TC Bertha

[wxmann_91]

Too many people utilize water vapor imagery for "dry air"/"moisture" judgments. You should look at the lower levels to gauge moisture and thermodynamics. The "dry air" on the water vapor image is actually at the mid levels, which may often enhance convection. The water vapor images only indicate the mid to upper levels. Mid level dry air is not detrimental to a TC's intensity, nor does it preclude intensification. However, low level dry air, dust, temperature/subsidence inversions, or a stable boundary layer is much more destructive or prohibitive for a TC. Currently, the LLC has been partially exposed because of southerly shear from convective outflow to the south and a stable boundary layer. Additionally, a SAL is present as well. Those are the real reasons for the relative lack of convection on Bertha's southern semicircle.

Tiny little correction here; mid level dry air is actually quite detrimental to TC's, as well as low level dry air. WV shows stuff in the upper levels of the atmosphere.

[robbielyn]

ok let me be more specific. Is my thoughts on the bermuda high and the westward movement of bertha without any nw movement without merit or is it a possibility? I am saying this could end up in the carribean or the gom maybe.

[Aric Dunn]

sorry but sal is very minimal at this point...but the stable boundary layer is still present .. but increasingly becoming more unstable as moisture is being advected north.

http://cimss.ssec.wisc.edu/tropic/real- ... 8split.jpg

[hurricanefloyd5]

sorry but sal is very minimal at this point...but the stable boundary layer is still present .. but increasingly becoming more unstable as moisture is being advected north.

http://cimss.ssec.wisc.edu/tropic/real- ... 8split.jpg

so what dose that mean aric?

[MiamiensisWx]

ok let me be more specific. Is my thoughts on the bermuda high and the westward movement of bertha without any nw movement without merit or is it a possibility? I am saying this could end up in the carribean or the gom maybe.

The bolded portion is impossible. However, the possibility of a path further west than indicated by some of the models is very real.

[Aric Dunn]

Too many people utilize water vapor imagery for "dry air"/"moisture" judgments. You should look at the lower levels to gauge moisture and thermodynamics. The "dry air" on the water vapor image is actually at the mid levels, which may often enhance convection. The water vapor images only indicate the mid to upper levels. Mid level dry air is not detrimental to a TC's intensity, nor does it preclude intensification. However, low level dry air, dust, temperature/subsidence inversions, or a stable boundary layer is much more destructive or prohibitive for a TC. Currently, the LLC has been partially exposed because of southerly shear from convective outflow to the south and a stable boundary layer. Additionally, a SAL is present as well. Those are the real reasons for the relative lack of convection on Bertha's southern semicircle.

Tiny little correction here; mid level dry air is actually quite detrimental to TC's, as well as low level dry air. WV shows stuff in the upper levels of the atmosphere.

yes it does .. but the WV depicts mid level dry air very well .. when looking at the WV you can clearly see the different shades moving in different directions.. the problem is you have to be able to determine its depth. thats one of the reason its used mostly for mid level

[cycloneye]

Outflow improving.

AXNT20 KNHC 060013
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 05 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURE....

TROPICAL STORM BERTHA IS CENTERED NEAR 16.7 NORTH...LONGITUDE
39.3 WEST OR ABOUT 1015 MILES...1635 KM...WEST OF THE CAPE VERDE
ISLANDS AND ABOUT 1570 MILES...2530 KM...EAST OF THE NORTHERN
LEEWARD ISLANDS. IT IS MOVING W AT 18 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WIND SPEED IS 45
KT WITH GUSTS TO 55 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT42 KNHC FOR MORE DETAILS. BERTHA
WIND VELOCITY IS HOLDING STEADY WHILE TRAVERSING OVER AN AREA
WITH COOLER SEA SURFACE TEMPERATURES. SATELLITE IMAGERY NOW
SHOWS A LARGER AREA OF UPPER LEVEL OUTFLOW OVER THE STORM THAN
YESTERDAY. BERTHA IS ALSO MAINTAINING CONVECTION NW OF THE
CENTER WITH SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
FROM 16N-19N BETWEEN 39W-42W.

http://www.storm2k.org/weather/hw3.php? ... hwvmetric=

[Aric Dunn]

ok let me be more specific. Is my thoughts on the bermuda high and the westward movement of bertha without any nw movement without merit or is it a possibility? I am saying this could end up in the carribean or the gom maybe.

