Tropical Storm Lee lingers off Louisiana coast
Tropical Storm Lee continues to bring heavy rain, moderately strong wind gusts, and tornado risk to the Gulf Coast states east of Texas. Lee is 55 miles south of Lafayette, Louisiana, and is drifting almost due north at 4 mph. Lee's central pressure dropped to 988 mb since this morning, but has maximum sustained wind speeds that have decreased to 50mph. The National Hurricane Center has extended the tropical storm warning eastward to Destin, Florida. Since this morning, New Orleans Lakefront Airport has received about another inch of rain for a storm total of 6.87 inches. Rainfall estimates from radar suggest some locations, especially close to the coast, might have already seen up to 8 inches of rain from Tropical Storm Lee. Although the New Orleans area is in a dry slot of the storm, more rain can be expected through the night in the form of isolated storms with heavy downpours. Louisiana's Jefferson Parish officials ordered a mandatory evacuation for three towns earlier today: Lafitte, Crown Point, and Barataria. Heavy rain and tidal surge pushed the water of Bayou Barataria into the surrounding low-lying areas, and officials warned that if residents didn't leave, they might become stranded for a couple of days.
Figure 1. Infrared satellite of Tropical Storm Lee captured around 6pm EDT. Source: NOAA.
Forecast for Tropical Storm Lee
Lee's forecast hasn't changed much since this morning. Dry air is being pulled in from the west, which is giving the storm a very subtropical appearance, and is mitigating intensification. Earlier today, two centers of circulation were visible in satellite and confirmed by Hurricane Hunters. The centers were rotating around each other in full Fujiwara fashion, and although they were scientifically interesting, it meant that there was no clear center of circulation, and probably helped to weaken storm. The National Hurricane Center expects that Lee will come ashore in Louisiana later this evening and linger over the region until Monday, when it will finally be pushed north by a mid-latitude wave.
Lee's tornado threat
A tornado watch is in effect for southern Louisiana and portions of Mississippi, Alabama, and the western Florida Panhandle until 10pm CDT. The forecast is for small and short-lived tornadoes, but the threat for tornado damage is still there. A PhD student at Georgia Tech (and my former group member), James Belanger, runs a skillful model to predict the number of tornadoes that a tropical cyclone could produce. The model uses variables such as the size of the storm, the maximum wind speed, and moisture. For the 2008 hurricane season, the model accurately predicted the number of tornadoes that would be spawned from a quite a few tropical cyclones, including Hurricane Dolly, Tropical Storm Edouard, Tropical Storm Fay, and Hurricane Ike. Given today's forecast track and intensity, Belanger's model is forecasting 30-40 tornadoes could be spawned from Tropical Storm Lee, mainly in the Southeast states east of and including Louisiana.
Interestingly, although the nose of dry air that's being pulled in from drought-stricken Texas (visible in the satellite image above) is acting to keep the storm weak, it's also playing a role in the number of tornadoes that could be spawned from Lee. The dry air is a crucial component for the storm to develop discrete, isolated thunderstorm cells (versus a large shield of heavy rain). The discrete cells, just like during severe weather season, are the storms that are most capable of producing a tornado.
Angela
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That bouy was a gem of information for the NHC folks to get the exact intensity.
1.5 inches for me. Please let that shift east!
looks like i will have to check my gauge again this evening wind gusty
Link
I'm thinking they probably had her estimated too low prior to the surface obs.
you mean too high right?
Too high pressure/Too low intensity.
