Special Weather Statement, 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
840 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>082-031345-
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-
840 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

An enhanced risk of severe thunderstorms exists tonight for much
of southeast Louisiana and southern Mississippi north and west of
a line from Gulfport to New Orleans to Thibodaux. There is a
slight risk of severe thunderstorms for the remainder of the area.
Severe thunderstorms will be capable of producing tornadoes,
strong damaging winds of 60 to 75 mph, and large hail as large as
quarter to golf ball size.

A moderate risk of excessive rainfall exists through Monday
morning for Wilkinson County Mississippi. A slight risk of
excessive rainfall exists for portions of southern Mississippi and
southeast Louisiana to the north of a line from Poplarville to
Hammond to Baton Rouge, with a marginal risk to the south of that
line.

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 is in effect 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 is in effect 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 is in effect through 1 pm Monday for all
coastal waters.

.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.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
644 PM CDT SUN APR 02 2017

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

0638 PM     HAIL             5 SSW LIBERTY           31.09N 90.83W
04/02/2017  E0.75 INCH       AMITE              MS   EMERGENCY MNGR

            DIME TO PENNY SIZE HAIL REPORTED NEAR UNITY CHURCH ALONG
            HIGWAY 569.

&&

GPHILLIP

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

LAZ049-050-057-058-072-030115-
Livingston LA-Ascension LA-Southern Tangipahoa LA-
St. John The Baptist LA-St. James LA-
722 PM CDT SUN APR 2 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN ST. JOHN THE
BAPTIST...EAST CENTRAL ASCENSION...NORTHEASTERN ST. JAMES...
SOUTHEASTERN LIVINGSTON AND SOUTHERN TANGIPAHOA PARISHES UNTIL 815 PM
CDT...

At 722 PM CDT, Doppler radar was tracking a strong thunderstorm near
Sorrento, or 10 miles east of Gonzales, moving northeast at 50 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Hammond, Ponchatoula, Gramercy, Lutcher, Sorrento, French Settlement,
Albany, Springfield, Natalbany, Robert, Whitehall, Garyville, Killian
and Tickfaw.

A tornado watch remains in effect until 200 AM CDT for southeastern
Louisiana.

LAT...LON 3045 9024 3030 9043 3032 9043 3034 9048
      3030 9054 3030 9056 3026 9058 3022 9057
      3020 9060 3017 9058 3004 9073 3016 9089
      3068 9043 3068 9039
TIME...MOT...LOC 0022Z 220DEG 42KT 3016 9075

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

LAZ034-036-046>048-030130-
Iberville LA-East Feliciana LA-Pointe Coupee LA-West Baton Rouge LA-
East Baton Rouge LA-
749 PM CDT SUN APR 2 2017

...SIGNIFICANT WEATHER ADVISORY FOR WEST BATON ROUGE...SOUTHEASTERN
POINTE COUPEE...SOUTHWESTERN EAST FELICIANA...CENTRAL IBERVILLE AND
EAST BATON ROUGE PARISHES UNTIL 830 PM CDT...

At 748 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from Rosedale to 9 miles west of Bayou Sorrel.
Movement was northeast at 50 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Baton Rouge, Zachary, Baker, Plaquemine, Port Allen, Addis, Brusly,
Maringouin, Slaughter, Rosedale, Grosse Tete, Merrydale, Erwinville,
Ramah, Brownfields and Baton Rouge Airport.

A tornado watch remains in effect until 200 AM CDT for southeastern
Louisiana.

LAT...LON 3066 9134 3065 9131 3068 9131 3091 9104
      3061 9099 3043 9109 3012 9147 3019 9147
      3020 9149 3023 9148 3024 9151 3024 9155
      3046 9157
TIME...MOT...LOC 0048Z 217DEG 45KT 3042 9148 3016 9150

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

LAZ039-040-071-072-030130-
Washington LA-Northern Tangipahoa LA-Southern Tangipahoa LA-
St. Tammany LA-
751 PM CDT SUN APR 2 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN ST. TAMMANY...
SOUTHERN TANGIPAHOA AND WESTERN WASHINGTON PARISHES UNTIL 830 PM
CDT...

At 751 PM CDT, Doppler radar was tracking a strong thunderstorm over
Springfield, or 7 miles south of Hammond, moving northeast at 50 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Hammond, Franklinton, Ponchatoula, Folsom, Springfield, Robert, Enon
and Natalbany.

A tornado watch remains in effect until 200 AM CDT for southeastern
Louisiana.

LAT...LON 3076 8991 3032 9043 3037 9050 3038 9050
      3039 9051 3041 9052 3043 9055 3045 9055
      3094 9014
TIME...MOT...LOC 0051Z 222DEG 42KT 3040 9050

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

LAZ036-037-048-MSZ069-070-030230-
St. Helena LA-East Feliciana LA-East Baton Rouge LA-Pike MS-Amite MS-
850 PM CDT SUN APR 2 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN ST. HELENA...EASTERN
EAST FELICIANA AND NORTHEASTERN EAST BATON ROUGE PARISHES...
SOUTHWESTERN PIKE AND SOUTHEASTERN AMITE COUNTIES UNTIL 930 PM CDT...

At 849 PM CDT, Doppler radar was tracking a strong thunderstorm over
Pride, or 9 miles south of Clinton, moving northeast at 55 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Mccomb, Magnolia, Summit, Darlington, Gillsberg, Easleyville and
Mccomb Airport.

A tornado watch remains in effect until 200 AM CDT for southeastern
Louisiana...and southern Mississippi.

LAT...LON 3116 9031 3100 9050 3100 9057 3094 9057
      3067 9088 3073 9110 3134 9055
TIME...MOT...LOC 0149Z 221DEG 48KT 3073 9097

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

LAZ037-071-MSZ069>071-030330-
St. Helena LA-Northern Tangipahoa LA-Pike MS-Walthall MS-Amite MS-
939 PM CDT SUN APR 2 2017

...SPECIAL WEATHER STATEMENT...

At 939 PM CDT, Doppler radar was tracking a strong thunderstorm near
Easleyville, or 9 miles north of Greensburg, moving northeast at 60
mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Mccomb, Magnolia, Kentwood, Summit, Osyka, Gillsberg, Easleyville and
Mccomb Airport.

A tornado watch remains in effect until 200 AM CDT for southeastern
Louisiana...and southern Mississippi.

LAT...LON 3124 9016 3084 9064 3096 9080 3135 9045
      3135 9030
TIME...MOT...LOC 0239Z 220DEG 52KT 3097 9065