ATL: LEE - Remnants - Discussion

[bamajammer4eva]

Tornado watch no 826

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 826
NWS STORM PREDICTION CENTER NORMAN OK
145 AM CDT SAT SEP 3 2011

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

FAR SOUTHERN ALABAMA
WESTERN FLORIDA PANHANDLE
SOUTHEASTERN LOUISIANA
FAR SOUTHERN MISSISSIPPI
COASTAL WATERS

EFFECTIVE THIS SATURDAY MORNING FROM 145 AM UNTIL 1000 AM CDT.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 30 MILES WEST OF HOUMA
LOUISIANA TO 40 MILES EAST NORTHEAST OF PENSACOLA FLORIDA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU6).

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.

OTHER WATCH INFORMATION...CONTINUE...WW 824...WW 825...

DISCUSSION...THREAT FOR ISOLD TORNADOES EXPECTED TO GRADUALLY
INCREASE OVER THE CNTRL GULF CST THROUGH LATER TODAY AS T.S. LEE
MOVES SLOWLY NWD. ENVELOPE OF RICH TROPICAL MOISTURE ASSOCIATED
WITH LEE APPEARS TO HAVE EDGED NW INTO EXTREME SERN LA...AND SHOULD
SPREAD FARTHER NNW ACROSS SE LA AND EXTREME SRN MS LATER THIS
MORNING. WITH NEIGHBORING UPR LOW MAINTAINING SOMEWHAT COOLER THAN
NORMAL MID LVL TEMPS INVOF THE TROPICAL DISTURBANCE...DEEP
INSTABILITY HAS BEEN SUFFICIENT TO MAINTAIN SCTD TSTMS CLOSE JUST
OFF THE SE LA CST...WITH OTHER STORMS PRESENT OVER THE GULF WATERS S
OF VPS. GIVEN EXPECTED STRENGTHENING OF LOW LVL DIRECTIONAL/SPEED
SHEAR...AND INCREASING LOW LVL MOISTURE...SETUP MAY POSE AN
INCREASING RISK FOR LOW LVL MESOCYCLONES/TORNADOES WITH THE
CONVECTION THROUGH LATER THIS MORNING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 15035.

[pwrdog]

It's that time of night when the sattellite blanks out.....

It's about time to upgrade the GOES to the SUPER GOES with battery backup...

That would create a few jobs Uncle Sam..

[pwrdog]

The 18z doubles my rain... probably because it shifted a little west when comparing the 54h on the 12z and the 48h on the 18z... landfall in SW LA. Still on the dry side, but 2.5 inches would be better than 1.25 inches. Of course, I take it all with a grain of salt and just keep on praying for rain!

Btw, it's quite breezy here.

Are you thinking more of a landfall in Vermilion Bay rather than St. Mary Parish. Rainfall has definitely increased here in Vermilion Parish and winds are gusty.

Looking at the Lake Charles long range radar there seems to be a little more westerly movement recently... Maybe the models will adjust some..?
http://radar.weather.gov/radar.php?prod ... h&loop=yes

[hriverajr]

Sure looks like the center has jumped doesn't it. Not too far off the coast.

[pwrdog]

Looking at the Lake Charles long range radar there seems to be a little more westerly movement recently

http://radar.weather.gov/radar.php?rid= ... 0&loop=yes

[LaBreeze]

Sure looks like the center has jumped doesn't it. Not too far off the coast.

Jumped in which direction? North?

[hriverajr]

From satellite looks like it is strengthening and the center definitely reformed. Yes north.... Look at the obs and satellite pics plus radar

[pwrdog]

From satellite looks like it is strengthening and the center definitely reformed. Yes north.... Look at the obs and satellite pics plus radar

What is your thought about that Lake Charles long Range Radar loop....

Is it moving a little west or what????

I know the rain sheild is moving west fairly quick..

http://radar.weather.gov/radar.php?rid= ... 0&loop=yes

[bamajammer4eva]

Center appears on radar here----My guess

[hriverajr]

The rain shield is moving west.. the storm itself not sure.. as it looks like the center basically reformed. You have some 40 kt winds above the surface in that rain shield, so gonna get a tad windy under it.

[pwrdog]

Center appears on radar here

That is the eye on the Lake Charles Radar Loop...

[hriverajr]

[quote="bamajammer4eva"]Center appears on radar here----My guess

Seems about right

[pwrdog]

The rain shield is moving west.. the storm itself not sure.. as it looks like the center basically reformed. You have some 40 kt winds above the surface in that rain shield, so gonna get a tad windy under it.

That would put the eye at aprox 29n and 92w..

On the satellite does show a new small blowup of storms very near there..

Basically due south of LFT.....

That is NW of the last fix...

[hurr123]

Power is already out here in Northern Lafourche Parish--For a TS!!!! Winds are gusting over 55 mph or more.

