TC Bertha

[RL3AO]

120hr shifted 1 degree north. No big deal.

[MiamiensisWx]

Reposted from http://www.storm2k.org/phpbb2/viewtopic.php?p=1729273#p1729273:

The following post is NOT an official prognosis.

It honestly looks like the upper level ridge is already building west as the TUTT quickly lifts out of the area. Note that Bertha's forward movement during tomorrow and the next few days is going to exert some significant influences in regards to its track. Currently, a shortwave trough at H5 is moving east from the Ohio Valley to the Mid-Atlantic region. Water vapor imagery of the upper levels indicates the shortwave trough is moving rather rapidly to the east as the weak H5 vort max transects the area. The fast northern stream suggests the shortwave trough will exit the Mid-Atlantic fairly quickly, allowing the upper level ridge to H5 to re-assert itself and briefly build to the west. This trend may likely commence as soon as tomorrow and the following day. If you combine the unfolding current situation with an extrapolation of Bertha's ongoing rapid movement, it could indicate that Bertha may be closer to the CONUS earlier than some people anticipate. Bertha has been persistently moving further west faster than expected over the past ~24-36 hours. I highly doubt that Bertha will only come within a certain distance of the CONUS by late next week. After analysis of current trends and the pattern, it appears that it may occur earlier than that time frame. Depending on the timing of the next H5 trough progged to affect the East and the amplification of the upper ridge in the West, Bertha could certainly pose a threat to the Southeast (primarily North Carolina).

One possible concern in regards to the intensity is the fact that a small upper low NE of Bermuda is moving SSE as the TUTT moves NE. This new upper low could deepen and develop a new TUTT (the second one progged by the operational GFS at 200-250 mb?) over the next few days in a similar position to the current TUTT. This could increase the upper level divergence/shear in the vicinity north of the Leeward Islands and Puerto Rico. Therefore, after gradual intensification, Bertha's intensity could fluctuate in that area. That leads to the possibility of a more southerly and westerly track in the long range, depending on the actual intensity of Bertha at that time and the degree of the possible TUTT's influence.

I'm not a person who casually ignores or disputes models, especially if they are latching on to a pattern. I also regularly utilize climatology in my analysis. However, based on all available evidence, I believe it is premature to sound the all clear for the Southeast. It is also premature to make a definite statement that Bertha will strike the CONUS, Bermuda, the NE Caribbean, or any land mass. Both approaches should be discouraged, especially given the considerable uncertainties and complexities involved. Everyone should be prepared, regardless of their location. The evolution of this system, the analysis of the models, and the "kinks" thrown in to the synoptic pattern will present an exceptionally fascinating and extremely intriguing situation. Regardless of the final result, Bertha will present an incredibly tough forecasting challenge and a bastion of knowledge for everyone involved. This system has already been impressive itself.

BERTHA CONTINUES TO MOVE RAPIDLY WESTWARD WITH AN INITIAL MOTION OF
280/18. THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT
36-48 HOURS COURTESY OF A STRONG RIDGE TO THE NORTH. THEREAFTER...
THE CYCLONE BEGINS TO ENCOUNTER A WEAKNESS IN THE SUBTROPICAL RIDGE
AND TRACK MODELS DIVERGE SIGNIFICANTLY. IN FACT...THE SPREAD IN
THE TRACK MODELS SPAN NEARLY 1300 MILES AT DAY 5 WITH THE UKMET
MODEL KEEPING BERTHA HEADED WESTWARD AND THE HWRF TURNING THE
CYCLONE NORTHWARD. GIVEN THE UNCERTAINTY...THE OFFICIAL FORECAST
IS SIMILAR TO THE PREVIOUS FORECAST AND LIES IN THE MIDDLE OF THE
TRACK MODEL ENVELOPE.