ID T1 TIME LAT LON DIST HDG WDIR WSPD GST WVHT DPD APD MWD PRES PTDY ATMP WTMP DEWP VIS TCC TIDE S1HT S1PD S1DIR S2HT S2PD S2DIR Ice Sea SwH SwP SwD WWH WWP WWD STEEPNESS
(GMT) nm °T °T kts kts ft sec sec °T in in °F °F °F nmi 8th ft ft sec °T ft sec °T Acc Ice ft sec ft sec
------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -----------------------------------------
41044 B 1150 21.65 -58.70 16 340 100 71.9 89.4 32.5 11 8.3 - - - 79.2 83.5 78.4 - - - - - - - - - ---- ----- 20.67 11.4 N/A 24.93 7.1 N/A STEEP
SHIP S 1100 17.50 -59.20 236 188 250 15.9 - - - - - 29.88 +0.01 82.8 84.6 76.5 - - - - - - - - - ---- ----- - - - - - - -
2 observations reported for 1100 GMT
ID T1 TIME LAT LON DIST HDG WDIR WSPD GST WVHT DPD APD MWD PRES PTDY ATMP WTMP DEWP VIS TCC TIDE S1HT S1PD S1DIR S2HT S2PD S2DIR Ice Sea SwH SwP SwD WWH WWP WWD STEEPNESS
(GMT) nm °T °T kts kts ft sec sec °T in in °F °F °F nmi 8th ft ft sec °T ft sec °T Acc Ice ft sec ft sec
------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -------------------------------------------------- -----------------------------------------
41044 B 1050 21.65 -58.70 16 340 70 54.4 68.0 30.8 12 8.3 - 29.04 -0.37 79.3 83.7 78.1 - - - - - - - - - ---- ----- 19.36 12.1 N/A 23.95 8.3 N/A STE
Good morning from Mobile! what a wonderful post to wake up to...lol
If Lee does not clear the Northeast per NAM and ends up stalling across the Ohio valley, the implications are Katia will be drawn west and could hit the Outerbanks the end of the week. In any case, the trend of Katia has been to come west with every run of the models which is concerning for the East coast. I still don't have a good feel for how far west Katia will come this week.
NHC has stated in the past frequently that their weak point isn't track but intensity.
Charley was supposed to be a 2 when it hit FL, it was a 4.
Felix wasn't ever supposed to become a Category 5 only a day or so later after it became a TS.
Humberto, Lorenzo, Ida, and Paula where never supposed to go from TD to Category 1 hurricanes in 18 hours or so.
Difference with Katia is that her winds are there, whereas with Irene, the winds never caught up to the pressure.
Definite "grain of salt" right now.
If that latest buoy report isn't anomalous or anything (which I expect it isn't)...man, that's pretty rapid strengthening you got there.
CIMSS Vertical Shear Magnitude : 8.8 m/s (17 knots)
Direction : 209.6 deg
Outlook for TC Intensification Based on Current
Env. Shear Values and MPI Differential
Forecast Interval :
6hr - Favorable
12hr - Favorable
18hr - Favorable
24hr - Favorable
"Favorable" discerns an pressure drop of between 1 and 3 millibars every 6 hours.
Prob of RI for 25 kt RI threshold= 23% is 1.8 times the sample mean(12.8%)
HUM
Yikes!
Katia 7am AST
21.4N 58.6N
Station 41044 (LLNR 825)
21.652 N 58.695 W
Re:1174. CoopsWife
29.5 feet
I think we're seeing more uncertainty with intensity this year with the larger systems we've been having.
Agreed
Is it post season analysis time already? ;)
Apparently so. LOL
she was having problems getting stacked,that looks more better
000
AXNT20 KNHC 041147
TWDAT
TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 04 2011
...TROPICAL WAVES...
TROPICAL WAVE IS ANALYZED FROM 09N22W TO 17N23W MOVING W AT
10-15 KT. EXAMINING RECENT UPPER AIR TIME SECTION ANALYSES FROM
DAKAR SENEGAL AND HOVMOLLER DIAGRAMS OF SATELLITE IMAGERY OVER
WESTERN AFRICA AND THE EASTERN TROPICAL ATLC FROM THE PAST FEW
DAYS...IT APPEARS THIS WAVE PASSED DAKAR BETWEEN 03/0600 UTC AND
03/1200 UTC ALOFT IN THE 800-900 MB RANGE. GLOBAL MODEL GUIDANCE
ALSO INDICATES THE CYCLONIC ATTRIBUTES ASSOCIATED WITH THE WAVE
ARE EXPECTED TO CONTINUE A WESTWARD MOTION AT LOW LATITUDE THE
NEXT FEW DAYS. SCATTERED MODERATE CONVECTION IS FROM 05N-10N
BETWEEN 22W-29W.
Looks like all eyes are on Katia now. I live in north Jersey and I went a week without power and water after Irene. Our water went back to normal on Friday and we only just got our power back yesterday. Now I know how important it is to stock up on food and water during hurricane season. Fortunately I stockpiled many gallons of water beforehand and that made our lives much easier, but overall it's not an experience I'd care to repeat.
I'll be carefully watching Katia.
Kosher salt.
Love you too, CRS. And a few others, heh heh heh...
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