Bertha may pose a long-range threat to the U.S.
Tropical Storm Bertha has maintained it's strength overnight, but is having trouble with Sea Surface Temperatures (SSTs) of 25°C--one degree below the threshold of 26°C considered beneficial for tropical storms. This morning's QuikSCAT pass missed Bertha, but last night's pass confirmed winds of at least 40mph. Satellite estimates of Bertha's strength have consistently put the storm's strength at 50 mph over the past day. The storm is under about 10-15 knots of wind shear.
Figure 1. Latest satellite image of Bertha.
The forecast
The models are now more confident that Bertha will not take a turn to the north east of Bermuda, with two models--the UKMET and NOGAPS--calling for the storm to pass very near the northern Lesser Antilles Islands by Tuesday night and Wednesday morning. These islands should anticipate the possibility of tropical storm conditions as early as Tuesday night, even though the current official track keeps Bertha well north of the islands. Bertha may be large enough to bring tropical storm force winds 100-200 miles from the center by Tuesday. A threat to the East Coast of the U.S. is now possible, with such an event most likely to occur about 7-10 days from now. It is also possible that high wind shear will tear apart Bertha (as predicted by the ECMWF model), or that the storm will recurve to the north just east of North Carolina, missing the U.S. The long range track of Bertha is highly uncertain, and it is too early to speculate how likely each of these scenarios is.
By Sunday morning, Bertha will be over SSTs of 26°C, which will warm to 27°C by Monday and 28°C Tuesday. this should allow Bertha to intensify to near Category 1 hurricane strength. However, by Tuesday, wind shear is expected to increase to 20 knots and remain high for several days, as Bertha encounters a branch of the subtropical jet stream. The higher shear should weaken the storm.
Elsewhere in the tropics
There are no threat areas to discuss in the tropical Atlantic, and none of the models are forecasting tropical storm formation in the next seven days.
I'll post an update by Sunday afternoon.
Jeff Masters
Reader Comments
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convection illusion, like when yesterday it seemed to be going SW but it was the convection =P
1700. weathermanwannabe 9:23 PM CDT on July 05, 2008
That ULL over Central Florida is starting to suck down convection from GA and North Florida towards it; looks like it will be pretty rainy around the FL peninsula tommorow (and in North Florida this evening)........
I've had rain...thunderstorms....40 MPH winds earlier...since around 3 o'clock...6 hours of rain!!!! Around 2 inches at my house.
To fish or not to fish...seems to be the question this evening. Quite interesting to follow although I have learned from a few years watching that I just have to watch and see - too early to tell. (thanks JP, StormW, Nash et al for being so patient.)
Tno/CI Rules : Constraint Limits : NO LIMIT Weakening Flag : ON
Rapid Dissipation Flag : OFF
1687. IKE 10:20 PM EDT on July 05, 2008 Still around this evening?...Looks like some rain headed your way any minute now...(You know it's Summer when Florida gets T-storms in the evening/overnight hours)
It's moved south of me...I'm north of HWY. 90 by about 2-3 miles...it's over for the evening. FINALLY!
Bertha lost her anticlone
I think she's just moved out of there on the IR image, while the wind shear layer has not been updated. Note the spin to her east.
To answer you JFV, I do not see anything out there that would cause a fundamental track change. Certainly the relatively small burst of convection would not do that. The ridge remains in place and while there may be a wobble in the track from time to time I expect due West to continue for a while.
IR images at night can be illusory. The next few sat frames may suggest a move back to the West. It's the average track that matters
umm
Bertha lost her anticlone
She can build a new one.
LOCATED NEAR LATITUDE 17.0 NORTH...LONGITUDE 41.2
WTNT32 KNHC 060232
TCPAT2
BULLETIN
TROPICAL STORM BERTHA ADVISORY NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
1100 PM AST SAT JUL 05 2008
...BERTHA RACING WESTWARD OVER THE CENTRAL ATLANTIC...
AT 1100 PM AST...0300Z...THE CENTER OF TROPICAL STORM BERTHA WAS
LOCATED NEAR LATITUDE 17.0 NORTH...LONGITUDE 41.2 WEST OR ABOUT 1140
MILES...1835 KM...WEST OF THE CAPE VERDE ISLANDS AND ABOUT 1445
MILES...2325 KM...EAST OF THE NORTHERN LEEWARD ISLANDS.
BERTHA IS MOVING TOWARD THE WEST NEAR 21 MPH...33 KM/HR...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE OVER THE NEXT COUPLE OF DAYS.
MAXIMUM SUSTAINED WINDS ARE NEAR 50 MPH...85 KM/HR...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24
HOURS.
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 85 MILES...140 KM
FROM THE CENTER.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB...29.53 INCHES.
REPEATING THE 1100 PM AST POSITION...17.0 N...41.2 W. MOVEMENT
TOWARD...WEST NEAR 21 MPH. MAXIMUM SUSTAINED WINDS...50 MPH.
MINIMUM CENTRAL PRESSURE...1000 MB.
THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM AST.
$$
FORECASTER RHOME
she lost it, she alone now =P
----
yep Drak =)
So am I JFV. Unless I'm missing something here, according to the 5 day track has Bertha headed towards NC/VA. Unless theirs a trough that would curve her out to sea! I remember Hurricane Floyd was forecasted to be steered out to sea by a trough. Well that trough missed Hurricane Floyd altogether sending him our way here in Virginia. I'm not no expert when it comes to tropical storms. But I have seen storms change track only to strike land. My eye is on Bertha until its a definite that shes going out to sea.
I eat my words. My bad!
.3N
.9W
since the earlier advisory.
from the update
"latest satellite imagery indicates that Bertha continues to exhibit
a convective bursting pattern with the center currently located
near the south side of the coldest cloud tops."
Viewing: 1701 - 1751
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