TC Bertha

[ncweatherwizard]

Between W and WNW heading.If a ridge is building north of Florida westward why are the models predicting a NW turn?

A trough will exit the East coast in a couple of days and provide a weakness in ridging over the Central Atlantic that's steering Bertha.

[cycloneye]

[Hurricanewatcher2007]

eye is becoming visible on the Dvorak Color Infrared Loop

http://www.ssd.noaa.gov/goes/flt/t1/loop-bd.html

[boca]

Between W and WNW heading.If a ridge is building north of Florida westward why are the models predicting a NW turn?

A trough will exit the East coast in a couple of days and provide a weakness in ridging over the Central Atlantic that's steering Bertha.

I do understand that but according to the NWS in Miami a ridge is building westward north of Florida which doesn't mean trough to me in the Tues- Sat time frame.
LONG TERM...TUESDAY THROUGH SUNDAY...FINALLY, A SIGNIFICANT
CHANGE IN THE WX CONDITIONS ACROSS MAINLAND SOUTH FLORIDA. AS THE
DEEP LAYER RIDGE BUILDS WESTWARD NORTH OF THE LOCAL AREA, NOT ONLY
THE CONVECTIVE PATTERN WILL CHANGE, BUT ALSO DRIER AIR WILL BE
ADVECTED OVER S. FL AND A SLIGHT INCREASE IN M/U SUBSIDENCE IS
EXPECTED. YET, DIURNAL HEATING AND LOCAL SEA/LAKE BREEZES COULD
COMBINE TO INDUCE THE DEVELOPMENT OF AFTERNOON SHWRS/TSTMS. WL
EXPECT THEM TO CONCENTRATE MAINLY OVER WEST COAST/WRN INTERIOR
WITH LESS COVERAGE OVER ERN AREAS

[wxman57]

I do understand that but according to the NWS in Miami a ridge is building westward north of Florida which doesn't mean trough to me in the Tues- Sat time frame.

Yes, a high will build over Florida, but east of the high will be low pressure. See the graphic I posted earlier valid on Thursday. High pressure over Florida will block Bertha's westward motion. The low pressure area east of Florida will provide an avenue for Bertha to turn northward:

[cycloneye]

The ACE for the 2008 season continues to climb.

Code: Select all

Season total
Storm Type ACE (104 kt2)
01L (Arthur) Operational 0.3675
02L (Bertha) Operational 2.9400
Total  3.3075


http://en.wikipedia.org/wiki/Talk:2008_ ... /ACE_calcs

[Aric Dunn]

its showing up some more on the ir here now
http://www.ssd.noaa.gov/goes/flt/t1/loop-avn.html

eye should be more noticeable as the hours go by tonight..

[HURAKAN]

ACE 2008 Percentage Per Storm (PPS):

Arthur: 11%
Bertha: 89%

[boca]

I do understand that but according to the NWS in Miami a ridge is building westward north of Florida which doesn't mean trough to me in the Tues- Sat time frame.

Yes, a high will build over Florida, but east of the high will be low pressure. See the graphic I posted earlier valid on Thursday. High pressure over Florida will block Bertha's westward motion. The low pressure area east of Florida will provide an avenue for Bertha to turn northward:

I see said the blind man thanks wxman57.I thought their was solid ridging out to Bertha.I was mistaken,but that map is 4 days from now.

[Aric Dunn]

latest microwave,... very nice.. again



still below the 19n line very little n motion at all.. 275

[Steve]

>>Between W and WNW heading.

While I agree, longer loops do show Bertha picking up latitude over time (obviously reflected in the location of the center of the system).

>>A trough will exit the East coast in a couple of days and weaken the ridging over the Central Atlantic that's steering Bertha.

This was always where things were key. The trough has been digging down, but it is hard to tell whether it is going to lift out or lift out and split a piece back (seems more likely). Run the WV on 30 and you will see it on the map way down in Dixie:

http://wwwghcc.msfc.nasa.gov/GOES/goeseasthurrwv.html

The key to what happens after the mid-week trough lifts by was always the next airmass, a high pressure system coming down out of Canada. If there is going to be a stall, block or trap, it would be with that airmass which should be in play late week. Who knows?

http://weather.msfc.nasa.gov/GOES/goeseastconuswv.html

Steve

[MiamiensisWx]

The following post is NOT an official prognosis.