The bolded portion is impossible. However, the possibility of a path further west than indicated by some of the models is very real.

and its not impossible..

[MiamiensisWx]

TUTT is starting to rapidly move out of the area:

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

This may pave the way for a more conducive upper level environment with a gradual reduction of shear ahead of Bertha. The big question involves the TUTT at 200-250 mb that the operational GFS is developing over the W Atlantic by ~96 hours. Since that is the upper levels, it could aid Bertha's intensification via good divergence, especially if Bertha is weaker and shallower at that time.

[wxmann_91]

ok let me be more specific. Is my thoughts on the bermuda high and the westward movement of bertha without any nw movement without merit or is it a possibility? I am saying this could end up in the carribean or the gom maybe.

Though it is 5 days out, troughs this time of year tend to be relatively low-amplitude and positive tilt, which favors a rapid recurve. Either that or the ridge remains strong enough and/or and it builds back in, which favors this to turn back west.

Given the progged timing of the trough and the system I think the most favored possibility is a recurve off the coast (assuming the TUTT doesn't kill it). The second most favored possibility is a turn back to the west into FL/GOM. If the trough slows down a little this might brush by Cape Hatteras, but again, the zonal nature of the trough argues that it will be heading NE or even nearly E as opposed to N if it makes it to the Cape latitude.

Still a ways away, but something to consider.

[jaxfladude]

Bertha
Bertha No
Yes!

Edit: NC hit okay only if Bertha is a TS with a lot of rain for the hard hit drought areas in Eastern NC

[robbielyn]

Remember last year the bermuda high was west and very strong and all the storms went south of the ridge going westward all the way. Now I am now ruling out a wnw notion just a nw movement. I am not even saying that I am right. I just going by what I saw on the weather and need more information on the forecasted bermuda high. What is the correlation between the setup of the high and the nw movement of bertha? If the high is over the coastline of the southern have of the us, how is it possible for bertha to ride up the coast unless there's a weakness forecasted? I just want to understand all this. My limited knowledge believe it or not has helped me in my forecasting because I go by what i see with the conditions. I don't know all about the complicated stuff that sometimes can get in the way like climatology and the such. miamiensiswx, why is the bolded wording of my earlier post impossible?

[robbielyn]

ok let me be more specific. Is my thoughts on the bermuda high and the westward movement of bertha without any nw movement without merit or is it a possibility? I am saying this could end up in the carribean or the gom maybe.

Though it is 5 days out, troughs this time of year tend to be relatively low-amplitude and positive tilt, which favors a rapid recurve. Either that or the ridge remains strong enough and/or and it builds back in, which favors this to turn back west.

Given the progged timing of the trough and the system I think the most favored possibility is a recurve off the coast (assuming the TUTT doesn't kill it). The second most favored possibility is a turn back to the west into FL/GOM. If the trough slows down a little this might brush by Cape Hatteras, but again, the zonal nature of the trough argues that it will be heading NE or even nearly E as opposed to N if it makes it to the Cape latitude.

Still a ways away, but something to consider.

Ok so you are saying that there's a trough of low pressure that is going to push the bh east again or break it down and allow an opening for bertha to ride of the coast possibly brushing the coast and boomerang ne? Can you post a map showing the upcoming trough please? I am sorry I don't quite know where to get these maps myself.

[RL3AO]

984
WHXX01 KWBC 060035
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0035 UTC SUN JUL 6 2008

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE BERTHA (AL022008) 20080706 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
080706 0000 080706 1200 080707 0000 080707 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 16.8N 40.3W 17.7N 43.5W 18.9N 46.6W 19.8N 49.4W
BAMD 16.8N 40.3W 17.9N 43.5W 19.1N 46.5W 20.3N 48.7W
BAMM 16.8N 40.3W 17.6N 43.8W 18.7N 47.1W 19.6N 49.5W
LBAR 16.8N 40.3W 17.7N 43.9W 18.9N 47.4W 19.9N 50.7W
SHIP 45KTS 49KTS 54KTS 61KTS
DSHP 45KTS 49KTS 54KTS 61KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
080708 0000 080709 0000 080710 0000 080711 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 20.7N 51.9W 22.0N 56.0W 23.7N 59.4W 25.5N 61.7W
BAMD 21.5N 49.8W 23.4N 50.2W 25.2N 49.9W 25.5N 49.1W
BAMM 20.4N 51.1W 21.8N 53.2W 23.7N 54.8W 25.4N 56.2W
LBAR 20.9N 53.3W 23.2N 56.6W 25.7N 58.0W 26.4N 58.4W
SHIP 67KTS 71KTS 67KTS 70KTS
DSHP 67KTS 71KTS 67KTS 70KTS