[bamajammer4eva]

Power is already out here in Northern Lafourche Parish--For a TS!!!! Winds are gusting over 55 mph or more.

lixchat 2011/09/03 2:49 AM iembot LIX issues Tornado Warning for Jefferson, Lafourche, St. Charles [LA] till 3:15 AM CDT ...* AT 244 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 24 MILES SOUTHEAST OF DES ALLEMANDS...OR 8 MILES EAST OF CUT OFF...MOVING NORTHWEST AT 50 MPH.

Edit
Sounds like the NWS likes your Parish! Be safe!

lixchat 2011/09/03 2:46 AM iembot LIX issues Tornado Warning for Lafourche, St. James, St. John The Baptist [LA] till 3:15 AM CDT ...* AT 245 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR MATHEWS... OR 13 MILES NORTHEAST OF HOUMA...MOVING NORTHWEST AT 35 MPH.
lixchat 2011/09/03 2:37 AM iembot LIX issues Tornado Warning for St. Bernard [LA] till 3:00 AM CDT ...* AT 235 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE STORM CAPABLE OF PRODUCING A TORNADO NEAR YSCLOSKEY... MOVING NORTHWEST AT 40 MPH.
lixchat 2011/09/03 2:23 AM iembot LIX issues Tornado Warning for Ascension, East Baton Rouge, Iberville, West Baton Rouge [LA] till 2:45 AM CDT ...* AT 221 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR PRAIRIEVILLE...OR 6 MILES NORTHWEST OF GONZALES...MOVING WEST AT 55 MPH.
lixchat 2011/09/03 2:16 AM iembot LIX issues Tornado Warning for Lafourche [LA] till 2:45 AM CDT ...* AT 212 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR GALLIANO... MOVING NORTHWEST AT 35 MPH.

[Airboy]

Water levels going up in NO area, Shell Beach, is about +3.5 feet above normal.

[bamajammer4eva]

N FL, SE AL, SW GA NWS Tallahassee just wrote up a whole paragraph on our Tornado threat

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
345 AM EDT SAT SEP 3 2011

.SYNOPSIS...
THE 03 UTC REGIONAL SURFACE ANALYSIS SHOWED TROPICAL STORM LEE ABOUT
60 MILES SOUTH OF THE LA COAST...MOVING VERY SLOWLY NORTHWARD. A
TROUGH EXTENDED FROM LEE EASTWARD ACROSS APALACHEE BAY. A POCKET OF
DRY CONTINENTAL AIR (WITH DEWPOINTS IN THE 50S) COVERED MUCH OF
SOUTHEAST AL AND SOUTHWEST GA..AND (ALONG THE FRESH BREEZES) WILL
HELP IT TO FEEL RELATIVELY COMFORTABLE TODAY...AT LEAST FOR THE LATE
SUMMER. VAPOR IMAGERY AND UPPER AIR DATA SHOWED THE RIDGE THAT HAD
BEEN BLOCKING LEE FROM THE NORTH WAS SHIFTING EASTWARD AS A TROUGH
DEVELOPED OVER THE NORTHERN PLAINS. LEE DID NOT LOOK LIKE THE PUREST
TROPICAL SYSTEM IN THE WORLD...AS HE WAS INGESTING PLENTY OF DRY AIR
ALOFT FROM THE WEST.

