Gulf Coast Tornado Outbreak next Tuesday?

[Ed Mahmoud]

Negative tilted trough, and strong 850 mb wind fields. If Euro is right, I'd day we are a week from a significant Louisiana/Mississippi/Alabama and vicinity severe weather outbreak.

[Aslkahuna]

That impulse will be coming through AZ some 36 hours earlier so you will get to see how energetic it is when it does so.

Steve

[Ed Mahmoud]

GFS predicts a neutral or even slightly positively tilted trough, and a weaker surface low.

[Ed Mahmoud]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CST WED DEC 31 2008

VALID 031200Z - 081200Z

...DISCUSSION...
GFS AND ECMWF REMAIN FAIRLY CONSISTENT THROUGH DAY 5 /SUN.
1-4/...BUT BEGIN DIVERGING DAY 6 -- PARTICULARLY FROM THE LATTER
HALF OF DAY 6 ONWARD. THE MODEL DIFFERENCES BETWEEN THE TWO
DETERMINISTIC MODELS ARE GREATER THAN 24 HOURS AGO...AND LIKEWISE
MORE SPREAD IS EVIDENT WITHIN THE MOST RECENT NCEP MEDIUM-RANGE
ENSEMBLE RUN.

A VERY LIMITED SEVERE POTENTIAL IS EVIDENT DAY 4 /SAT. 1-3/ ACROSS
ERN PORTIONS OF THE SRN PLAINS AND INTO THE LOWER MS VALLEY
REGION...AS A SURFACE LOW -- AND ASSOCIATED WARM SECTOR -- SHIFTS
EWD WITH TIME FROM THE CENTRAL HIGH PLAINS INTO TO THE LOWER OH
VALLEY VICINITY.

GREATER POTENTIAL THREAT HOWEVER STILL APPEARS POSSIBLE BEGINNING
LATE DAY 6...AS A STRONGER UPPER TROUGH -- A PIECE OF WHICH IS
PROGGED TO CROSS NRN MEXICO AND THE SWRN/S CENTRAL CONUS --
APPROACHES. WHILE THE GFS IS MUCH FARTHER S WITH THE RESULTING
SURFACE CYCLOGENESIS THAN PRIOR RUNS...KEEPING THE LOW INVOF THE
GULF COAST...THE ECMWF -- AND TO A LESSER DEGREE THE MREF --
CONTINUE TO DEPICT A LOW MOVING NEWD ACROSS THE LOWER MS VALLEY INTO
THE TN VALLEY/MID-SOUTH REGION. THOUGH SEVERE POTENTIAL IN THE GFS
WOULD LIKELY REMAIN CONFINED TO THE GULF COASTAL REGION AT
BEST...THE ECMWF AND MREF STILL IMPLY A THREAT FOR A FAIRLY
SUBSTANTIAL SEVERE EVENT FARTHER INLAND ACROSS THE SOUTHEAST QUARTER
OF THE CONUS FOR DAY 7 /TUE. 1-6/. DESPITE THE CONTINUED
POTENTIAL...WILL REFRAIN ONCE AGAIN FROM HIGHLIGHTING A THREAT AREA
THIS FORECAST...AS MODEL DIFFERENCES STILL CAST DOUBT UPON THE
OVERALL PREDICTABILITY OF THIS SYSTEM.

..GOSS.. 12/31/2008

[Ed Mahmoud]

GFS about 12 hours faster than the Canadian, both show a surface low moving onshore from the Gulf, putting parts of the Eastern Gulf in the warm sector.

Monday evening, GFS shows low coming ashore, MU CAPE near 750 Joules/Kg on the coast, not overly impressive mid-level lapse rates.

[CrazyC83]

I'd say farther north in the mid-South is also possible.

