April 13th - 14th Severe Weather/Heavy Rain Threat

Looking at the HRRR this afternoon around 3 - 4pm when the storms are firing up we have 2000 j/kg + CAPE, dew points in the mid 70s, CIN of 0

NAM is similar, but with 3000 j/kg CAPE, and SIGTOR of 2.5-3 for a small period.

  

MESOSCALE DISCUSSION 0349
NWS STORM PREDICTION CENTER NORMAN OK
0434 AM CDT MON APR 14 2014

AREAS AFFECTED...NERN LA AND CENTRAL MS

CONCERNING...TORNADO WATCH 79...

VALID 140934Z - 141030Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 79 CONTINUES.

SUMMARY...LOCALLY STRONG WIND GUSTS AND A TORNADO THREAT PERSIST
ACROSS THE SERN PORTION OF WW 79 DURING THE PRE-DAWN HOURS EARLY
THIS MORNING.

DISCUSSION...AT 0920Z...REGIONAL RADAR IMAGERY SHOWED A LINE OF
STORMS IN CENTRAL MS EXTENDING FROM SRN WINSTON TO NRN HINDS
COUNTIES... WITH THIS ACTIVITY MOVING ESEWD AT 35-40 KT.
MEANWHILE...RADAR IMAGERY AND A DIMINISHING TREND IN LIGHTNING DATA
INDICATED THE SQUALL LINE THAT MOVED E/SEWD ACROSS THE MID SOUTH HAS
WEAKENED...WITH THE ATTENDANT CONVECTIVE OUTFLOW APPROACHING THE
AFOREMENTIONED BAND OF STORMS IN CENTRAL MS. LOW-LEVEL AND DEEP
LAYER SHEAR HAS INCREASED GIVEN A 60 KT SSWLY LLJ BENEATH A 60 KT
SWLY 500 MB JET PER JAN WSR-88D VAD...WITH SFC-1 KM SHEAR EXCEEDING
40 KT. WEAKER INSTABILITY OVER CENTRAL MS /MUCAPE AOB 500 J PER KG/
MAY BE TENDING TO LIMIT THE POTENTIAL FOR MORE ROBUST/SUSTAINED AND
ORGANIZED STORMS. HOWEVER...TRENDS WILL CONTINUE TO BE MONITORED AS
THE OUTFLOW BOUNDARY MERGES WITH AND POTENTIALLY ENHANCES UPDRAFTS.
THUS...AVAILABLE KINEMATICS SUGGEST LOCALLY STRONG WIND GUSTS AND/OR
A TORNADO CANNOT BE RULED OUT.

The tornado watch has been cancelled for central MS and northeast LA. The main threat from these storms is heavy rain and flooding.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
545 AM CDT MON APR 14 2014

...STRONG TO SEVERE THUNDERSTORMS AND VERY HEAVY RAINFALL POSSIBLE
TODAY AND EARLY TONIGHT...

.SYNOPSIS...

COLD FRONT AT 3 AM EXTENDED FROM ST. LOUIS TO TEXARKANA TO THE
BIG BEND OF TEXAS. A PRE-FRONTAL BAND OF CONVECTION HAS SAGGED
SOUTH TO INTERSTATE 20. ANOTHER BAND OF CONVECTION HAS BEEN
ASSOCIATED WITH THE COLD FRONT...BUT HAS BECOME DRIVEN BY A COLD
POOL ON THE NORTH END AND HAS CAUGHT UP TO THE PREFRONTAL
CONVECTION. IT APPEARS THAT ALL CONVECTION WILL REMAIN NORTH AND
WEST OF THE AREA THROUGH SUNRISE...ALTHOUGH PERHAPS JUST BARELY.
SOUTHEAST WINDS AT 10 TO 20 MPH ARE HOLDING TEMPERATURES UP IN THE
LOWER 70S THIS MORNING WITH DEW POINTS IN THE UPPER 60S.

&&

.SHORT TERM...

THROUGH TUESDAY NIGHT...

