Severe Thunderstorm Warning 54, NWS New Orleans, LA

Area Forecast Discussion
National Weather Service New Orleans LA
351 PM CDT Sun Apr 2 2017

.SYNOPSIS...

Surface low pressure centered over east Texas this afternoon with
a warm front extending eastward that is approaching Interstate 20.
This puts our entire CWA in the warm sector with temperatures in
the mid 70s to lower 80s and dew points in the mid 60s to lower
70s. Line of thunderstorms ahead of the low extends from near
Shreveport to Houston at 3 pm with scattered strong to severe
storms in advance of that line across the western half of
Louisiana. Some of the storms in that area have been tornadic this
afternoon. No significant precipitation in the CWA at 3 pm, but
thunderstorms are approaching the Atchafalaya River Basin.

&&

.SHORT TERM...

Main weather issues are in the first 24 hours of the forecast.
Upper low over Texas appears to be about to take on a negative
tilt, which may cause the best divergence to be somewhat north of
earlier expectations. Will still keep Flash Flood Watch in place
with 2-4 inch totals more common than the earlier 3-6 inch totals
mentioned. 18z sounding still showed precipitable water values
around 1.6 inches and likely still increasing with moderate
southerly flow. All modes of severe weather still in play with
Moderate Risk of severe weather north of Interstate 12. Have
trimmed a bit of the wind advisory, mainly over the Baton Rouge
area, but left the rest as is. Coastal Flood Advisory will also
remain in effect.

Timing of main line is crossing Atchafalaya River a little after
midnight and exiting the Mississippi coast by 9 or 10 am. Still
could have scattered severe with supercells in advance of the main
line, so people need to stay weather aware all evening. Should
quickly dry out during the afternoon Monday with dry weather
expected Tuesday. Next shortwave moves through the Middle
Mississippi River Valley Tuesday night into Wednesday. This will
push another front through the area, but with little recovery time
for moisture return, rain chances should be less than with the
current system.

Temperatures will remain well above normal through the short term
portion of the forecast with the possible exception of Monday
night/Tuesday morning, which could be a little cooler than the
other two nights. 35

&&

.LONG TERM...

High pressure will control the weather across the area for
Thursday through the weekend. No precipitation expected through
that period. Somewhat cooler temperatures expected, with below
normal temperatures expected for Thursday through Friday night,
then warming again. Have used a blend of guidance. 35

&&

.AVIATION...

General MVFR to IFR conditions expected through 18z Monday with
mention of convection across all terminals.

&&

.MARINE...

Have left Small Craft Advisories in place. Could see some gusts to
gale force overnight and early tomorrow morning, but not confident
that there will be enough gusts to justify Gale Warning. Mariners
should be prepared for a line of thunderstorms to move through the
coastal waters overnight though. Conditions not likely to ease
until tomorrow evening. Will get back into headline criteria with
next system on Wednesday.

&&

.DECISION SUPPORT...

DSS CODE...Orange.
DEPLOYED...None.
ACTIVATION...High Impact and coordinators desk, Ozone and Baton
             Rouge Amateur Radio clubs.
ACTIVITIES...Short fused warnings, EM support

Decision Support Service (DSS) Code Legend:
GREEN  = No weather impacts that require action
BLUE   = Long fused Watch/Warning/Advisory in effect or high
         visibility event
YELLOW = Heightened impacts with short fused
         Watch/Warning/Advisory issuances; Radar support
ORANGE = High Impacts - Slight to Moderate risk of severe weather;
         Nearby tropical events, HAZMAT or other large episodes
RED    = Full engagement for moderate risk of severe weather; Direct
         tropical threats; events of national significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  67  81  57  86 / 100  40  10   0
BTR  68  81  59  85 / 100  20   0   0
ASD  72  83  61  84 /  90  70  10   0
MSY  70  82  63  85 /  90  60  10   0
GPT  74  80  65  81 /  70  90  10   0
PQL  71  83  61  84 /  60 100  10   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Flash Flood Watch through Monday afternoon for LAZ034>037-039-
     040-046>050-056>072.

     Coastal Flood Advisory until 7 PM CDT Monday for LAZ040-050-058-
     062-064-066>070-072.

     Wind Advisory from 7 PM this evening to 10 AM CDT Monday for
     LAZ040-059>070.

GM...Small Craft Advisory until 1 PM CDT Monday for GMZ530-532-534-
     536-538-550-552-555-557-570-572-575-577.

MS...Flash Flood Watch through Monday afternoon for MSZ068>071-077-
     080.

     Coastal Flood Advisory until 7 PM CDT Monday for MSZ080>082.

     Wind Advisory from 7 PM this evening to 10 AM CDT Monday for
     MSZ080>082.

GM...Small Craft Advisory until 1 PM CDT Monday for GMZ532-534-536-
     538-550-552-555-557-570-572-575-577.

&&

Hazardous Weather Outlook
National Weather Service New Orleans LA
416 PM CDT Sun Apr 2 2017