[Ed Mahmoud]

New Euro still shows a pretty good LLJ

[Ed Mahmoud]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0359 AM CST THU JAN 01 2009

VALID 041200Z - 091200Z

...DISCUSSION...
DETERMINISTIC GFS AND ECMWF MODEL RUNS CONTINUE TO DIFFER IN
HANDLING THE LARGE-SCALE PATTERN THIS PERIOD...SPECIFICALLY
PERTAINING TO THE POTENTIAL SEVERE EVENT FROM LATE DAY 5 /MON. 1-5/
THROUGH DAY 6 /TUE. 1-6/.

AN INITIAL FRONT IS FORECAST BY BOTH MODELS TO CROSS THE ERN HALF OF
THE U.S. DAY 4 /SUN. 1-4/...ACCOMPANIED BY LITTLE SEVERE THREAT.

AS THE TRAILING PORTION OF THIS BOUNDARY SAGS INTO THE GULF OF
MEXICO/NRN MEXICO DAY 5...MODELS FORECAST CYCLOGENESIS ALONG THIS
BOUNDARY AS A SRN STREAM UPPER TROUGH CROSSES THE SWRN CONUS/MEXICO.
MODEL DIFFERENCES WITH RESPECT TO THE TIMING OF THIS TROUGH -- AND
ITS POTENTIAL PHASING WITH A NRN STREAM FEATURE -- RESULT IN
SIGNIFICANT DISCREPANCIES IN TERMS OF THE SURFACE PATTERN.

THE ECMWF BEGINS CYCLOGENESIS OVER NRN MEXICO DAY 5...WHICH THEN
SHIFTS NEWD ACROSS THE WRN GULF INTO THE LOWER MS VALLEY THROUGH THE
END OF DAY 5. THE ECMWF THEN TAKES THIS LOW NWD THROUGH THE TN AND
INTO/ACROSS THE OH VALLEY AND GREAT LAKES REGIONS DAY 6...DURING
WHICH TIME A LARGE WARM SECTOR EXPANDS ACROSS THE SRN QUARTER OF THE
CONUS. MEANWHILE...THE GFS DEPICTS INITIAL CYCLOGENESIS OVER THE
WRN GULF...WITH THE LOW THEN MOVING ENEWD ALONG THE GULF COAST
THROUGH THE AFTERNOON DAY 5...AND THEN ON ACROSS GA/SC LATE DAY
5/EARLY DAY 6. WITH THIS LOW TRACK...LITTLE ONSHORE WARM SECTOR
WOULD EXIST...WITH THE EXCEPTION OF SRN GA/FL AND THE ERN CAROLINAS.

ATTM...BOTH MODELS SEEM TO SUGGEST SEVERE POTENTIAL...BUT THE GFS
SEVERE THREAT -- CONFINED MAINLY TO GA/SC/FL -- WOULD PEAK LATE DAY
5/EARLY DAY 6. MEANWHILE...THE PRIMARY SEVERE THREAT ACCORDING TO
THE ECMWF WOULD BEGIN EARLY DAY 6 ACROSS THE LOWER MS/TN VALLEYS AND
CENTRAL GULF COAST REGION...WITH THE FRONT MOVING OFF THE E COAST
EARLY DAY 7 ENDING THE SEVERE POTENTIAL.

THE DETERMINISTIC RUN OF THE GFS REMAINS AN OUTLIER...WITH THE NCEP
MREF MUCH MORE SIMILAR TO THE ECMWF IN TRACKING A LOW INTO THE TN
VALLEY REGION DAY 6. THUS -- CONFIDENCE IS INCREASING THAT A FAIRLY
SUBSTANTIAL SEVERE EVENT MAY OCCUR PRIMARILY DAY 6 /TUE. 1-6/
CENTERED OVER THE CENTRAL GULF COAST REGION. ONCE AGAIN...WILL
REFRAIN FROM ISSUING AN OUTLOOK AREA...WITH THE GFS SOLUTION STILL
DRIVING SOME LACK OF CONFIDENCE IN THE EVENTUAL SCENARIO. IF THE
ECMWF AND MREF SOLUTIONS REMAIN CONSISTENT HOWEVER...EXPECT THE
POSSIBLE INTRODUCTION OF A THREAT AREA IN LATER FORECASTS.

