Hurricane Bertha: 6th strongest early season hurricane on record

By: Dr. Jeff Masters , 1:45 PM GMT on July 08, 2008

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Hurricane Bertha put on a remarkable burst of rapid intensification Monday afternoon, reaching major hurricane status--Category 3--with 120 mph winds and an estimated central pressure of 948 mb. Among early season hurricanes that have formed before August 1, Bertha is the sixth strongest early-season Atlantic hurricane on record. Only 12 early season major hurricanes have formed since record keeping began in 1851, though several were no doubt undocumented before the advent of the aircraft reconnaissance in 1944. Bertha holds the record for the farthest east a major hurricane has formed so early in the season (52°W longitude), easily beating the mark set in 1996 (67°W) by a previous incarnation of Hurricane Bertha. This year's Bertha now holds the record for farthest east formation as a tropical storm, hurricane, and major hurricane, so early in the season.


Figure 1. Bertha at peak intensity: 21:15 GMT Monday July 7, 2008. At this time, satellite estimates of Bertha's strength were 115 kt (135 mph), making the storm a weak Category 4 hurricane.

Bertha may even have intensified to Category 4 status between 1900 and 2300 GMT yesterday. Satellite estimates of the storm's intensity (Figure 2) from both NHC and the University of Wisconsin during that period were 115 knots (135 mph), which would have made Bertha a low-end Category 4 hurricane. However, it is unclear what Bertha's final official intensity maximum will be, since it reached maximum strength in between the official 6-hourly times used by NHC to document a storm's strength.


Figure 2. Satellite estimates of Bertha's strength using the Automated Dvorak Technique (ADT) showed the storm peaking at 115 knots (135 mph) for a four hour period on July 7, 2008. The "Best Track" line is the official NHC advisory strength, which peaked at 105 knots (120 mph); the AMSU dots are estimates from a polar orbiting instrument, the Advanced Microwave Sounding Unit; SATCON is a SATellite CONsensus estimate of Bertha's intensity combining several satellite strength estimates. Image credit: University of Wisconsin CIMSS.

Bertha's intensification was somewhat surprising, because environmental conditions for intensification were good, but not great. Wind shear was a modest 10-15 knots, Sea Surface Temperatures were 27°C--only 1° above the minimum needed to support a hurricane--and the oceanic heat content was only 20 KJ/cm**2, which is well below the value of 80 typically associated with rapid intensification.

Bertha is probably not a major hurricane any more. Wind shear has increased to 15-20 knots, and the eye has become less distinct and the cloud pattern degraded, as seen on visible satellite loops. The Hurricane Hunter mission scheduled for today has been canceled, and no future missions are planned.

The intensity forecast
SSTs will continue to warm to 28°C Wednesday morning underneath Bertha, but wind shear is expected to remain high and possibly increase some later this week. Bertha should gradually decline in strength to Category 1 status by the end of the week.

The track forecast
Bertha is slowing down and turning northward as it "feels" the approach of a trough of low pressure to the north. All of the computer models turn Bertha northwards east of Bermuda, and it currently appears that the island will feel only peripheral effects of Bertha. However, the trough of low pressure turning Bertha to the north may not be strong enough to fully drag the storm into the far North Atlantic, so Bertha may wander close to Bermuda early next week while it waits for another trough of low pressure to finish the job. It is very unlikely Bertha will threaten the U.S., but it could eventually affect Newfoundland, Canada.

Elsewhere in the tropics
There are no threat areas to discuss in the tropical Atlantic. The UKMET and GFS models are showing some possible development in the region between Africa and the Lesser Antilles Islands about a week from now.