INITIAL SHORTWAVE TROUGH AND ASSOCIATED STRONG COLD FRONT AND
OUTFLOW BOUNDARIES HAVE BEEN PUSHING INTO MID/LOWER MISSISSIPPI
VALLEY...AND THIS HAS BEEN THE FOCUS FOR STRONG THUNDERSTORMS AND
TORRENTIAL RAINFALL ACROSS PORTIONS OF THE ARK-LA-MISS AREA THE LAST
SEVERAL HOURS. THIS HAS GENERATED A COLD POOL AND MERGED BOUNDARIES
OVER CENTRAL MISSISSIPPI WHERE FLASH FLOOD WARNINGS HAVE BEEN ISSUED
DUE TO REPEAT THUNDERSTORMS AND EXTREMELY EFFICIENT RAINFALL
PRODUCTION. OUTFLOW WILL LIKELY CAUSE SHOWERS AND THUNDERSTORMS TO
DEVELOP SOUTH ACROSS SOUTHWEST AND SOUTH CENTRAL MISSISSIPPI EARLY
THIS MORNING...POSSIBLY CROSSING OVER INTO THE ADJACENT UPPER
SOUTHEAST LOUISIANA PARISHES DURING THE MORNING. THERE SHOULD BE
A LULL PERIOD AS FAR AS SUPPORT FOR SEVERE THUNDERSTORMS AND
PERSISTENT HEAVY RAINFALL AS THE MORNING PROGRESSES AND ACTIVITY
MOVES INTO THE FORECAST AREA...HOWEVER AN ISOLATED STRONG TO SEVERE
STORM CANNOT BE RULED OUT ACROSS THE FAR NORTHERN AREAS.

THE FIRST SHORTWAVE WILL LIFT AWAY FROM THE AREA BY LATE MORNING. A
STRONGER LONGWAVE TROUGH WILL DEVELOP AND MOVE ACROSS THE PLAINS/MS
VALLEY TODAY AND TONIGHT WITH AN ASSOCIATED COLD FRONT MOVING
THROUGH SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI LATE THIS
AFTERNOON AND EVENING. PWS OF 1.6-1.9 INCHES WILL POOL AHEAD OF THE
FRONT WHICH WILL BE FROM NEAR TWO STANDARD DEVIATIONS TO THE 99TH
PERCENTILE OF CLIMATOLOGY FOR MID APRIL. INSTABILITY WILL BE RATHER
IMPRESSIVE WITH SURFACE BASED CAPE 2000 TO 3000 J/KG...MEAN LAYER
CAPE OF 1500-2000 J/KG AND LIS OF -4 TO -8 FROM AROUND MIDDAY
THROUGH AT LEAST MID AFTERNOON. SHEAR PROFILES ARE NOT IDEAL FOR
TORNADOES...BUT STILL ADEQUATE TO SUPPORT A BRIEF WINDOW FOR
SUPERCELLS BEFORE CONVECTION BECOMES MOSTLY LINEAR. EVEN AFTER
THUNDERSTORMS BECOME LINEAR...THERE COULD STILL BE THE POTENTIAL FOR
A FEW STORMS EMBEDDED IN THE SQUALL LINE TO ROTATE AND PRODUCE A
BRIEF TORNADO. OTHERWISE...THE MAIN CONCERNS WILL BE FOR STRONG TO
DAMAGING WINDS ALONG BOWING SEGMENTS...FREQUENT LIGHTNING...AND
POTENTIAL FLASH FLOODING FROM ANY SLOW MOVING BANDS OF THUNDERSTORMS
WITH TORRENTIAL RAINFALL.