...INITIAL CONDITIONS...
LATCUR = 16.8N LONCUR = 40.3W DIRCUR = 280DEG SPDCUR = 18KT
LATM12 = 16.4N LONM12 = 36.4W DIRM12 = 275DEG SPDM12 = 19KT
LATM24 = 15.8N LONM24 = 32.6W
WNDCUR = 45KT RMAXWD = 30NM WNDM12 = 45KT
CENPRS = 1000MB OUTPRS = 1012MB OUTRAD = 180NM SDEPTH = D
RD34NE = 75NM RD34SE = 30NM RD34SW = 0NM RD34NW = 75NM

$$
NNNN

[SouthFloridawx]

TUTT is starting to rapidly move out of the area:
http://hadar.cira.colostate.edu/ramsdis/online/trop_ge_wv_ls_0.html
This may pave the way for a more conducive upper level environment with a gradual reduction of shear ahead of Bertha. The big question involves the TUTT at 200-250 mb that the operational GFS is developing over the W Atlantic by ~96 hours. Since that is the upper levels, it could aid Bertha's intensification via good divergence, especially if Bertha is weaker and shallower at that time.

Yes I agree you can see that very clearly on WV.

You can also see it on this 200mb Relative Vorticity loop...
Warning its a five day loop, give it a moment to load.
http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/movies/wg8vor1/wg8vor1java.html

[Aric Dunn]

I imagine we me see some strengthening tonight as the shear lessening which is allowing convection to wrap around a very very well defined center.. it would not take much more.

[wxmann_91]

ok let me be more specific. Is my thoughts on the bermuda high and the westward movement of bertha without any nw movement without merit or is it a possibility? I am saying this could end up in the carribean or the gom maybe.

Though it is 5 days out, troughs this time of year tend to be relatively low-amplitude and positive tilt, which favors a rapid recurve. Either that or the ridge remains strong enough and/or and it builds back in, which favors this to turn back west.

Given the progged timing of the trough and the system I think the most favored possibility is a recurve off the coast (assuming the TUTT doesn't kill it). The second most favored possibility is a turn back to the west into FL/GOM. If the trough slows down a little this might brush by Cape Hatteras, but again, the zonal nature of the trough argues that it will be heading NE or even nearly E as opposed to N if it makes it to the Cape latitude.

Still a ways away, but something to consider.

Ok so you are saying that there's a trough of low pressure that is going to push the bh east again or break it down and allow an opening for bertha to ride of the coast possibly brushing the coast and boomerang ne? Can you post a map showing the upcoming trough please? I am sorry I don't quite know where to get these maps myself.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_120m.gif

Assuming that Bertha smack dab in the middle between the Bahamas and Bermuda, that is a clear recurve.

Of course, this is a 120 hr GFS model map. But you get the picture. Negative height anomalies in ern Canada = very likely recurve into Maritimes/out to sea.

[RL3AO]

AL, 02, 2008070500, , BEST, 0, 158N, 326W, 45, 1000, TS
AL, 02, 2008070506, , BEST, 0, 163N, 344W, 45, 1000, TS
AL, 02, 2008070512, , BEST, 0, 164N, 364W, 45, 1000, TS
AL, 02, 2008070518, , BEST, 0, 166N, 384W, 45, 1000, TS
AL, 02, 2008070600, , BEST, 0, 168N, 403W, 45, 1000, TS

Six hour movement of 276 and 24 hour movement of 277.

[robbielyn]

Ok so you are saying that there's a trough of low pressure that is going to push the bh east again or break it down and allow an opening for bertha to ride of the coast possibly brushing the coast and boomerang ne? Can you post a map showing the upcoming trough please? I am sorry I don't quite know where to get these maps myself.[/quote]
http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_120m.gif

Assuming that Bertha smack dab in the middle between the Bahamas and Bermuda, that is a clear recurve.

Of course, this is a 120 hr GFS model map. But you get the picture. Negative height anomalies in ern Canada = very likely recurve into Maritimes/out to sea.[/quote]

Ok please don't laugh but is there an ukmet model map supporting it's forecast? I realize that it is an outlier right now but you never know.

[HURAKAN]

Looking nice.