I'll post an update Wednesday morning.
Jeff Masters

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1206. seflagamma
1:06 PM GMT on July 10, 2008
new blog up.
Member Since: August 29, 2005 Posts: 294 Comments: 40839
1205. TheWeatherMan504
1:30 PM GMT on July 09, 2008
Bertha is about to show her colors again.Her eye will be back shortly.
Member Since: May 18, 2008 Posts: 2 Comments: 1042
1204. extreme236
1:19 PM GMT on July 09, 2008
Water temps are probably even warmer than they were when her last RI was. But wind shear would have to remain low and it should, but the NHC's thinking on wind shear is all over the place lol
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1203. OSUWXGUY
1:18 PM GMT on July 09, 2008
New Blog Up...
1202. Stormchaser2007
1:17 PM GMT on July 09, 2008
Member Since: June 9, 2007 Posts: 4 Comments: 15718
1201. NEwxguy
1:17 PM GMT on July 09, 2008
1188. TampaSpin 1:02 PM GMT on July 09, 2008
Quoting 1179. NEwxguy:
Tampa,I'm having a personality conflict,I find myself rooting for the yankees,but its very painful doing that.We're not going to let you get too comfortable.


Tell me you did not say that.......You can't be a true Sox if you ever root for those dam Yanks.......ROFLMAO

Found myself doing that last night,but can't do that two nights in a row,would put me in a deep depression.
Member Since: September 6, 2007 Posts: 862 Comments: 15053
1200. Stormchaser2007
1:16 PM GMT on July 09, 2008
Quoting 1196. Thundercloud01221991:
looks like they initialized models at hurricane meaning it will remain a hurricane at the 11 AM advisory

does anyone think that there could be another burst of RI today or is it too cool of water temps


Hmm not expected...but Bertha's last RI wasnt expected either so maybe.
Member Since: June 9, 2007 Posts: 4 Comments: 15718
1199. guygee
1:16 PM GMT on July 09, 2008
Re: 1156. nrtiwlnvragn 12:02 PM GMT on July 09, 2008

Very unusual for HPC to issue a mid-morning update to their Preliminary Extended Forecast Discussion. Notice the mention of the closed Mid-Atlantic coastal low. Recent GFS runs and GFS ensembles have been hinting at this idea for several runs. Whether or not this feature develops could have an effect on the eventual track of Bertha and the strength of the storm as it transitions to extratropical.
Member Since: September 16, 2005 Posts: 0 Comments: 3055
1198. Stormchaser2007
1:13 PM GMT on July 09, 2008
Another eye forming...

Member Since: June 9, 2007 Posts: 4 Comments: 15718
1197. Thundercloud01221991
1:12 PM GMT on July 09, 2008
looks like they initialized models at hurricane meaning it will remain a hurricane at the 11 AM advisory

does anyone think that there could be another burst of RI today or is it too cool of water temps
Member Since: August 1, 2006 Posts: 28 Comments: 3716
1195. HurrikanEB
1:10 PM GMT on July 09, 2008
IT IS STILL TOO EARLY TO KNOW WHETHER BERTHA WILL HAVE AN IMPACT ON
BERMUDA. INTERESTS ON THAT ISLAND SHOULD CONTINUE TO MONITOR THE
PROGRESS OF THIS HURRICANE OVER THE NEXT COUPLE OF DAYS.



so much for having a clear idea of what she's gonna do...

good morning everyone
Member Since: May 2, 2008 Posts: 12 Comments: 1289
1194. Stormchaser2007
1:10 PM GMT on July 09, 2008
Whoa!
Member Since: June 9, 2007 Posts: 4 Comments: 15718
1192. Stormchaser2007
1:06 PM GMT on July 09, 2008
1184. Uhm well thats gonna be hard when we had these monsters to deal with last year. lol

Dean:


Felix:
Member Since: June 9, 2007 Posts: 4 Comments: 15718
1191. Stormchaser2007
1:03 PM GMT on July 09, 2008
Yep, Looks clear to me. Thank god! I dont want to have to deal with the blog when theres another CV storm that has potential to hit the US.

Member Since: June 9, 2007 Posts: 4 Comments: 15718
1190. TheCaneWhisperer
1:02 PM GMT on July 09, 2008
Post 1184

Possibly, LOL. Good observation
1189. extreme236
1:02 PM GMT on July 09, 2008
1181.

Looks like the eye is trying to poke out again.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1188. TampaSpin
1:02 PM GMT on July 09, 2008
Quoting 1179. NEwxguy:
Tampa,I'm having a personality conflict,I find myself rooting for the yankees,but its very painful doing that.We're not going to let you get too comfortable.