HAVE ISSUED A FLASH FLOOD WATCH THIS AFTERNOON AND EVENING FOR AREAS
SOUTH OF THE TIDAL LAKES...ST. TAMMANY PARISH...AND THE MISSISSIPPI
GULF COAST WHERE THE COMBINATION OF THE BEST INITIALIZED ECMWF AND
THE SUITE OF MESOSCALE BASED MODELS ARE SHOWING THE HEAVIEST
RAINFALL DURING PEAK HEATING AND AHEAD OF THE COLD FRONT THIS
AFTERNOON AND EVENING. JUST BASED OFF THE SYNOPTIC PATTERN AND ECMWF
QPF...MOST AREAS SHOULD EXPERIENCE AT LEAST 1 TO 3 INCHES. A MAJOR
CONCERN OF PROPAGATION VECTORS COULD BE EXACTLY OPPOSED TO THE MEAN
STEERING CURRENTS WHICH COULD RESULT IN BACK-BUILDING OR
REGENERATIVE THUNDERSTORMS ALONG LINE SEGMENTS. THIS SUPPORTS SOME
OF THE WRF MODELS THAT INDICATE AS MUCH AS 3 TO 6 INCHES OF RAIN
OVER SOME AREAS FROM SOUTH OF LAKE PONTCHARTRAIN TO NEAR OR JUST
OFFSHORE FROM THE MISSISSIPPI GULF COAST.

OTHER BIG CONCERN WILL BE STRONG WINDS DEVELOPING BEHIND THE COLD
FRONT. NUMEROUS CONSECUTIVE RUNS OF THE MAV MOS FOR KNEW/LAKEFRONT
AIRPORT HAVE INDICATED AROUND 40 KNOTS OR GREATER DURING THE PERIOD
FROM 1 AM TO 7 AM TONIGHT/EARLY TUESDAY MORNING. MOST OF THE MODELS
INDICATE AT LEAST 35 KNOTS AT THE 925 MB LEVEL DEVELOPING ACROSS
MUCH OF THE COASTAL AREAS DURING THIS TIME FRAME...AND THERE WILL
LIKELY BE SUFFICIENT SUBSIDENCE TO BRING THESE WINDS DOWN TO THE
SURFACE AT LEAST IN GUSTS. AM ANTICIPATING NORTH WINDS WILL EASILY
BE IN THE 25 TO 35 MPH RANGE OVER MOST AREAS JUST INLAND FROM THE
SOUTH SHORE OF THE TIDAL LAKES...AND NEAR THE EXTREME SOUTHEAST
LOUISIANA COAST. IT IS POSSIBLE AS INDICATED IN THE MOS GUIDANCE
THAT THE IMMEDIATE LAKEFRONT OF THE SOUTHSHORE COULD BE IN HIGH WIND
WARNING CRITERIA OF 40 TO 45 MPH FOR A FEW HOURS. HAVE DECIDED NOT
TO GO WITH A HIGH WIND WARNING OR WATCH AT THIS TIME...BUT HAVE
ISSUED A STRONGLY WORDED WIND ADVISORY ADDRESSING THE POTENTIAL FOR
STRONGER WINDS DURING THE LATE NIGHT AND EARLY TUESDAY MORNING
HOURS. AS IS OFTEN THE CASE IN SUCH STRONG NORTHERLY WINDS...LARGE
BATTERING WAVES ON THE SOUTH SHORE OF LAKE PONTCHARTRAIN COULD CAUSE
MINOR FLOODING OF LOW LYING AREAS OUTSIDE THE HURRICANE PROTECTION
LEVEE SYSTEM...LIKE ON THE LOW LYING SECTIONS OF LAKESHORE DRIVE IN
NEW ORLEANS. THIS HAS ALSO BEEN MENTIONED IN THE WIND ADVISORY
PRODUCT.

AFTER A WARMER THAN NORMAL SPELL...AN UNSEASONABLY COLD AND MUCH
DRIER AIRMASS WILL TAKE HOLD TUESDAY INTO TUESDAY NIGHT...AND
TEMPERATURES HAVE TRENDED LOWER TUESDAY NIGHT WHEN A BRIEF LIGHT
FREEZE COULD OCCUR IN SOME OF THE COLDER NORTHERN LOCATIONS.

22/TD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSON MS
705 AM CDT MON APR 14 2014

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

0530 AM FLASH FLOOD LUDLOW 32.57N 89.71W
04/14/2014 SCOTT MS LAW ENFORCEMENT

PARTS OF RIVER BEND RD AROUND LUDLOW ARE UNDER WATER.


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