IT SHOULD BE NOTED THAT THERE IS LARGER THAN NORMAL UNCERTAINTY IN
BOTH THE TRACK AND INTENSITY FORECASTS OF BERTHA. ACCORDINGLY...IT
IS MUCH TOO EARLY TO DETERMINE IF BERTHA WILL OR WILL NOT POSE A
THREAT TO ANY LAND AREAS.

http://www.nhc.noaa.gov/text/refresh/MIATCDAT2+shtml/060234.shtml

[gotoman38]

The NHC fcst agrees with what I think is consensus here, that we are dealing with an uncertain situation.

3-5 day uncertainty falls right into when we might see recon flights (my guess is Tues am) so at that point we will start to have some more "hard data" input to the fcst models.

Middle of the week the picture will be much clearer.

[Matt-hurricanewatcher]

Reposted from http://www.storm2k.org/phpbb2/viewtopic.php?p=1729273#p1729273:

The following post is NOT an official prognosis.

It honestly looks like the upper level ridge is already building west as the TUTT quickly lifts out of the area. Note that Bertha's forward movement during tomorrow and the next few days is going to exert some significant influences in regards to its track. Currently, a shortwave trough at H5 is moving east from the Ohio Valley to the Mid-Atlantic region. Water vapor imagery of the upper levels indicates the shortwave trough is moving rather rapidly to the east as the weak H5 vort max transects the area. The fast northern stream suggests the shortwave trough will exit the Mid-Atlantic fairly quickly, allowing the upper level ridge to H5 to re-assert itself and briefly build to the west. This trend may likely commence as soon as tomorrow and the following day. If you combine the unfolding current situation with an extrapolation of Bertha's ongoing rapid movement, it could indicate that Bertha may be closer to the CONUS earlier than some people anticipate. Bertha has been persistently moving further west faster than expected over the past ~24-36 hours. I highly doubt that Bertha will only come within a certain distance of the CONUS by late next week. After analysis of current trends and the pattern, it appears that it may occur earlier than that time frame. Depending on the timing of the next H5 trough progged to affect the East and the amplification of the upper ridge in the West, Bertha could certainly pose a threat to the Southeast (primarily North Carolina).

One possible concern in regards to the intensity is the fact that a small upper low NE of Bermuda is moving SSE as the TUTT moves NE. This new upper low could deepen and develop a new TUTT (the second one progged by the operational GFS at 200-250 mb?) over the next few days in a similar position to the current TUTT. This could increase the upper level divergence/shear in the vicinity north of the Leeward Islands and Puerto Rico. Therefore, after gradual intensification, Bertha's intensity could fluctuate in that area. That leads to the possibility of a more southerly and westerly track in the long range, depending on the actual intensity of Bertha at that time and the degree of the possible TUTT's influence.

I'm not a person who casually ignores or disputes models, especially if they are latching on to a pattern. I also regularly utilize climatology in my analysis. However, based on all available evidence, I believe it is premature to sound the all clear for the Southeast. It is also premature to make a definite statement that Bertha will strike the CONUS, Bermuda, the NE Caribbean, or any land mass. Both approaches should be discouraged, especially given the considerable uncertainties and complexities involved. Everyone should be prepared, regardless of their location. The evolution of this system, the analysis of the models, and the "kinks" thrown in to the synoptic pattern will present an exceptionally fascinating and extremely intriguing situation. Regardless of the final result, Bertha will present an incredibly tough forecasting challenge and a bastion of knowledge for everyone involved. This system has already been impressive itself.

Great write up, I'm within 100 percent ageement.

[CajunMama]

Cone and track shifted northward.

Just barely. They must not want to make a drastic shift in one update. They'll gradually nudge it further and further north every update so it's not such a shock to people when they see it. I've seen it many times before. Still favor the HWRF track and intensity.

you only have 4 posts. how many times could you possibly say it before, other than 3?

was your response necessary? Maybe he lurked for a good while? geesh, post count doesn't matter.

[RL3AO]

Hypothetical: Dvokak#/Microwave image comes an hour after advisory showing a storm 20 kts stronger than the advisory. Would the NHC issue a special advisory? Maybe an STDS? Wait until 5?

What is the standard for RI storms not near land?

PS: I'm not implying that I think Bertha is undergoing RI.

[cycloneye]

Looking very good!