Tell me you did not say that.......You can't be a true Sox if you ever root for those dam Yanks.......ROFLMAO
Member Since: September 2, 2007 Posts: 177 Comments: 20430
1187. TheCaneWhisperer
1:01 PM GMT on July 09, 2008
1185

1157. TheCaneWhisperer 12:06 PM GMT on July 09, 2008
Post 1130

GFS I looked at yesterday was hinting at development off the coast of Africa next week. Definitely something to keep an eye on. As we seen with Bertha the CV season is early but fully open and ready to go. Hopefully we'll see a lot of re curving storms with them forming so far out there. Troughs are still relatively strong.
1186. Stormchaser2007
1:00 PM GMT on July 09, 2008
Quoting 1184. Kibkaos:
There is definitely a lot of activity coming off the coast of Africa. Anybody care to comment on the possibilites of Tropical Development. Are there any models that mention it?


Were? Theres nothing on this view.
Member Since: June 9, 2007 Posts: 4 Comments: 15718
1185. Kibkaos
12:57 PM GMT on July 09, 2008
There is definitely a lot of activity coming off the coast of Africa. Anybody care to comment on the possibilites of Tropical Development. Are there any models that mention it?
Member Since: January 3, 2007 Posts: 0 Comments: 41
1184. MTCseadrifter
12:54 PM GMT on July 09, 2008
So... Is Bertha going to be a wanderer now? I wonder if she'll make more active Hurricane hours than we had total for last season?
Member Since: July 28, 2007 Posts: 0 Comments: 260
1183. NEwxguy
12:54 PM GMT on July 09, 2008
Going to get some wobbling,especially if that front coming of New England and mid atlantic doesn't pick her up.
Member Since: September 6, 2007 Posts: 862 Comments: 15053
1181. Stormchaser2007
12:53 PM GMT on July 09, 2008
Member Since: June 9, 2007 Posts: 4 Comments: 15718
1180. NEwxguy
12:53 PM GMT on July 09, 2008
Tampa,I'm having a personality conflict,I find myself rooting for the yankees,but its very painful doing that.We're not going to let you get too comfortable.
Member Since: September 6, 2007 Posts: 862 Comments: 15053
1179. MasterForecaster
12:53 PM GMT on July 09, 2008
It looks like its headed more wnw now...anyone else agree? And no one really thinks she could do a loop de loop right?
1178. Bobbyweather
12:53 PM GMT on July 09, 2008
...INITIAL CONDITIONS...
LATCUR = 23.6N LONCUR = 57.0W DIRCUR = 300DEG SPDCUR = 10KT
LATM12 = 22.8N LONM12 = 55.2W DIRM12 = 297DEG SPDM12 = 9KT
LATM24 = 21.8N LONM24 = 53.5W
WNDCUR = 65KT RMAXWD = 15NM WNDM12 = 70KT
CENPRS = 987MB OUTPRS = 1014MB OUTRAD = 200NM SDEPTH = D
RD34NE = 120NM RD34SE = 60NM RD34SW = 45NM RD34NW = 90NM

$$
NNNN



Member Since: September 7, 2006 Posts: 89 Comments: 2649
1177. TampaSpin
12:51 PM GMT on July 09, 2008
1176. NEwxguy 8:44 AM EDT on July 09, 2008

You picked up a game last night.....
Member Since: September 2, 2007 Posts: 177 Comments: 20430
1176. NEwxguy
12:44 PM GMT on July 09, 2008
Thanks,Storm,real nice write up.I'm always fascinated how these storms can linger in the vicinity,as if waiting for the proper train to jump on and ride on out.
Member Since: September 6, 2007 Posts: 862 Comments: 15053
1175. TampaSpin
12:43 PM GMT on July 09, 2008
I did a blog update last nite late if anyone would like to review.....TampaSpin's Blog
Member Since: September 2, 2007 Posts: 177 Comments: 20430
1174. bethie
12:40 PM GMT on July 09, 2008
Thanks for the update StormW. I appreciate your informative forecasts & posts.