I believe it is becoming increasingly plausible that Bertha may eventually linger between Bermuda and the Southeast coast. Currently, the TC is clearly intensifying, with a persistent banding type eye feature evident on GOES IR satellite data. It would not be surprising if the current 55 kt intensity for the 11 p.m. EDT package is slightly conservative, and Forecaster Lixion Avila is known to adhere to a more stringent "wait for persistence of organization" approach. Therefore, it is possible that the actual peak 1-min winds at the surface are currently near ~60 kt (70 mph). Regardless, I strongly expect Bertha to attain hurricane intensity shortly tonight or early tomorrow. The departing TUTT is currently resulting in favorable upper level divergence, especially as the upper level shear decreases, coinciding with the exiting TUTT and the rebuilding upper level ridging.

http://hadar.cira.colostate.edu/ramsdis/online/trop_ge_wv_ls_0.html

The timing and movement of Bertha and the H5 shortwave trough that will exit the East Coast is critical in regards to the track. A recurvature is inevitable, but there are numerous complexities that make it difficult to "pinpoint" any particular track. In the short term, I believe the model "cluster" is too slow with the expansion of the upper level ridging to the west. The fast forward movement of Bertha (just N of due west) will likely result in a track to the left of the model "cluster" within the short term. The current development of a weak surface low over the Carolinas and the H5 shortwave will temporarily weaken the western extent of the low level and upper level ridging. The weakness in the ridging will allow Bertha to briefly turn more NW within the medium to long term. The forecasting becomes extremely complex and tricky after the shortwave departs from the W Atlantic. Depending on the persistence of Bertha's fast current movement just N of due west, the TC could range from just S of Bermuda to just E of the Southeast coastline by the medium term (which will be the critical period as we move into the long term). A track E of Bermuda is highly unlikely. Based on the evolution of the current situation, it is likely that Bertha will be briefly "trapped" between Bermuda and the Southeast coast until the next trough arrives in the East.

In a nutshell, I still remain true to my original view that the Southeast (primarily NC) is not out of the woods from Bertha, though a recurvature just offshore appears to be most probable. Earlier, Bertha briefly exhibited a WNW movement, but that has changed, so I still believe the Southeast (read: Carolinas) face a possible risk. There is EXTREMELY HIGH uncertainity in regards to Bertha's track during the medium term, and as I mentioned, a track ranging from just W of Bermuda to just E of the Southeast is equally probable. The scenario for Bertha may be very reminescent of Felix in 1995. Bermuda should be extremely alert for Bertha, and residents are advised to have made and completed their preparations for the season. Based on my analysis of the upcoming pattern, Bertha will likely be a solid hurricane between Bermuda and the Southeast. All in all, residents in the Southeast (especiallu the Carolinas) and Bermuda retain a very real risk from Bertha, and this will likely be a grueling and very close call for someone.

All residents in the Carolinas and Bermuda should be prepared.

[MiamiensisWx]

The following post is NOT an official prognosis.

I believe it is becoming increasingly plausible that Bertha may eventually linger between Bermuda and the Southeast coast. Currently, the TC is clearly intensifying, with a persistent banding type eye feature evident on GOES IR satellite data. It would not be surprising if the current 55 kt intensity for the 11 p.m. EDT package is slightly conservative, and Forecaster Lixion Avila is known to adhere to a more stringent "wait for persistence of organization" approach. Therefore, it is possible that the actual peak 1-min winds at the surface are currently near ~60 kt (70 mph). Regardless, I strongly expect Bertha to attain hurricane intensity shortly tonight or early tomorrow. The departing TUTT is currently resulting in favorable upper level divergence, especially as the upper level shear decreases, coinciding with the exiting TUTT and the rebuilding upper level ridging.