..GOSS.. 01/01/2009

[Ed Mahmoud]

ZCZC SPCSWOD48 ALL
ACUS48 KWNS 020938
SPC AC 020938

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0338 AM CST FRI JAN 02 2009

VALID 051200Z - 101200Z

...DISCUSSION...

LATEST MEDIUM-RANGE IS RELATIVELY CONSISTENT IN THE EVOLUTION OF THE
LARGE-SCALE PATTERN /NAMELY IN THE MID AND UPPER-TROPOSPHERE/
THROUGH THE EXTENDED PERIOD. THE PRIMARY FEATURE OF INTEREST
CONTINUES TO BE LOW-LATITUDE TROUGH WHICH WILL TRANSLATE EWD FROM
BAJA/GULF OF CA AND NWRN MEXICO AT THE BEGINNING OF D4 /MON JAN 5TH/
TO TX BY THE BEGINNING OF D5 /TUE JAN 6TH/. THIS FEATURE THEN
DE-AMPLIFIES AS IT RAPIDLY LIFTS NEWD INTO THE OH VALLEY DURING THE
DAY TUE IN RESPONSE TO THE EVOLUTION OF AN UPSTREAM...FULL-LATITUDE
TROUGH OVER THE CNTRL PART OF THE NATION. THIS TROUGH THEN
PROGRESSES EWD THROUGH THE MS VALLEY AND EVENTUALLY OFF THE E COAST
BY D8 /FRI JAN 9TH/.

AT THE SURFACE...CONSISTENT DIFFERENCES ARE MAINTAINED ON D5 AS THE
ECMWF /WHEN COMPARED TO THE GFS/ DEVELOPS A LARGER WARM SECTOR OVER
THE GULF COAST STATES INTO TN VALLEY IN ADVANCE OF THE LEAD SHORT
WAVE TROUGH. MOREOVER...THE ECMWF DEVELOPS A BETTER-DEFINED SURFACE
LOW NEWD FROM LA AT 06/12Z INTO THE UPPER OH VALLEY BY 07/00Z. THIS
MODEL HAS SHOWN MUCH MORE RUN-TO-RUN CONSISTENCY THAN THE GFS...THUS
IT/S SOLUTION WAS GENERALLY FOLLOWED. WHILE THERE IS SOME CONCERN
REGARDING THE DEGREE OF INSTABILITY WITHIN THE SYSTEM WARM
SECTOR...SURFACE DEWPOINTS AOA 60 F AND STRONG VERTICAL SHEAR WILL
BE QUITE FAVORABLE FOR AN ORGANIZED SEVERE STORM EPISODE OVER PARTS
OF THE LOWER MS AND TN VALLEYS INTO THE CNTRL GULF STATES TUE INTO
TUE NIGHT. SOME SEVERE WEATHER MAY CONTINUE INTO D6 /WED JAN 7TH/ OVER THE SERN
STATES IN ADVANCE OF LARGE-SCALE TROUGH. HOWEVER...GIVEN
UNCERTAINTIES IN CONVECTIVE EVOLUTION ON D5...NO ADDITIONAL AREAS
WILL BE DELINEATED ATTM.

..MEAD.. 01/02/2009

CLICK TO GET WUUS48 PTSD48 PRODUCT

[Shockwave]

I've been watching this system for my area and I'm not overly impressed with this system for our area, but we have a chance if the models keep placing the sfc low into Central IL and IN. Cause if that was to materialize like that, we would be in the warm sector longer enhancing our instability values. I think we will all have a better handle on the situation once the low comes on shore out of northern Mexico.

[Ed Mahmoud]

GFS doesn't show a sounding particularly favorable for tornadoes, with limited instability and not a boatload of directional shear, but 60 knot winds just above the deck suggests even an otherwise garden variety thunderstorm could produce wind damage.



Further inland, like Athens, very limited surface based instability, but incredible low level wind fields.

