About Jeff Masters
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
Disorganized Leslie headed towards Bermuda
By: Dr. Jeff Masters , 4:18 PM GMT on September 03, 2012
Tropical Storm Leslie continues to struggle with moderately high wind shear of 15 - 20 knots, due to strong upper-level winds out of the northwest. The shear is keeping heavy thunderstorms confined to the southeast quadrant of the storm. These thunderstorms are as far removed from the center as we've so far with Leslie, as seen on satellite loops. According to the latest SHIPS model forecast, the shear is expected to stay moderately high through Tuesday night, then drop to the low category, 5 - 10 knots, by Wednesday night. At that time, Leslie will be over warm ocean waters of 29°C, and the reduction in shear and warm waters should allow Leslie to intensify into at least a Category 1 hurricane by Friday, as predicted by most of the intensity forecast models. Intensification to a stronger storm may be hampered by its slow motion, which will cause Leslie to churn up cool water from the depths that will slow intensification. Once Leslie begins moving more quickly on Saturday, this effect will diminish, and Leslie could be at Category 2 strength on Saturday, as predicted by the HWRF and LGEM models. Steering currents for Leslie are expected to be weak on Tuesday - Friday, as Leslie gets stuck between two upper level lows. The latest guidance from our top computer continues to show Leslie making a very close pass by Bermuda on Saturday, and that island can expect a 3-day period of rough weather Friday through Sunday. Leslie will stay stuck in a weak steering current environment until a strong trough of low pressure approaches the U.S. East Coast on Saturday. This trough should be strong enough to pull Leslie quickly to the north on Saturday and Sunday, and Leslie may be close enough to the coast that the storm will make landfall in Canada on Monday, September 10. None of the reliable models have shown that a direct hit on New England will occur, but we can't rule that possibility out yet. The most likely long-term fate of Leslie will be for it to miss land entirely and brush by the coasts of Nova Scotia and Newfoundland, but any forecast of what a tropical cyclone might do a full seven days in advance is pretty speculative. Regardless, Leslie will bring an extended period of high waves to Bermuda, the U.S. East Coast, and Nova Scotia and Newfoundland this week. These waves will be capable of causing significant beach erosion and dangerous rip currents.
Figure 1. Morning satellite image of Tropical Storm Leslie. The low-level circulation center is fully exposed to view, thanks to strong northwest winds creating 15 - 20 knots of wind shear.
Invest 99L in the Central Atlantic
A small extratropical low pressure system that got cut off from the jet stream and is now spinning away in the Central Atlantic, near 26°N 42°W, (Invest 99L), is headed west at 10 mph, and has developed a small amount of heavy thunderstorm activity. This storm is not a threat to any land areas, and in their 8 am EDT Tropical Weather Outlook on Monday, NHC gave 99L a 30% chance of developing into a tropical cyclone by Wednesday morning.
Jeff Masters
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
Reader Comments
Category 6™
1172. weatherh98
1171. VR46L
You might want to check the Euro 72 hrs ..
1170. icmoore
So what he wants another swim in the Gulf?
1169. weatherh98
Maybe it will loop back around and hit the dems convention would that be ironic or what?!
1168. weatherh98
*shudders*
Thank God it ain't coming back this way
1167. icmoore
Sorry about your neighbors but happy for you! Oh, and thanks for my first laugh of the morning. Hey what the heck am I laughing about :)
1166. Tazmanian
may be
1165. Patrap
Mees tink's so, bra'
1164. weatherh98
You prolly know more than he/she does
I'm fairly confident there aren't any teachers or students who know more about tropical weather than I do....
1163. weatherh98
It is so!
We did well although some neighbors did end up under water...
Tampa may get its hit anyway:)
1162. Tazmanian
do you no how too ues a key board seems like you dont
how about some space in your words
like this come back. Just shower
1161. wxchaser97
Lol, I'm pretty sure Isaac is getting retired.
Depends on what my teacher who is supervising me says as to if I need to be following it.
1160. GeoffreyWPB
1159. weatherh98
Is dat eerrr eyezack?
1158. wanzewurld
target="_blank">http://www.ssd.noaa.gov/goes/east /gmex/loop-wv.html and saw a fair-sized low pressure with what seems to be rapid rotation and wonder if someone would care to comment on this - I'm guessing it's simply a localized storm but have just never seen anything like it with the size and rotation; I'm still trying to learn the connections with water vapor loops and surface or tropical systems. I'm still guessing here that this has no chance of developing into a tropical depression or even holding up to cross Florida into the GOM. Any replies or comments please use my user name, "wanzewurld" so I can locate replies easily
1157. wxchaser97
1156. Patrap
Night IR to Day RGB
1155. icmoore
Good morning everyone.
Hey there and welcome back. I am sorry I just started at the bottom of the page and will be reading up. I hope you fared okay through Isaac and what the heck is this I see about a possible Issac reincarnation in the Gulf? Say it ain't so..
1154. weatherh98
If he's not I'll run over and do it myself... It's getting retired
If there were a major weather happening what would you do
1153. wxchaser97
Check post 1144 for the answer.
The US should not forget Leslie, but I don't think a direct hit will happen. Bermuda will be staring down the barrel of a hurricane and Canada will get impacts.
