 NM OUT-AMITE-
ASCENSION-ASSUMPTION-EAST BATON ROUGE-EAST FELICIANA-HANCOCK-
HARRISON-IBERVILLE-JACKSON-LAKES PONTCHARTRAIN AND MAUREPAS-
LIVINGSTON-LOWER JEFFERSON-LOWER LAFOURCHE-LOWER PLAQUEMINES-
LOWER ST BERNARD-LOWER TERREBONNE-ORLEANS-PEARL RIVER-PIKE-
POINTE COUPEE-ST CHARLES-ST HELENA-ST JAMES-ST JOHN THE BAPTIST-
ST TAMMANY-TANGIPAHOA-UPPER JEFFERSON-UPPER LAFOURCHE-
UPPER PLAQUEMINES-UPPER ST BERNARD-UPPER TERREBONNE-WALTHALL-
WASHINGTON-WEST BATON ROUGE-WEST FELICIANA-WILKINSON-
700 PM CDT THU OCT 15 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF COASTAL WATERS
OF SOUTHEAST LOUISIANA AND SOUTH MISSISSIPPI...SOUTHEAST
LOUISIANA AND SOUTHERN MISSISSIPPI.

.DAY ONE...TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT FOR ALL OF
COASTAL AND SOUTHWEST MISSISSIPPI AS WELL AS PORTIONS OF SOUTHEAST
LOUISIANA NORTH OF THE INTERSTATE 10/12 CORRIDOR. A MORE GENERAL
RISK OF STRONG THUNDERSTORMS EXISTS OVER THE REMAINDER OF SOUTHEAST
LOUISIANA THROUGH TONIGHT. MOST OF THESE THUNDERSTORMS SHOULD REMAIN
BELOW SEVERE LIMITS...BUT AN ISOLATED SEVERE THUNDERSTORM WILL BE
POSSIBLE. THESE THUNDERSTORMS COULD PRODUCE FREQUENT LIGHTNING
STRIKES...HEAVY DOWNPOURS...AND STRONG GUSTY WINDS IN EXCESS OF 45
MPH. SOME PONDING OF WATER IN LOW LYING AND POOR DRAINAGE AREAS CAN
BE EXPECTED WITH THE HEAVIER DOWNPOURS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

STRONG NORTHERLY WINDS IN THE WAKE OF THE COLD FRONT WILL RESULT
IN HAZARDOUS SEAS AND WAVES ACROSS THE TIDAL LAKES AND COASTAL
WATERS EARLY FRIDAY MORNING THROUGH EARLY SUNDAY AFTERNOON. THERE
COULD BE FREQUENT GUSTS EXCEEDING GALE FORCE LATE SATURDAY AFTERNOON
AND SATURDAY NIGHT. A SMALL CRAFT ADVISORY IS IN EFFECT FROM FRIDAY
INTO SUNDAY MORNING FOR ALL OF THE COASTAL WATERS AND TIDAL LAKES
...AND A GALE WARNING MAY BE NECESSARY ON SATURDAY AND SATURDAY
NIGHT ACROSS THE GULF COASTAL WATERS.

NO HAZARDOUS WEATHER IS EXPECTED MONDAY THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS...MAY BE NEEDED TONIGHT...BUT OTHERWISE IS NOT EXPECTED
THROUGH NEXT WEDNESDAY.

32

In the hours before

Local storm report, Oct 15, 11:13 PM CDT, 4 hours 29 minutes before

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Special weather statement, Oct 16, 1:02 AM CDT, 2 hours 40 minutes before

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Local storm report, Oct 16, 1:53 AM CDT, 1 hour 49 minutes before

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Local storm report, Oct 16, 2:08 AM CDT, 1 hour 34 minutes before

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Local storm report, Oct 16, 2:13 AM CDT, 1 hour 29 minutes before

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Local storm report, Oct 16, 2:15 AM CDT, 1 hour 27 minutes before

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The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 15, 8:11 PM CDT	Areal Flood Advisory	LIX	East Feliciana, Saint Helena	2 hr
Oct 15, 8:34 PM CDT	Severe Thunderstorm Warning	LIX	Washington	34 min
Oct 15, 8:46 PM CDT	Flash Flood Warning	LIX	Washington	3 hr
Oct 15, 9:52 PM CDT	Special Marine Warning	LIX		53 min
Oct 15, 10:42 PM CDT	Special Marine Warning	LIX		48 min
Oct 16, 12:03 AM CDT	Special Marine Warning	LIX		57 min
Oct 16, 12:58 AM CDT	Special Marine Warning	LIX		62 min
Oct 16, 1:22 AM CDT	Severe Thunderstorm Warning	LIX	Lafourche, Saint Charles	38 min
Oct 16, 2:49 AM CDT	Special Marine Warning	LIX		56 min
Oct 16, 7:40 AM CDT	River Flood Warning	LIX	Saint Tammany	24 hr
Oct 16, 11:36 AM CDT	River Flood Warning	LIX	Saint Tammany	13 days
Oct 15, 7:24 PM CDT	Areal Flood Advisory	LIX	Pearl River	111 min
Oct 15, 8:20 PM CDT	Areal Flood Advisory	LIX	Amite, Wilkinson	115 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2009 Every severe thunderstorm warning in 2009

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.