[Ed Mahmoud]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0316 AM CST SAT JAN 03 2009

VALID 061200Z - 111200Z

...DISCUSSION...

LATEST MEDIUM-RANGE GUIDANCE REMAINS IN REASONABLY GOOD AGREEMENT IN
THE EVOLUTION OF THE LARGE-SCALE PATTERN THROUGH THE FIRST PART OF
THE EXTENDED PERIOD. THEREAFTER...DIFFERENCES BEGIN TO ARISE IN THE
HANDLING OF THE NEXT WRN U.S. TROUGH.

...D4 /TUE JAN 6TH/...

SHORT WAVE TROUGH OVER TX AT THE BEGINNING OF THE PERIOD WILL
RAPIDLY EJECT NEWD INTO THE OH VALLEY DURING THE DAY IN ADVANCE OF
POWERFUL...FULL-LATITUDE TROUGH SHIFTING EWD THROUGH THE CNTRL
CONUS. IN THE LOW LEVELS...BROAD LOW PRESSURE OVER THE PLAINS INTO
GULF STATES WILL EVENTUALLY CONSOLIDATE INTO A PRIMARY CYCLONE
TUESDAY NIGHT OVER THE UPPER OH VALLEY OR CUMBERLAND PLATEAU.
HOWEVER...IT STILL APPEARS THAT A WEAKER LOW PRESSURE CENTER WILL
TRACK ACROSS THE CNTRL AND ERN GULF STATES TUESDAY.

PLAN VIEW FIELDS AND FORECAST SOUNDINGS SUGGEST THAT WARM SECTOR AIR
MASS WILL BECOME ONLY WEAKLY UNSTABLE LARGELY DUE TO WEAK MIDLEVEL
LAPSE RATES. HOWEVER...THE PRESENCE OF 60+ F DEWPOINTS...VERY
STRONG WIND SHEAR AND INCREASED FORCING FOR ASCENT ALL SUGGEST THE
POTENTIAL FOR AN ORGANIZED SEVERE WEATHER EPISODE AHEAD OF COLD
FRONT AND SURFACE LOW FROM PORTIONS OF THE LOWER MS VALLEY INTO ERN
GULF STATES.

...D5 /WED JAN 7TH/...

ANY LINGERING SEVERE THREAT ALONG THE SERN ATLANTIC COAST SHOULD
QUICKLY MOVE OFF THE COAST EARLY IN THE PERIOD WITH PASSAGE OF COLD
FRONT. FARTHER S OVER THE FL PENINSULA...DECREASING CONVERGENCE
ALONG FRONT SHOULD TEND TO LIMIT A MORE SUBSTANTIAL SEVERE THREAT.

...D6 /THU JAN 8TH/ THROUGH D8 /SAT JAN 10TH/...

A RETURN FLOW REGIME WILL BECOME ESTABLISHED OVER THE WRN GULF OF
MEXICO ON D6 INTO D7 AS HEIGHTS BEGIN TO FALL OVER THE WRN STATES.
WHILE THERE DOES APPEAR TO BE SOME POTENTIAL FOR TSTMS OVER ERN TX
INTO LOWER MS VALLEY TOWARD THE END OF THE PERIOD WITH THE ARRIVAL
OF ANOTHER COLD FRONT...UNCERTAINTIES EXIST IN THE EVOLUTION OF
ASSOCIATED MIDLEVEL TROUGH AND FRONTAL MOTION. THEREFORE...NO
ADDITIONAL AREAS WILL BE DELINEATED.

..MEAD.. 01/03/2009

[southerngale]

I hope it's not as bad as today's severe weather event.

[Ed Mahmoud]

I hope it's not as bad as today's severe weather event.

I myself woke up this morning and was somewhat amazed at how uneventful the radar was.

Points East, however...