GMZ530-532-534-536-538-550-552-555-557-570-572-575-577-LAZ034>037-
039-040-046>050-056>072-MSZ068>071-077-080>082-030930-
Lake Pontchartrain and Lake Maurepas-Mississippi Sound-
Lake Borgne-Chandeleur Sound-Breton Sound-
Coastal Waters from Port Fourchon LA to Lower Atchafalaya River
LA out 20 nm-
Coastal waters from the Southwest Pass of the Mississippi River
to Port Fourchon Louisiana out 20 NM-
Coastal Waters from Boothville LA to Southwest Pass of the
Mississippi River out 20 nm-
Coastal waters from Pascagoula Mississippi to Stake Island out
20 NM-
Coastal waters from Port Fourchon Louisiana to Lower Atchafalaya
River LA from 20 to 60 NM-
Coastal waters from Southwest Pass of the Mississippi River to
Port Fourchon Louisiana from 20 to 60 NM-
Coastal Waters from Stake Island LA to Southwest Pass of the
Mississippi River from 20 to 60 nm-
Coastal waters from Pascagoula Mississippi to Stake Island
Louisiana out 20 to 60 NM-Pointe Coupee-West Feliciana-
East Feliciana-St. Helena-Washington-St. Tammany-Iberville-
West Baton Rouge-East Baton Rouge-Ascension-Livingston-Assumption-
St. James-St. John The Baptist-Upper Lafourche-St. Charles-
Upper Jefferson-Orleans-Upper Plaquemines-Upper St. Bernard-
Upper Terrebonne-Lower Terrebonne-Lower Lafourche-Lower Jefferson-
Lower Plaquemines-Lower St. Bernard-Northern Tangipahoa-
Southern Tangipahoa-Wilkinson-Amite-Pike-Walthall-Pearl River-
Hancock-Harrison-Jackson-
416 PM CDT Sun Apr 2 2017

This Hazardous Weather Outlook is for portions of Southeast
Louisiana...South Mississippi and the adjacent coastal waters.

.DAY ONE...Tonight

A moderate risk of severe thunderstorms exists through tonight
for all of southwest Mississippi, as well as portions of
southeast Louisiana north of a line from Franklinton to New
Roads. An enhanced risk of severe thunderstorms exists through
tonight for much of the remainder of southeast Louisiana along and
west of a line from Slidell to Galliano; while a slight risk of
severe thunderstorms will exist for areas to the east of this
line. Severe thunderstorms associated with this scenario will be
capable of producing tornadoes, strong damaging winds of 60 to 75
mph, and large hail quarter to golf ball size diameters.

A moderate risk of excessive rainfall exists through Monday
morning for Wilkinson County, East and West Feliciana Parishes,
East and West Baton Rouge Parishes, Pointe Coupee Parish, and
Iberville Parish. Elsewhere, a slight risk of excessive rainfall
will exist during the same time.

A flash flood watch is in effect through 3 pm Monday. Total
rainfall accumulations through Monday are expected to be 3 to 6
inches with isolated higher amounts possible.

A wind advisory will begin at 7 pm today through 10 am Monday for
winds around 25 mph with higher gusts. This will include much of
the area south of the interstate 10/12 corridor.

A coastal flood advisory will begin at 1 pm today through 7 pm
Monday for most coastal counties and parishes as tides should
rise to 1 to 2 feet above normal.

A small craft advisory will begin at 6 pm today through 1 pm
Monday.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

All warnings, advisories, and risk levels are expected to lower
through the day Monday. Otherwise, no hazardous weather is
expected.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is requested through at least 9 am Monday
morning for severe thunderstorm and flash flood monitoring and
support.

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Special Weather Statement
National Weather Service New Orleans LA
352 PM CDT SUN APR 2 2017

LAZ034-035-MSZ068-022115-
Pointe Coupee-West Feliciana-Wilkinson-
352 PM CDT SUN APR 2 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN WEST FELICIANA...
NORTHWESTERN POINTE COUPEE PARISHES IN SOUTHEASTERN LOUISIANA AND
SOUTHWESTERN WILKINSON COUNTIES...

At 352 PM CDT, a strong thunderstorm was located near Bayou Current,
moving northeast at 55 mph.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Fort Adams and Lettsworth.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3087 9180 3098 9180 3104 9172 3104 9165
      3097 9166 3098 9165 3104 9156 3107 9156
      3111 9163 3122 9158 3124 9155 3122 9153
      3123 9149 3126 9148 3128 9150 3128 9148
      3119 9132 3082 9174 3081 9181 3086 9182
TIME...MOT...LOC 2052Z 213DEG 47KT 3087 9176

24/RR

Special Weather Statement
National Weather Service New Orleans LA
421 PM CDT SUN APR 2 2017

LAZ034-035-MSZ068-022145-
Pointe Coupee-West Feliciana-Wilkinson-
421 PM CDT SUN APR 2 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN WEST FELICIANA...
NORTHWESTERN POINTE COUPEE PARISHES IN SOUTHEASTERN LOUISIANA AND
SOUTHWESTERN WILKINSON COUNTIES...

At 420 PM CDT, a strong thunderstorm was located near Palmetto,
moving northeast at 50 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Fort Adams, Lettsworth and Batchelor.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3087 9180 3094 9180 3105 9167 3103 9164
      3097 9166 3100 9164 3103 9157 3106 9156
      3110 9161 3114 9156 3093 9136 3071 9174
      3074 9176 3078 9176 3081 9181 3084 9180
      3086 9182
TIME...MOT...LOC 2120Z 230DEG 43KT 3075 9187

24/RR

Special Weather Statement
National Weather Service New Orleans LA
457 PM CDT SUN APR 2 2017

LAZ034>036-047-048-022230-
East Feliciana-Pointe Coupee-West Baton Rouge-West Feliciana-East
Baton Rouge-
457 PM CDT SUN APR 2 2017

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN WEST FELICIANA...
NORTH CENTRAL WEST BATON ROUGE...SOUTHEASTERN POINTE COUPEE...EAST
FELICIANA AND NORTHWESTERN EAST BATON ROUGE PARISHES...

At 456 PM CDT, a strong thunderstorm was located near New Roads,
moving northeast at 60 mph.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Zachary, New Roads, Jackson, St. Francisville, Clinton, Slaughter,
Wilson, Norwood and Felps.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3100 9121 3100 9090 3096 9085 3054 9138
      3066 9153
TIME...MOT...LOC 2156Z 223DEG 53KT 3066 9140

24/RR