I'm still lurking and learning...
Member Since: July 31, 2006 Posts: 0 Comments: 5
1173. TampaSpin
12:39 PM GMT on July 09, 2008
Morning everyone i did a red eye last nite......lol
Member Since: September 2, 2007 Posts: 177 Comments: 20430
1172. nrtiwlnvragn
12:34 PM GMT on July 09, 2008
Quoting 1167. extreme236:
1159.

Is that an eye open on the south side? Because that matches up with about where the center is on ADT


Yes, but that image is from 5:39 AM this morning.
Member Since: September 23, 2005 Posts: 13 Comments: 10458
1168. extreme236
12:28 PM GMT on July 09, 2008
1159.

Is that an eye open on the south side? Because that matches up with about where the center is on ADT
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1166. earthlydragonfly
12:22 PM GMT on July 09, 2008
First off storm w Thank you for breaking down all of the acronyms!!!!
Member Since: July 1, 2005 Posts: 10 Comments: 1681
1165. TheCaneWhisperer
12:21 PM GMT on July 09, 2008
Morning SW.
1163. cg2916
12:20 PM GMT on July 09, 2008
1160.
Right.
Member Since: December 21, 2007 Posts: 13 Comments: 3026
1162. TheCaneWhisperer
12:20 PM GMT on July 09, 2008
Your right TAZ. Our local MET said last night she's going to be moving painfully slow over the next couple of days.
1161. cg2916
12:19 PM GMT on July 09, 2008
Quoting 1157. extreme236:
The ADT says the center is in a warmer spot in the middle of the CDO...makes me wonder if that eye might come back later today.


Could be. Look at this, the clouds are sinking in:
Member Since: December 21, 2007 Posts: 13 Comments: 3026
1160. Tazmanian
12:19 PM GMT on July 09, 2008
one thing you have to take note is that she has slow way down
Member Since: May 21, 2006 Posts: 5089 Comments: 114040
1159. nrtiwlnvragn
12:17 PM GMT on July 09, 2008
Click on image to view original size in a new window



Member Since: September 23, 2005 Posts: 13 Comments: 10458
1158. extreme236
12:05 PM GMT on July 09, 2008
The ADT says the center is in a warmer spot in the middle of the CDO...makes me wonder if that eye might come back later today.

Member Since: August 2, 2007 Posts: 19 Comments: 19234
1157. TheCaneWhisperer
12:06 PM GMT on July 09, 2008
Post 1130

GFS I looked at yesterday was hinting at development off the coast of Africa next week. Definitely something to keep an eye on. As we seen with Bertha the CV season is early but fully open and ready to go. Hopefully we'll see a lot of re curving storms with them forming so far out there. Troughs are still relatively strong.
1156. nrtiwlnvragn
12:02 PM GMT on July 09, 2008
PRELIMINARY EXTENDED FORECAST DISCUSSION



EAST/CENTRAL
PRIOR TO THE MAIN HT FALLS COMING INTO WRN CONUS EARLY NEXT WEEK
HI RES ECMWF/CMC AND UKMET INDICANT A SIG MID LEVEL
WEAKNESS/CLOSED LOW DEVELOPMENT OFF LOWER MID ATLC COAST WITH SFC
LOW DEVELOPMENT OFF NC. THIS SMALL SCALE COASTAL LOW MAY PRODUCE
SOME HVY COASTAL RAINS BEFORE BEING PICKED UP AND MOVING NWD UP
THE OFFSHORE ERN SEABOARD. COASTAL AREAS FROM FL NWD THRU SRN NEW
ENG WILL EXPERIENCE SWELL FROM OFF HURCN BERTHA THIS PERIOD. COLD
FRONT WILL SLOWLY MOVE OFF THE EAST COAST FROM NEW ENG TO THE
SOUTHEAST COAST MON AND TUES WITH COOLER HIGH PRESSSURE BUILDING
OVER THE GREAT LAKES REGION AND OH VALLEY.
Member Since: September 23, 2005 Posts: 13 Comments: 10458

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.