[HURAKAN]

We should see an increase in the winds by 5 AM.

[Aric Dunn]

Looking very good!

even better on the latest microwave ... image.. that will continue to wrap around tonight and we should see some intesification by morning .. if it can maintain ..

[gotoman38]

Hypothetical: Dvokak#/Microwave image comes an hour after advisory showing a storm 20 kts stronger than the advisory. Would the NHC issue a special advisory? Maybe an STDS? Wait until 5?

What is the standard for RI storms not near land?

PS: I'm not implying that I think Bertha is undergoing RI.

disclaimer: I have no idea what standards are for this.

I think it should be a line call - 20 kts from where? 45-65? I'm not sure it's worth the air time 1500 miles from land.

20 kts is a big number, not unheard of I think, but that kind of number almost always happens when storms are not in "long track" mode, as I think we are in with Bertha.

My thought is that it would take a bigger "bomb" to justify special notices this far from land.

[MGC]

Bertha has a good chance of slight intensification the next couple of days. Beyond that, increasing shear should weaken Bertha. With Bertha trucking along at 18KTS this evening, the ridge to its north is strong. Bertha is going to be a difficult TC to figure out where it will end up. I'm thinking that Bertha will recurve west of Bermuda as there has been a persistant EC trough as of late. Of course, if the shear really gets to Bertha than a more west track is possible......MGC

[cheezyWXguy]

Bertha has a good chance of slight intensification the next couple of days. Beyond that, increasing shear should weaken Bertha. With Bertha trucking along at 18KTS this evening, the ridge to its north is strong. Bertha is going to be a difficult TC to figure out where it will end up. I'm thinking that Bertha will recurve west of Bermuda as there has been a persistant EC trough as of late. Of course, if the shear really gets to Bertha than a more west track is possible......MGC

The TUTT is weakening...unless another TUTT forms, it looks like conditions MAY maintain until recurvature/landfall. Conditions wont be perfect, but if there is any weakening at the end of the forecast period, it looks to be slight, according to SHIPS, which even shows reintensification on day 5.

[MiamiensisWx]

Convection has been developing directly over the LLC, and additional thunderstorms are initiating SW of the LLC as well. Low shear is evident with decreasing shear ahead as the TUTT "lifts out" of the area. Bertha is entering and moving over higher SSTs and oceanic heat content, too.

http://www.ssd.noaa.gov/goes/east/tatl/loop-ir2.html

[NDG]

She is definitely looking better tonight, she has reached 26 deg C SST tonight, close to 27 deg C by tomorrow night or Monday morning where she could gain more strength.

[RL3AO]

ADT has the weakening flag on.

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 06 JUL 2008 Time : 031500 UTC
Lat : 17:00:54 N Lon : 41:16:32 W


CI# /Pressure/ Vmax
3.1 /1001.0mb/ 47.0kt


Final T# Adj T# Raw T#
(3hr avg)
2.8 2.7 2.7

Latitude bias adjustment to MSLP : +2.2mb

Center Temp : -49.1C Cloud Region Temp : -47.5C

Scene Type : CURVED BAND with 0.42 ARC in LT GRAY
Maximum CURVED BAND with 0.44 ARC in LT GRAY
at Lat: 17:00:36 N Lon: 42:16:12 W

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : OFF

[JonathanBelles]

new burst of convection coming!

[Derek Ortt]

the microwave from the afternoon was just a bit more impressive than the latest one.

A partial eye-type feature was forming this afternoon. Since then, the feature has deteriorated

[Aric Dunn]

the microwave from the afternoon was just a bit more impressive than the latest one.

A partial eye-type feature was forming this afternoon. Since then, the feature has deteriorated

hardly .. the convection is deeper. and wraping around..

[RL3AO]

Different microwave, about an hour before the one posted above.

[ROCK]

the microwave from the afternoon was just a bit more impressive than the latest one.

A partial eye-type feature was forming this afternoon. Since then, the feature has deteriorated

I agree with you Derek. The convection ( or lack thereof) seems to displace to the N and NE attm. I dont see any RI in the near term.