1152. Tropicsweatherpr
04/1145 UTC 26.9N 43.5W T2.5/2.5 13L -- Atlantic
1151. Patrap
NEXRAD Radar
Base Reflectivity 0.50° Elevation
Range 248 NMI
1150. wxchaser97
Hey, that's my plan unless there is major weather happening or I need to finish homework.
1149. wxchaser97
With all that Isaac has done damage wise, I think he will get retired.
1148. weatherh98
What! Lemme do tht! Id wanna sit home and blog for an hour
1147. RTSplayer
Maybe still needs some adjustments.
Unofficial Hurricane Severity Index for Isaac: 20.44
http://en.wikipedia.org/wiki/Hurricane_Severity_I ndex
Using the Hurricane Severity Index guidelines and definitions, I unofficially ranked Isaac as being no more than 20.44.
I assumed the maximum size for each of the 3 wind fields that it qualified for, because it really was a very large system.
However, I think it once had a maximum Integrated Kinetic Energy value of 4.1.
This scale may need some adjusting, I think.
Andrew at landfall ranks somewhere between 29 and 33, but not over 33.
Wilma is cheated for maximum over-water intensity, while Camille and Labor Day are cheated slightly, because they were far more intense than the maximum scale.
Labor Day and Wilma were 180kts storms, and should have gotten 36 points from intensity alone, but the scale ends at 25.
Camille was a 165kts storm at landfall and should get 30 points from intensity alone, but it was not very large compared to Katrina, and probably mid grade on size, giving about 41 if the intensity scale went to that height, but they officially rated it as 36, because the intensity points stops at 25, which is exactly 5 points below what I rated it, given existing knowledge.
Wilma on first landfall in Mexico should get 25 points for size and 18.7 for intensity, giving about 43.7 for it's total score at Mexico Landfall. This is higher than any U.S. landfall on record.
Over water, Wilma would officially be close to 50, but weaker than Katrina. Unofficially, Wilma would be close to 60 at peak intensity.
Katrina's max severity over water at peak intensity was very close to a perfect 50, possibly exceeding 50 if the "sized" scale didn't end.
Katrina ranked "only" 36 at landfall, most of this difference is in loss of maximum wind speed.
So anyway, Isaac is 20.44 at landfall.
The system needs some work, but it's probably better than the SS scale...
Super-Typhoon Tip would probably rank in the 70's if both halves of the scoring system kept going up with the same logic, but it would be an automatic 50 at a mere glance even on the real scale...
1146. islander101010
1145. weatherh98
He was getting retired for sure.... One giant head ache now its like icing on the cake for him
1144. wxchaser97
For me its the first day back from summer break. At least I get to start at 8:40 instead of 7:40am like the rest of my classmates due to my independent study in meteorology.
1143. allancalderini
1142. weatherh98
1141. VR46L
I dont think its wrong to be hopeful that Leslie wont visit you ...Think its Bermuda and Canada problem in the next week but a few extra supplies would not go a miss for the just in case scenario...
1140. wxchaser97
Isaac, the storm that went right on living. I think we will see Michael today with the increase of convection and organization.
1139. allancalderini
1138. weatherh98
1137. wxchaser97
I'm in MI and state law requires public schools to start the day after labor day. As to exactly where I am I won't say but in metro Detroit.
1136. weatherh98
Stay safe Florida he's a mean machine
1135. washingtonian115
1134. SFLWeatherman
1133. forecaster1
1132. Tazmanian
1131. SFLWeatherman
1130. AegirsGal
1129. washingtonian115
1128. wxchaser97
Bye ncstorm, Leslie will be producing some big waves and swells for sure.
1127. ncstorm
1126. wxchaser97
Finally got some decent cloud cover and some convection over the center.
1125. CaicosRetiredSailor
1124. HurrAndrew
2.6 /1007.3mb/ 37.0kt
Final T# Adj T# Raw T#
2.6 3.0 3.1
I think this may encourage an upgrade (to Michael).
Also currently due to its disheveled appearance Leslie's T#'s are lower currently in this set than TD13's.
1123. wxchaser97
NHC forecast(5:00am this morning):
Besides some small track and intensity differences they are pretty similar.
1122. RTSplayer
In fact, I regretted using too much of my memory, because I wasn't able to film the record flooding during the next day, because without power I couldn't upload my videos and empty the SD card to start filming again.
I can only hope that someone else down the street filmed the record flooding on Yellow Water Creek so that the appropriate authorities will have good records to examine the drainage and potential levee situation.
Something will need to be done on the north and north west shores of Lake Maurepas, because this amount of storm surge from a category 1 is unacceptable.
Anyway, my point here is gettng good coverage of what's "happening" in a storm is nearly impossible. While trying to film, I quickly discovered that by the time you realize something is happening worth filming, with regards to wind, rain, or debris/damage, it's too late to catch it, because it happens that fast and it's already over.
You basically need multiple cameras running non-stop pointing in at least 2 or 3 directions to catch that sort of stuff consistently.
And if you want to catch levee breaches or important structural damage, tough luck. I found out first hand driving in the thing is stupid, even with only TS force winds, because I got two flat tires from hitting sign debris I couldn't see until it was like 10 feet in front of me.