&&

.SHORT TERM...
(TODAY THROUGH MONDAY) THE LATEST NWP GUIDANCE CONSENSUS REMAINS IN
DECENT AGREEMENT...SHOWING LEE MOVING SLOWLY NORTH TODAY...THEN
DOING AN ACROBATIC ANTICYCLONIC LOOP OVER SOUTHERN LA TONIGHT AND
SUNDAY...THEN FINALLY GETTING PICKED UP BY THE DEVELOPING TROUGH
(CURRENTLY OVER THE NORTHERN PLAINS) AND MOVING NORTHEAST AT A
FASTER SPEED MONDAY AND TUESDAY. THE PHASE DIAGRAM FROM THE 00 UTC
GFS (COURTESY OF DR. HART'S F.S.U. WEB PAGE) SHOWED LEE BECOMING
POST-TROPICAL ON MONDAY AND TUESDAY AS IT MERGES WITH AN APPROACHING
FRONTAL SYSTEM. OF COURSE LEE WILL HAVE A SIGNIFICANT IMPACT TO
LOCAL WOULD-BE BEACH GOERS AND BOATERS THIS HOLIDAY WEEKEND...BUT
THOSE EFFECTS CAN EASILY BE MITIGATED BY STAYING OUT OF THE OCEAN.
THERE ARE TWO POTENTIAL IMPACTS FROM LEE THAT CAN NOT BE AVOIDED AS
EASILY. ONE IS FLASH FLOODING. FORECASTING RAINFALL FROM HYBRID
TROPICAL CYCLONES LIKE THIS CAN BE VERY CHALLENGING AS THEIR
ASYMMETRICAL STRUCTURE ADDS TO THE NORMAL FORECAST UNCERTAINTY. FOR
INSTANCE...IT IS NOT CLEAR HOW AND IF THE CURRENTLY-DEVELOPING DRY
SLOT WILL CHANGE THE RAINFALL DISTRIBUTION PATTERN OF THE
STORM ...THE NWP GUIDANCE IS SIMPLY NOT GOOD ENOUGH TO PREDICT THESE
SMALL-SCALE BUT IMPORTANT CHANGES TO A STORM CORE. AT THIS TIME WE
ARE FOLLOWING THE CONSENSUS OF THE LATEST GLOBAL MODELS AND
NCEP...WITH 3 TO 6INCHES OF RAIN FORECAST OVER THE FL
PANHANDLE...THEN TAPERING OFF TO AN INCH OVER THE EASTERN PORTIONS
OF OUR REGION. THAT ENCOMPASSES THE PERIOD FROM TODAY THROUGH MONDAY
AFTERNOON...THOUGH MOST OF THIS RAIN WILL LIKELY OCCUR SUNDAY AND
MONDAY. TROPICAL CYCLONES...EVEN WEAK ONES...ARE NOTORIOUS FOR
CAUSING LOCALIZED RAINFALL TOTALS 2 TO 3 TIMES THAT OF THE LARGER
SCALE RAIN AMOUNTS. THE QPF VALUES WE CURRENTLY HAVE WOULD NOT BE
VERY PROBLEMATIC FOR OUR AREA...BUT AMOUNTS MUCH HIGHER THAN THIS
OVER A SHORT TIME WOULD BE...ESPECIALLY IF THEY OCCUR IN FLOOD-PRONE
AREAS. (THE REMNANTS OF ALLISON IN JUNE 2000 COME TO MIND). IT IS
TOO EARLY TO ISSUE A FLASH FLOOD WATCH...BUT ONE MAY BE NEEDED LATER
TODAY OR EARLY SUNDAY AS THE RAINFALL STRUCTURE OF LEE BECOMES MORE
EVIDENT.

ANOTHER CONCERN IS THE POTENTIAL FOR TORNADOES. IN THE LAST DECADE
OR SO WE HAVE SEEN WEAKENING TROPICAL CYCLONES TAKE THIS PATH AND
PRODUCE TORNADOES. SUCH TORNADOES TEND TO BE A LITTLE WEAKER THAN
THE MASSIVE ONES THAT OFTEN OCCUR IN THE CENTRAL PLAINS...BUT THEY
ARE STILL DANGEROUS AS THEY CAN DEVELOP QUICKLY WITH LITTLE WARNING.
THERE IS A LOW-END TORNADO THREAT...ABOUT 2 PERCENT WITHIN 25 MILES
OF A POINT...ALONG THE FL PANHANDLE COAST TODAY. A SIMILAR THREAT IS
EXPECTED SUNDAY ACROSS A SOMEWHAT LARGER AREA...AS THE BOUNDARY
LAYER GRADUALLY DESTABILIZES AND MOISTENS FROM SOUTHWEST TO
NORTHEAST. MONDAY MAY HOLD A MORE SIGNIFICANT THREAT AS THE GFS
FORECASTS A 60 KT 850 MB JET PROPAGATING FROM WEST TO EAST ACROSS
OUR FORECAST AREA MONDAY AND MONDAY NIGHT. THE 0-1 KM VERTICAL WIND
SHEAR VALUES ARE FORECAST TO EXCEED 30 KT....WHICH IS QUITE HIGH FOR
THIS TIME OF YEAR. AGAIN...THIS THREAT WILL DEPEND ON THE
INTENSITY...STRUCTURE...AND TRACK OF LEE...SO WE WILL HAVE PLENTY OF
TIME TO RE-ASSESS THIS THREAT IN SUBSEQUENT FORECAST
PACKAGES.

[MWatkins]

Coastal flooding will be a prob as the center pushes in, but latest sat images and radar suggests (to me anyway) that the center has jumped north some and is already getting ready to come inland.

Lets see if this does happen in the next few hours, but if it does the flooding time tables will be accelerated in the areas getting the heavy rain bands.

Still longer term, the faster inland, the less the overall flooding threat.

MW

[Kory]

Wind is really picking up in New Orleans...gusting to about 40 mph. Moderate rain, but another heavier band rotating in.

[dwsqos2]

I'm not trying to belittle this. But after staring at water vapor loops and a 3Z upper-level wind analysis on CIMSS, this looks rather subtropical to me, or at least subtropicalish.