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
836 PM CST SAT JAN 03 2009

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

0730 PM TSTM WND DMG 9 NE THIBODAUX 29.88N 90.71W
01/03/2009 LAFOURCHE LA EMERGENCY MNGR

POSSIBLE TORNADO DAMAGED 2 MOBILE HOMES AT THE
INTERSECTION OF HIGHWAY 307 AND SANCHEZ ROAD NEAR THE
COMMUNITY OF KRAEMER. ONE MOBILE HOME HAD A WALL BLOWN
OUT. THE SECOND MOBILE HOME HAD SIDING DAMAGE.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAKE CHARLES LA
320 PM CST SAT JAN 03 2009

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

0300 PM TORNADO 2 W ALEXANDRIA 31.29N 92.50W
01/03/2009 RAPIDES LA EMERGENCY MNGR

911 RAPIDES PARISH REPORTING A TORNADO NEAR ROSS LANE AND
HWY 28 WEST. DAMAGE TO A HOUSE WITH ROOF BLOWN OFF ON TO
CAR AND POWERLINES DOWN. JUST SOUTH OF THE AEX AIRPORT.


&&

$$

MGRIFFIN

Finally, I had a summer job in 1992 in Jena, in La Salle Parish.

NWUS54 KSHV 032308
LSRSHV

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
508 PM CST SAT JAN 03 2009

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

0450 PM FUNNEL CLOUD 2 SW TULLOS 31.80N 92.35W
01/03/2009 LA SALLE LA LAW ENFORCEMENT

LAW ENFORCEMENT SITED A FUNNEL CLOUD ALONG THE
GRANT/LASALLE PARISH LINE BETWEEN GEORGETOWN AND TULLOS.
NO KNOWN TOUCHDOWNS AT THIS TIME.


&&

$$

15

[Bunkertor]

Hm, not bad Ed. !

[Ed Mahmoud]

Hm, not bad Ed. !

2 tornado watches and an MD. Not like last Winter's outbreaks, I hope.

But again, not a bad job by the European Community model spotting a favorable situation for severe weather from a week away.

[Bunkertor]

GFS ?

[Brent]

My old hometown:

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
547 PM CST TUE JAN 06 2009

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

0453 PM TSTM WND GST OXFORD 33.60N 85.83W
01/06/2009 E0.00 MPH CALHOUN AL EMERGENCY MNGR

NUMEROUS LARGE TREES SNAPPED OFF. DAMAGE AT SHELL
STATION. DAMAGE AROUND QUINTARD MALL AND AT HIGH
SCHOOL.SEVERAL EATERIES AND FUEL STATIONS SUSTAINED
SIGNIFICANT ROOF AND STRUCTURAL DAMAGES.

Sounds like a tornado.

[CrazyC83]

That sounds like a high EF1-low EF2.

[JonathanBelles]

TOR Issued!

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 5
NWS STORM PREDICTION CENTER NORMAN OK
1050 PM CST TUE JAN 6 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

PART OF SOUTHEAST ALABAMA
WESTERN FLORIDA PANHANDLE
PARTS OF SOUTHWEST AND CENTRAL GEORGIA
COASTAL WATERS

EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 1050 PM
UNTIL 600 AM CST.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHWEST OF MACON
GEORGIA TO 40 MILES SOUTH OF CRESTVIEW FLORIDA. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU5).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...THUNDERSTORMS ARE INTENSIFYING ALONG COLD FRONT FROM
ERN AL TO E OF MOB AS STRONG ASCENT ASSOCIATED WITH UPPER TROUGH
APPROACHES. ALTHOUGH INSTABILITY IS LIMITED...THE VERY STRONG SHEAR
PROFILES SUPPORTS EMBEDDED ROTATING UPDRAFTS/SUPERCELLS WITHIN THE
BAND OF INCREASING THUNDERSTORMS. ALONG WITH WIND
DAMAGE...TORNADOES WILL BE POSSIBLE WITH ANY SUPERCELL AS ACTIVITY
SHIFT EWD 20-25KT... WHILE INDIVIDUAL STORMS TRACK RAPIDLY NEWD.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 23045.