http://hadar.cira.colostate.edu/ramsdis/online/trop_ge_wv_ls_0.html

The timing and movement of Bertha and the H5 shortwave trough that will exit the East Coast is critical in regards to the track. A recurvature is inevitable, but there are numerous complexities that make it difficult to "pinpoint" any particular track. In the short term, I believe the model "cluster" is too slow with the expansion of the upper level ridging to the west. The fast forward movement of Bertha (just N of due west) will likely result in a track to the left of the model "cluster" within the short term. The current development of a weak surface low over the Carolinas and the H5 shortwave will temporarily weaken the western extent of the low level and upper level ridging. The weakness in the ridging will allow Bertha to briefly turn more NW within the medium to long term. The forecasting becomes extremely complex and tricky after the shortwave departs from the W Atlantic. Depending on the persistence of Bertha's fast current movement just N of due west, the TC could range from just S of Bermuda to just E of the Southeast coastline by the medium term (which will be the critical period as we move into the long term). A track E of Bermuda is highly unlikely. Based on the evolution of the current situation, it is likely that Bertha will be briefly "trapped" between Bermuda and the Southeast coast until the next trough arrives in the East.

In a nutshell, I still remain true to my original view that the Southeast (primarily NC) is not out of the woods from Bertha, though a recurvature just offshore appears to be most probable. Earlier, Bertha briefly exhibited a WNW movement, but that has changed, so I still believe the Southeast (read: Carolinas) face a possible risk. There is EXTREMELY HIGH uncertainity in regards to Bertha's track during the medium term, and as I mentioned, a track ranging from just W of Bermuda to just E of the Southeast is equally probable. The scenario for Bertha may be very reminescent of Felix in 1995. Bermuda should be extremely alert for Bertha, and residents are advised to have made and completed their preparations for the season. Based on my analysis of the upcoming pattern, Bertha will likely be a solid hurricane between Bermuda and the Southeast. All in all, residents in the Southeast (especiallu the Carolinas) and Bermuda retain a very real risk from Bertha, and this will likely be a grueling and very close call for someone.

All residents in the Carolinas and Bermuda should be prepared.

If there is an analog for the possible "scenario" of Bertha with the evolving pattern, I believe this is the one, in my view. The main difference is that Bertha's track will be further west than Felix (between Bermuda and the SE coast) in the medium term.

[HURAKAN]

'til tomorrow. Going to sleep!

[srainhoutx]

Long week coming folks. Good night

[luvstorms]

lol! That pic of Bertha looks like she's giving the "OK" sign!

[gatorcane]

I do understand that but according to the NWS in Miami a ridge is building westward north of Florida which doesn't mean trough to me in the Tues- Sat time frame.

Yes, a high will build over Florida, but east of the high will be low pressure. See the graphic I posted earlier valid on Thursday. High pressure over Florida will block Bertha's westward motion. The low pressure area east of Florida will provide an avenue for Bertha to turn northward:

I see said the blind man thanks wxman57.I thought their was solid ridging out to Bertha.I was mistaken,but that map is 4 days from now.

NWS Miami discussion indicating the building ridge...

LONG TERM...TUESDAY THROUGH SUNDAY...FINALLY, A SIGNIFICANT
CHANGE IN THE WX CONDITIONS ACROSS MAINLAND SOUTH FLORIDA. AS THE
DEEP LAYER RIDGE BUILDS WESTWARD NORTH OF THE LOCAL AREA, NOT ONLY
THE CONVECTIVE PATTERN WILL CHANGE, BUT ALSO DRIER AIR WILL BE
ADVECTED OVER S. FL AND A SLIGHT INCREASE IN M/U SUBSIDENCE IS
EXPECTED. YET, DIURNAL HEATING AND LOCAL SEA/LAKE BREEZES COULD
COMBINE TO INDUCE THE DEVELOPMENT OF AFTERNOON SHWRS/TSTMS. WL
EXPECT THEM TO CONCENTRATE MAINLY OVER WEST COAST/WRN INTERIOR
WITH LESS COVERAGE OVER ERN AREAS

[dixiebreeze]

Excellent analysis MiamiensisWx

[fci]

I do understand that but according to the NWS in Miami a ridge is building westward north of Florida which doesn't mean trough to me in the Tues- Sat time frame.

Yes, a high will build over Florida, but east of the high will be low pressure. See the graphic I posted earlier valid on Thursday. High pressure over Florida will block Bertha's westward motion. The low pressure area east of Florida will provide an avenue for Bertha to turn northward:

Thanks for the quick analysis and the news that you present!
May the combination of blocking highs and weaknesses to our Northeast keep all of our tropical friends away.

[MiamiensisWx]

We can definitely eliminate a FL threat. I concur.